Wild-type Males Research Articles

The contribution of a novel PHEX gene mutation to X-linked hypophosphatemic rickets: a case report and an analysis of the gene mutation dosage effect in a rat model.

A Chinese family was identified to have two patients with rickets, an adult female and a male child (proband), both exhibiting signs related to X-linked hypophosphatemic rickets (XLH). Gene sequencing analysis revealed a deletion of adenine at position 1985 (c.1985delA) in the PHEX-encoding gene. To investigate the relationship between this mutation and the pathogenicity of XLH, as well as analyze the effects of different dosages of PHEX gene mutations on clinical phenotypes, we developed a rat model carrying the PHEX deletion mutation. The CRISPR/Cas9 gene editing technology was employed to construct the rat model with the PHEX gene mutation (c.1985delA). Through reproductive procedures, five genotypes of rats were obtained: female wild type (X/X), female heterozygous (-/X), female homozygous wild type (-/-), male wild type (X/Y), and male hemizygous (-/Y). The rats with different genotypes underwent analysis of growth, serum biochemical parameters, and bone microstructure. The results demonstrated the successful generation of a stable rat model inheriting the PHEX gene mutation. Compared to the wild-type rats, the mutant rats displayed delayed growth, shorter femurs, and significantly reduced bone mass. Among the female rats, the homozygous individuals exhibited the smallest body size, decreased bone mass, shortest femur length, and severe deformities. Moreover, the mutant rats showed significantly lower blood phosphorus concentration, elevated levels of FGF23 and alkaline phosphatase, and increased expression of phosphorus regulators. In conclusion, the XLH rat model with the PHEX gene mutation dosage demonstrated its impact on growth and development, serum biochemical parameters, and femoral morphology.

Investigating neuronal senescence marker, p19INK4d, in mouse and human brains

AbstractBackgroundThe cellular senescence stress response allows damaged, toxic cells to survive. Clearing senescent cells is a promising therapeutic approach and has moved to clinical trials for Alzheimer’s disease and related dementias (ADRD). We previously identified a link between the cell cycle inhibitor CDKN2D/p19INK4d and neuronal senescence in human postmortem brains with various levels of AD neuropathology. We hypothesized that senescence could be induced by overexpressing this gene in mouse neurons in vivo.MethodAdeno‐associated virus 9 (AAV9) with the neuron specific human Synapsin I (hSyn1) promoter was used to deliver experimental Cdkn2d‐GFP, or control GFP gene expression. Precise delivery of 0.5µl of 1013 IU virus into four neuronal populations per mouse, bilateral hippocampal CA1 and cortical layer 5 neurons was accomplished with the assistance of a stereotaxic robot. Male and female wild type, human tau transgenic and mouse tau knockout mice were used (12‐13 months‐old, n = 47). Mice were euthanized at either two weeks or eight weeks post‐surgery to determine the short‐ and long‐term effects of Cdkn2d expression. GeoMx digital spatial profiler was utilized to quantify protein expression between Cdkn2d infected and uninfected neighboring neurons. ROI selection is displayed in Figure 1.ResultHistological analyses confirmed p19INK4d protein expression in AAV9‐infected cells. GeoMx DSP analyses performed on hippocampus, cortex, and thalamus revealed a protein expression pattern consistent with senescence (i.e., resistance to apoptosis), in Cdkn2d‐expressing neurons of the hippocampus and cortex compared to the un‐infected thalamus (Figure 2). Moreover, proteins associated with apoptosis were higher in the thalamus compared to the cortex and hippocampus.ConclusionsThe data indicates that AAV9‐hSyn1‐Cdkn2d‐GFP is an appropriate method to increase p19INK4d expression in mouse neurons in vivo. Over‐expressing p19INK4d caused neurons to acquire a protein expression signature consistent with senescence. The concomitant expression of apoptosis proteins in the thalamus leads me to hypothesize that the senescent cells in the cortex may cause cell death in the thalamus through the corticothalamic tract. Further studies with increased sample size are needed to confirm the results and continue exploring the effects of Cdkn2d on neuronal senescence, and how tau protein may influence this stress response.

Glial cells are affected more than interneurons by the loss of Engrailed 2 gene in the mouse cerebellum.

Glial cells play a pivotal role in the inflammatory processes, which are common features of several neurodevelopmental and neurodegenerative disorders. Their major role in modulating neuroinflammation underscores their significance in these conditions. Engrailed-2 knockout mice (En2-/- ) are considered a valuable model for autism spectrum disorder (ASD) due to their distinctive neuroanatomical and behavioral traits. Given the higher prevalence of ASD in males, our objective was to investigate glial and interneuron alterations in the cerebellum of En2-/- mice compared with wild-type (WT) mice in both sexes. We employed immunohistochemical analysis to assess cell density for all cell types studied and analyzed the area (A) and shape factor (SF) of microglia cell bodies. Our findings revealed the following: (a) In WT mice, the density of microglia and astrocytes was higher in females than in males, while interneuron density was lower in females. Notably, in En2-mutant mice, these differences between males and females were not present. (b) In both male and female En2-/- mice, astrocyte density exceeded that in WT mice, with microglia density being greater only in females. (c) In WT females, microglia cell bodies exhibited a larger area and a lower shape factor compared to WT males. Remarkably, the En2 mutation did not appear to influence these sex-related differences. (d) In both male and female En2-/- mice, we observed a consistent pattern: microglia cell bodies displayed a larger area and a smaller shape factor. Given the ongoing debate surrounding the roles of glia and sex-related factors in ASD, our observations provide valuable insights into understanding how an ASD-associated gene En2 affects specific cell types in the cerebellum.

MiR-324-5p inhibition after intrahippocampal kainic acid-induced status epilepticus does not prevent epileptogenesis in mice.

Acquired epilepsies are caused by an initial brain insult that is followed by epileptogenesis and finally the development of spontaneous recurrent seizures. The mechanisms underlying epileptogenesis are not fully understood. MicroRNAs regulate mRNA translation and stability and are frequently implicated in epilepsy. For example, antagonism of a specific microRNA, miR-324-5p, before brain insult and in a model of chronic epilepsy decreases seizure susceptibility and frequency, respectively. Here, we tested whether antagonism of miR-324-5p during epileptogenesis inhibits the development of epilepsy. We used the intrahippocampal kainic acid (IHpKa) model to initiate epileptogenesis in male wild type C57BL/6 J mice aged 6-8 weeks. Twenty-four hours after IHpKa, we administered a miR-324-5p or scrambled control antagomir intracerebroventricularly and implanted cortical surface electrodes for EEG monitoring. EEG data was collected for 28 days and analyzed for seizure frequency and duration, interictal spike activity, and EEG power. Brains were collected for histological analysis. Histological analysis of brain tissue showed that IHpKa caused characteristic hippocampal damage in most mice regardless of treatment. Antagomir treatment did not affect latency to, frequency, or duration of spontaneous recurrent seizures or interictal spike activity but did alter the temporal development of frequency band-specific EEG power. These results suggest that miR-324-5p inhibition during epileptogenesis induced by status epilepticus does not convey anti-epileptogenic effects despite having subtle effects on EEG frequency bands. Our results highlight the importance of timing of intervention across epilepsy development and suggest that miR-324-5p may act primarily as a proconvulsant rather than a pro-epileptogenic regulator.

Estradiol-mediated small GTP-binding protein GDP dissociation stimulator induction contributes to sex differences in resilience to ferroptosis in takotsubo syndrome

BackgroundDeclining beneficial cardiovascular actions of estradiol (E2) have been associated with disproportionate susceptibility to takotsubo syndrome (TTS) in postmenopausal women. However, the underlying mechanisms between E2 and this marked disproportion remain unclear. SmgGDS (small GTP-binding protein GDP dissociation stimulator), as a key modulator of cardiovascular disease, plays protective roles in reducing oxidative stress and exerts pleiotropic effects of statins. Whether SmgGDS levels are influenced by E2 status and the effect of SmgGDS on sex differences in TTS are poorly understood. MethodsClinical data were reviewed from TTS inpatients. Echocardiography, immunofluorescence, and immunohistochemistry were performed together with expression analysis to uncover phenotypic and mechanism changes in sex differences in TTS-like wild-type (WT) and SmgGDS± mice. HL-1 cardiomyocytes were used to further examine and validate molecular mechanisms. ResultsIn 14 TTS inpatients, TTS had a higher incidence in postmenopausal women as compared to premenopausal women and men. In murine TTS, female WT mice exhibited higher cardiac SmgGDS levels than male WT mice. Ovariectomy reduced SmgGDS expression in female WT mice similar to that observed in male mice, whereas E2 replacement in these ovariectomized (OVX) female mice reversed this effect. The physiological importance of this sex-specific E2-mediated SmgGDS response is underscored by the disparity in cardiac adaptation to isoproterenol (ISO) stimulation between both sexes of WT mice. E2-mediated SmgGDS induction conferred female protection against TTS-like acute cardiac injury involving ferritinophagy-mediated ferroptosis. No such cardioprotection was observed in male WT mice and OVX female. A causal role for SmgGDS in this sex-specific cardioprotective adaptation was indicated, inasmuch as SmgGDS deficiency abolished E2-modulated cardioprotection against ferritinophagy and aggravates TTS progression in both sexes. Consistently, knockdown of SmgGDS in HL-1 cardiomyocytes exacerbated ferroptosis in a ferritinophagy-dependent manner and abrogated the protective role of E2 against ferritinophagy. Mechanistically, our findings revealed that SmgGDS regulated E2-dependent cardioprotective effects via AMPK/mTOR signaling pathway. SmgGDS deficiency abolished E2-conferred protection against ferritinophagy through activating AMPK/mTOR pathway, while treatment with recombinant SmgGDS in HL-1 cells significantly mitigated this pathway-associated ferritinophagy activity. ConclusionsThese results demonstrate that SmgGDS is a central mediator of E2-conferred female cardioprotection against ferritinophagy-mediated ferroptosis in TTS.

Protein misfolding: an additional player in the stroke-heart syndrome

Abstract Background Patients suffering from acute ischemic stroke experience an increased risk of major adverse cardiovascular events, introducing the term of stroke-heart syndrome (SHS). Beside common risk factors, the so-called brain-heart axis represents a relevant yet not fully understood biological matrix driving this multi-organ condition. Together with inflammatory and neurohormonal signals, protein misfolding appears as an additional component of this matrix. In fact, previous studies employing animal models of cerebral ischemia identified wrongly arranged toxic proteins (oligomers). In light of the spreading capabilities of such proteins, we questioned whether protein misfolding plays a role in the SHS. Purpose The purpose of this study is to investigate the occurrence of protein misfolding in the post-stroke cardiac dysfunction by assessing presence, origin, localization and routes of oligomers in the heart following an acute ischemic stroke. Its biological and physiological relevance are evaluated by in vivo and in vitro assessments of the myocardium. Methods Acute cerebral ischemic injury was induced in the mouse by left transient middle cerebral artery occlusion for 45 minutes followed by 48 hours of reperfusion in 3-4 month-old C57BL/6J wild type males. Sham operated littermate mice were used as controls. Forty-eight hours after acute cerebral ischemia, cardiac function was evaluated by electrocardiography and compared to pre-operative assessment. Organs were harvested after the abovementioned assessment for the localization and semi-quantification of oligomers in heart and lymph nodes. Furthermore, biological responses related to protein homeostasis in the myocardium were assessed on mRNA and protein levels. Results Our preliminary results show that acute ischemic stroke is associated with an increased presence of oligomers in the heart. In addition, higher levels of oligomers were detected in axillary lymph nodes isolated from stroke mice, suggesting a possible route of oligomers spreading (Fig 1A). Correlating with oligomers occurrence, molecular analyses showed significant upregulation of the inositol-requiring enzyme 1 (IRE1), and catalase at mRNA level (Fig 1B). On the other hand, the expression of the 78-kDa glucose-regulated protein (GRP78), and catalase significantly decreased at protein level, indicating impaired myocardial protein quality control and oxidative stress after acute ischemic stroke (Fig 1C). Stroke-induced cardiac dysfunction was presented by decreased heart weight to tibia length ratio as well as slower and irregular heart rhythm suggesting signs of arrhythmia (Fig 2). Conclusions Acute ischemic stroke is associated with an increased oligomers occurrence in the myocardium and ultimately correlates with altered cardiac resistance against proteotoxicity. Further experiments will be conducted in order to elucidate the role of oligomers as active players or bystanders in the stroke-heart syndrome.

Cardioprotective O-GlcNAc signaling is elevated in murine female hearts via enhanced O-GlcNAc transferase activity

The post-translational modification of intracellular proteins by O-linked β-N-acetylglucosamine (O-GlcNAc) has emerged as a critical regulator of cardiac function. Enhanced O-GlcNAcylation activates cytoprotective pathways in cardiac models of ischemia reperfusion (I/R) injury; however, the mechanisms underpinning O-GlcNAc-cycling in response to I/R injury have not been comprehensively assessed. The cycling of O-GlcNAc is regulated by the collective efforts of two enzymes: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), which catalyze the addition and hydrolysis of O-GlcNAc respectively. It has previously been shown that baseline heart physiology and pathophysiology are impacted by sex. Here, we hypothesized that sex differences in molecular signaling may target protein O-GlcNAcylation both basally and in ischemic hearts. To address this question, we subjected male and female wild type murine hearts to ex vivo ischemia or ischemia-reperfusion injury. We assessed hearts for protein O-GlcNAcylation, abundance of OGT, OGA, and glutamine:fructose-6-phosphate aminotransferase (GFAT2), activity of OGT and OGA, and UDP-GlcNAc levels. Our data demonstrate elevated O-GlcNAcylation in female hearts both basally and during ischemia. We show OGT activity was enhanced in female hearts in all treatments, suggesting a mechanism for these observations. Furthermore, we found ischemia led to reduced O-GlcNAcylation and OGT specific activity. Our findings provide a foundation for understanding molecular mechanisms that regulate O-GlcNAcylation in the heart and highlight the importance of sex as a significant factor when assessing key regulatory events that control O-GlcNAc-cycling. These data suggest the intriguing possibility that elevated O-GlcNAcylation in females contributes to reduced ischemic susceptibility.

Abstract 15308: NLRP3 Activation and Calcium-Dependent Contractile Function in Rat Right Ventricle Cardiomyocytes (RVCMs) Are Sexually Dimorphic and Controlled by 17β-Estradiol-via Estrogen Receptor-α

Introduction: NLRP3 inflammasome activation promotes right ventricle (RV) contractile dysfunction in pulmonary hypertension (PH). However, the role of NLRP3 signaling in RVCMs has not been studied. 17β-estradiol (E2) improves RVCM function in PH. Hypothesis: E2, via estrogen receptor-α (ERα), prevents RVCM NLRP3 inflammasome activation and contractile dysfunction in experimental PH. Methods: RV failure in male and female Sprague Dawley rats were induced with monocrotaline (MCT). Co-localization of NLRP3 and its partner ASC was assessed. RVCMs isolated from healthy male or female wildtype (WT) or ERα loss of function mutant (ERα mut ) rats were treated with NLRP3 activators lipopolysaccharide (LPS 1 μg/mL, 4 h) and ATP (2 mM, 10 min) ± E2 (1 nM, 24 h) or NLRP3 inhibitor MCC950 (1 μM, 30 min). RVCM contractility and Ca 2+ levels were evaluated via IONOPTIX system. Protein levels of NLRP3 and its targets were assessed. ERα binding to the NLRP3 promoter was assessed by immunoprecipitation. RNA-seq was performed in RV tissues from male and intact or ovariectomized female rats with RV failure. Results: RNA-seq demonstrated that transcripts involved in NLRP3 activation are E2-regulated. RVCMs from male, but not female, MCT rats showed increased NLRP3 and ASC co-localization/activation (p<0.05). In addition, male MCT rats RVs exhibited increased activation of NLRP3 downstream mediators caspase-1 and IL-1β (p<0.05). Cultured male RVCMs treated with LPS+ATP demonstrated more pronounced NLRP3 activation and decreased contractility and Ca 2+ levels than female RVCMs (p<0.05). NLRP3 activation in RVCMs from male rats resulted in reduced contractility; this was abolished with NLRP3 inhibition (p<0.05). E2 treatment in male RVCMs reduced NLRP3 and ASC interaction and increased contractility Ca 2+ levels in male WT but not in ERα mut RVCMs (p<0.05). IP demonstrated ERα binding to the NLRP3 promoter. Conclusion: NLRP3 signaling in RVCMs from MCT-PH rats is sexually dimorphic, with more pronounced activation and contractile dysfunction in males. E2 prevents RVCM NLRP3 activation and contractile dysfunction in an ERα-dependent manner, likely mediated by ERα binding to the NLRP3 promoter. NLRP3 activation may be therapeutically targetable in PH patients of either sex.

Abstract 15406: Loss of Estrogen Receptor α Inhibits Angiogenic Function in Right Ventricular Endothelial Cells (RVECs)

Introduction: Right ventricular failure (RVF) is the leading cause of death in patients with pulmonary hypertension (PH). While the pathophysiology of RVF is complex and multifactorial, insufficient angiogenesis and impaired RV endothelial cell (RVEC) function have been identified as key contributors. 17β-estradiol (E2), the most abundant female sex steroid, exerts RV-protective effects including stimulation of angiogenesis. However, the mechanism underlying E2’s pro-angiogenic function are unknown. Hypothesis: Estrogen Receptor (ER) α is necessary for RV angiogenesis. Methods: To identify the role of ERα in RVEC function and RV angiogenesis, ERα loss-of-function mutant (ERα Mut ) rats were generated by CRISPR-Cas9. In vivo studies were performed in both male and female wild-type (WT) and ERα Mut rats. RV capillary density was assessed by immunofluorescence. RVECs were isolated from male or female WT and ERα Mut rats. Angiogenic function was evaluated by matrigel tube formation assay at 10h. RVEC proliferation (at 24h) was measured by Incucyte image-based analysis and Thymidine incorporation assay. RVEC migration (at 24h) was examined by transwell migration assay. Angiogenesis mediators in RVECs were quantified via Western Blot. P<0.05 was considered significant. Results: Female WT rats exhibited increased RV capillary density compared to males (p<0.001). However, loss of functioning ERα decreased RV capillary density (p<0.05). Loss of ERα impaired proliferation (24h) capability in female, but not male, RVECs (p<0.001). On the other hand, male, but not female, ERα Mut RVECs exhibited reduced cell migration in response to VEGF-A (p<0.01). Loss of ERα reduced RVEC tube formation in both sexes (p<0.05). At a molecular level, male ERα Mut RVECs expressed less VEGF-A, angiopoietin-2, and Id1 than WT (p<0.01) . Conclusions: ERα is necessary for RVEC angiogenic function. However, ERα effects on angiogenesis are sexually dimorphic. Male ERα Mut RVECs exhibit reduced cell migration potential and less angiogenesis mediators, whereas female ERα Mut RVECs exhibit decreased proliferation potential in vitro and reduced female RV capillary density in vivo . Targeting ERα may allow for sex-specific therapies aimed at enhancing RV adaptation in PH.

Taste receptor type 1 member 3 enables western diet-induced anxiety in mice

BackgroundAccumulating evidence supports that the Western diet (WD), a diet high in saturated fat and sugary drinks, contributes to the pathogenesis of anxiety disorders, which are the most prevalent mental disorders worldwide. However, the underlying mechanisms by which WD causes anxiety remain unclear. Abundant expression of taste receptor type 1 member 3 (TAS1R3) has been identified in the hypothalamus, a key brain area involved in sensing peripheral nutritional signals and regulating anxiety. Thus, we investigated the influence of excessive WD intake on anxiety and mechanisms by which WD intake affects anxiety development using wild-type (WT) and Tas1r3 deficient (Tas1r3−/−) mice fed a normal diet (ND) or WD for 12 weeks.ResultsWD increased anxiety in male WT mice, whereas male Tas1r3−/− mice were protected from WD-induced anxiety, as assessed by open field (OF), elevated plus maze (EPM), light–dark box (LDB), and novelty-suppressed feeding (NSF) tests. Analyzing the hypothalamic transcriptome of WD-fed WT and Tas1r3−/− mice, we found 1,432 genes significantly up- or down-regulated as a result of Tas1r3 deficiency. Furthermore, bioinformatic analysis revealed that the CREB/BDNF signaling-mediated maintenance of neuronal regeneration, which can prevent anxiety development, was enhanced in WD-fed Tas1r3−/− mice compared with WD-fed WT mice. Additionally, in vitro studies further confirmed that Tas1r3 knockdown prevents the suppression of Creb1 and of CREB-mediated BDNF expression caused by high levels of glucose, fructose, and palmitic acid in hypothalamic neuronal cells.ConclusionsOur results imply that TAS1R3 may play a key role in WD-induced alterations in hypothalamic functions, and that inhibition of TAS1R3 overactivation in the hypothalamus could offer therapeutic targets to alleviate the effects of WD on anxiety.

The suppression of a selfish genetic element increases a male's mating success in a fly.

X chromosome meiotic drive (XCMD) kills Y-bearing sperm during spermatogenesis, leading to the biased transmission of the selfish X chromosome. Despite this strong transmission, some natural XCMD systems remain at low and stable frequencies, rather than rapidly spreading through populations. The reason may be that male carriers can have reduced fitness, as they lose half of their sperm, only produce daughters, and may carry deleterious alleles associated with XCMD. Thus, females may benefit from avoiding mating with male carriers, yielding a further reduction in fitness. Genetic suppressors of XCMD, which block the killing of Y sperm and restore fair Mendelian inheritance, are also common and could prevent the spread of XCMD. However, whether suppressed males are as fit as a wild-type male remains an open question, as the effect that genetic suppressors may have on a male's mating success is rarely considered. Here, we investigate the mating ability of XCMD males and suppressed XCMD males in comparison to wild-type males in the fruit fly Drosophila subobscura, where drive remains at a stable frequency of 20% in wild populations where it occurs. We use both competitive and non-competitive mating trials to evaluate male mating success in this system. We found no evidence that unsuppressed XCMD males were discriminated against. Remarkably, however, their suppressed XCMD counterparts had a higher male mating success compared to wild-type controls. Unsuppressed XCMD males suffered 12% lower offspring production in comparison to wild-type males. This cost appears too weak to counter the transmission advantage of XCMD, and thus the factors preventing the spread of XCMD remain unclear.

Leucine Supplementation Exacerbates Morbidity in Male but Not Female Mice with Colorectal Cancer-Induced Cachexia.

Cancer cachexia (CC) is a multifactorial wasting syndrome characterized by a significant loss in lean and/or fat mass and represents a leading cause of mortality in cancer patients. Nutraceutical treatments have been proposed as a potential treatment strategy to mitigate cachexia-induced muscle wasting. However, contradictory findings warrant further investigation. The purpose of this study was to determine the effects of leucine supplementation on skeletal muscle in male and female ApcMin/+ mice (APC). APC mice and their wild-type (WT) littermates were given normal drinking water or 1.5% leucine-supplemented water (n = 4-10/group/sex). We measured the gene expression of regulators of inflammation, protein balance, and myogenesis. Leucine treatment lowered survival rates, body mass, and muscle mass in males, while in females, it had no effect on body or muscle mass. Leucine treatment altered inflammatory gene expression by lowering Il1b 87% in the APC group and decreasing Tnfa 92% in both WT and APC males, while it had no effect in females (p < 0.05). Leucine had no effect on regulators of protein balance and myogenesis in either sex. We demonstrated that leucine exacerbates moribundity in males and is not sufficient for mitigating muscle or fat loss during CC in either sex in the ApcMin/+ mouse.

SAT276 Glucocorticoid Excess Elevates Metabolic Rate Via A 11b-HSD1 Dependent Mechanism In C57BL/6J Mice

Abstract Disclosure: S. Heaselgrave: None. S. Heising: None. S.A. Morgan: None. A. Kabli: None. M. Sagmeister: None. C. Doig: None. R.S. Hardy: None. N.M. Morton: None. K. Tsintzas: None. G.G. Lavery: None. Introduction: Glucocorticoids are vital metabolic regulators. However, glucocorticoid excess (GE) causes severe metabolic dysfunction, ultimately leading to Cushing’s Syndrome. This dysfunction is often dependent on the presence of the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Whether GE also alters metabolic rate, and whether this is also dependent on 11β-HSD1, remains unclear and merits investigation in a mouse model of GE and 11β-HSD1 inhibition. Methods: Male and female wild type (WT) C57BL/6J and 11β-HSD1KO mice were treated with corticosterone or vehicle control ad libitum via drinking water for 3 weeks whilst being fed a standard chow diet (n=12). Mice were housed in a TSE Phenomaster system for the final week of treatment for comprehensive metabolic assessment. Results: Corticosterone treatment in WT mice resulted in a phenotype typical of GE, however female mice experienced greater fat accumulation and bodyweight gain compared to males. 11β-HSD1KO mice did not experience this phenotype. Corticosterone treatment elevated energy expenditure (EE) in female WT mice during the day alone (25±5.9%). Male WT mice did not experience a significant increase. Corticosterone did significantly elevate the respiratory exchange ratio (RER) towards 1 in both male (10.7±5.7%) and female (11.8±7.0%) WT mice during the day. RER remained elevated in female WT mice (7.6±4.8%) and moderately so in male WT mice (3.2±2.6%) at night, indicating a continued suppression of lipid oxidation in favour of carbohydrate oxidation. Activity, assessed in female WT mice only, was continually decreased by corticosterone treatment (-53.1±54.8%). Corticosterone treated WT mice became hyperphagic and polydipsic, continuously eating and drinking more than controls. Male and female 11β-HSD1KO mice treated with corticosterone did not experience these effects. Conclusion: These findings provide further insights into the metabolic consequences of GE as well as the dependency on 11β-HSD1 to facilitate them. Whilst elevations are seen in both male and female WT mice, they are greater in females. Activity is decreased meaning it is not responsible for the elevations. However, hyperphagia and the subsequent chemical energy cost of de novo lipogenesis might be responsible and merits further investigation. Presentation: Saturday, June 17, 2023

OR22-01 Sex Differences In Enterohepatic Circulation Mediated By Hepatic FXR And SHP Depletions In Mice

Abstract Disclosure: F. Reichardt: None. C. Galuke: None. S. Anakk: None. Bile acids are transported via the portal vein to the liver after their absorption through the distal intestine mucosa. In hepatocytes, they activate the nuclear receptors, Farnesoid-X-receptor (FXR) and Small Heterodimer Partner (SHP), which exert negative feedback on bile acids synthesis. The aim of this project is to decipher how hepatic FXR/SHP deletion impact BA composition, enterohepatic circulation, and its cross talk with the gut microbiota. Enterohepatic circulation was investigated by measuring total bile acids in intestinal, hepatic tissues and fecal tissues and in portal and systemic blood, using 3-5 months-old fed female and male wildtype (WT) and LDKO (liver specific FXR/SHP depletions) mice. We also examined if intestinal dysmotility mediated the alteration in bile acids absorption by following methylene blue dye progression in overnight fasted WT and LDKO mice. Portal and systemic total bile acids concentrations were higher in LDKO mice compared to WT, despite of no significant change in hepatic and intestinal levels. Sex differences were seen only in LDKO mice with higher systemic and portal concentrations in females compared to males. Intestinal transit time and fecal total bile acids were equivalent between all mice. Intriguingly, we observed that portal bile acids levels correlated to the liver weight to body weight ratio and to cecum weight to body weight ratio, suggesting that bile acids alterations within the enterohepatic loop could be associated to cecal dysbiosis. These preliminary findings highlight altered BA recirculation in LDKO mice compared to WT, but also between females and males LDKO. We hypothesize that these sex-specific modifications are associated with intestinal dysbiosis impacting bile acid compositions, and to test this we will be analyzing the influence of sex, and BA composition on the microbiome. Further investigations using fasted or HFD-fed LDKO and WT mice will help us to better understand the role of hepatic FXR and SHP in bile acids circulation between intestine and liver. Acknowledgement: University of Illinois Urbana-Champaign, American Cancer Society and Cancer Center at Illinois Seed grant Presentation: Saturday, June 17, 2023

OR04-06 Mkrn3, Dlk1 And Mecp2 Have Distinct Hypothalamic Expression Patterns Across Pubertal Maturation In Male And Female Mice

Abstract Disclosure: F.R. Tinano: None. S.A. Pereira: None. N.P. Boris: None. D.B. Macedo: None. A.P. Canton: None. A. Abreu: None. R.S. Carroll: None. A. Latronico: None. U.B. Kaiser: None. Context: Central precocious puberty (CPP) results from premature re-activation of the hypothalamic-pituitary-gonadal (HPG) axis. The most prevalent genetic cause of CPP is loss-of-function mutations in makorin ring finger 3 (MKRN3), with loss-of-function mutations in delta-like 1 homolog (DLK1) occurring less frequently. While the mechanisms by which MKRN3 regulates puberty onset have been partially elucidated in recent years, the manner by which DLK1 regulates HPG axis maturation remains unknown. Methyl CpG binding protein 2 (MeCP2) is associated with the neurodevelopmental Rett syndrome, with reports of early pubertal development among affected patients. Recently, rare variants in MeCP2 were identified in children with CPP with or without neurologic abnormalities. The pathways by which MECP2 may influence pubertal timing have not been determined. The aim of this study was to characterize Mkrn3, Dlk1 and Mecp2 expression patterns in the hypothalamus of male and female mice at different pubertal stages.Methods and Results: Male and female wild type C57BL/6 mice were euthanized at postnatal (P) age 10, 15, 22, 30 and 60 days. The mediobasal hypothalamus (MBH) and pre-optic area (POA) were isolated from the brains of each mouse. mRNA levels of Mkrn3, Dlk1 and Mecp2 were quantified by RT-qPCR and compared across the ages studied. Mkrn3 expression in both MBH and POA was highest at P10, then significantly lower at P15 and P22, remaining low until adulthood, with a similar pattern in male and female mice. In contrast, Dlk1 expression was higher at P60 compared to P22 in the MBH of male mice, while in female mice it was higher at P22 and P30 compared to P10. In the POA of male mice, Dlk1 expression was higher at P30 and P60 compared to P10, while no significant difference with age was seen in the POA of female mice. Mecp2 had higher expression in the MBH at P10 compared to P15 and P22 in male mice, and compared to P15, P30 and P60 in female mice. Mecp2 expression in the POA of both male and female mice was higher at P10 compared to all the other ages. No differences were observed in the hypothalamic expression of the three genes between male and female mice. Statistical significance was set at p &amp;lt; 0.05. Conclusions:Mkrn3 and Mecp2 had decreased hypothalamic expression in male and female mice with age, suggesting inhibitory roles on the HPG axis, consistent with the phenotype of CPP in patients with loss-of-function mutations in these genes. In contrast, hypothalamic expression of Dlk1 increased in both male and female mice toward adulthood, which is intriguing considering the association of loss-of-function mutations in this gene with CPP and suggests that the role of Dlk1 in the HPG axis is distinct from those of Mkrn3 and Mecp2. Defining the changes in hypothalamic expression of these three genes across pubertal development is critical to understanding their roles and mechanisms of action in regulating the HPG axis. Presentation: Thursday, June 15, 2023

CARMA3 Deficiency Aggravates Angiotensin II-Induced Abdominal Aortic Aneurysm Development Interacting Between Endoplasmic Reticulum and Mitochondria.

Abdominal aortic aneurysm (AAA) is life threatening and associated with vascular walls' chronic inflammation. However, a detailed understanding of the underlying mechanisms is yet to be elucidated. CARMA3 assembles the CARMA3-BCL10-MALT1 (CBM) complex in inflammatory diseases and is proven to mediate angiotensin II (Ang II) response to inflammatory signals by modulating DNA damage-induced cell pyroptosis. In addition, interaction between endoplasmic reticulum (ER) stress and mitochondrial damage is one of the main causes of cell pyroptosis. Male wild type (WT) or CARMA3-/- mice aged 8 to 10 weeks were subcutaneously implanted with osmotic minipumps, delivering saline or Ang II at the rate of 1 μg/kg/min for 1, 2, and 4 weeks. We discovered that CARMA3 knockout promoted formation of AAA and prominently increased diameter and severity of the mice abdominal aorta infused with Ang II. Moreover, a significant increase in the excretion of inflammatory cytokines, expression levels of matrix metalloproteinases (MMPs) and cell death was found in the aneurysmal aortic wall of CARMA3-/- mice infused with Ang II compared with WT mice. Further studies found that the degree of ER stress and mitochondrial damage in the abdominal aorta of CARMA3-/- mice was more severe than that in WT mice. Mechanistically, CARMA3 deficiency exacerbates the interaction between ER stress and mitochondrial damage by activating the p38MAPK pathway, ultimately contributing to the pyroptosis of vascular smooth muscle cells (VSMCs). CARMA3 appears to play a key role in AAA formation and might be a potential target for therapeutic interventions of AAA.

Role of membrane estrogen receptor alpha (ERα) in the rapid regulation of male sexual behavior.

The activation of male sexual behavior depends on brain estrogen synthesis. Estrogens act through nuclear and membrane receptors producing effects within hours/days or seconds/minutes, respectively. In mice, estrogen receptor alpha (ERα) is the main estrogen receptor (ER) controlling the activation of male sexual behavior. Although neuroestrogens rapidly modulate mouse sexual behavior, it is not known whether these effects involve membrane ERα (mERα). This study combines two complementary approaches to address this question. C451A-ERα mice carry an ERα that cannot signal at the membrane, while estetrol (E4) is a natural estrogen acting as an agonist on nuclear ERα but as an antagonist on membrane ERα. In wild-type males, E4 decreased the number of mounts and intromissions after 10 min. In C451A-ERα males, E4 also altered sexual performance but after 30 min. E4 did not affect time spent near the female in both wild-type and C451A-ERα mice. However, regardless of genotype, the aromatase inhibitor 1,4,6-Androstatriene-3,17-dione (ATD) decreased both sexual performance and the time spent near the female after 10 and 30 min, confirming the key role of aromatization in the rapid control of sexual behavior and motivation. In conclusion, the shift in timing at which the effect of E4 is observed in mice lacking mERα suggests a role for mERα in the regulation of rapid effects of neuroestrogens on sexual performance, thus providing the first demonstration that E4 acts as an antagonist of a mER in the brain. The persisting effect of ATD on behavior in C451A-ERα mice also suggests the implication of another ER.

Genetic Deletion of DNAJB3 Using CRISPR-Cas9, Produced Discordant Phenotypes.

Several pathways and/or genes have been shown to be dysregulated in obesity-induced insulin resistance (IR) and type 2 diabetes (T2D). We previously showed, for the first time, impaired expression of DNAJB3 mRNA and protein in subjects with obesity, which was concomitant with increased metabolic stress. Restoring the normal expression of DNAJB3 attenuated metabolic stress and improved insulin signaling both in vivo and in vitro, suggesting a protective role of DNAJB3 against obesity and T2D. The precise underlying mechanisms remained, however, unclear. This study was designed to confirm the human studies in a mouse model of dietary obesity-induced insulin resistance, and, if validated, to understand the underlying mechanisms. We hypothesized that mice lacking DNAJB3 would be more prone to high-fat (HF)-diet-induced increase in body weight and body fat, inflammation, glucose intolerance and insulin resistance as compared with wild-type (WT) littermates. Three DNAJB3 knockout (KO) lines were generated (KO 30, 44 and 47), using CRISPR-Cas9. Male and female KO and WT mice were fed a HF diet (45% kcal fat) for 16 weeks. Body weight was measured biweekly, and a glucose tolerance test (GTT) and insulin tolerance test (ITT) were conducted at week 13 and 14, respectively. Body composition was determined monthly by nuclear magnetic resonance (NMR). Following euthanasia, white adipose tissue (WAT) and skeletal muscle were harvested for further analyses. Compared with WT mice, male and female KO 47 mice demonstrated higher body weight and fat mass. Similarly, KO 47 mice also showed a slower rate of glucose clearance in GTT that was consistent with decreased mRNA expression of the GLUT4 gene in WAT but not in the muscle. Both male and female KO 47 mice exhibited higher mRNA levels of the pro-inflammatory marker TNF-a in WAT only, whereas increased mRNA levels of MCP1 chemokine and the ER stress marker BiP/Grp78 were observed in male but not in female KO 47 mice. However, we did not observe the same changes in the other KO lines. Taken together, the phenotype of the DNAJB3 KO 47 mice was consistent with the metabolic changes and low levels of DNAJB3 reported in human subjects. These findings suggest that DNAJB3 may play an important role in metabolic functions and glucose homeostasis, which warrants further phenotyping and intervention studies in other KO 47 and other KO mice, as well as investigating this protein as a potential therapeutic target for obesity and T2D.

CAR Protects Females from Diet-Induced Steatosis and Associated Metabolic Disorders.

Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common cause of chronic liver disease worldwide, affecting 70-90% of obese individuals. In humans, a lower NAFLD incidence is reported in pre-menopausal women, although the mechanisms affording this protection remain under-investigated. Here, we tested the hypothesis that the constitutive androstane nuclear receptor (CAR) plays a role in the pathogenesis of experimental NAFLD. Male and female wild-type (WT) and CAR knock-out (CAR-/-) mice were subjected to a high-fat diet (HFD) for 16 weeks. We examined the metabolic phenotype of mice through body weight follow-up, glucose tolerance tests, analysis of plasmatic metabolic markers, hepatic lipid accumulation, and hepatic transcriptome. Finally, we examined the potential impact of HFD and CAR deletion on specific brain regions, focusing on glial cells. HFD-induced weight gain and hepatic steatosis are more pronounced in WT males than females. CAR-/- females present a NASH-like hepatic transcriptomic signature suggesting a potential NAFLD to NASH transition. Transcriptomic correlation analysis highlighted a possible cross-talk between CAR and ERα receptors. The peripheral effects of CAR deletion in female mice were associated with astrogliosis in the hypothalamus. These findings prove that nuclear receptor CAR may be a potential mechanism entry-point and a therapeutic target for treating NAFLD/NASH.

Hyodeoxycholic acid ameliorates nonalcoholic fatty liver disease by inhibiting RAN-mediated PPARα nucleus-cytoplasm shuttling

Nonalcoholic fatty liver disease (NAFLD) is usually characterized with disrupted bile acid (BA) homeostasis. However, the exact role of certain BA in NAFLD is poorly understood. Here we show levels of serum hyodeoxycholic acid (HDCA) decrease in both NAFLD patients and mice, as well as in liver and intestinal contents of NAFLD mice compared to their healthy counterparts. Serum HDCA is also inversely correlated with NAFLD severity. Dietary HDCA supplementation ameliorates diet-induced NAFLD in male wild type mice by activating fatty acid oxidation in hepatic peroxisome proliferator-activated receptor α (PPARα)-dependent way because the anti-NAFLD effect of HDCA is abolished in hepatocyte-specific Pparα knockout mice. Mechanistically, HDCA facilitates nuclear localization of PPARα by directly interacting with RAN protein. This interaction disrupts the formation of RAN/CRM1/PPARα nucleus-cytoplasm shuttling heterotrimer. Our results demonstrate the therapeutic potential of HDCA for NAFLD and provide new insights of BAs on regulating fatty acid metabolism.