Female Knockout Research Articles

TMIC-82. LIPOCALIN-2 MEDIATES CELL-INTRINSIC AND CELL-EXTRINSIC FUNCTIONS IN GLIOBLASTOMA

Abstract Glioblastoma (GBM) is the most common primary brain tumor with a median survival of 17-20 months. Despite therapeutic treatments including surgery, radiation, chemotherapy, a subset of GBM clones, termed cancer stem cells (CSCs) are radio-resistant and chemo-resistant, leading to mortality of the patient. CSCs also have altered metabolic profiles and have an enhanced capacity to scavenge nutrients from their microenvironment, including iron. Lipocalin-2 (LCN2) functions to sequester iron and is traditionally considered an inflammatory marker through its function of limiting iron for bacterial usage. LCN2 has been described to have both a pro and anti-tumorigenic and has context-dependent functions depending on iron status. LCN2 has been shown to be important in brain metastasis, but its role in GBM is still largely unknown. To investigate how LCN2 plays a role in the GBM microenvironment, we orthotopically implanted syngeneic mouse GBM cells into male and female LCN2 knockout and wild-type mice. Female LCN2 knockout mice succumbed to tumors faster compared to males, revealing another example of sex differences in the tumor microenvironment. To assess a cell-intrinsic function for LNC2, we added recombinant LCN2 to mouse GBM cell lines and saw that proliferation also increased. When we probed for receptor expression in our knockdown cell lines, we saw that the LCN2 canonical receptor, SLC22a17, was upregulated in response. Furthermore, in a subset of slow-cycling cells of CSCs, LCN2 was shown to be up-regulated. Taken together, these data suggest that LCN2 functions in an iron-dependent manner to affect proliferation and sex-specific tumorigenesis. Given the fact that males have more iron than females, it is worth investigating the role of iron in GBM sex difference progression and therapeutic targets.

Gpr88 Deletion Impacts Motivational Control Without Overt Disruptions to Striatal Dopamine

BackgroundDisrupted motivational control is a common—but poorly treated—feature of psychiatric disorders, arising via aberrant mesolimbic dopaminergic signaling. GPR88 is an orphan G protein–coupled receptor that is highly expressed in the striatum and therefore well placed to modulate disrupted signaling. While the phenotype of Gpr88 knockout mice suggests a role in motivational pathways, it is unclear whether GPR88 is involved in reward valuation and/or effort-based decision making in a sex-dependent manner and whether this involves altered dopamine function. MethodsIn male and female Gpr88 knockout mice, we used touchscreen-based progressive ratio, with and without reward devaluation, and effort-related choice tasks to assess motivation and cost/benefit decision making, respectively. To explore whether these motivational behaviors were related to alterations in the striatal dopamine system, we quantified expression of dopamine-related genes and/or proteins and used [18F]DOPA positron emission tomography and GTPγ[35S] binding to assess presynaptic and postsynaptic dopamine function, respectively. ResultsWe showed that male and female Gpr88 knockout mice displayed greater motivational drive than wild-type mice, which was maintained following reward devaluation. Furthermore, we showed that cost/benefit decision making was impaired in male, but not female, Gpr88 knockout mice. Surprisingly, we found that Gpr88 deletion had no effect on striatal dopamine by any of the measures assessed. ConclusionsOur results highlight that GPR88 regulates motivational control but that disruption of such behaviors following Gpr88 deletion occurs independently of gross perturbations to striatal dopamine at a gene, protein, or functional level. This work provides further insights into GPR88 as a drug target for motivational disorders.

Abstract 15352: Lung Endothelial Transport in Glypican 1 Knockout Mice

Introduction: Pulmonary edema is a life-threatening condition that can result from the acute increase in hemodynamic forces in the lung vasculature. The mechanisms whereby pulmonary edema develops are unresolved but increased lung endothelial permeability may be important. The endothelial glycocalyx is a surface layer known to mediate the effects of mechanical forces in the lung vasculature by eNOS-dependent mechanisms. Among the components of the glycocalyx, glypican 1 (Gpc1) is considered a potential mechano-transducer due to its physical interaction with the cellular membrane. Herein we sought to investigate the mechanisms whereby Gpc1 regulates pulmonary permeability. Hypothesis: We hypothesize that Gpc1 regulates endothelial transport by eNOS-dependent mechanisms. Methods: Mouse lung endothelial cells (MLEC) isolated from male and female wild-type (WT) and Gpc1 knockout mice (Gpc1KO, 6-8 weeks old) were used. Endothelial transport was assessed by dextran permeability in vitro, lung barrier stability was assessed by TEER, eNOS pathway was assessed by immunoblotting. To assess the role of eNOS to Gpc1 effects on endothelial transport, MLEC were exposed to an eNOS decoy peptide. Results: Gpc1KO MLEC formed a tighter barrier in vitro when compared to WT MLEC (3.18±0.11 [Gpc1KO] vs 2.34±0.11 [WT], normalized TEER, n=3/group). This was preserved during high pressure conditions. High pressure increased transcellular but not paracellular transport in both WT and Gpc1KO MLEC (1.8 fold in WT and 1.2 fold in Gpc1KO, n=6/group). Gpc1KO showed decreased eNOS expression (0.3 fold, n=4/group ) and activity during (1.947±0.32 [WT] vs 1.316±0.13 [Gpc1KO], n=4/group). The eNOS decoy peptide increased transcellular transport only in Gpc1KO MLEC (3 fold, n=5/group). Conclusions: In conclusion, these data suggest that intracellular transport may be the main mechanism for pressure-induced changes in endothelial permeability in MLEC . The mechanisms whereby Gpc1 regulates transcellular transport seem to be associated with eNOS signaling. This may be important for the management of acute changes in pressure seen in clinical settings when NO donors are used as vasodilators to decrease blood pressure.

Sex-related differences in the response of anti-platelet drug therapies targeting purinergic signaling pathways in sepsis.

Sepsis, a complex clinical syndrome resulting from a serious infection, is a major healthcare problem associated with high mortality. Sex-related differences in the immune response to sepsis have been proposed but the mechanism is still unknown. Purinergic signaling is a sex-specific regulatory mechanism in immune cell physiology. Our studies have shown that blocking the ADP-receptor P2Y12 but not P2Y1 receptor was protective in male mice during sepsis, but not female. We now hypothesize that there are sex-related differences in modulating P2Y12 or P2Y1 signaling pathways during sepsis. Male and female wild-type (WT), P2Y12 knock-out (KO), and P2Y1 KO mice underwent sham surgery or cecal ligation and puncture (CLP) to induce sepsis. The P2Y12 antagonist ticagrelor or the P2Y1 antagonist MRS2279 were administered intra-peritoneally after surgery to septic male and female mice. Blood, lungs and kidneys were collected 24 hours post-surgery. Sepsis-induced changes in platelet activation, secretion and platelet interaction with immune cells were measured by flow cytometry. Neutrophil infiltration in the lung and kidney was determined by a myeloperoxidase (MPO) colorimetric assay kit. Sepsis-induced platelet activation, secretion and aggregate formation were reduced in male CLP P2Y12 KO and in female CLP P2Y1 KO mice compared with their CLP WT counterpart. Sepsis-induced MPO activity was reduced in male CLP P2Y12 KO and CLP P2Y1 KO female mice. CLP males treated with ticagrelor or MRS2279 showed a decrease in sepsis-induced MPO levels in lung and kidneys, aggregate formation, and platelet activation as compared to untreated male CLP mice. There were no differences in platelet activation, aggregate formation, and neutrophil infiltration in lung and kidney between female CLP mice and female CLP mice treated with ticagrelor or MRS2279. In human T lymphocytes, blocking P2Y1 or P2Y12 alters cell growth and secretion in vitro in a sex-dependent manner, supporting the data obtained in mice. In conclusion, targeting purinergic signaling represents a promising therapy for sepsis but drug targeting purinergic signaling is sex-specific and needs to be investigated to determine sex-related targeted therapies in sepsis.

RF36 | PSUN77 Female Dexras1 WT & KO Mice Fed a High Fat Diet Do Not Have Different Body Compositions nor Bone Densities

Abstract Glucocorticoids are a frequently prescribed class of medications, widely used for their anti-inflammatory and immunosuppressive effects. However, long term usage of glucocorticoids is associated with a variety of adverse effects, including adrenal suppression, increased adiposity, and decreased bone density. DEXRAS1, also known as RASD1, is a member of the Ras family of GTPases that is upregulated by glucocorticoids. In in vitro experiments, DEXRAS1 has been shown to promote differentiation of adipocytes and decrease differentiation of osteoblasts. Studies conducted in male Dexras1 knockout (KO) and wild type (WT) mice treated with dexamethasone found decreased body weight and visceral fat, and increased bone density in KO mice when compared to WT mice; together, these experiments suggest that the removal of the Dexras1 gene can prevent glucocorticoid-induced osteoporosis and fat-accumulation.A major limitation of the aforementioned studies is that they were performed using only male mice, despite well-known sex related differences in body composition and bone density. On average, females have a higher percentage of body fat and lower bone density. While obesity is prevalent across all sexes, osteoporosis is 4 times more common in females. Therefore, in order to better understand sex as a biological variable on the effects of the Dexras1 gene, we compared female Dexras1 KO and WT mice fed a high-fat diet (HFD) containing 45 kcal% fat over the course of 14 weeks. Body composition was assessed by quantitative magnetic resonance. Bone morphometry was analyzed with micro-CT, and bone density was analyzed with micro-CT and dual-energy x-ray absorptiometry (DXA) scans of female murine femurs. Interestingly, there were no differences in the overall body weight, fat mass, nor lean mass over this period between WT and KO female mice. Similarly, the female Dexras1 KO and WT mice mice showed no differences in their bone density, cortical thickness, and average trabecular separation. Since there was no difference in the fat mass, it is not surprising that there was also no difference in bone density, as they are often inversely related. These data in conjunction with previous experiments on male mice suggest that sex strongly impacts the phenotype observed as a result of knocking out the Dexras1 gene. The mechanisms underlying differential regulation between the sexes is unclear, and could include differences in sex hormones, the presence of estrus cycle in females, differences in stress response, or even differences in microbiome. Consequently, more studies are necessary to fully understand the function and regulation of Dexras1. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:36 p.m. - 12:41 p.m.

LBSUN132 Adipocyte-specific Ablation Of Fgf23 Attenuates Diet-induced Obesity In Female Mice

Abstract Fibroblast growth factor 23 (FGF23) is a bone-derived hormone that regulates phosphate homeostasis and vitamin D metabolism. In addition to its central role in mineral balance, recent findings suggested that FGF23 is associated with chronic metabolic conditions including cardiovascular disease, diabetes mellitus, and obesity. Circulating FGF23 levels are elevated in obese individuals, and they are correlated with body fat mass and abdominal obesity. Moreover, consumption of high fat diet (HFD) increases serum FGF23 levels. However, the actions of FGF23 in adipocytes and its role in lipid metabolism have not been demonstrated. To understand the role of FGF23 in adipocytes, particularly in obesity, we generated adipocyte-specific Fgf23 null mice using Cre recombinase under the control of the mouse adiponectin (Adipoq) promoter. Both male and female control (Fgf23flox/flox) and knockout (KO, AdipoqCreFgf23flox/flox) mice were fed either HFD (60%kcal fat) or normal fat diet (NFD) at 8 weeks of age for 24 weeks. Body weight measurements were taken every week and percentage of body fat was determined after longitudinally during 24 weeks of diet interventation using in vivo by an EchoMRI scannermicroCT. Serum, adipose tissue, and liver were collected upon sacrifice. After 24 weeks of HFD, male control and KO mice had comparable gain in body weight (BW) and body fat percentage. However, female KO mice had significantly lower body weight and percentage of body fat. Moreover, serum total cholesterol levels were reduced in female KO mice. Triglyceride (TG) content in the liver was significantly reduced in female KO mice, and it corresponded with downregulation of lipid droplet protein Perilipin and fatty acid transporter CD36 mRNA expression in the liver. Transcript levels of hepatic PPARγ, which is positively correlated with fat accumulation in obesity, were also suppressed in female KO mice compared to controls. Obesity is associated with low-grade chronic inflammation, and we found that hepatic mRNA expression of the inflammatory cytokine TNFα was diminished in female KO mice, suggesting that adipocytic Fgf23 modulates lipid accumulation and inflammation. In summary, our results demonstrate for the first time that adipocyte-specific ablation of Fgf23 alleviates attenuates diet-induced obesity and regulates lipid metabolism in a sex-specific manner. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

PSUN136 CCN5/WISP2 gene deficiency improves insulin sensitivity and glucose tolerance in diet-induced obesity, especially in male mice

Abstract CCN5/WISP2 is a matricellular protein, the expression of which is under the regulation of Wnt signaling and IGF-1. Our initial characterization supports the notion that CCN5 promotes the proliferation and survival of pancreatic β-cells leading to metabolic benefits [1]. Recently, the effects of CCN5 gene deficiency and ectopic, transgenic overexpression of CCN5 have been established. A systemic deficiency of CCN5 gene expression caused adipocyte hypertrophy, increased adipogenesis, and lipid accumulation, resulting in insulin resistance and glucose intolerance which are further exacerbated upon high-fat diet (HFD) feeding [2]. On the other hand, an adipocyte-specific and systemic overexpression of CCN5 caused an increase in lean body mass, improved insulin sensitivity, hyperplasia of cardiomyocytes and increased heart mass but decreased fasting glucose levels [3]. CCN5 is clearly a regulator of adipocyte proliferation and maturation, affecting lean/fat mass ratio and insulin sensitivity. In order to consolidate those findings and further establish the metabolic roles played by endogenous CCN5, we characterized CCN5 knockout mice fed in chow diet or 60% HFD. Unlike being reported [2], however, CCN5 knockout mice in our hands, both male and female, exhibited no significant change in lean/fat mass, insulin sensitivity, nor glucose tolerance when fed a chow diet, despite 2-5-fold elevations in serum insulin concentration. Upon HFD feeding, CCN5 knockout mice gained similar amounts of weight as their wild-type counterparts (male 2.0 vs. 1.9-fold; female 2.7 vs. 2.4-fold) but demonstrated sexual dimorphic changes in insulin sensitivity. Interestingly, male knockout mice displayed significant improvements in insulin sensitivity and glucose tolerance, despite being equally obese as their wild-type controls. The smaller improvements in female knockout mice were not as significant. At the end of the 27 weeks of HFD, the increased levels of serum insulin in response to obesity, were 30-60% lower in knockout mice (both male and female) than in wild-type counterparts, also supporting improved insulin sensitivity. Although our previous work has demonstrated that CCN5 stimulates pancreatic β-cell proliferation and survival, our assessment of the CCN5 knockout mice seems to indicate that normal, endogenous expression of CCN5/WISP2 gene is rather detrimental to metabolic compensations against diet-induced obesity, especially in male mice. These observations are not only unexpected but also contradicts to a previous report [2]. We are further characterizing potential changes in pancreatic islet morphometry and molecular markers of beta-cell function, in knockout vs. wild-type mice after HFD feeding.

Arylalkylamine N-acetyltransferase 1 gene (AANAT1) regulates cuticle pigmentation and ovary development of the adult oriental fruit fly, Bactrocera dorsalis

The arylalkylamine N-acetyltransferase (AANAT) enzymes catalyze the acetyl-CoA-dependent acetylation of an amine or arylalkylamine, which is involved in important biological processes of insects. Here, we carried out the molecular and biochemical identification of an arylalkylamine N-acetyltransferase (AANAT) from the oriental fruit fly, Bactrocera dorsalis. Using a bacterial expression system, we expressed and purified the encoded recombinant BdorAANAT1-V3 protein. The purified recombinant protein acts on a wide range of substrates, including dopamine, tyramine, octopamine, serotonin, methoxytryptamine, and tryptamine, and shows similar substrate affinity (i.e., Km values: 0.16–0.26 mM) except for serotonin (Km = 0.74 mM) and dopamine (Km = 0.84 mM). Transcriptional profile analysis of BdorAANAT1 revealed that this gene is most prevalent in adults and abundant in the adult brain, gut, and ovary. Using the CRISPR/Cas9 technique, we successfully obtained a BdorAANAT1 knockout strain based on a wild-type strain (WT). Compared with the WT, the cuticle color of larvae and pupae is normal; however, in adult mutants, the yellow region of their thorax is darkly pigmented, and two black spots were evident at the abdomen's end. Moreover, the female BdorAANAT1 knockout mutant had a smaller ovary than the WT, and laid far fewer eggs. Loss of function of BdorAANAT1 caused by RNAi with mature adult females in which the reproductive system is fully developed had no effect on their fecundity. Altogether, these results indicate that BdorAANAT1 regulates ovary development. Our findings provide evidence for the insect AANAT1 modulating adult cuticle pigmentation and female fecundity.

Sexually dimorphic activation of innate antitumor immunity prevents adrenocortical carcinoma development.

Unlike most cancers, adrenocortical carcinomas (ACCs) are more frequent in women than in men, but the underlying mechanisms of this sexual dimorphism remain elusive. Here, we show that inactivation of Znrf3 in the mouse adrenal cortex, recapitulating the most frequent alteration in ACC patients, is associated with sexually dimorphic tumor progression. Although female knockouts develop metastatic carcinomas at 18 months, adrenal hyperplasia regresses in male knockouts. This male-specific phenotype is associated with androgen-dependent induction of senescence, recruitment, and differentiation of highly phagocytic macrophages that clear out senescent cells. In contrast, in females, macrophage recruitment is delayed and dampened, which allows for aggressive tumor progression. Consistently, analysis of TCGA-ACC data shows that phagocytic macrophages are more prominent in men and are associated with better prognosis. Together, these data show that phagocytic macrophages are key players in the sexual dimorphism of ACC that could be previously unidentified allies in the fight against this devastating cancer.

GPR39 Knockout Worsens Microcirculatory Response to Experimental Stroke in a Sex-Dependent Manner.

No current treatments target microvascular reperfusion after stroke, which can contribute to poor outcomes even after successful clot retrieval. The G protein-coupled receptor GPR39 is expressed in brain peri-capillary pericytes, and has been implicated in microvascular regulation, but its role in stroke is unknown. We tested the hypothesis that GPR39 plays a protective role after stroke, in part due to preservation of microvascular perfusion. We generated GPR39 knockout (KO) mice and tested whether GPR39 gene deletion worsens capillary blood flow and exacerbates brain injury and functional deficit after focal cerebral ischemia. Stroke was induced in male and female GPR39 KO and WT littermates by 60-min middle cerebral artery occlusion (MCAO). Microvascular perfusion was assessed via capillary red blood cell (RBC) flux in deep cortical layers in vivo using optical microangiography (OMAG). Brain injury was assessed by measuring infarct size by 2,3,5-triphenyltetrazolium chloride staining at 24h or brain atrophy at 3weeks after ischemia. Pole and cylinder behavior tests were conducted to assess neurological function deficit at 1 and 3weeks post-stroke. Male but not female GPR39 KO mice exhibited larger infarcts and lower capillary RBC flux than WT controls after stroke. Male GPR39 KO mice also exhibited worse neurologic deficit at 1week post-stroke, though functional deficit disappeared in both groups by 3weeks. GPR39 deletion worsens brain injury, microvascular perfusion, and neurological function after experimental stroke. Results indicate that GPR39 plays a sex-dependent role in re-establishing microvascular flow and limiting ischemic brain damage after stroke.

Deletion of Growth Hormone Secretagogue Receptor in Kisspeptin Neurons in Female Mice Blocks Diet-Induced Obesity.

The gut peptide, ghrelin, mediates energy homeostasis and reproduction by acting through its receptor, growth hormone secretagogue receptor (GHSR), expressed in hypothalamic neurons in the arcuate (ARC). We have shown 17β-estradiol (E2) increases Ghsr expression in Kisspeptin/Neurokinin B/Dynorphin (KNDy) neurons, enhancing sensitivity to ghrelin. We hypothesized that E2-induced Ghsr expression augments KNDy sensitivity in a fasting state by elevating ghrelin to disrupt energy expenditure in females. We produced a Kiss1-GHSR knockout to determine the role of GHSR in ARC KNDy neurons. We found that changes in ARC gene expression with estradiol benzoate (EB) treatment were abrogated by the deletion of GHSR and ghrelin abolished these differences. We also observed changes in metabolism and fasting glucose levels. Additionally, knockouts were resistant to body weight gain on a high fat diet (HFD). Behaviorally, we found that knockouts on HFD exhibited reduced anxiety-like behavior. Furthermore, knockouts did not refeed to the same extent as controls after a 24 h fast. Finally, in response to cold stress, knockout females had elevated metabolic parameters compared to controls. These data indicate GHSR in Kiss1 neurons modulate ARC gene expression, metabolism, glucose homeostasis, behavior, and thermoregulation, illustrating a novel mechanism for E2 and ghrelin to control Kiss1 neurons.

Genetic ablation of the preptin-coding portion of Igf2 impairs pancreatic function in female mice.

Preptin is a 34-amino acid peptide derived from the E-peptide of pro-insulin-like growth factor 2 and is co-secreted with insulin from β-cells. Little is understood about the effects of endogenous preptin on whole body glucose metabolism. We developed a novel mouse model in which the preptin portion of Igf2 was genetically ablated in all tissues, hereafter referred to as preptin knockout (KO), and tested the hypothesis that the removal of preptin will lead to a decreased insulin response to a metabolic challenge. Preptin KO and wild-type (WT) mice underwent weekly fasting blood glucose measurements, intraperitoneal insulin tolerance tests (ITT) at 9, 29, and 44 wk of age, and an oral glucose tolerance test (GTT) at 45 wk of age. Preptin KO mice of both sexes had similar Igf2 exon 2-3 mRNA expression in the liver and kidney compared with WT mice, but Igf2 exon 3-4 (preptin) expression was not detectable. Western blot analysis of neonatal serum indicated that processing of pro-IGF2 translated from the KO allele may be altered. Preptin KO mice had similar body weight, body composition, β-cell area, and fasted glucose concentrations compared with WT mice in both sexes up to 47 wk of age. Female KO mice had a diminished ability to mount an insulin response following glucose stimulation in vivo. This effect was absent in male KO mice. Although preptin is not essential for glucose homeostasis, when combined with previous in vitro and ex vivo findings, these data show that preptin positively impacts β-cell function.NEW & NOTEWORTHY This is the first study to describe a model in which the preptin-coding portion of the Igf2 gene has been genetically ablated in mice. The mice do not show reduced size at birth associated with Igf2 knockout suggesting that IGF2 functionality is maintained, yet we demonstrate a change in the processing of mature Igf2. Female knockout mice have diminished glucose-stimulated insulin secretion, whereas the insulin response in males is not different to wild type.

Investigation and modulation of interleukin-6 following subarachnoid hemorrhage: targeting inflammatory activation for cerebral vasospasm

BackgroundCerebral vasospasm (CV) can contribute to significant morbidity in subarachnoid hemorrhage (SAH) patients. A key unknown is how CV induction is triggered following SAH.MethodsHuman aneurysmal blood and cerebral spinal fluid were collected for evaluation. To confirm mechanism, c57/bl6 wild type and c57/bl6 IL-6 female knockout (KO) mice were utilized with groups: saline injected, SAH, SAH + IL-6 blockade, SAH IL-6 KO, SAH IL-6 KO + IL-6 administration, SAH + p-STAT3 inhibition. Dual-labeled microglia/myeloid mice were used to show myeloid diapedesis. For SAH, 50 μm blood was collected from tail puncture and administered into basal cisterns. IL-6 blockade was given at various time points. Various markers of neuroinflammation were measured with western blot and immunohistochemistry. Cerebral blood flow was also measured. Vasospasm was measured via cardiac injection of India ink/gelatin. Turning test and Garcia’s modified SAH score were utilized. P < 0.05 was considered significant.ResultsIL-6 expression peaked 3 days following SAH (p < 0.05). Human IL-6 was increased in aneurysmal blood (p < 0.05) and in cerebral spinal fluid (p < 0.01). Receptor upregulation was periventricular and perivascular. Microglia activation following SAH resulted in increased caveolin 3 and myeloid diapedesis. A significant increase in BBB markers endothelin 1 and occludin was noted following SAH, but reduced with IL-6 blockade (p < 0.01). CV occurred 5 days post-SAH, but was absent in IL-6 KO mice and mitigated with IL-6 blockade (p < 0.05). IL-6 blockade, and IL-6 KO mitigated effects of SAH on cerebral blood flow (p < 0.05). SAH mice had impaired performance on turn test and poor modified Garcia scores compared to saline and IL-6 blockade. A distinct microglia phenotype was noted day 5 in the SAH group (overlap coefficients r = 0.96 and r = 0.94) for Arg1 and iNOS, which was altered by IL-6 blockade. Day 7, a significant increase in toll-like receptor 4 and Stat3 was noted. This was mitigated by IL-6 blockade and IL-6 KO, which also reduced Caspase 3 (p < 0.05). To confirm the mechanism, we developed a p-STAT3 inhibitor that targets the IL-6 pathway and this reduced NFΚB, TLR4, and nitrotyrosine (p < 0.001). Ventricular dilation and increased Tunel positivity was noted day 9, but resolved by IL-6 blockade (p < 0.05).ConclusionCorrelation between IL-6 and CV has been well documented. We show that a mechanistic connection exists via the p-STAT3 pathway, and IL-6 blockade provides benefit in reducing CV and its consequences mediated by myeloid cell origin diapedesis.Graphical abstract

Determination and analysis of sex ratios in heme oxygenase 1 gene targeted mouse embryos.

Heme oxygenase 1 or Hmox1 enzyme is involved in catalyzing the first and rate-limiting step in heme breakdown reactions. Many studies have reported a partial lethality of Hmox1 knockout mice obtained from heterozygous breeding pairs. Similar results were obtained in our transgenic mice colony and a sex specific bias was observed in the favor of males in the adult mice. Hmox1 independent factors which could have caused this bias were initially analyzed and it was found that those factors were not a reason behind this anomaly. Certain studies involving gene knockout hinted toward a prenatal or neonatal lethality of female knockout mice embryos or pups, respectively. In order to check if this bias was occurring in embryonic stages, that is, either if mutant female embryos were dying or if heterozygous mothers were not carrying embryos to term, we analyzed the sex-ratios in mid- and late-gestational ages (9.5-13.5dpc and 14.5-18.5dpc, respectively). Our results did not indicate any significant difference in the sex ratios in embryonic stages; hence, it was concluded that females are not dying in embryonic stages. It can be speculated that these deaths were probably occurring at neonatal age. More studies are required to confirm that the lack of Hmox1 gene products is the sole reason for this female lethality.

Sexually dimorphic effects of estrogen receptor 2 deletion in the dorsal raphe nucleus on emotional behaviors.

Sex differences in emotional behaviors and affective disorders have been widely noted, of which sexually dimorphic secretion of gonadal steroid hormones such as estrogen is suspected to play a role. However, the underlying neural mechanisms remain poorly understood. We noted that the expression of estrogen receptor 2 (Esr2, or ERβ), a key mediator of estrogen signaling in the brain, was enriched in the dorsal raphe nucleus (DRN), a region involved in emotion regulation. To investigate whether DRN Esr2 expression confers sex-specific susceptibility or vulnerability in emotional behaviors, we generated a conditional allele of Esr2 that allowed for site-specific deletion of Esr2 in the DRN via local injection of Cre-expressing viruses. DRN-specific Esr2 deletion mildly increased anxiety behaviors in females, as shown by decreased time spent in the center zone of an open field in knockout females. By contrast, DRN Esr2 deletion had no effects on anxiety levels in males, as demonstrated by knockout males spending comparable time in the center zone of an open field and open arms of an elevated-plus maze. Furthermore, in the tail suspension test, DRN Esr2 deletion reduced immobility, a depression-like behavior, in a male-biased manner. Together, these results reveal sex-specific functions of DRN Esr2 in regulating emotional behaviors and suggest targeted manipulation of DRN Esr2 signaling as a potential therapeutic strategy to treat sex-biased affective disorders.

CB1 Receptor Silencing Attenuates Ketamine-Induced Hyperlocomotion Without Compromising Its Antidepressant-Like Effects.

Introduction: The antidepressant properties of ketamine have been extensively demonstrated in experimental and clinical settings. However, the psychotomimetic side effects still limit its wider use as an antidepressant. It was recently observed that endocannabinoids are inolved in ketamine induced reward properties. As an increase in endocannabinoid signaling induces antidepressant effects, this study aimed to investigate the involvement of cannabinoid type 1 receptors (CB1R) in the antidepressant and psychostimulant effects induced by ketamine. Methods: We tested the effects of genetic and pharmacological inhibition of CB1R in the hyperlocomotion and antidepressant-like properties of ketamine. The effects of ketamine (10-20 mg/kg) were assessed in the open-field and the forced swim tests (FSTs) in CB1R knockout (KO) and wild-type (WT) mice (male and female), and mice pre-treated with rimonabant (CB1R antagonist, 3-10 mg/kg). Results: We found that the motor hyperactivity elicited by ketamine was impaired in CB1R male and female KO mice. A similar effect was observed upon pharmacological blockade of CB1R in WT mice. However, genetic CB1R deletion did not modify the antidepressant effect of ketamine in male mice submitted to the FST. Surprisingly, pharmacological blockade of CB1R induced an antidepressant-like effect in both male and female mice, which was not further potentiated by ketamine. Conclusions: Our results support the hypothesis that CB1R mediate the psychostimulant side effects induced by ketamine, but not its antidepressant properties.

Uncoupling Protein-1 Modulates Anxiety-Like Behavior in a Temperature-Dependent Manner.

A strong bidirectional link between metabolic and psychiatric disorders exists; yet, the molecular basis underlying this interaction remains unresolved. Here we explored the role of the brown adipose tissue (BAT) as modulatory interface, focusing on the involvement of uncoupling protein 1 (UCP-1), a key metabolic regulator highly expressed in BAT, in the control of emotional behavior. Male and female constitutive UCP-1 knock-out (KO) mice were used to investigate the consequences of UCP-1 deficiency on anxiety-related and depression-related behaviors under mild thermogenic (23°C) and thermoneutral (29°C) conditions. UCP-1 KO mice displayed a selective enhancement of anxiety-related behavior exclusively under thermogenic conditions, but not at thermoneutrality. Neural and endocrine stress mediators were not affected in UCP-1 KO mice, which showed an activation of the integrated stress response alongside enhanced fibroblast-growth factor-21 (FGF-21) levels. However, viral-mediated overexpression of FGF-21 did not phenocopy the behavioral alterations of UCP-1 KO mice and blocking FGF-21 activity did not rescue the anxiogenic phenotype of UCP-1 KO mice. No effects of surgical removal of the intrascapular BAT on anxiety-like behavior or FGF-21 levels were observed in either UCP-1 KO or WT mice. We provide evidence for a novel role of UCP-1 in the regulation of emotions that manifests as inhibitory constraint on anxiety-related behavior, exclusively under thermogenic conditions. We propose this function of UCP-1 to be independent of its activity in the BAT and likely mediated through a central role of UCP-1 in brain regions with converging involvement in energy and emotional control.SIGNIFICANCE STATEMENT In this first description of a temperature-dependent phenotype of emotional behavior, we propose uncoupling protein-1 (UCP-1), the key component of the thermogenic function of the brown adipose tissue, as molecular break controlling anxiety-related behavior in mice. We suggest the involvement of UCP-1 in fear regulation to be mediated through its expression in brain regions with converging roles in energy and emotional control. These data are important and relevant in light of the largely unexplored bidirectional link between metabolic and psychiatric disorders, which has the potential for providing insight into novel therapeutic strategies for the management of both conditions.

Sex-dependent role of Pannexin 1 in regulating skeletal muscle and satellite cell function.

The development and regeneration of skeletal muscle are mediated by satellite cells (SCs), which ensure the efficient formation of myofibers while repopulating the niche that allows muscle repair following injuries. Pannexin 1 (Panx1) channels are expressed in SCs and their levels increase during differentiation in vitro, as well as during skeletal muscle development and regeneration in vivo. Panx1 has recently been shown to regulate muscle regeneration by promoting bleb-based myoblast migration and fusion. While skeletal muscle is largely influenced in a sex-specific way, the sex-dependent roles of Panx1 in regulating skeletal muscle and SC function remain to be investigated. Here, using global Panx1 knockout (KO) mice, we demonstrate that Panx1 loss reduces muscle fiber size and strength, decreases SC number, and alters early SC differentiation and myoblast fusion in male, but not in female mice. Interestingly, while both male and female Panx1 KO mice display an increase in the number of regenerating fibers following acute injury, the newly formed fibers in male Panx1 KO mice are smaller. Overall, our results demonstrate that Panx1 plays a significant role in regulating muscle development, regeneration, and SC number and function in male mice and reveal distinct sex-dependent functions of Panx1 in skeletal muscle.

Abstract P3012: Syndecan 1 Regulates Lung Endothelial Barrier Function In Homeostatic And Injury Conditions

Introduction: Acute lung injury (ALI) is an inflammatory syndrome that may occur secondarily to bacterial infection. Pulmonary edema is a severe complication of ALI and it may result from endothelial barrier disruption. The mechanisms that initiate ALI during bacterial infection remains unresolved. Syndecan 1 (Sdc1) is a heparan sulfate proteoglycan that contributes to endothelial barrier stability and is cleaved during inflammatory processes. Whether Sdc1 contributes to ALI progression is unresolved. Herein we investigated if Sdc1 mediates LPS-induced ALI in mice. Methods: Male and Female Sdc1 knockout (Sdc1KO) and wild type (WT) mice, with 5-8 weeks of age, were injected with lipopolysaccharide&amp;nbsp;(LPS, 10mg/Kg, IP) or PBS and euthanized after 6hr. Bronchoalveolar lavage fluid (BAL) and lung tissue were collected and assessed for myeloperoxidase (MPO) activity, albumin content, RhoA activity using commercially available spectrometric and ELISA kits. Lung edema was assessed by lung wet/dry ratio (W/D). Results and Conclusions: LPS increased lung W/D by 1.5-fold (p=0.0042, n≥5/group) in WT but not Sdc1KO mice. Sdc1KO showed higher basal lung W/D vs WT (Sdc1KO=3.55 vs WT=2.21, p=0.044, n≥5/group). Similarly, a trend increase in basal lung MPO activity was seen in Sdc1KO when compared to WT (p=0.33, n≥5/group). A significant increase in MPO activity was seen in LPS-treated WT (LPS=0.47±0.03 vs. PBS=0.26±0.03, p=0.003) but not LPS-treated Sdc1KO mice (p=0.11; n≥5/group) when compared to matched PBS-treated strain controls. Albumin content was increased by LPS only in WT BAL (LPS=106.9±8.9 vs PBS=63.65±6.15, p=0.03, n≥5/group). LPS increased RhoA activity exclusively in WT lungs. (LPS=0.04±0.002 vs PBS= 0.02±0.003, p=0.04, n≥5/group). A trend increase in RhoA activity was seen in PBS-treated Sdc1KO when compared to PBS-treated WT (p=0.06, n≥4/group). Collectively, our data suggest that Sdc1KO show basal lung endothelial barrier failure. This phenotype is associated with decreased response to LPS. The mechanisms whereby Sdc1 regulate barrier function may involve RhoA-dependent pathway. Sdc1 may participate in lung edema development during ALI.

The major urinary protein gene cluster knockout mouse as a novel model for translational metabolism research

Scientific evidence suggests that not only murine scent communication is regulated by major urinary proteins, but that their expression may also vary in response to metabolism via a yet unknown mechanism. Major urinary proteins are expressed mainly in the liver, showing a sexually dimorphic pattern with substantially higher expression in males. Here, we investigate the metabolic implications of a major urinary protein knockout in twelve-week-old male and female C57BL/6N mice during ad libitum feeding. Despite both sexes of major urinary protein knockout mice displayed numerically increased body weight and visceral adipose tissue proportions compared to sex-matched wildtype mice, the main genotype-specific metabolic differences were observed exclusively in males. Male major urinary protein knockout mice exhibited plasma and hepatic lipid accumulation accompanied by a hepatic transcriptome indicating an activation of lipogenesis. These findings match the higher major urinary protein expression in male compared to female wildtype mice, suggesting a more distinct reduction in energy requirements in male compared to female major urinary protein knockout mice. The observed sex-specific anabolic phenotype confirms a role of major urinary protein in metabolism and, since major urinary proteins are not expressed in humans, suggests the major urinary protein knockout mouse as a potential alternative model for translational metabolism research which needs to be further elucidated.