Endocrine Signaling Research Articles

Influence of Hypothyroidism on the Variability of Carotenoid Coloration in Amatitlania nigrofasciata Females (Cichlidae)

The study of the effect of thyroid hormones on the development of the pigment pattern, including the expression of sexual dichromatism, contributes to our understanding of the role of endocrine signaling in the evolution of cichlid fishes, one of the most diverse groups of teleosts. This work shows the effect of reduced thyroid hormone signaling on the development of reversed sexual dichromatism in Amatitlania nigrofasciata, a Neotropical cichlid in which females, unlike males, have carotenoid coloration. In hypothyroid fishes, there was a slowdown in the rate of metamorphic transformations of the pigment pattern and an increase in phenotypic variability. The adult pattern based on carotenoids began to develop in females only after the completion of treatment of thiourea, which suppresses the synthesis of endogenous thyroid hormones. The data obtained indicate a potentially important role of thyroid hormone-mediated developmental plasticity in the diversification of carotenoid coloration in Neotropical cichlids.

Temporal dynamics of muscle mitochondrial uncoupling-induced integrated stress response and ferroptosis defense.

Mitochondria play multifaceted roles in cellular function, and impairments across domains of mitochondrial biology are known to promote cellular integrated stress response (ISR) pathways as well as systemic metabolic adaptations. However, the temporal dynamics of specific mitochondrial ISR related to physiological variations in tissue-specific energy demands remains unknown. Here, we conducted a comprehensive 24-hour muscle and plasma profiling of male and female mice with ectopic mitochondrial respiratory uncoupling in skeletal muscle (mUcp1-transgenic, TG). TG mice are characterized by increased muscle ISR, elevated oxidative stress defense, and increased secretion of FGF21 and GDF15 as ISR-induced myokines. We observed a temporal signature of both cell-autonomous and systemic ISR in the context of endocrine myokine signaling and cellular redox balance, but not of ferroptotic signature which was also increased in TG muscle. We show a progressive increase of muscle ISR on transcriptional level during the active phase (night time), with a subsequent peak in circulating FGF21 and GDF15 in the early resting phase. Moreover, we found highest levels of muscle oxidative defense (GPX and NQO1 activity) between the late active to early resting phase, which could aim to counteract excessive iron-dependent lipid peroxidation and ferroptosis in muscle of TG mice. These findings highlight the temporal dynamics of cell-autonomous and endocrine ISR signaling under skeletal muscle mitochondrial uncoupling, emphasizing the importance of considering such dissociation in translational strategies and sample collection for diagnostic biomarker analysis.

Influence of phthalate and non-phthalate plasticizers on reproductive endocrine system-related gene expression profiles in Japanese medaka (Oryzias latipes)

Plasticizers containing phthalates have the potential to alter endocrine function in vertebrates. While non-phthalate plasticizers were previously considered to be environmentally friendly and safe, our research team discovered that bis-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC) disrupt thyroid hormones in Japanese medaka (Oryzias latipes). We assessed reproductive- and estrogen-responsive gene expression patterns in Japanese medaka to determine whether the phthalate plasticizers bis-(2-ethylhexyl) phthalate (DEHP, positive control) and the non-phthalate plasticizers DEHA and ATBC disrupt endocrine signaling. The results showed that the levels of choriogenin H (chgH) and vitellogenin (vtg) genes increased after exposure to DEHP and ATBC, suggesting that these plasticizers may have estrogenic activity. Exposure to DEHP and DEHA resulted in the upregulation of kisspeptin (kiss), gonadotropin-releasing hormone (gnrh), and follicle-stimulating hormone beta (fshβ) genes, suggesting that these plasticizers may interfere with reproductive function. To the best of our knowledge, this is the first study to demonstrate that the non-phthalate plasticizers DEHA and ATBC can disrupt reproduction-related hormonal activity in fish.

OR29-03 Social Isolation Stress Leads To Bone Loss In Adult Male, But Not Female, C57BL/6J Mice

Abstract Disclosure: R. Mountain: None. A. Langlais: None. D. Hu: None. R.E. Baron: None. C. Lary: None. K.J. Motyl: None. Social isolation is a potent form of psychosocial stress and is a growing public health concern, particularly among older adults. Even prior to the onset of the COVID-19 pandemic, which has significantly increased the prevalence of isolation and loneliness, researchers have been concerned about a rising “Epidemic of Loneliness”. Social isolation is associated with increased risk for many health conditions, including mental health disorders, as well as higher overall morbidity and mortality. Previous clinical research has demonstrated that psychosocial stressors, and subsequent mental health disorders, are major risk factors for osteoporosis and fracture, which disproportionally affect older adults. The effects of social isolation on bone, however, have not been thoroughly investigated. The aim of this study was to test the hypothesis that social isolation would lead to bone loss in male and female C57BL/6J mice. 16-week-old mice were randomized into social isolation (1 mouse/cage) or grouped housing (4 mice/cage) for four weeks (N=16/group). Social isolation significantly decreased trabecular bone parameters, including bone volume fraction (BV/TV) by 26% (Grouped: 21.9 ± 3.6%; Isolated: 16.2 ± 2.1%) (p < 0.0001), as well as BMD, Tb. N., and Tb. Th, in the femur of male, but not female, mice. Femoral cortical bone parameters were also significantly decreased in isolated male mice, including a 9% decrease in cortical thickness (Ct.Th.) (Grouped: 0.187 ± 0.011 mm; Isolated: 0.169 ± 0.009 mm) (p < 0.0001), as well as Ct.Ar., Ct.Ar./Tt.Ar., and pMOI. There were no significant differences in cortical measurements in females. Additionally, isolated male mice had signs of reduced bone remodeling represented by reduced osteoblast numbers and osteoblast-related gene expression, and osteoclast-related gene expression. However, isolated females had increased bone resorption-related gene expression, without any change in bone mass. The magnitude of bone loss in isolated males is as high as that seen in previous studies 4 weeks after orchiectomy or ovariectomy. Overall, our data suggest that social isolation has a dramatic negative effect on bone in males, but may operate through different mechanisms or in a different time frame in females. Future studies will focus on investigating potential mechanisms involving changes in endocrine signaling via glucocorticoid, sympathetic nervous system, and estrogen pathways. These results provide critical insight into the effects of isolation on bone and have key clinical implications as we grapple with the long-term health impacts of the rise in social isolation related to the COVID-19 pandemic. Presentation: Sunday, June 18, 2023

SAT049 Goldfish LEAP2: Molecular Cloning, Functional Characterization, And Novel Regulation By IGF And Insulin At The Hepatic Level

Abstract Disclosure: F. Jin: None. X. Qin: None. C. Ye: None. M. He: None. A.O. Wong: None. Liver-expressed antimicrobial peptide 2 (LEAP2) is a peptide highly expressed in the liver and its secretion induced by bacterial infection constitutes an integral component of innate immunity in vertebrate species. Recently, LEAP2 has been confirmed to be the endogenous antagonist of the feeding regulator ghrelin, implying that the peptide may play a role in appetite control and energy homeostasis. However, whether LEAP2 can be regulated by metabolic/endocrine signals is still unclear and the signal transduction involved is totally unknown. Using goldfish as a model, three isoforms of LEAP2, namely LEAP2a, 2b & 2c, have been cloned and phylogenetic analysis confirmed that they could be clustered into the clade of fish LEAP2. Comparative synteny also revealed that the three isoforms were derived from separated genes with similar structural organization but located in different chromosomes of goldfish genome. The a.a. sequences and 3D protein structure of LEAP2a-c were found to be highly comparable with LEAP2 of other vertebrates and tissue expression profiling by RT-PCR also showed that they were expressed at high levels in the liver but to a lower extent in other tissues. As members of antimicrobial peptides, goldfish LEAP2a-c not only could exhibit antimicrobial activity against Staphylococcus epidermidis but also play important role in fish innate immunity, which is evidenced by their transcript expression induced by LPS & cytokines at hepatic level as well as in immune tissues in goldfish naturally infected with Aeromonas hydrophila. In goldfish liver cells, transcript expression of LEAP2a-c could be up-regulated in a time- and dose-dependent manner by IGF-I, IGF-II and insulin. Using a pharmacological approach, the stimulatory effects of IGF-I/-II and insulin on the three isoforms of LEAP2 were confirmed to be mediated by IGF-I receptor (IGF1R) but not insulin receptor activation. Furthermore, the PI3K/Akt, MEK/ERK and P38 MAPK pathways were shown to be involved in IGF-I induced LEAP2a-c gene expression. Our findings for the first time demonstrate that the endocrine signals targeting the liver (insulin) or produced locally within the liver (IGF-I & -II) can play a role in regulating LEAP2 expression at the hepatic level, which may shed light on a novel aspect of the functional crosstalk between innate immunity and feeding control/energy balance in fish model. Presentation: Saturday, June 17, 2023

FRI589 MicroRNAs In Maternal Plasma At 15 Weeks Gestation As Biomarkers For Later Preterm Birth: Evidence For Dysregulated Mirna Biogenesis And Implications For Pregnancy-related Endocrine Signaling Pathways

Abstract Disclosure: F. Ramzan: None. J. Rong: None. C. Roberts: None. J. O'Sullivan: None. J.K. Perry: None. R. Taylor: None. L. McCowan: None. M.H. Vickers: None. Introduction: Preterm birth (PTB) is a leading cause of morbidity and mortality in infants, with rates of PTB increasing globally over the last 20 years. MicroRNAs (miRNAs) have been reported to have widespread involvement in the development of and protection from many diseases, there is increasing interest in their potential role in the aetiology of a range of pregnancy-related disorders, including PTB. Objectives: To investigate differential miRNA abundances in mid-pregnancy plasma samples between mothers with term infants compared with moderate to late preterm infants (spontaneous PTB) and replication across independent cohorts. Method: The Auckland and Adelaide arms of the Screening for Pregnancy Endpoints (SCOPE) study were utilised. miRNAs in plasma at 15 weeks gestation from mothers of term and moderate to late preterm infants (n=54 per group) were quantified using the NanoString nCounter human v2 miRNA expression panel. Gene expression of key mediators of miRNA biogenesis, including Drosha, Dicer and Argonaut were quantified via RT-qPCR. In-silico analysis was performed to investigate the biological pathways associated with the dysregulated miRNAs. Results: Of the 800 miRNAs examined, the top four miRNAs identified were conserved across both cohorts and were significantly downregulated in the plasma of mothers who later experienced a PTB. The gene pathways associated with the top candidate miRNAs were linked to inflammatory processes, mitochondrial biogenesis, apoptosis and regulation of key pregnancy-related hormonal signaling pathways. Moreover, miRNAs were consistently downregulated in the PTB group concomitant with reduced gene expression of key miRNA biogenesis markers. Conclusions: We identified miRNAs in maternal plasma in mid-pregnancy that were highly predictive of later spontaneous PTB and, importantly, were conserved across two independent cohorts. Moreover, in addition to identifying potential early biomarkers for subsequent PTB, we provide evidence for persistent downregulation of miRNAs in those mothers who later delivered preterm, which is likely to have widespread effects on endocrine signaling pathways during pregnancy. Presentation: Friday, June 16, 2023

The biocide triclosan as a potential developmental disruptor in Mytilus early larvae

The broadly utilized biocide triclosan (TCS) is continuously discharged in water compartments worldwide, where it is detected at concentrations of ng-µg/L. Given its lipophilicity and bioaccumulation, TCS is considered potentially harmful to human and environmental health and also as a potential endocrine disruptor (ED) in different species. In aquatic organisms, TCS can induce a variety of effects: however, little information is available on its possible impact on invertebrate development. Early larval stages of the marine bivalve Mytilus galloprovincialis have been shown to be sensitive to environmental concentrations of a number of emerging contaminants, including EDs. In this work, the effects of TCS were first evaluated in the 48 h larval assay in a wide concentration range (0.001–1,000 μg/L). TCS significantly affected normal development of D-veligers (LOEC = 0.1 μg/L; EC50 = 236.1 μg/L). At selected concentrations, the mechanism of action of TCS was investigated. TCS modulated transcription of different genes involved in shell mineralization, endocrine signaling, ceramide metabolism, and biotransformation, depending on larval stage (24 and 48 h post-fertilization-hpf) and concentration (1 and 10 μg/L). At 48 hpf and 10 μg/L TCS, calcein staining revealed alterations in CaCO3 deposition, and polarized light microscopy showed the absence of shell birefringence due to the mineralized phase. Observations by scanning electron microscopy highlighted a variety of defects in shell formation from concentrations as low as 0.1 μg/L. The results indicate that TCS, at environmental exposure levels, can act as a developmental disruptor in early mussel larvae mainly by interfering with the processes of biomineralization.

FKBP51-Hsp90 Interaction-Deficient Mice Exhibit Altered Endocrine Stress Response and Sex Differences Under High-Fat Diet

FK506-binding protein 51 kDa (FKBP51), encoded by Fkbp5 gene, gained considerable attention as an important regulator of several aspects of human biology including stress response, metabolic dysfunction, inflammation, and age-dependent neurodegeneration. Its catalytic peptidyl-prolyl isomerase (PPIase) activity is mediated by the N-terminal FK506-binding (FK1) domain, whereas the C-terminal tetratricopeptide motif (TPR) domain is responsible for FKBP51 interaction with molecular chaperone heat shock protein 90 (Hsp90). To understand FKBP51-related biology, several mouse models have been created. These include Fkbp5 complete and conditional knockouts, overexpression, and humanized models. To dissect the role of FKBP51-Hsp90 interaction in FKBP51 biology, we have created an interaction-deficient mouse (Fkbp5TPRmut) by introducing two-point mutations in the TPR domain of FKBP51. FKBP51-Hsp90 interaction-deficient mice are viable, fertile and show Mendelian inheritance. Intracellular association of FKBP51 with Hsp90 is significantly reduced in homozygous mutants compared to wild-type animals. No behavioral differences between genotypes were seen at 2 months of age, however, sex-dependent differences were detected in Y-maze and fear conditioning tests at the age of 12 months. Moreover, we have found a significant reduction in plasma levels of corticosterone and adrenocorticotropic hormone in Fkbp5TPRmut mice after acute stress. In contrast to Fkbp5 knockout mice, females of Fkbp5TPRmut showed increased body weight gain under high-fat diet treatment. Our data confirm the importance of FKBP51-Hsp90 interactions for stress-related endocrine signaling. Also, Fkbp5TPRmut mice can serve as a useful in vivo tool to discriminate between Hsp90-dependent and independent functions of FKBP51.

Immunomodulatory and regenerative potentials of breast milk, prematurity and children’s heart

Recent expansion of fundamental knowledge on the physiology of lactation, and breast milk exosomes, stem cell biology, mother-child interactions from prenatal period to postnatal development requires a progressive, dynamic view from the scientific community and practicing physicians when analyzing known, generally accepted clinical phenomena and patterns (development of the immune system of infants and young children, natural and artificial feeding, features of postnatal development and growth of organs and tissues in children born prematurely). The components of the mother-breast-milk-infant triad are closely related to each other and influence developmental trajectory of the infant. According to modern concepts, breast milk of a nursing woman is a “living, metabolic / endocrine signaling system”, which may be considered an “immune organ” significant for postnatal growth and body programming of a premature baby. A valuable phenomenon of early postnatal development is actively discussed in the special literature, i,e., “microchimerism” caused by breastfeeding which, according to modern concepts, may play a key role in development of immune system and the whole body. Absence of protective (immunomodulatory and regenerative) effects of breast milk from a nursing woman on the spontaneous, uncorrectable impact of adverse factors of prematurity is likely predispose for remodeling and dysfunction of heart in prematurely born children, and, at longer range, in adults. The young children born prematurely show a unique cardiac phenotype characterized by reduced biventricular volume, relatively lower systolic and diastolic function, disproportionate muscle mass gain, clinically manifesting by increased risk of cardiovascular disease, hypertension, and decreased exercise tolerance. Hence, the premature birth may be considered a chronic disease state. Therefore, the natural feeding which provides a natural evolutionarily protective mechanism for the child’s heart should be attributed to the fundamental factors that play a vital role in prevention of cardiovascular diseases in prematurely born children and at later life periods.

Using neurons to maintain autonomy: Learning from C. elegans

Understanding how biological organisms are autonomous—maintain themselves far from equilibrium through their own activities—requires understanding how they regulate those activities. In multicellular animals, such control can be exercised either via endocrine signaling through the vasculature or via neurons. In C. elegans this control is exercised by a well-delineated relatively small but distributed nervous system that relies on both chemical and electric transmission of signals. This system provides resources to integrate information from multiple sources as needed to maintain the organism. Especially important for the exercise of neural control are neuromodulators, which we present as setting agendas for control through more traditional electrical signaling. To illustrate how the C. elegans nervous system integrates multiple sources of information in controlling activities important for autonomy, we focus on feeding behavior and responses to adverse conditions. We conclude by considering how a distributed nervous system without a centralized controller is nonetheless adequate for autonomy.

5’-tRNA fragments are syncytiotrophoblast-derived endocrine signals contributing to maternal sterile inflammation in preeclampsia

5’-tRNA fragments are syncytiotrophoblast-derived endocrine signals contributing to maternal sterile inflammation in preeclampsia

382. CARDIAC REMODELING IN PATIENTS WITH ESOPHAGEAL CANCER-ASSOCIATED CACHEXIA

Abstract Background Cachexia is a debilitating wasting syndrome affecting 60% of patients with esophageal cancer, regardless of stage. While cachexia is usually characterized by skeletal muscle atrophy, systemic inflammation and aberrant endocrine signaling is thought to also precipitate cardiac atrophy and dysfunction. Indeed, cachectic patients often display clinical signs of heart failure. In this initial study, we sought to characterize the relationships between weight loss, body composition and parameters of cardiac structure and function. Methods We performed a retrospective review of patients that received esophagectomy between 2015 and 2020 at our facility. Male patients with pre-operative transthoracic echocardiogram studies and no prior history of cardiac disease were included. Body composition was measured using PET/CT scans. Patients were classified as having cachexia if having more than 8% loss in body mass in the six months before surgery. Appropriate t-tests and correlational analyses were performed after assessing normality. A p-value less than 0.05 was considered statistically significant. Results Mean age was 65.8 ± 7.54 years. Mean six-month weight loss was 13.2%, and 65.4% of patients were classified as having cachexia. Patients with cachexia tended to have lower left ventricular mass (135 ± 7.38 g v. 148 ± 7.53 g, p = 0.2) and significantly lower left atrial diameter (3.32 ± 0.441 cm v. 4.47 ± 0.515 cm, p = 0.0261). Curiously, pre-operative weight loss positively correlated with left ventricular internal diameter end systole (R = 0.4521, p = 0.0204) and negatively correlated with diastolic blood pressure (R = -0.4102, p = 0.0417). When compared to segmented PET/CT scans, patients with increased deposition of adipose to muscle—a sign of pathologic remodeling—also had decreased left atrial diameter (R = 0.6497, p = 0.0222). Conclusions Various measures of heart structure and function are altered in cachectic patients with esophageal cancer. Patients were more weight loss have reduced left atrial and increased left ventricular diameters. These findings suggest that cardiac structure may dynamically change in response to cachexia. In summary, there is a profound need to better characterize the pathology of cardiac atrophy and dysfunction in patients with cachexia.

Endocrine-disrupting compounds and metabolomic reprogramming in breast cancer.

Endocrine-disrupting chemicals pose a growing threat to human health through their increasing presence in the environment and their potential interactions with the mammalian endocrine systems. Due to their structural similarity to hormones like estrogen, these chemicals can interfere with endocrine signaling, leading to many deleterious effects. Exposure to estrogenic endocrine-disrupting compounds (EDC) is a suggested risk factor for the development of breast cancer, one of the most frequently diagnosed cancers in women. However, the mechanisms through which EDCs contribute to breast cancer development remain elusive. To rapidly proliferate, cancer cells undertake distinct metabolic programs to utilize existing nutrients in the tumor microenvironment and synthesize macromolecules de novo. EDCs are known to dysregulate cell signaling pathways related to cellular metabolism, which may be an important mechanism through which they exert their cancer-promoting effects. These altered pathways can be studied via metabolomic analysis, a new advancement in -omics technologies that can interrogate molecular pathways that favor cancer development and progression. This review will summarize recent discoveries regarding EDCs and the metabolic reprogramming that they may induce to facilitate the development of breast cancer.

Artificial light at night disrupts male dominance relationships and reproductive success in a model fish species

Environmental light is perceived and anticipated by organisms to synchronize their biological cycles. Therefore, artificial light at night (ALAN) disrupts both diurnal and seasonal biological rhythms. Reproduction is a complex physiological process involving integration of environmental signals by the brain, and release of endocrine signals by the pituitary that regulate gametogenesis and spawning. In addition, males from many species form a dominance hierarchy that, through a combination of aggressive and protective behavior, influences their reproductive success. In this study, we investigated the effect of ALAN and continuous daylight on the behavior and fitness of male fish within a dominance hierarchy using a model fish, the Japanese medaka. In normal light/dark cycles, male medaka establish a hierarchy with the dominant males being more aggressive and remaining closer to the female thus limiting the access of subordinate males to females during spawning. However, determination of the paternity of the progeny revealed that even though subordinate males spend less time with the females, they are, in normal light conditions, equally successful at producing progeny due to an efficient sneaking behavior. Continuous daylight completely inhibited the establishment of male hierarchy, whereas ALAN did not affect it. Nonetheless, when exposed to ALAN, subordinate males fertilize far fewer eggs. Furthermore, we found that when exposed to ALAN, subordinate males produced lower quality sperm than dominant males. Surprisingly, we found no differences in circulating sex steroid levels, pituitary gonadotropin levels, or gonadosomatic index between dominant and subordinate males, neither in control nor ALAN condition. This study is the first to report an effect of ALAN on sperm quality leading to a modification of male fertilization success in any vertebrate. While this work was performed in a model fish species, our results suggest that in urban areas ALAN may impact the genetic diversity of species displaying dominance behavior.

Neurohypophysial and paracrine vasopressinergic signaling regulates aquaporin trafficking to hydrate marine teleost oocytes.

The dual aquaporin (Aqp1ab1/Aqp1ab2)-mediated hydration of marine teleost eggs, which occurs during oocyte meiosis resumption (maturation), is considered a key adaptation underpinning their evolutionary success in the oceans. However, the endocrine signals controlling this mechanism are almost unknown. Here, we investigated whether the nonapeptides arginine vasopressin (Avp, formerly vasotocin) and oxytocin (Oxt, formerly isotocin) are involved in marine teleost oocyte hydration using the gilthead seabream (Sparus aurata) as a model. We show that concomitant with an increased systemic production of Avp and Oxt, the nonapeptides are also produced and accumulated locally in the ovarian follicles during oocyte maturation and hydration. Functional characterization of representative Avp and Oxt receptor subtypes indicates that Avpr1aa and Oxtrb, expressed in the postvitellogenic oocyte, activate phospholipase C and protein kinase C pathways, while Avpr2aa, which is highly expressed in the oocyte and in the follicular theca and granulosa cells, activates the cAMP-protein kinase A (PKA) cascade. Using ex vivo, in vitro and mutagenesis approaches, we determined that Avpr2aa plays a major role in the PKA-mediated phosphorylation of the aquaporin subdomains driving membrane insertion of Aqp1ab2 in the theca and granulosa cells, and of Aqp1ab1 and Aqp1ab2 in the distal and proximal regions of the oocyte microvilli, respectively. The data further indicate that luteinizing hormone, which surges during oocyte maturation, induces the synthesis of Avp in the granulosa cells via progestin production and the nuclear progestin receptor. Collectively, our data suggest that both the neurohypophysial and paracrine vasopressinergic systems integrate to differentially regulate the trafficking of the Aqp1ab-type paralogs via a common Avp-Avpr2aa-PKA pathway to avoid competitive occupancy of the same plasma membrane space and maximize water influx during oocyte hydration.

Neuronal atg1 Coordinates Autophagy Induction and Physiological Adaptations to Balance mTORC1 Signalling.

The mTORC1 nutrient-sensing pathway integrates metabolic and endocrine signals into the brain to evoke physiological responses to food deprivation, such as autophagy. Nevertheless, the impact of neuronal mTORC1 activity on neuronal circuits and organismal metabolism remains obscure. Here, we show that mTORC1 inhibition acutely perturbs serotonergic neurotransmission via proteostatic alterations evoked by the autophagy inducer atg1. Neuronal ATG1 alters the intracellular localization of the serotonin transporter, which increases the extracellular serotonin and stimulates the 5HTR7 postsynaptic receptor. 5HTR7 enhances food-searching behaviour and ecdysone-induced catabolism in Drosophila. Along similar lines, the pharmacological inhibition of mTORC1 in zebrafish also stimulates food-searching behaviour via serotonergic activity. These effects occur in parallel with neuronal autophagy induction, irrespective of the autophagic activity and the protein synthesis reduction. In addition, ectopic neuronal atg1 expression enhances catabolism via insulin pathway downregulation, impedes peptidergic secretion, and activates non-cell autonomous cAMP/PKA. The above exert diverse systemic effects on organismal metabolism, development, melanisation, and longevity. We conclude that neuronal atg1 aligns neuronal autophagy induction with distinct physiological modulations, to orchestrate a coordinated physiological response against reduced mTORC1 activity.

Abstract P2045: Regulation Of Atrial Natriuretic Peptide Secretion By Palmitoylation And Modulation Of The Rab3a GTPase Cycle In Cardiac Myocytes

Despite the clinical relevance to cardiovascular disease, molecular regulation of atrial natriuretic peptide (ANP) release by cardiomyocytes remains ill-defined. We uncovered novel functions for Rab3gap1 and modulation of Rab3a nucleotide cycling in membrane fusion and atrial natriuretic peptide (ANP) release in cardiomyocytes. We generated transgenic mice overexpressing the Golgi-localized S-acyltransferase, zDHHC9, and identified Rab3gap1 as a novel cardiac substrate of zDHHC9 by S-acyl proteomics. Rab3gap1 palmitoylation and retention at the cardiomyocyte Golgi, Rab3a-GTP levels, and formation of Rab3a-positive post-Golgi vesicles were all enhanced in zDHHC9 overexpressing hearts as were Rab3gap1, Rab3a, and ANP atrial protein levels but circulating ANP levels were reduced, suggesting a defect in ANP secretion. Notably, treatment of cardiomyocytes with the secretagogue phenylephrine (PE) promoted substantial ANP release as expected, but also enhanced Rab3gap1 palmitoylation and Rab3a GTP-loading and peripheral vesicle formation, whereas knockdown of zDHHC9 repressed these PE-induced effects on Rab3gap1 and Rab3a but further enhanced PE-stimulated ANP secretion, suggesting zDHHC9-mediated palmitoylation of Rab3gap1 serves as an intrinsic mechanism to limit ANP release. Consistent with a role for Rab3a nucleotide exchange in modulation of ANP release, overexpression of Rab3gap1 in cardiomyocytes promoted a profound increase in ANP release whereas a GAP-deficient mutant of Rab3gap1 (Rab3gap1 R728A ) was resistant to this effect. Collectively, these data suggest disruption of Rab3a nucleotide cycling perturbs secretory vesicle membrane fusion and ANP release in cardiac myocytes and establish critical roles for Rab3a activity and its modulation by zDHHC9-mediated palmitoylation of Rab3gap1 in governing cardiac homeostasis and endocrine signaling.

Loss of Krüppel-like factor 9 deregulates both physiological gene expression and development

Krüppel-like factor 9 (Klf9) is a ubiquitously expressed transcription factor that is a feedforward regulator of multiple stress-responsive and endocrine signaling pathways. We previously described how loss of Klf9 function affects the transcriptome of zebrafish larvae sampled at a single time point 5 days post-fertilization (dpf). However, klf9 expression oscillates diurnally, and the sampled time point corresponded to its expression nadir. To determine if the transcriptomic effects of the klf9−/− mutation vary with time of day, we performed bulk RNA-seq on 5 dpf zebrafish embryos sampled at three timepoints encompassing the predawn peak and midmorning nadir of klf9 expression. We found that while the major effects of the klf9−/− mutation that we reported previously are robust to time of day, the mutation has additional effects that manifest only at the predawn time point. We used a published single-cell atlas of zebrafish development to associate the effects of the klf9−/− mutation with different cell types and found that the mutation increased mRNA associated with digestive organs (liver, pancreas, and intestine) and decreased mRNA associated with differentiating neurons and blood. Measurements from confocally-imaged larvae suggest that overrepresentation of liver mRNA in klf9−/− mutants is due to development of enlarged livers.

Pharmacomodulation of brain neuromedin U signaling as a potential therapeutic strategy.

Neuromedin U (NMU) belongs to a family of multifunctional neuropeptides that modulate the activity of several neural networks of the brain. Acting via metabotropic receptor NMUR2, NMU plays a role in the regulation of multiple systems, including energy homeostasis, stress responses, circadian rhythms, and endocrine signaling. The involvement of NMU signaling in the central regulation of important neurophysiological processes and its disturbances is a potential target for pharmacological modulation. Number of preclinical studies have proven that both modified NMU analogues such as PASR8-NMU or F4R8-NMU and designed NMUR2 agonists, for example, CPN-116, CPN-124 exhibit a distinct pharmacological activity especially when delivered transnasally. Their application can potentially be useful in the more convenient and safe treatment of obesity, eating disorders, Alzheimer's disease-related memory impairment, alcohol addiction, and sleep disturbances. Accumulating findings suggest that pharmacomodulation of the central NMU signaling may be a promising strategy in the treatment of several neuropsychiatric disorders.

In light of breathing: environmental light is an important modulator of breathing with clinical implications.

In vertebrate animals, the automatic, rhythmic pattern of breathing is a highly regulated process that can be modulated by various behavioral and physiological factors such as metabolism, sleep-wake state, activity level, and endocrine signaling. Environmental light influences many of these modulating factors both indirectly by organizing daily and seasonal rhythms of behavior and directly through acute changes in neural signaling. While several observations from rodent and human studies suggest that environmental light affects breathing, few have systematically evaluated the underlying mechanisms and clinical relevance of environmental light on the regulation of respiratory behavior. Here, we provide new evidence and discuss the potential neurobiological mechanisms by which light modulates breathing. We conclude that environmental light should be considered, from bench to bedside, as a clinically relevant modulator of respiratory health and disease.