Endocrinology

Steroid receptors are transcription factors activated by progesterone (PGR), androgen (AR) and glucocorticoid (GR), with shared canonical DNA binding sequence. In the ovary, PGR is the key determinant of ovulation while AR and GR play important roles in growing follicles. However, the mechanism that defines the unique physiological roles of these conserved receptors, and whether their functions overlap remains elusive. We investigated the relationship between AR, GR and PGR during folliculogenesis and ovulation. In response to ovulatory hormones, PGR and GR jointly gained binding to novel chromatin sites and had a substantial effect on periovulatory gene regulation, whereas AR-chromatin interactions were repressed. Two modes of PGR action to drive gene activation were identified. Induction of PGR leads to cooperative PGR/GR recruitment to novel promoters, increased histone acetylation and chromatin accessibility, culminating in transcription activation, with PGR being the key component in the unique ovulatory transcriptional complex. Alternatively, PGR tethered to enhancers interacts with pre-accessible, AR/GR-bound promoters to promote gene activation. Our findings illustrate the multi-faceted ovarian steroid receptor interactions which explain how the progressive change in steroid environments throughout folliculogenesis programs granulosa cells during the transition to ovulation.

Glucocorticoid-induced adrenal insufficiency (GIAI) can persist for months after discontinuation of chronic corticosteroid therapy, placing patients at risk for life-threatening adrenal crises. This prolonged suppression has been attributed primarily to delayed restoration of hypothalamic-pituitary signaling based on indirect, clinical measures of central axis activity. To identify the rate-limiting site of hypothalamic-pituitary-adrenal (HPA) axis recovery, we systematically evaluated the timing of functional and histologic recovery at each node of the axis following 8 weeks of dexamethasone (DEX) treatment in mice. DEX administration fully suppressed HPA axis activity. Unexpectedly, within one week of DEX withdrawal, hypothalamic Crh mRNA and plasma ACTH rebounded above control levels, whereas corticosterone (CORT) remained suppressed for an additional seven weeks. DEX-treated adrenals were markedly atrophic and contained large clusters of lipid-associated macrophages. Even after adjusting for macrophage content, CORT secretion was disproportionately low relative to the remaining adrenocortical cell mass despite supraphysiologic ACTH stimulation. These findings identify the adrenal gland, rather than the hypothalamus or pituitary, as the principal site of persistent dysfunction following glucocorticoid withdrawal. We next tested whether preserving adrenal trophic signaling during glucocorticoid exposure could prevent GIAI. Co-treatment with DEX and daily cosyntropin (a synthetic ACTH analog) failed to preserve adrenal function. In contrast, mice with non-suppressible endogenous ACTH due to targeted deletion of Nr3c1 (encoding the glucocorticoid receptor) in hypothalamic neurons maintained normal adrenal architecture and steroidogenic capacity despite prolonged DEX treatment. Pharmacologic treatments that mimic sustained, physiologic trophic signaling to the adrenal during chronic glucocorticoid treatment may thus prevent GIAI.

Aniridia is a congenital condition characterized by absence of iris and is caused by a semidominant mutation in the transcription factor encoded by the PAX6 gene. Although ocular phenotypes of this disorder are well characterized, recent studies report that individuals with aniridia have a higher propensity for obesity, infertility, polycystic ovarian disease, and severe eczema compared to their Pax6-normal siblings. These symptoms collectively suggest an underlying endocrine disturbance related to haploinsufficient levels of Pax6. In mice, during development, Pax6 expression in the pituitary gland begins at E9.0 in the primordial anterior pituitary gland (Rathkes Pouch). This expression becomes restricted to the dorsal anterior pituitary by E11.5, but is expressed throughout the anterior lobe by E14.5, and remains through adulthood. It is possible that a reduction in Pax6 could result in a change in pituitary hormone levels or cell numbers, which may explain symptoms experienced by aniridics. Using the Small eye mouse model, we find that Pax6 reduction results in a decrease in GH-producing cells and an increase in TSH-producing cells in neonate mice, with the TSH increase continuing into adulthood. Adult Pax6 haploinsufficient mice also have an increase in anterior pituitary volume and weigh significantly less than their wild-type littermates. Furthermore, we show that the increase in TSH-producing cells leads to an increase in thyroxin (T4) in mutant mice, although tri-iodothyronine (T3) levels remain unchanged. These findings present a new role for Pax6 in the endocrine system, which serves to refine our current understanding of Pax6 in endocrine development and maintenance and provides new avenues for investigating endocrine-related symptomatology in aniridia.

Children undergoing cancer treatments are at risk for impaired fertility. Cryopreserved prepubertal testicular biopsies could theoretically be later matured in vitro to produce spermatozoa for assisted reproductive technology. A complete in vitro spermatogenesis has been obtained from mouse prepubertal testicular tissue, although with low efficiency. Steroid hormones being essential for the progression of spermatogenesis, the aim of this study was to investigate steroidogenesis and steroid signaling in organotypic cultures. Histological, RT-qPCR, western blot analyses and steroid hormone measurements were performed on in vitro cultured mouse prepubertal testicular tissues and age-matched in vivo controls. Despite a conserved density of Leydig cells after 30 days of culture (D30), transcript levels of adult Leydig cell and steroidogenic markers were decreased. Increased amounts of progesterone and estradiol and reduced androstenedione levels were observed at D30, together with decreased transcript levels of steroid metabolizing genes and steroid target genes. hCG was insufficient to facilitate Leydig cell differentiation, restore steroidogenesis and improve sperm yield. In conclusion, this study reports the failure of adult Leydig cell development and altered steroid production and signaling in tissue cultures. The organotypic culture system will need to be further improved before it can be translated in clinics for childhood cancer survivors.

Polycystic ovary syndrome (PCOS) is a heterogenous reproductive disorder that is often associated with metabolic dysfunction, as well as comorbidities such as pregnancy complications. Although metabolic traits like hyperinsulinemia (i.e., elevated insulin without hypoglycemia) likely exacerbate the reproductive and metabolic features of PCOS, the precise impacts of specific metabolic traits on PCOS pathogenesis, symptom severity, and comorbidity incidence are not known. The aim of our study was to investigate the relationships between insulin levels, PCOS-like traits, and pregnancy complications by limiting endogenous insulin production in a mouse model of PCOS. Using Ins1-null mice with modulated Ins2 gene dosage (Ins1-/-:Ins2+/- versus Ins1-/-:Ins2+/+ littermates), we longitudinally assessed metabolic and reproductive phenotypes in PCOS-like mice generated via prenatal anti-Mullerian hormone (PAMH) exposure. We observed mild reproductive characteristics of PCOS in PAMH mice of both genotypes, including increased anogenital distances, delayed puberty, and disrupted estrous cycling, but did not detect robust PAMH-induced metabolic changes across six months. In the absence of PAMH-aggravated metabolic dysfunction or hyperinsulinemia--even in mice fed a high-fat, high-sucrose diet--reducing Ins2 gene dosage did not notably change most measured traits. However, high-fat, high-sucrose-fed PAMH pregnant dams exhibited a diminished pregnancy-induced insulinogenic response and a trend for reduced {beta}-cell mass compared to control mice, together with superior blood glucose homeostasis despite the physiological challenges of pregnancy. Therefore, while Ins1-null PAMH mice did not manifest pronounced PCOS-like metabolic features, prenatal AMH exposure can cause shifts in metabolic homeostasis during pregnancy.

Menopausal hormone therapy (MHT) is prescribed for climacteric symptoms including hot flushes and weight gain and contains estrogens such as 17 beta-estradiol (17{beta}E2). However, estrogen receptor activation by MHT may increase reproductive cancers and cardiovascular event risk in some people. As the protective metabolic effects of 17{beta}E2 are partly mediated through the arcuate nucleus of the hypothalamus, restricting 17{beta}E2 actions to the brain could serve as a safer mechanism of MHT. 10{beta},17{beta}-Dihydroxyestra-1,4-dien-3-one (DHED) is a prodrug of 17{beta}E2 which is enzymatically converted to the parent hormone exclusively within the brain. DHED has demonstrated positive benefit in rodent models of centrally-mediated maladies including hot flushes, depression and cognitive decline, without peripheral hormonal burden. Therefore, we hypothesized that DHED treatment in obese female mice would act within the hypothalamus to provide the same beneficial metabolic effects as 17{beta}E2. Female mice were ovariectomized, placed on a high fat diet and split into either control, DHED, or 17{beta}E2 treatment groups. Body weight, uterus weight and glucose tolerance were recorded along with gonadal hormone receptor expression in the brain. Delivery of DHED at a similar dose as 17{beta}E2 failed to improve metabolic parameters or recapitulate the hypothalamic responses induced by 17{beta}E2. Delivery of DHED at higher doses, which elicited estrogen-like actions within the brain, still failed to improve metabolic health. Our findings suggest that peripheral actions, in addition to hypothalamic targets, may be required to mediate 17{beta}E2s protective effects on metabolism and that brain-targeted MHT may be unsuitable for improving metabolic health during menopause.

Congenital hypopituitarism is characterized by deficient pituitary hormone production, affecting growth and development. The molecular mechanisms underlying pituitary development and dysfunction in hypopituitarism remain incompletely understood. We investigated the expression of key pituitary development markers in three mouse models of congenital hypopituitarism, with molecular alterations in the Prop1, Pou1f1, and GSU genes across critical postnatal developmental stages: neonatal (P0), early postnatal (P7), pubertal (4 weeks), and adult (8 weeks). We assessed mRNA and protein levels of the pituitary stem cell markers (SOX2), proliferation marker (Ki67) and pituitary hormones, correlating these with pituitary function and disease. Prop1 deficiency led to significant upregulation of Sox2 and Hesx1 during early postnatal development and in adulthood, diverging from the relatively stable expression patterns observed in Pou1f1 and GSU mutants. Despite some variations, overall Sox2 and Ki67 expression profiles were similar between Prop1 and Pou1f1 mutants. Prop1 mutants exhibited altered pituitary morphology, with increased SOX2-positive cells suggesting disrupted stem cell migration. During the pubertal period, a subset of hormone-producing cells in Prop1 mutants co-expressed SOX2, indicating differentiation without restoring normal pituitary function. Hormone analysis revealed transient gonadotropin production and secretion during sexual maturation in Prop1 mutants, without recovery of the hypogonadal phenotype. Our study elucidates the complex transcriptional dynamics of pituitary development markers in mouse models of congenital hypopituitarism, highlighting the pivotal role of Prop1 in regulating stem cell marker expression. The distinct transcriptional responses in Prop1 mutants during key developmental windows shed light on the mechanisms of pituitary dysgenesis and the persistent inability to fully recover pituitary function, despite transient hormonal changes during puberty. These insights contribute to a better understanding of pituitary development and dysfunction in congenital hypopituitarism.

Maternal pancreatic {beta}-cells undergo functional and structural changes to adapt to increased metabolic demands during pregnancy. Lactogen signaling via the prolactin receptor (PRLR) contributes to these adaptations by increasing {beta}-cell mass, insulin transcription and glucose-stimulated insulin secretion[1-4]. In other lactogen-responsive tissues such as the mammary glands and specific hypothalamic nuclei, gestation induces epigenetic changes, some of which persist long after birth[5, 6]. We have previously found that prolactin treatment in islets regulates the expression of epigenetic modifiers[7, 8]. However, whether lactogen signaling in {beta}-cells mediates epigenetic changes to regulate chromatin accessibility has not been examined. Therefore, our objective was to determine whether PRLR signaling alters chromatin accessibility of {beta}-cells to facilitate transcriptional regulation. Using single-cell ATAC-sequencing, we identified differentially accessible regions (DARs) in {beta}-cells which had 718 overrepresented motifs following prolactin treatment of murine islets. Validating this approach, these included motifs bound by established PRLR signaling effectors such as the STAT family of transcription factors (TFs). Using RNA-sequencing we identified transcriptional changes in 41 TFs whose motifs were overrepresented in DARs, including several previously linked to PRLR signaling within {beta}-cells, including Myc, Mafb and Esr1. Importantly, we also identified TFs not previously associated with PRLR signaling, including OVOL2 an established regulator of epigenetic landscape within cells. OVOL2 is a transcription factor involved in EMT inhibition and energy homeostasis with unknown roles in pancreatic {beta}-cells. Here, we establish that OVOL2 acts as a negative regulator of lactogen-dependent effects on {beta}-cell proliferation, establishing a novel regulator of PRLR signaling.

The anterior pituitary secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) regulate gonadal development, gametogenesis and the secretion of the gonadal steroid hormones. The gonadotroph is primarily regulated by hypothalamic secretion of gonadotropin-releasing hormone (GnRH) from neurons of the rostral hypothalamus and is mediated by GnRH receptor signaling. Kisspeptin (KISS1)/kisspeptin receptor (KISS1R) signaling in GnRH neurons plays an essential role in reproductive function. As the kisspeptin receptor is present in the pituitary, kisspeptin signaling via the Kiss1r may regulate reproductive function at the level of pituitary. Using Cre/Lox technology, we deleted the Kiss1r gene in pituitary gonadotropes (PKiRKO). PKiRKO male and females have normal genital development, puberty onset, and fertility. Females have normal LH, FSH and estradiol while males had significantly increased basal serum FSH levels with no differences in basal serum LH, or testosterone levels. Overall, these findings indicate that the pituitary KISS1R does not play a role in male reproduction.

Estrogens act through nuclear and membrane-initiated signaling. Estrogen receptor alpha (ER) is critical for reproduction, but the relative contribution of its nuclear and membrane signaling is unclear. To address this question, we used two complementary approaches: estetrol (E4) a natural estrogen described to act as an agonist of nuclear ER and a mER antagonist and the C451A-ER mouse lacking mER. E4 dose-dependently blocks ovulation in female rats, but the mechanism underlying this effect is unknown. To determine whether E4 acts centrally to control ovulation, we tested its effect on the positive feedback of estradiol (E2) on LH secretion. In ovariectomized females chronically exposed to a low dose of E2, estradiol benzoate (EB) alone or combined with progesterone (P) induced a LH surge and the associated increase in the number of activated kisspeptin (Kp) and gonadotropin-releasing hormone (GnRH) neurons. However, E4 blocked these effects of EB when provided alone, but not when combined to P. These results indicate that E4 blocked the induction of the positive feedback and the associated neuronal activation in the absence of P, suggesting an antagonistic effect of E4 on mER as shown in peripheral tissues. In parallel, C451A-ER females do not show a pre-ovulatory LH surge and the associated activation of Kp and GnRH neurons in response to EB unless they are treated with P. The similarity of the responses of C451A-ER mice and wild-type females treated with E4 supports a role for membrane-initiated estrogen signaling in the EB-induced LH surge.

Despite the importance of the mouse in biomedical research, the levels of circulating gonadal steroids across the estrous cycle are not established with any temporal precision. Using liquid chromatography-mass spectrometry, now considered the gold standard for steroid hormone analysis, we aimed to generate a detailed profile of gonadal steroid levels across the estrous cycle of C57BL/6J mice. For reference, luteinizing hormone (LH) and prolactin concentrations were measured in the same samples by sandwich ELISA. Terminal blood samples were collected at 8-hour intervals (10 am, 6 pm, 2 am) throughout the four stages of the estrous cycle. As expected, the LH surge was detected at 6 pm on proestrus with a mean ({+/-}SEM) concentration of 11{+/-}3 ng/mL and occurred coincident with the peak in progesterone levels (22{+/-}4 ng/mL). Surprisingly, estradiol concentrations peaked at 10 am on diestrus (51{+/-}8 pg/mL), with levels on proestrus 6 pm reaching only two-thirds of this value (31{+/-}5 pg/mL). We also observed a proestrous peak in prolactin concentrations (132.5{+/-}17 ng/mL) that occurred earlier than expected at 2 am. Estrone and androstenedione levels were often close to the LOD and showed no consistent changes across the estrous cycle. Testosterone levels were rarely above the LOD (0.01 ng/mL). These observations provide the first detailed assessment of fluctuating gonadal steroid and reproductive hormone levels across the mouse estrous cycle and indicate that species differences exist between mice and other spontaneously ovulating species.

Androgen excess drives metabolic and reproductive complications in polycystic ovary syndrome (PCOS), affecting 10-15% of women globally. Aldo-keto reductase 1C3 (AKR1C3) converts inactive precursors from both the classic and the recently identified 11-oxygenated androgen pathways, generating testosterone and 11-ketotestosterone, respectively, which exert comparable androgen receptor activation. Both circulate in similar concentrations in premenopausal women while 11-ketotestosterone is predominant after menopause and in PCOS. Here, we show that adipocytes are a major site of AKR1C3 and androgen receptor expression, with increased expression in women and individuals with obesity. Using human female adipose tissue explants, we find a much higher activation of 11-oxygenated over classic androgens, observing a decrease in 11-oxygenated but not classic androgen activation by AKR1C3 inhibition. Correspondingly, we demonstrate that AKR1C3 inhibitor treatment in premenopausal women selectively disrupts the activation of 11-oxygenated androgens. Pharmacological targeting of AKR1C3 provides a novel strategy to alleviate systemic and intra-adipose 11-oxygenated androgen excess. One Sentence SummaryInhibition of the androgen-activating enzyme AKR1C3 results in a major decrease in 11-oxygenated but not classic androgens in women.

Serum anti-Mullerian hormone (AMH) is the primary clinical indicator of mature oocyte counts in the ovaries, but its biological role remains poorly understood. Mammalian ovaries have a finite lifetime of oocytes that are slowly depleted as the dormant follicles housing the oocytes initiate maturation. Less than 0.1% of these follicles will reach maturity and ovulate an oocyte. Recent studies suggest that AMH is a key regulator that removes most of these follicles at early stages of follicle maturation. Most AMH is secreted as an inactive precursor protein, and we show that the required activating-enzymes are largely present outside the follicle. We then measured AMH concentrations in ovarian stroma with microdialysis showing that activity is confined to a short range from the site of secretion. To examine short-range interactions between follicles, we reconstructed the ovarian follicle positions from sheep ovaries in 3D space. This showed that most early follicles develop in proximity to more advanced follicles. Active immunisation of sheep against AMH to inhibit signalling, greatly expanded early follicle numbers, but almost entirely in proximity to large follicles. Large follicle proximity appears to greatly enhance early follicle survival, and AMH appears to attenuate this effect to prevent follicle overgrowth beyond sustainable limits.

26RFa (QRFP) is a biologically active peptide that regulates glucose homeostasis by acting as an incretin and by increasing insulin sensitivity at the periphery. 26RFa is also produced by a neuronal population localized in the hypothalamus. In the present study, we have investigated whether the 26RFa neurons may be involved in the hypothalamic regulation of glucose homeostasis. Our data indicate that 26RFa, i.c.v. injected, induces a robust antihyperglycemic effect associated with an increase of insulin production by the pancreatic islets. In addition, we found that insulin strongly stimulates 26RFa expression and secretion by the hypothalamus. RNAscope experiments revealed that neurons expressing 26RFa in the lateral hypothalamic area and the ventromedial hypothalamic nucleus also express the insulin receptor and that insulin induces the expression of 26RFa in these neurons. Concurrently, we show that the central antihyperglycemic effect of insulin is abolished in presence of a 26RFa receptor (GPR103) antagonist as well as in mice deficient for 26RFa. Finally, our data indicate that the hypothalamic 26RFa neurons are not involved in the central inhibitory effect of insulin on hepatic glucose production, but mediate the central effects of the hormone on its own peripheral production. To conclude, in the present study we have identified a novel actor of the hypothalamic regulation of glucose homeostasis, the 26RFa/GPR103 system and we provide the evidence that this neuronal peptidergic system is a key relay for the central regulation of glucose metabolism by insulin.

Pregnancy leads to many adaptations in the maternal body, most of which are reversible. However, reproductive experience can also result in permanent effects. Here, we investigated how pregnancy influences the somatotrophic system and the lasting effects of reproductive experience on the maternal organism. Reproductive experience induced a pronounced increase in lean body mass and longitudinal growth in both wild-type and growth hormone (GH)-deficient mice compared with age-matched virgins. Body growth was primarily observed during the first pregnancy, whereas a second gestation was mostly associated with increased adiposity. Data from a cohort of women with isolated GH deficiency (IGHD) caused by a loss-of-function mutation in the GHRHR gene revealed that nulliparous women were 7 cm shorter than those with one or more pregnancies. Increased GH secretion was observed in pregnant wild-type mice but not in pregnant GHRHR-deficient mice. Pregnancy-induced body growth is preserved despite disruption of GH-, ghrelin-, and estrogen-related signaling pathways. In conclusion, reproductive experience induces permanent changes in the maternal organism, promoting body growth in models that allow this response. Pregnancy-induced body growth appears to be independent of GH action. These findings underscore the need for further studies to investigate the long-lasting consequences of reproductive experience in females.

30% of people in the United States have diabetes or pre-diabetes. Many of these individuals will develop diabetic neuropathy as a comorbidity, which is often treated with exogenous opioids like morphine, oxycodone, or tramadol. Although these opioids are effective analgesics, growing evidence indicates that they may directly impact the endocrine pancreas function in human and preclinical models. One common feature of these exogenous opioid ligands is their preference for the mu opioid receptor (MOPR), so we aimed to determine if endogenous MOPRs directly regulate pancreatic islet metabolism and hormone secretion. We show that pharmacological antagonism of MOPRs enhances glucagon secretion, but not insulin secretion, from human islets under high glucose conditions. This increased secretion is accompanied by increased cAMP signaling. mRNA expression of MOPRs is enriched in human islet -cells, but downregulated in T2D islet donors, suggesting a link between metabolism and MOPR expression. Conditional genetic knockout of MOPRs in murine -cells increases glucagon secretion in high glucose conditions without increasing glucagon content. Consistent with downregulation of MOPRs during metabolic disease, conditional MOPR knockout mice treated with a high fat diet show impaired glucose tolerance, increased glucagon secretion, increased insulin content, and increased islet size. Finally, we show that MOPR-mediated changes in glucagon secretion are driven, in part, by KATP channel activity. Together, these results demonstrate a direct mechanism of action for endogenous opioid regulation of endocrine pancreas.

Evidence suggests that estradiol-sensing preoptic area GABA neurons are involved in the pre-ovulatory surge mechanism necessary for ovulation. In vivo CRISPR-Cas9 editing was used to achieve a 60-70% knockdown in estrogen receptor alpha (ESR1) expression by GABA neurons located within the region of the rostral periventricular of the third ventricle (RP3V) and medial preoptic nuclei (MPN) in adult female mice. Mice exhibited variable reproductive phenotypes with the only significant finding being those mice with bilateral ESR1 deletion in RP3V GABA neurons that had reduced cFos expression in GnRH neurons at the time of the surge. One sub-population of RP3V GABA neurons expresses kisspeptin. Re-grouping ESR1-edited mice on the basis of their RP3V kisspeptin expression revealed a highly consistent phenotype; mice with a near complete loss of kisspeptin immunoreactivity displayed constant estrus and failed to exhibit surge activation but retained pulsatile LH secretion. These observations demonstrate ESR1-expressing GABA-kisspeptin neurons in the RP3V are essential for the murine preovulatory LH surge mechanism.

The thyroid gland is susceptible to abnormal epithelial cell growth, often resulting in thyroid dysfunction. The serine-threonine protein kinase mechanistic target of rapamycin (mTOR) regulates cellular metabolism, proliferation, and growth through two different protein complexes, mTORC1 and mTORC2. The PI3K-Akt-mTORC1 pathways overactivity is well associated with heightened aggressiveness in thyroid cancer, but recent studies indicate the involvement of mTORC2 as well. To elucidate mTORC1s role in thyrocytes, we developed a novel mouse model with mTORC1 gain of function in thyrocytes by deleting Tuberous Sclerosis Complex 2 (TSC2), an intracellular inhibitor of mTORC1. The resulting TPO-TSC2KO mice exhibited a significant reduction in TSC2 levels, leading to a six-fold increase in mTORC1 activity. Thyroid glands of both male and female TPO-TSC2KO mice displayed rapid enlargement and continued growth throughout life, accompanied by heterogeneity among thyroid follicles, larger follicles, increased colloid and epithelium. We observed elevated thyrocyte proliferation as indicated by Ki67 staining and elevated Cyclin D3 expression in the TPO-TSC2KO mice. mTORC1 activation resulted in a progressive downregulation of key genes involved in thyroid hormone (TH) biosynthesis, including thyroglobulin, thyroid peroxidase, and sodium-iodide symporter (NIS), while TTF1, PAX8, and MCT8 mRNA levels remained unaffected. NIS protein expression was also diminished in TPO-TSC2KO mice. Treatment with the mTORC1 inhibitor rapamycin prevented thyroid mass expansion and restored the gene expression alterations in TPO-TSC2KO mice. Although T4, T3 and TSH plasma levels were normal at 2 months of age, a slight decrease in T4 and an increase in TSH levels were observed at 6 and 12 months of age while T3 remained similar in TPO-TSC2KO compared to littermate control mice. TPO-TSC2KO mice aged to 12 months or older developed aberrant thyroid conditions, including follicular hyperplasia, inflammation, and thyroid tumors. In conclusion, our thyrocyte-specific mouse model reveals that mTORC1 activation inhibits TH biosynthesis, suppresses thyrocyte gene expression, and promotes growth and proliferation. Chronic mTORC1 activation leads to thyroid tumor formation, highlighting the role of mTORC1 in thyroid dysfunction and tumorigenesis.

Aim/HypothesisLong non-coding RNAs (lncRNAs) are emerging as crucial regulators of beta cell development and function. Here, we investigate roles for an antisense lncRNA expressed from the Pax6 locus (annotated as Pax6os1 in mice and PAX6-AS1 in humans) in beta cell identity and functionality. MethodsPax6os1 expression was silenced in MIN6 cells using siRNAs and changes in gene expression were determined by RNA sequencing or qRT-PCR. Mice inactivated for Pax6os1 and human PAX6-AS1-null EndoC-{beta}H1 cells, were generated using CRISPR/Cas9 technology. Human islets were infected with lentiviral vectors bearing a targeted shRNA or PAX6-AS1, which were used to silence or overexpress, respectively, the lncRNA. RNA sequencing or RT-qPCR were used to measure transcriptomic changes and RNA pulldown in mice and human cells followed by mass spectrometry/western blot were performed to explore RNA protein interactions. ResultsPax6os1/PAX6-AS1 expression was upregulated at high glucose concentrations in derived beta cell lines as well as in mouse and human islets, and in pancreatic islets isolated from mice fed a high fat diet (n=6, p=0.003) and patients with type 2 diabetes (n=11-5, p<0.01). Silencing or deletion of Pax6os1/PAX6-AS1 in MIN6 or EndoC-{beta}H1cells increased the expression of several {beta}-cell signature genes, including PDX1 and INS. Female, but not male, Pax6os1 null mice fed a high fat diet showed slightly enhanced glucose clearance. ShRNA-mediated silencing of PAX6-AS1 in human islets robustly increased INS mRNA, enhanced glucose-stimulated insulin secretion and calcium dynamics, while overexpression of the lncRNA exerted opposing effects. Pax6os1/AS-1 interacted with histones H3 and H4 in mouse and human cells, indicating a possible role for this lncRNA in histone modifications in both species. ConclusionsIncreased expression of PAX6-AS1 at high glucose levels may impair beta cell functionality and thus contribute to the development of type 2 diabetes. Thus, targeting PAX6-AS1 may provide a promising strategy to enhance insulin secretion and improve glucose homeostasis in this disease. Research in contextO_ST_ABSWhat is already known about the subject?C_ST_ABSLong non-coding RNAs (lncRNAs) are crucial components of the pancreatic islet regulome, whose misexpression may contribute to the development of diabetes. What is the key question?Is the lncRNA Pax6os1/PAX6-AS1 involved in beta cell functionality and type 2 diabetes? What are the new findings?The expression of Pax6os1/PAX6-AS1 is upregulated in mice fed a high fat diet and in pancreatic islets from type 2 diabetes donors. Overexpression of PAX6-AS1 in human pancreatic islets reduces insulin expression, glucose stimulated secretion and intracellular calcium dynamics. Silencing PAX6-AS1 in human pancreatic islets upregulates insulin expression, enhances glucose stimulated insulin secretion and increases intracellular calcium dynamics. How may this impact the clinic in the foreseeable future?Understanding the genetic factors induced by high glucose/obesity involved in beta cell dysfunction is crucial for the development of new therapies to treat T2D.

Follicle-stimulating hormone (FSH) is traditionally known for its role in reproduction, but recent studies suggest it may also influence metabolic processes. This study aimed to examine FSH receptor (FSHR) expression in human pancreatic islets and the direct effects of FSH on insulin secretion, as well as explore FSHs metabolic role during puberty, focusing on enhanced insulin secretion during this critical period. FSHR gene and protein expression were detected in isolated human pancreatic islets and co-localized with insulin-producing beta-cells. Additionally, FSH at prepubertal (0.1 IU/L) and pubertal concentrations (10 IU/L) significantly enhanced glucose-stimulated insulin secretion (GSIS) and increased intracellular cAMP concentrations in intact human pancreatic islets. In children with obesity from the Beta-JUDO cohort (n=608), plasma FSH levels were positively associated with several insulin secretion indices, particularly in pubertal children. These findings suggest that FSH has significant metabolic roles beyond reproduction, involving insulin secretion and potentially contributing to puberty-related hyperinsulinemia and insulin resistance.