Pituitary lineage determination by the Prophet of Pit-1 homeodomain factor defective in Ames dwarfism

Impact of visceral adipose tissue on longevity and metabolic health: a comparative study of gene expression in perirenal and epididymal fat of Ames dwarf mice

Emerging research underscores the pivotal role of adipose tissue in regulating systemic aging processes, particularly when viewed through the lens of the endocrine hypotheses of aging. This study delves into the unique adipose characteristics in an important animal model of aging - the long-lived Ames dwarf (df/df) mice. Characterized by a Prop1df gene mutation, these mice exhibit a deficiency in growth hormone (GH), prolactin, and TSH, alongside extremely low circulating IGF-1 levels. Intriguingly, while surgical removal of visceral fat (VFR) enhances insulin sensitivity in normal mice, it paradoxically increases insulin resistance in Ames dwarfs. This suggests an altered profile of factors produced in visceral fat in the absence of GH, indicating a unique interplay between adipose tissue function and hormonal influences in these models. Our aim was to analyze the gene expression related to lipid and glucose metabolism, insulin pathways, inflammation, thermoregulation, mitochondrial biogenesis, and epigenetic regulation in the visceral (perirenal and epididymal) adipose tissue of Ames dwarf and normal mice. Our findings reveal an upregulation in the expression of key genes such as Lpl, Adrβ3, Rstn, Foxo1, Foxo3a, Irs1, Cfd, Aldh2, Il6, Tnfα, Pgc1α, Ucp2, and Ezh2 in perirenal and Akt1, Foxo3a, PI3k, Ir, Acly, Il6, Ring1a, and Ring 1b in epididymal fat in df/df mice. These results suggest that the longevity phenotype in Ames dwarfs, which is determined by peripubertal GH/IGF-1 levels, may also involve epigenetic reprogramming of adipose tissue influenced by hormonal changes. The increased expression of genes involved in metabolic regulation, tumor suppression, mitochondrial biogenesis, and insulin pathways in Ames dwarf mice highlights potentially beneficial aspects of this model, opening new avenues for understanding the molecular underpinnings of longevity and aging.

Gene Misexpression in a Smoc2+ve/Sox2-Low Population in Juvenile Prop1-Mutant Pituitary Gland

Mutations in the pituitary-specific transcription factor Prophet of Pit-1 (PROP1) are the most common genetic etiology of combined pituitary hormone deficiency (CPHD). CPHD is associated with short stature, attributable to growth hormone deficiency and/or thyroid-stimulating hormone deficiency, as well as hypothyroidism and infertility. Pathogenic lesions impair pituitary development and differentiation of endocrine cells. We performed single-cell RNA sequencing of pituitary cells from a wild-type and a Prop1-mutant P4 female mouse to elucidate population-specific differential gene expression. We observed a Smoc2+ve population that expressed low Sox2, which trajectory analyses suggest are a transitional cell state as stem cells differentiate into endocrine cells. We also detected ectopic expression of Sox21 in these cells in the Prop1df/df mutant. Prop1-mutant mice are known to overexpress Pou3f4, which we now show to be also enriched in this Smoc2+ve population. We sought to elucidate the role of Pou3f4 during pituitary development and to determine the contributions of Pou3f4 upregulation to pituitary disease by utilizing double-mutant mice lacking both Prop1 and Pou3f4. However, our data showed that Pou3f4 is not required for normal pituitary development and function. Double mutants further demonstrated that the upregulation of Pou3f4 was not causative for the overexpression of Sox21. These data indicate loss of Pou3f4 is not a potential cause of CPHD, and further studies may investigate the functional consequence of upregulation of Pou3f4 and Sox21, if any, in the novel Smoc2+ve cell population.

A review of complex hormone regulation in thyroid cancer: novel insights beyond the hypothalamus-pituitary-thyroid axis

Like the ovaries and prostate, the thyroid exhibits characteristic hormone secretion and regulation. Thyroid cancer (TC), especially differentiated thyroid carcinoma, has typical sex-specific and age-specific hormone-driven clinical features. Previous research has primarily focused on the effects of thyroid stimulating hormone, thyroid hormones, and estrogens on the onset and progression of TC, while the roles of growth hormone (GH), androgens, and glucocorticoids have largely been overlooked. Similarly, few studies have investigated the interactions between hormones and hormone systems. In fact, numerous studies of patients with acromegaly have shown that serum levels of GH and insulin-like growth factor-1 (IGF-1) may be associated with the onset and progression of TC, although the influences of age, sex, and other risk factors, such as obesity and stress, remain unclear. Sex hormones, the GH/IGF axis, and glucocorticoids are likely involved in the onset and progression of TC by regulating the tumor microenvironment and metabolism. The aim of this review was to clarify the roles of hormones and hormone systems in TC, especially papillary thyroid carcinoma, as references for further investigations.

Obesity disrupts the pituitary-hepatic UPR communication leading to NAFLD progression

Obesity alters levels of pituitary hormones that govern hepatic immune-metabolic homeostasis, dysregulation of which leads to nonalcoholic fatty liver disease (NAFLD). However, the impact of obesity on intra-pituitary homeostasis is largely unknown. Here, we uncovered a blunted unfolded protein response (UPR) but elevated inflammatory signatures in pituitary glands of obese mice and humans. Furthermore, we found that obesity inflames the pituitary gland, leading to impaired pituitary inositol-requiring enzyme 1α (IRE1α)-X-box-binding protein 1 (XBP1) UPR branch, which is essential for protecting against pituitary endocrine defects and NAFLD progression. Intriguingly, pituitary IRE1-deletion resulted in hypothyroidism and suppressed the thyroid hormone receptor B (THRB)-mediated activation of Xbp1 in the liver. Conversely, activation of the hepatic THRB-XBP1 axis improved NAFLD in mice with pituitary UPR defect. Our study provides the first evidence and mechanism of obesity-induced intra-pituitary cellular defects and the pathophysiological role of pituitary-liver UPR communication in NAFLD progression.

Primary Cilia are Required for Cell-Type Determination and Angiogenesis in Pituitary Development

The functional maturation of the pituitary gland requires adequate cell differentiation and vascular network formation. Although spatiotemporal signaling and transcription factors are known to govern pituitary development, the involvement of primary cilia, nonmoving hair-like organelles, remains unclear. In this study, we uncovered the contribution of primary cilia to cell-type determination and vascular network formation during pituitary development. Homozygous knockout mice lacking a ciliary kinase, Dyrk2-/-, exhibit abnormalities in ciliary structure and pituitary hypoplasia, accompanied by varying degrees of failure in differentiation among all types of hormone-producing cells in the anterior lobe. Aberrations in cell differentiation in Dyrk2-/- mice arise from a decrease in the expression of crucial transcription factors, Lhx4, Lhx3, and Prop1, resulting from the inactivity of Hedgehog (Hh) signaling during the early stages of development. Furthermore, the loss of Dyrk2 results in vascular system abnormalities during the middle to late stages of development. Mechanistically, transcriptome analyses revealed the downregulation of vitronectin-integrin αvβ3-VEGFR2 signaling, essential for orchestrating vascular development. Collectively, our findings demonstrate that primary cilia play a pivotal role as critical regulators of cell survival, cell determination, and angiogenesis during pituitary gland development through the activation of Hh signaling. These findings expand our understanding of the potential link between pituitary dysfunction in human disorders and ciliopathies.

Common and uncommon mouse models of growth hormone deficiency

Mouse models of growth hormone deficiency (GHD) have provided important tools for uncovering the various actions of GH. Nearly 100 years of research using these mouse lines has greatly enhanced our knowledge of the GH/IGF-1 axis. Some of the shared phenotypes of the five "common" mouse models of GHD include reduced body size, delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, and enhanced insulin sensitivity. Since these common mouse lines outlive their normal-sized littermates - and have protection from age-associated disease - they have become important fixtures in the aging field. On the other hand, the twelve "uncommon" mouse models of GHD described herein have tremendously divergent health outcomes ranging from beneficial aging phenotypes (similar to those described for the common models) to extremely detrimental features (such as improper development of the CNS, numerous sensory organ defects, and embryonic lethality). Moreover, advancements in next generation sequencing technologies have led to the identification of an expanding array of genes that are recognized as causative agents to numerous rare syndromes with concomitant GHD. Accordingly, this review provides researchers with a comprehensive up-to-date collection of the common and uncommon mouse models of GHD that have been used to study various aspects of physiology and metabolism associated with multiple forms of GHD. For each mouse line presented, the closest comparable human syndromes are discussed providing important parallels to the clinic.

The Musashi RNA binding proteins direct the translational activation of key pituitary mRNAs

The pituitary functions as a master endocrine gland that secretes hormones critical for regulation of a wide variety of physiological processes including reproduction, growth, metabolism and stress responses. The distinct hormone-producing cell lineages within the pituitary display remarkable levels of cell plasticity that allow remodeling of the relative proportions of each hormone-producing cell population to meet organismal demands. The molecular mechanisms governing pituitary cell plasticity have not been fully elucidated. Our recent studies have implicated a role for the Musashi family of sequence-specific mRNA binding proteins in the control of pituitary hormone production, pituitary responses to hypothalamic stimulation and modulation of pituitary transcription factor expression in response to leptin signaling. To date, these actions of Musashi in the pituitary appear to be mediated through translational repression of the target mRNAs. Here, we report Musashi1 directs the translational activation, rather than repression, of the Prop1, Gata2 and Nr5a1 mRNAs which encode key pituitary lineage specification factors. We observe that Musashi1 further directs the translational activation of the mRNA encoding the glycolipid Neuronatin (Nnat) as determined both in mRNA reporter assays as well as in vivo. Our findings suggest a complex bifunctional role for Musashi1 in the control of pituitary cell function.

Neural plate progenitors give rise to both anterior and posterior pituitary cells

The pituitary is the master neuroendocrine gland, which regulates body homeostasis. It consists of the anterior pituitary/adenohypophysis harboring hormones producing cells and the posterior pituitary/neurohypophysis, which relays the passage of hormones from the brain to the periphery. It is accepted that the adenohypophysis originates from the oral ectoderm (Rathke's pouch), whereas the neural ectoderm contributes to the neurohypophysis. Single-cell transcriptomics of the zebrafish pituitary showed that cyp26b1-positive astroglial pituicytes of the neurohypophysis and prop1-positive adenohypophyseal progenitors expressed common markers implying lineage relatedness. Genetic tracing identifies that, in contrast to the prevailing dogma, neural plate precursors of zebrafish (her4.3+) and mouse (Sox1+) contribute to both neurohypophyseal and a subset of adenohypophyseal cells. Pituicyte-derived retinoic-acid-degrading enzyme Cyp26b1 fine-tunes differentiation of prop1+ progenitors into hormone-producing cells. These results challenge the notion that adenohypophyseal cells are exclusively derived from non-neural ectoderm and demonstrate that crosstalk between neuro- and adeno-hypophyseal cells affects differentiation of pituitary cells.

Missing pieces of the pituitary puzzle: participation of extra-adenohypophyseal placode-lineage cells in the adult pituitary gland

The pituitary gland is a major endocrine tissue composing of two distinct entities, the adenohypophysis (anterior pituitary, cranial placode origin) and the neurohypophysis (posterior pituitary, neural ectoderm origin), and plays important roles in maintaining vital homeostasis. This tissue is maintained by a slow, consistent cell-renewal system of adult stem/progenitor cells. Recent accumulating evidence shows that neural crest-, head mesenchyme-, and endoderm lineage cells invade during pituitary development and contribute to the maintenance of the adult pituitary gland. Based on these novel observations, this article discusses whether these lineage cells are involved in pituitary organogenesis, maintenance, regeneration, dysplasia, or tumors.

A cluster of X-linked miRNAs are de-repressed with age in mouse liver and target growth hormone signaling

Growth hormone (GH) signaling influences lifespan in a wide variety of mammalian species. We previously reported that a cluster of miRNAs located on the X-chromosome are de-repressed with age in male mouse liver, and a subset, the mir-465 family, can directly attenuate expression of the growth hormone receptor (GHR) in vitro leading to a reduction in GH signaling. Here we show that this cluster of miRNAs is also upregulated in the liver with age in females, and that calorie restriction and the Ames dwarf genotype, both known to delay aging, attenuate the upregulation of the miRNA cluster. Upregulation of mir-465 in vivo leads to a reduction in GHR mRNA in the liver and an attenuation of GH signaling, indicated by a reduction in GHR, IGF-1, IGFBP3, and ALS mRNA expression. There is a corresponding reduction in IGF-1 protein levels in the liver and plasma. These results suggest that the age-associated upregulation of the X-chromosomal cluster of miRNAs could influence lifespan.

PICK1-Deficient Mice Maintain Their Glucose Tolerance During Diet-Induced Obesity

Context

Metabolic disorders such as obesity represent a major health challenge. Obesity alone has reached epidemic proportions, with at least 2.8 million people worldwide dying annually from diseases caused by overweight or obesity. The brain-metabolic axis is central to maintain homeostasis under metabolic stress via an intricate signaling network of hormones. Protein interacting with C kinase 1 (PICK1) is important for the biogenesis of various secretory vesicles, and we have previously shown that PICK1-deficient mice have impaired secretion of insulin and growth hormone.

Objective

The aim was to investigate how global PICK1-deficient mice respond to high-fat diet (HFD) and assess its role in insulin secretion in diet-induced obesity.

Methods

We characterized the metabolic phenotype through assessment of body weight, composition, glucose tolerance, islet morphology insulin secretion in vivo, and glucose-stimulated insulin secretion ex vivo.

Results

PICK1-deficient mice displayed similar weight gain and body composition as wild-type (WT) mice following HFD. While HFD impaired glucose tolerance of WT mice, PICK1-deficient mice were resistant to further deterioration of their glucose tolerance compared with already glucose-impaired chow-fed PICK1-deficient mice. Surprisingly, mice with β-cell-specific knockdown of PICK1 showed impaired glucose tolerance both on chow and HFD similar to WT mice.

Conclusion

Our findings support the importance of PICK1 in overall hormone regulation. However, importantly, this effect is independent of the PICK1 expression in the β-cell, whereby global PICK1-deficient mice resist further deterioration of their glucose tolerance following diet-induced obesity.

Mechanisms of ageing: growth hormone, dietary restriction, and metformin

Tackling the mechanisms underlying ageing is desirable to help to extend the duration and improve the quality of life. Life extension has been achieved in animal models by suppressing the growth hormone-insulin-like growth factor 1 (IGF-1) axis and also via dietary restriction. Metformin has become the focus of increased interest as a possible anti-ageing drug. There is some overlap in the postulated mechanisms of how these three approaches could produce anti-ageing effects, with convergence on common downstream pathways. In this Review, we draw on evidence from both animal models and human studies to assess the effects of suppression of the growth hormone-IGF-1 axis, dietary restriction, and metformin on ageing.

Making a head: Neural crest and ectodermal placodes in cranial sensory development

During development of the vertebrate sensory system, many important components like the sense organs and cranial sensory ganglia arise within the head and neck. Two progenitor populations, the neural crest, and cranial ectodermal placodes, contribute to these developing vertebrate peripheral sensory structures. The interactions and contributions of these cell populations to the development of the lens, olfactory, otic, pituitary gland, and cranial ganglia are vital for appropriate peripheral nervous system development. Here, we review the origins of both neural crest and placode cells at the neural plate border of the early vertebrate embryo and investigate the molecular and environmental signals that influence specification of different sensory regions. Finally, we discuss the underlying molecular pathways contributing to the complex vertebrate sensory system from an evolutionary perspective, from basal vertebrates to amniotes.

The molecular pathogenesis of craniopharyngiomas

Research from the last 20 years has provided important insights into the molecular pathogenesis of craniopharyngiomas (CPs). Besides the well-known clinical and histological differences between the subtypes of CPs, adamantinomatous (ACP) and papillary (PCP) craniopharyngiomas, other molecular differences have been identified, further elucidating pathways related to the origin and development of such tumors. The present minireview assesses current knowledge on embryogenesis and the genetic, epigenetic, transcriptomic, and signaling pathways involved in the ACP and PCP subtypes, revealing the similarities and differences in their profiles. ACP and PCP subtypes can be identified by the presence of mutations in CTNNB1 and BRAF genes, with prevalence around 60% and 90%, respectively. Therefore, β-catenin accumulates in the nucleus-cytoplasm of cell clusters in ACPs and, in PCPs, cell immunostaining with specific antibody against the V600E-mutated protein can be seen. Distinct patterns of DNA methylation further differentiate ACPs and PCPs. In addition, research on genetic and epigenetic changes and tumor microenvironment specificities have further clarified the development and progression of the disease. No relevant transcriptional differences in ACPs have emerged between children and adults. In conclusion, ACPs and PCPs present diverse genetic signatures and each subtype is associated with specific signaling pathways. A better understanding of the pathways related to the growth of such tumors is paramount for the development of novel targeted therapeutic agents.

Pituitary Stem Cell Regulation by Zeb2 and BMP Signaling

Epithelial to mesenchymal transition (EMT) is important for many developing organs, and for wound healing, fibrosis, and cancer. Pituitary stem cells undergo an EMT-like process as they migrate and initiate differentiation, but little is known about the input of signaling pathways or the genetic hierarchy of the transcriptional cascade. Prop1 mutant stem cells fail to undergo changes in cellular morphology, migration, and transition to the Pou1f1 lineage. We used Prop1 mutant mice to identify the changes in gene expression that are affiliated with EMT-like processes. BMP and TGF-β family gene expression was reduced in Prop1 mutants and Elf5, a transcription factor that characteristically suppresses EMT, had elevated expression. Genes involved in cell-cell contact such as cadherins and claudins were elevated in Prop1 mutants. To establish the genetic hierarchy of control, we manipulated gene expression in pituitary stem cell colonies. We determined that the EMT inducer, Zeb2, is necessary for robust BMP signaling and repression of Elf5. We demonstrated that inhibition of BMP signaling affects expression of target genes in the Id family, but it does not affect expression of other EMT genes. Zeb2 is necessary for expression of the SHH effector gene Gli2. However, knock down of Gli2 has little effect on the EMT-related genes, suggesting that it acts through a separate pathway. Thus, we have established the genetic hierarchy involved in the transition of pituitary stem cells to differentiation.

Pituitary multi-hormone cells in mammals and fish: history, origin, and roles

The vertebrate pituitary is a dynamic organ, capable of adapting its hormone secretion to different physiological demands. In this context, endocrinologists have debated for the past 40 years if endocrine cells are mono- or multi-hormonal. Since its establishment, the dominant "one cell, one hormone" model has been continuously challenged. In mammals, the use of advanced multi-staining approaches, sensitive gene expression techniques, and the analysis of tumor tissues have helped to quickly demonstrate the existence of pituitary multi-hormone cells. In fishes however, only recent advances in imaging and transcriptomics have enabled the identification of such cells. In this review, we first describe the history of the discovery of cells producing multiple hormones in mammals and fishes. We discuss the technical limitations that have led to uncertainties and debates. Then, we present the current knowledge and hypotheses regarding their origin and biological role, which provides a comprehensive review of pituitary plasticity.

Characterization of pituitary stem/progenitor cell populations in spontaneous dwarf rats

Spontaneous dwarf rat (SDR) is a primary experimental animal model for the study of pituitary dwarfism with a point mutation in the Gh gene encoding growth hormone (GH). In previous studies, SDR has been reported to be associated with the GH deficiency as well as combined hormone deficiencies, the cause of which is unknown. In this study, we focused on the characteristics of pituitary stem/progenitor cell populations, which are a source of hormone-producing cells, in SDR. Immunofluorescence and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analyses confirmed the defects in GH-producing cells, the decreased number of prolactin- and thyroid-stimulating hormone-producing cells, and the increased number of adrenocorticotropic hormone- and luteinizing hormone-producing cells. Additionally, qRT-PCR analysis showed increased Prop1 (an embryonic stem/progenitor cell marker) expression and decreased S100b (a putative adult stem/progenitor cell marker) expression in SDRs. In the pituitary stem/progenitor cell niche, the marginal cell layer, the proportion of SOX2/PROP1-double positive cells was higher in adult SDRs than in adult Sprague Dawley (SD) rats but that of SOX2/S100β-double positive cells was much lower. Furthermore, the number of SOX2/PROP1-double positive cells in SD rats significantly decreased with growth; however, the decrease was smaller in SDRs. In contrast, the number of SOX2/S100β-double positive cells in SD rats significantly increased with growth; however, they were few in SDRs. Thus, S100β-positive pituitary stem/progenitor cells failed to settle in pituitary dwarfism with the Gh gene mutation, leading to multiple hypopituitarism including GH deficiency.

Early Life Interventions Can Shape Aging

It is well documented that the environment of the developing fetus, including availability of nutrients and presence of toxins, can have major impact on adult phenotype, age-related traits and risk of chronic disease. There is also accumulating evidence that postnatal environment can impact adult characteristics related to evolutionary fitness, health, and aging. To determine whether early life hormonal interventions can alter trajectory of aging, we have examined the effects of early life growth hormone (GH) replacement therapy in Prop1^df (Ames dwarf) mice which are GH deficient and remarkably long lived. Twice-daily GH injections between the ages of two and eight weeks completely normalized ("rescued") a number of adult metabolic characteristics believed to contribute to extended longevity of these mutants. Importantly, longevity of Ames dwarf mice was reduced by early life GH treatment. This was associated with histone H3 modifications. We conclude that the trajectory of mammalian aging can be modified by early life interventions. Mechanistic links among interventions during postnatal development, adult metabolic characteristics, aging, and longevity, apparently involve epigenetic phenomena.

miR-146a-5p modulates cellular senescence and apoptosis in visceral adipose tissue of long-lived Ames dwarf mice and in cultured pre-adipocytes

MicroRNAs (miRNAs) are potent regulators of multiple biological processes. Previous studies have demonstrated that miR-146a-5p increases in normal mice during aging, while long-living Ames dwarf (df/df) mice maintain youthful levels of this miRNA. The aim of this study was to elucidate the involvement of miR-146a-5p in modulating cellular senescence and apoptosis in visceral adipose tissue of df/df mice and cultured pre-adipocytes. To test the effects of miR-146a-5p overexpression on visceral adipose tissue, wild-type, and df/df mice, were treated with miRNA-negative control-base and df/df were transfected with 4 or 8 µg/g of a miR-146a-5p mimetic, respectively. Effects of miR-146a-5p overexpression were also evaluated in 3T3-L1 cells cultured under high and normal glucose conditions. Treatment with miR-146a-5p mimetic increased cellular senescence and inflammation and decreased pro-apoptotic factors in visceral adipose tissue of df/df mice. The miR-146a-5p mimetic induced similar effects in 3T3-L1 cells cultivated at normal but not high glucose levels. Importantly, 3T3-L1 HG cells in high glucose conditions showed significantly higher expression of miR-146a-5p than 3T3-L1 grown in normal glucose conditions. These results indicate that miR-146a-5p can be a marker for cellular senescence. This miRNA represents one of the significant SASP factors that if not precisely regulated, can accentuate inflammatory responses and stimulate senescence in surrounding non-senescent cells. The role of miR-146a-5p is different in healthy versus stressed cells, suggesting potential effects of this miRNA depend on overall organismal health, aging, and metabolic state.

Dwarf mice as models for reproductive ageing research

Dwarf mice are characterized by extremely long lifespan, delayed ovarian ageing, altered metabolism, lower age-related oxidative damage and cancer incidence rate. Snell dwarf, Ames dwarf and growth hormone receptor knockout mice are three commonly used models. Despite studies focusing on ageing and metabolism, the reproductive features of female dwarf mice have also attracted interest over the last decade. Female Snell and Ames dwarf mice have regular oestrous cycles and ovulation rates, as in normal mice, but with a larger ovarian reserve and delayed ovarian ageing. The primordial follicle reserve in dwarf mice is greater than in normal littermates. Anti-Müllerian hormone (AMH) concentration is seven times higher in Ames dwarf mice than in their normal siblings, and ovarian transcriptomic profiling showed distinctive patterns in older Ames dwarf mice, especially enriched in inflammatory and immune response-related pathways. In addition, microRNA profiles also showed distinctive differences in Ames dwarf mice compared with normal control littermates. This review aims to summarize research progress on dwarf mice as models in the reproductive ageing field. Investigations focusing on the mechanisms of their reserved reproductive ability are much needed and are expected to provide additional molecular biological bases for the clinical practice of reproductive medicine in women.

New insights into the role and origin of pituitary S100β-positive cells

In the anterior pituitary, S100β protein (S100β) has been assumed to be a marker of folliculo-stellate cells, which are one of the non-hormone-producing cells existing in the parenchyma of the adult anterior lobe and are composed of subpopulations with various functions. However, recent accumulating studies on S100β-positive cells, including non-folliculo-stellate cells lining the marginal cell layer (MCL), have shown the novel aspect that most S100β-positive cells in the MCL and parenchyma of the adult anterior lobe are positive for sex determining region Y-box 2 (SOX2), a marker of pituitary stem/progenitor cells. From the viewpoint of SOX2-positive cells, the majority of these cells in the MCL and in the parenchyma are positive for S100β, suggesting that S100β plays a role in the large population of stem/progenitor cells in the anterior lobe of the adult pituitary. Reportedly, S100β/SOX2-double positive cells are able to differentiate into hormone-producing cells and various types of non-hormone-producing cells. Intriguingly, it has been demonstrated that extra-pituitary lineage cells invade the pituitary gland during prenatal pituitary organogenesis. Among them, two S100β-positive populations have been identified: one is SOX2-positive population which invades at the late embryonic period through the pituitary stalk and another is a SOX2-negative population that invades at the middle embryonic period through Atwell's recess. These two populations are likely the substantive origin of S100β-positive cells in the postnatal anterior pituitary, while S100β-positive cells emerging from oral ectoderm-derived cells remain unclear.

Male and female gonadal ageing: its impact on health span and life span

Ageing is linked to changes in the hypothalamic-pituitary-gonadal axis and a progressive decline in gonadal function. While women become infertile when they enter menopause, fertility decline in ageing men does not necessarily involve a complete cessation of spermatogenesis. Gonadal dysfunction in elderly people is characterized by morphological, endocrine and metabolic alterations affecting the reproductive function and quality of life. With advancing age, sexuality turns into a critical emotional and physical factor actually defining the number of years that ageing people live a healthy life. Gonadal ageing correlates with comorbidities and an increased risk of age-related diseases including diabetes, kidney problems, cardiovascular failures and cancer. This article briefly summarizes the current state of knowledge on ovarian and testicular senescence, explores the experimental models used in the study of gonadal ageing, and describes the local pro-inflammatory, oxidative and apoptotic events and the associated signalling pathways that take place in the gonads while people get older. Overall, literature reports that ageing exacerbates a mutual crosstalk among oxidative stress, apoptosis and the inflammatory response in the gonads leading to detrimental effects on fertility. Data also highlight the clinical implications of novel therapeutic interventions using antioxidant, anti-apoptotic and anti-inflammatory drugs on health span and life span.

Growth hormone increases DNA damage in ovarian follicles and macrophage infiltration in the ovaries

Evidence points to an important role of the growth hormone (GH) in the aging process and longevity. GH-deficient mice are smaller, live longer than normal littermates, and females have an increased ovarian reserve. The aim of the study was to evaluate the role of GH in the ovarian reserve by evaluating DNA damage, macrophage infiltration, and granulosa cell number in primordial and primary follicles. Experiment 1 used GH-deficient Ames dwarf mice (df/df, n = 12) and their normal littermates (N/df, n = 12), receiving GH or saline injections. Experiment 2 included transgenic mice overexpressing bovine GH (bGH) (n = 6) and normal mice (N, n = 6). DNA damage (anti-γH2AX) and macrophage counting (anti-CD68) were evaluated by immunofluorescence. Female df/df mice had lower γH2AX foci intensity in both oocytes and granulosa cells of primordial and primary follicles (p < 0.05), indicating fewer DNA double-strand breaks (DSBs). GH treatment increased DSBs in both df/df and N/df mice. Inversely, bGH mice had a higher quantity of DSBs in both oocytes and granulosa cells of primordial and primary follicles (p < 0.05). Df/df mice showed ovarian tissue with less macrophage infiltration than N/df mice (p < 0.05) and GH treatment increased macrophage infiltration (p < 0.05). In contrast, bGH mice had ovarian tissue with more macrophage infiltration compared to normal mice (p < 0.05). The current study shows that GH increases DNA DSBs in oocytes and granulosa cells and raises macrophage infiltration in the ovaries, pointing to the role of the GH/IGF-I axis in maintenance of oocyte DNA integrity and ovarian macrophage infiltration in mice.

Pituitary disease and recovery: How are stem cells involved?

The pituitary gland embodies our endocrine hub and rigorously regulates hormone balances in the body, thereby ruling over vital developmental and physiological processes. Pituitary dysfunction and disease strongly impact the organism's biology. Physical damage, tumour development and ageing all negatively affect pituitary state and functionality. On top of its hormone-producing cells, the pituitary contains a population of stem cells. Not only their physiological role is still largely unknown, also whether or how these stem cells are involved in pituitary disease and recovery from defective functionality remains enigmatic. Here, we summarize what is known on the phenotypical and functional behaviour of pituitary stem cells in diseased or dysfunctional gland, as particularly caused by injury, tumourigenesis and ageing.

Physiological and metabolic characteristics of novel double-mutant female mice with targeted disruption of both growth hormone-releasing hormone and growth hormone receptor

Mice with disruptions of growth hormone-releasing hormone (GHRH) or growth hormone receptor (GHR) exhibit similar phenotypes of prolonged lifespan and delayed age-related diseases. However, these two models respond differently to calorie restriction indicating that they might carry different and/or independent mechanisms for improved longevity and healthspan. In order to elucidate these mechanisms, we generated GHRH and GHR double-knockout mice (D-KO). In the present study, we focused specifically on the characteristics of female D-KO mice. The D-KO mice have reduced body weight and enhanced insulin sensitivity compared to wild-type (WT) controls. Growth retardation in D-KO mice is accompanied by decreased GH expression in pituitary, decreased circulating IGF-1, increased high-molecular-weight (HMW) adiponectin, and leptin hormones compared to WT controls. Generalized linear model-based regression analysis, which controls for body weight differences between D-KO and WT groups, shows that D-KO mice have decreased lean mass, bone mineral density, and bone mineral content, but increased adiposity. Indirect calorimetry markers including oxygen consumption, carbon dioxide production, and energy expenditure were significantly lower in D-KO mice relative to the controls. In comparison with WT mice, the D-KO mice displayed reduced respiratory exchange ratio (RER) values only during the light cycle, suggesting a circadian-related metabolic shift toward fat utilization. Interestingly, to date survival data suggest extended lifespan in D-KO female mice.

Activating mutations in BRAF disrupt the hypothalamo-pituitary axis leading to hypopituitarism in mice and humans

Germline mutations in BRAF and other components of the MAPK pathway are associated with the congenital syndromes collectively known as RASopathies. Here, we report the association of Septo-Optic Dysplasia (SOD) including hypopituitarism and Cardio-Facio-Cutaneous (CFC) syndrome in patients harbouring mutations in BRAF. Phosphoproteomic analyses demonstrate that these genetic variants are gain-of-function mutations leading to activation of the MAPK pathway. Activation of the MAPK pathway by conditional expression of the BrafV600E/+ allele, or the knock-in BrafQ241R/+ allele (corresponding to the most frequent human CFC-causing mutation, BRAF p.Q257R), leads to abnormal cell lineage determination and terminal differentiation of hormone-producing cells, causing hypopituitarism. Expression of the BrafV600E/+ allele in embryonic pituitary progenitors leads to an increased expression of cell cycle inhibitors, cell growth arrest and apoptosis, but not tumour formation. Our findings show a critical role of BRAF in hypothalamo-pituitary-axis development both in mouse and human and implicate mutations found in RASopathies as a cause of endocrine deficiencies in humans.

Dynamic Expression of Imprinted Genes in the Developing and Postnatal Pituitary Gland

In mammals, imprinted genes regulate many critical endocrine processes such as growth, the onset of puberty and maternal reproductive behaviour. Human imprinting disorders (IDs) are caused by genetic and epigenetic mechanisms that alter the expression dosage of imprinted genes. Due to improvements in diagnosis, increasing numbers of patients with IDs are now identified and monitored across their lifetimes. Seminal work has revealed that IDs have a strong endocrine component, yet the contribution of imprinted gene products in the development and function of the hypothalamo-pituitary axis are not well defined. Postnatal endocrine processes are dependent upon the production of hormones from the pituitary gland. While the actions of a few imprinted genes in pituitary development and function have been described, to date there has been no attempt to link the expression of these genes as a class to the formation and function of this essential organ. This is important because IDs show considerable overlap, and imprinted genes are known to define a transcriptional network related to organ growth. This knowledge deficit is partly due to technical difficulties in obtaining useful transcriptomic data from the pituitary gland, namely, its small size during development and cellular complexity in maturity. Here we utilise high-sensitivity RNA sequencing at the embryonic stages, and single-cell RNA sequencing data to describe the imprinted transcriptome of the pituitary gland. In concert, we provide a comprehensive literature review of the current knowledge of the role of imprinted genes in pituitary hormonal pathways and how these relate to IDs. We present new data that implicate imprinted gene networks in the development of the gland and in the stem cell compartment. Furthermore, we suggest novel roles for individual imprinted genes in the aetiology of IDs. Finally, we describe the dynamic regulation of imprinted genes in the pituitary gland of the pregnant mother, with implications for the regulation of maternal metabolic adaptations to pregnancy.

Hypothalamic-pituitary organoid generation through the recapitulation of organogenesis

This paper overviews the development and differentiation of the hypothalamus and pituitary gland from embryonic stem (ES) and induced pluripotent stem (iPS) cells. It is important to replicate the developmental process in vivo to create specific cells/organoids from ES/iPS cells. We also introduce the latest findings and discuss future issues for clinical application. Neuroectodermal progenitors are induced from pluripotent stem cells by strictly removing exogenous patterning factors during the early differentiation period. The induced progenitors differentiate into rostral hypothalamic neurons, in particular magnocellular vasopressin⁺  neurons. In three-dimensional cultures, ES/iPS cells differentiate into hypothalamic neuroectoderm and nonneural head ectoderm adjacently. Rathke's pouch-like structures self-organize at the interface between the two layers and generate various endocrine cells, including corticotrophs and somatotrophs. Our next objective is to sophisticate our stepwise methodology to establish a novel transplantation treatment for hypopituitarism and apply it to developmental disease models.

Growth hormone and aging

Growth hormone (GH) actions impact growth, metabolism, and body composition and have been associated with aging and longevity. Lack of GH results in slower growth, delayed maturation, and reduced body size and can lead to delayed aging, increased healthspan, and a remarkable extension of longevity. Adult body size, which is a GH-dependent trait, has a negative association with longevity in several mammalian species. Mechanistic links between GH and aging include evolutionarily conserved insulin/insulin-like growth factors and mechanistic target of rapamycin signaling pathways in accordance with long-suspected trade-offs between anabolic/growth processes and longevity. Height and the rate and regulation of GH secretion have been related to human aging, but longevity is not extended in humans with syndromes of GH deficiency or resistance. However, the risk of age-related chronic disease is reduced in individuals affected by these syndromes and various indices of increased healthspan have been reported.

Mouse models of growth hormone deficiency

Nearly one century of research using growth hormone deficient (GHD) mouse lines has contributed greatly toward our knowledge of growth hormone (GH), a pituitary-derived hormone that binds and signals through the GH receptor and affects many metabolic processes throughout life. Although delayed sexual maturation, decreased fertility, reduced muscle mass, increased adiposity, small body size, and glucose intolerance appear to be among the negative characteristics of these GHD mouse lines, these mice still consistently outlive their normal sized littermates. Furthermore, the absence of GH action in these mouse lines leads to enhanced insulin sensitivity (likely due to the lack of GH's diabetogenic actions), delayed onset for a number of age-associated physiological declines (including cognition, cancer, and neuromusculoskeletal frailty), reduced cellular senescence, and ultimately, extended lifespan. In this review, we provide details about history, availability, growth, physiology, and aging of five commonly used GHD mouse lines.

The Role of Ames Dwarfism and Calorie Restriction on Gut Microbiota

The gut microbiome (GM) represents a large and very complex ecosystem of different microorganisms. There is an extensive interest in the potential role of the GM in different diseases including cancer, diabetes, cardiovascular diseases, and aging. The GM changes over the lifespan and is strongly associated with various age-related diseases. Ames dwarf (df/df) mice are characterized by an extended life- and healthspan, and although these mice are protected from many age-related diseases, their microbiome has not been studied. To determine the role of microbiota on longevity animal models, we investigated the changes in the GM of df/df and normal control (N) mice, by comparing parents before mating and littermate mice at three distinct time points during early life. Furthermore, we studied the effects of a 6-month calorie restriction (CR), the most powerful intervention extending the lifespan. Our data revealed significant changes of the GM composition during early life development, and we detected differences in the abundance of some bacteria between df/df and N mice, already in early life. Overall, the variability of the microbiota by genotype, time-point, and breeding pair showed significant differences. In addition, CR caused significant changes in microbiome according to gastrointestinal (GI) location (distal colon, ileum, and cecum), genotype, and diet. However, the overall impact of the genotype was more prominent than that of the CR. In conclusion, our findings suggest that the gut microbiota plays an important role during postnatal development in long-living df/df mice and CR dietary regimen can significantly modulate the GM.

Intronic variant in POU1F1 associated with canine pituitary dwarfism

The anterior pituitary gland secretes several endocrine hormones, essential for growth, reproduction and other basic physiological functions. Abnormal development or function of the pituitary gland leads to isolated or combined pituitary hormone deficiency (CPHD). At least 30 genes have been associated with human CPHD, including many transcription factors, such as POU1F1. CPHD occurs spontaneously also in mice and dogs. Two affected breeds have been reported in dogs: German Shepherds with a splice defect in the LHX3 gene and Karelian Bear Dogs (KBD) with an unknown genetic cause. We obtained samples from five KBDs presenting dwarfism and abnormal coats. A combined analysis of genome-wide association and next-generation sequencing mapped the disease to a region in chromosome 31 and identified a homozygous intronic variant in the fourth exon of the POU1F1 gene in the affected dogs. The identified variant, c.605-3C>A, resided in the splice region and was predicted to affect splicing. The variant's screening in three new prospective cases, related breeds, and ~ 8000 dogs from 207 breeds indicated complete segregation in KBDs with a carrier frequency of 8%, and high breed-specificity as carriers were found at a low frequency only in Lapponian Herders, a related breed. Our study establishes a novel canine model for CPHD with a candidate POU1F1 defect.

Physiological and metabolic features of mice with CRISPR/Cas9-mediated loss-of-function in growth hormone-releasing hormone

Our previous study demonstrated that the loss of growth hormone releasing hormone (GHRH) results in increased lifespan and improved metabolic homeostasis in the mouse model generated by classical embryonic stem cell-based gene-targeting method. In this study, we targeted the GHRH gene using the CRISPR/Cas9 technology to avoid passenger alleles/mutations and performed in-depth physiological and metabolic characterization. In agreement with our previous observations, male and female GHRH-/- mice have significantly reduced body weight and enhanced insulin sensitivity when compared to wild type littermates. Dual-energy X-ray absorptiometry showed that there were significant decreases in lean mass, bone mineral content and density, and a dramatic increase in fat mass of GHRH-/- mice when compared to wild type littermates. Indirect calorimetry measurements showed dramatic reductions in oxygen consumption, carbon dioxide production and energy expenditure in GHRH-/- mice compared to wild type mice in both light and dark cycles. Respiratory exchange ratio was significantly lower in GHRH-/- mice during the light cycle, but not during the dark cycle, indicating a circadian related metabolic shift towards fat utilization in the growth hormone deficient mice. The novel CRISPR/Cas9 GHRH-/- mice are exhibiting the consistent and unique physiological and metabolic characteristics, which might mediate the longevity effects of growth hormone deficiency in mice.

Development of the Pituitary Gland

The development of the anterior pituitary gland occurs in distinct sequential developmental steps, leading to the formation of a complex organ containing five different cell types secreting six different hormones. During this process, the temporal and spatial expression of a cascade of signaling molecules and transcription factors plays a crucial role in organ commitment, cell proliferation, patterning, and terminal differentiation. The morphogenesis of the gland and the emergence of distinct cell types from a common primordium are governed by complex regulatory networks involving transcription factors and signaling molecules that may be either intrinsic to the developing pituitary or extrinsic, originating from the ventral diencephalon, the oral ectoderm, and the surrounding mesenchyme. Endocrine cells of the pituitary gland are organized into structural and functional networks that contribute to the coordinated response of endocrine cells to stimuli; these cellular networks are formed during embryonic development and are maintained or may be modified in adulthood, contributing to the plasticity of the gland. Abnormalities in any of the steps of pituitary development may lead to congenital hypopituitarism that includes a spectrum of disorders from isolated to combined hormone deficiencies including syndromic disorders such as septo-optic dysplasia. Over the past decade, the acceleration of next-generation sequencing has allowed for rapid analysis of the patient genome to identify novel mutations and novel candidate genes associated with hypothalmo-pituitary development. Subsequent functional analysis using patient fibroblast cells, and the generation of stem cells derived from patient cells, is fast replacing the need for animal models while providing a more physiologically relevant characterization of novel mutations. Furthermore, CRISPR-Cas9 as the method for gene editing is replacing previous laborious and time-consuming gene editing methods that were commonly used, thus yielding knockout cell lines in a fraction of the time. © 2020 American Physiological Society. Compr Physiol 10:389-413, 2020.

Probing Pedomorphy and Prolonged Lifespan in Naked Mole-Rats and Dwarf Mice

Pedomorphy, maintenance of juvenile traits throughout life, is most pronounced in extraordinarily long-lived naked mole-rats. Many of these traits (e.g., slow growth rates, low hormone levels, and delayed sexual maturity) are shared with spontaneously mutated, long-lived dwarf mice. Although some youthful traits likely evolved as adaptations to subterranean habitats (e.g., thermolability), the nature of these intrinsic pedomorphic features may also contribute to their prolonged youthfulness, longevity, and healthspan.

DNA aptamers against the DUX4 protein reveal novel therapeutic implications for FSHD

Aberrant expression of the transcription factor double homeobox protein 4 (DUX4) can lead to a number of diseases including facio‐scapulo‐humeral muscular dystrophy (FSHD), acute lymphoblastic leukemia, and sarcomas. Inhibition of DUX4 may represent a therapeutic strategy for these diseases. By applying Systematic Evolution of Ligands by EXponential Enrichment (SELEX), we identified aptamers against DUX4 with specific secondary structural elements conveying high affinity to DUX4 as assessed by fluorescence resonance energy transfer and fluorescence polarization techniques. Sequences analysis of these aptamers revealed the presence of two consensus DUX4 motifs in a reverse complementary fashion forming hairpins interspersed with bulge loops at distinct positions that enlarged the binding surface with the DUX4 protein, as determined by crystal structure analysis. We demonstrate that insertion of specific structural elements into transcription factor binding oligonucleotides can enhance specificity and affinity.

PROP1-Dependent Retinoic Acid Signaling Regulates Developmental Pituitary Morphogenesis and Hormone Expression

Dietary vitamin A is metabolized into bioactive retinoic acid (RA) in vivo and regulates the development of many embryonic tissues. RA signaling is active in the oral ectoderm-derived tissues of the neuroendocrine system, but its role there has not yet been fully explored. We show here that RA signaling is active during pituitary organogenesis and dependent on the pituitary transcription factor Prop1. Prop1-mutant mice show reduced expression of the aldehyde dehydrogenase gene Aldh1a2, which metabolizes the vitamin A-intermediate retinaldehyde into RA. To elucidate the specific function of RA signaling during neuroendocrine development, we studied a conditional deletion of Aldh1a2 and a dominant-negative mouse model of inhibited RA signaling during pituitary organogenesis. These models partially phenocopy Prop1-mutant mice by exhibiting embryonic pituitary dysmorphology and reduced hormone expression, especially thyrotropin. These findings establish the role of RA in embryonic pituitary stem cell progression to differentiated hormone cells and raise the question of gene-by-environment interactions as contributors to pituitary development and disease.

Primordial follicle reserve, DNA damage and macrophage infiltration in the ovaries of the long-living Ames dwarf mice

The aim of this study was to evaluate the effect of growth hormone (GH) deficiency in primordial follicle reserve, DNA damage and macrophage infiltration in the ovaries of young mice. Ovaries from six-month-old GH-deficient Ames Dwarf (df/df) and Normal (N/df) mice were used. The number of primordial follicles was higher in df/df mice (p = 0.0026). Also, df/df mice had a lower number of primary (p = 0.023), secondary (p = 0.0052) and tertiary (p = 0.019) follicles. These findings indicate a slower rate of primordial follicle activation in df/df mice. Female df/df mice had decreased γH2AX foci intensity in oocytes of primordial (p = 0.015) and primary (p = 0.0004) follicles compared to N/df mice. Also, df/df mice had reduced γH2AX intensity in granulosa cells of primordial (p = 0.0002) and primary (p < 0.0001) follicles. Overall, this indicate to us that df/df mice accumulate less DNA damage in the ovarian reserve compared to N/df mice. Additionally, macrophage infiltration was also reduced in ovaries of df/df mice compared to N/df mice (p = 0.033). Interestingly, df/df mice had a reduced number of granulosa cells around primordial (p = 0.0024) and primary (p = 0.007) follicles compared to N/df mice. Also, df/df mice had a small diameter of primordial follicle nuclei (p = 0.0093), secondary follicle oocyte (p = 0.046) and tertiary follicle (p = 0.012). This points to the role of granulosa cell proliferation and oocyte growth for primordial follicle activation. The current study points to the role of the GH/IGF-I axis in extending lifespan of reproductive health, along with maintenance of oocyte DNA integrity and reduced ovarian inflammation.

Growth hormone-mediated reprogramming of macrophage transcriptome and effector functions

Macrophages are an important component of the innate immune response. Priming and activation of macrophages is stimulated by cytokines (i.e IFNγ). However, growth hormone (GH) can also stimulate macrophage activation. Based on these observations, the goal of this work was to 1) to compare the transcriptome profile of macrophages activated in vitro with GH and IFNγ, and 2) to assess the impact of GH on key macrophage functional properties like reactive oxygen species (ROS) production and phagosomal proteolysis. To assess the global transcriptional and functional impact of GH on macrophage programming, bone marrow derived macrophages were treated with GH or IFNγ. Our data strongly support a potential link between GH, which wanes with age, and impaired macrophage function. The notable overlap of GH with IFNγ-induced pathways involved in innate immune sensing of pathogens and antimicrobial responses argue for an important role for GH in macrophage priming and maturation. By using functional assays that report on biochemical activities within the lumen of phagosomes, we have also shown that GH alters physiologically relevant processes such as ROS production and proteolysis. These changes could have far reaching impacts on antimicrobial capacity, signaling, and antigen presentation.

Comprehensive genome and transcriptome analyses reveal genetic relationship, selection signature, and transcriptome landscape of small-sized Korean native Jeju horse

The Jeju horse, indigenous to the Jeju Island in Korea may have originated from Mongolian horses. Adaptations to the local harsh environment have conferred Jeju horse with unique traits such as small-sized body, stocky head, and shorter limbs. These characteristics have not been studied previously at the genomic level. Therefore, we sequenced and compared the genome of 41 horses belonging to 6 breeds. We identified numerous breed-specific non-synonymous SNPs and loss-of-function mutants. Demographic and admixture analyses showed that, though Jeju horse is genetically the closest to the Mongolian breeds, its genetic ancestry is independent of that of the Mongolian breeds. Genome wide selection signature analysis revealed that genes such as LCORL, MSTN, HMGA2, ZFAT, LASP1, PDK4, and ACTN2, were positively selected in the Jeju horse. RNAseq analysis showed that several of these genes were also differentially expressed in Jeju horse compared to Thoroughbred horse. Comparative muscle fiber analysis showed that, the type I muscle fibre content was substantially higher in Jeju horse compared to Thoroughbred horse. Our results provide insights about the selection of complex phenotypic traits in the small-sized Jeju horse and the novel SNPs identified will aid in designing high-density SNP chip for studying other native horse breeds.

Stem Cells, Self-Renewal, and Lineage Commitment in the Endocrine System

The endocrine system coordinates a wide array of body functions mainly through secretion of hormones and their actions on target tissues. Over the last decades, a collective effort between developmental biologists, geneticists, and stem cell biologists has generated a wealth of knowledge related to the contribution of stem/progenitor cells to both organogenesis and self-renewal of endocrine organs. This review provides an up-to-date and comprehensive overview of the role of tissue stem cells in the development and self-renewal of endocrine organs. Pathways governing crucial steps in both development and stemness maintenance, and that are known to be frequently altered in a wide array of endocrine disorders, including cancer, are also described. Crucially, this plethora of information is being channeled into the development of potential new cell-based treatment modalities for endocrine-related illnesses, some of which have made it through clinical trials.

Complex integration of intrinsic and peripheral signaling is required for pituitary gland development

The coordination of pituitary development is complicated and requires input from multiple cellular processes. Recent research has provided insight into key molecular determinants that govern cell fate specification in the pituitary. Moreover, increasing research aimed to identify, characterize, and functionally describe the presumptive pituitary stem cell population has allowed for a better understanding of the processes that govern endocrine cell differentiation in the developing pituitary. The culmination of this research has led to the ability of investigators to recapitulate some of embryonic pituitary development in vitro, the first steps to developing novel regenerative therapies for pituitary diseases. In this current review, we cover the major players in pituitary stem/progenitor cell function and maintenance, and the key molecular determinants of endocrine cell specification. In addition, we discuss the contribution of peripheral hormonal regulation of pituitary gland development, an understudied area of research.

Mitochondria in the signaling pathways that control longevity and health span

Genetic and pharmacological intervention studies have identified evolutionarily conserved and functionally interconnected networks of cellular energy homeostasis, nutrient-sensing, and genome damage response signaling pathways, as prominent regulators of longevity and health span in various species. Mitochondria are the primary sites of ATP production and are key players in several other important cellular processes. Mitochondrial dysfunction diminishes tissue and organ functional performance and is a commonly considered feature of the aging process. Here we review the evidence that through reciprocal and multilevel functional interactions, mitochondria are implicated in the lifespan modulation function of these pathways, which altogether constitute a highly dynamic and complex system that controls the aging process. An important characteristic of these pathways is their extensive crosstalk and apparent malleability to modification by non-invasive pharmacological, dietary, and lifestyle interventions, with promising effects on lifespan and health span in animal models and potentially also in humans.

Intestinal immunity in hypopituitary dwarf mice: effects of age

Hypopituitary dwarf mice demonstrate advantages of longevity, but little is known of their colon development and intestinal immunity. Herein we found that Ames dwarf mice have shorter colon and colonic crypts, but larger ratio of mesenteric lymph nodes (MLNs) over body weight than age-matched wild type (WT) mice. In the colonic lamina propria (cLP) of juvenile Ames mice, more inflammatory neutrophils (Ā: 0.15% vs. 0.03% in WT mice) and monocytes (Ā: 7.97% vs. 5.15%) infiltrated, and antigen presenting cells CD11c+ dendritic cells (Ā: 1.39% vs. 0.87%), CD11b+ macrophages (Ā: 3.22% vs. 0.81%) and gamma delta T (γδ T) cells (Ā: 5.56% vs. 1.35%) were increased. In adult Ames dwarf mice, adaptive immune cells, such as IL-17 producing CD4+ T helper (Th17) cells (Ā: 8.3% vs. 4.7%) were augmented. In the MLNs of Ames dwarf mice, the antigen presenting and adaptive immune cells also altered when compared to WT mice, such as a decrease of T-regulatory (Treg) cells in juvenile Ames mice (Ā: 7.7% vs.10.5%), but an increase of Th17 cells (Ā: 0.627% vs.0.093%). Taken together, these data suggest that somatotropic signaling deficiency influences colon development and intestinal immunity.

Anti-aging interventions affect lifespan variability in sex, strain, diet and drug dependent fashion

Decreased forkhead box O1 (FoxO1) activity induces hyperlipidemia and increased PPARγ, leading to hyperlipidemia in association with endoplasmic reticulum (ER) stress. In the liver, aging and comorbidities such as hyperlipidemia and diabetes significantly influence a wide variety of steatosis, but the underlying mechanisms are complex and remain elusive.

To establish the modulatory role of FoxO1 and the functional consequences of its altered interaction with PPARγ in the present study, we utilized a cell culture system, aged rats and diabetic db/db mice.

We found that, under ER stress, FoxO1 induces PPARγ-mediated lipid accumulation in aged rat livers. Our data showed that the FoxO1-induced hepatic lipid accumulation was negatively regulated by Akt signaling. PPARγ, a key lipogenesis transcription factor, was increased in aged liver, resulting in lipid accumulation via hepatic ER stress under hyperglycemic conditions. We further demonstrated that loss of FoxO1 causes a decline in PPARγ expression and reduces lipid accumulation. In addition, the interaction between FoxO1 and PPARγ was shown to induce hepatic steatosis in aging and db/db mice.

We provide evidence that, in aged rats, FoxO1 interaction with PPARγ promotes hepatic steatosis, due to hyperglycemia-induced ER stress, which causes an impairment in Akt signaling, such in aging-related diabetes.

Sex differences in health and aging: a dialog between the brain and gonad?

Women live longer than men in virtually all circumstances. However, a more common pattern among animals is that one sex lives longer under some conditions, the other lives longer under other conditions. In laboratory mice, interventions that extend longevity are surprisingly often sex-specific in their effects. Understanding these conditional sex differences could provide mechanistic insight into how longevity could be modulated in humans. One way that longevity can be consistently enhanced is by inhibiting reproduction or eliminating the capacity to reproduce. Thus, there appears to be a mechanistic link between gonadal activity and longevity. There also appears to be a mechanistic link between some types of neuroendocrine signaling and longevity. Combining these two observations suggest that communication between the brain and gonad is a ripe avenue for further exploring longevity-assurance mechanisms. Also, because the timing and activity of specific brain-gonad endocrine differs between the sexes, neuroendocrine linkages between the brain and gonad, particularly among the less obvious hormones such as activin and inhibin, could provide additional insight into mechanisms of sex differences in aging.

Combined pituitary hormone deficiency caused by PROP1 mutations: update 20 years post-discovery

The first description of patients with combined pituitary hormone deficiencies (CPHD) caused by PROP1 mutations was made 20 years ago. Here we updated the clinical and genetic characteristics of patients with PROP1 mutations and summarized the phenotypes of 14 patients with 7 different pathogenic PROP1 mutations followed at the Hospital das Clínicas of the University of Sao Paulo. In addition to deficiencies in GH, TSH, PRL and gonadotropins some patients develop late ACTH deficiency. Therefore, patients with PROP1 mutations require permanent surveillance. On magnetic resonance imaging, the pituitary stalk is normal, and the posterior lobe is in the normal position. The anterior lobe in patients with PROP1 mutations is usually hypoplastic but may be normal or even enlarged. Bi-allelic PROP1 mutations are currently the most frequently recognized genetic cause of CPHD worldwide. PROP1 defects occur more frequently among offspring of consanguineous parents and familial cases, but they also occur in sporadic cases, especially in countries in which the prevalence of PROP1 mutations is relatively high. We classified all reported PROP1 variants described to date according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines: 29 were pathogenic, 2 were likely pathogenic, and 2 were of unknown significance. An expansion of the phenotype of patients with PROP1 mutations was observed since the first description 20 years ago: variable anterior pituitary size, different pathogenic mutations, and late development of ACTH deficiency. PROP1 mutations are the most common cause of autosomal recessive CPHD with a topic posterior pituitary lobe. Arch Endocrinol Metab. 2019;63(2):167-74.

Unmasking a new prognostic marker and therapeutic target from the GDNF-RET/PIT1/p14ARF/p53 pathway in acromegaly

Background

Acromegaly is produced by excess growth hormone secreted by a pituitary adenoma of somatotroph cells (ACRO). First-line therapy, surgery and adjuvant therapy with somatostatin analogs, fails in 25% of patients. There is no predictive factor of resistance to therapy. New therapies are investigated using few dispersed tumor cells in acute primary cultures in standard conditions where the cells do not grow, or using rat pituitary cell lines that do not maintain the full somatotroph phenotype. The RET/PIT1/p14ARF/p53 pathway regulates apoptosis in normal pituitary somatotrophs whereas the RET/GDNF pathway regulates survival, controlling PIT1 levels and blocking p14ARF (ARF) and p53 expression.

Methods

We investigated these two RET pathways in a prospective series of 32 ACRO and 63 non-functioning pituitary adenomas (NFPA), studying quantitative RNA and protein gene expression for molecular-clinical correlations and how the RET pathway might be implicated in therapeutic success. Clinical data was collected during post-surgical follow-up. We also established new'humanized’ pituitary cultures, allowing 20 repeated passages and maintaining the pituitary secretory phenotype, and tested five multikinase inhibitors (TKI: Vandetanib, Lenvatinib, Sunitinib, Cabozantinib and Sorafenib) potentially able to act on the GDNF-induced RET dimerization/survival pathway. Antibody arrays investigated intracellular molecular pathways.

Findings

In ACRO, there was specific enrichment of all genes in both RET pathways, especially GDNF. ARF and GFRA4 gene expression were found to be opposing predictors of response to first-line therapy. ARF cut-off levels, calculated categorizing by GNAS mutation, were predictive of good response (above) or resistance (below) to therapy months later. Sorafenib, through AMPK, blocked the GDNF/AKT survival action without altering the RET apoptotic pathway.

Interpretation

Tumor ARF mRNA expression measured at the time of the surgery is a prognosis factor in acromegaly. The RET inhibitor, Sorafenib, is proposed as a potential treatment for resistant ACRO.

Fund

This project was supported by national grants from Agencia Estatal de Investigación (AEI) and Instituto Investigación Carlos III, with participation of European FEDER funds, to IB (PI150056) and CVA (BFU2016-76973-R). It was also supported initially by a grant from the Investigator Initiated Research (IIR) Program (WI177773) and by a non-restricted Research Grant from Pfizer Foundation to IB. Some of the pituitary acromegaly samples were collected in the framework of the Spanish National Registry of Acromegaly (REMAH), partially supported by an unrestricted grant from Novartis to the Spanish Endocrine Association (SEEN).

CVA is also supported from a grant of Medical Research Council UK MR/M018539/1.