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.

Impaired EIF2S3 function associated with a novel phenotype of X-linked hypopituitarism with glucose dysregulation.

Background: The heterotrimeric GTP-binding protein eIF2 forms a ternary complex with initiator methionyl-tRNA and recruits it to the 40S ribosomal subunit for start codon selection and thereby initiates protein synthesis. Mutations in EIF2S3, encoding the eIF2γ subunit, are associated with severe intellectual disability and microcephaly, usually as part of MEHMO syndrome.

Methods: Exome sequencing of the X chromosome was performed on three related males with normal head circumferences and mild learning difficulties, hypopituitarism (GH and TSH deficiencies), and an unusual form of glucose dysregulation.

Somatostatin triggers rhythmic electrical firing in hypothalamic GHRH neurons.

Hypothalamic growth hormone-releasing hormone (GHRH) neurons orchestrate body growth/maturation and have been implicated in feeding responses and ageing. However, the electrical patterns that dictate GHRH neuron functions have remained elusive. Since the inhibitory neuropeptide somatostatin (SST) is considered to be a primary oscillator of the GH axis, we examined its acute effects on GHRH neurons in brain slices from male and female GHRH-GFP mice.

Sustained alterations of hypothalamic tanycytes during posttraumatic hypopituitarism in male mice.

Traumatic brain injury is a leading cause of hypopituitarism, which compromises patients' recovery, quality of life, and life span. To date, there are no means other than standardized animal studies to provide insights into the mechanisms of posttraumatic hypopituitarism. We have found that GH levels were impaired after inducing a controlled cortical impact (CCI) in mice.

Pituitary growth hormone network responses are sexually dimorphic and regulated by gonadal steroids in adulthood.

There are well-recognized sex differences in many pituitary endocrine axes, usually thought to be generated by gonadal steroid imprinting of the neuroendocrine hypothalamus. However, the recognition that growth hormone (GH) cells are arranged in functionally organized networks raises the possibility that the responses of the network are different in males and females. We studied this by directly monitoring the calcium responses to an identical GH-releasing hormone (GHRH) stimulus in populations of individual GH cells in slices taken from male and female murine GH-eGFP pituitary glands.

Repetitive stimulation of the pituitary with growth-hormone-releasing hormone alters the proportion of 22 and 20 kilodalton human-growth hormone released.

Background/Aims. 20 Kilodalton-hGH (20 K-hGH) is the second most abundant pituitary GH variant after 22 K-hGH. In the steady state the proportion of 20 : 22 K-hGH appears constant; does this proportion change with repetitive somatotroph stimulation? Methods.

Ghrelin stimulation of growth hormone-releasing hormone neurons is direct in the arcuate nucleus.

Background: Ghrelin targets the arcuate nucleus, from where growth hormone releasing hormone (GHRH) neurones trigger GH secretion. This hypothalamic nucleus also contains neuropeptide Y (NPY) neurons which play a master role in the effect of ghrelin on feeding. Interestingly, connections between NPY and GHRH neurons have been reported, leading to the hypothesis that the GH axis and the feeding circuits might be co-regulated by ghrelin.

Cellular in vivo imaging reveals coordinated regulation of pituitary microcirculation and GH cell network function.

Growth hormone (GH) exerts its actions via coordinated pulsatile secretion from a GH cell network into the bloodstream. Practically nothing is known about how the network receives its inputs in vivo and releases hormones into pituitary capillaries to shape GH pulses. Here we have developed in vivo approaches to measure local blood flow, oxygen partial pressure, and cell activity at single-cell resolution in mouse pituitary glands in situ.

The effect of different patterns of growth hormone administration on the IGF axis and somatic and skeletal growth of the dwarf rat.

Normal childhood growth is determined by ultradian and infradian variations in GH secretion, yet GH treatment of children with short stature is restricted to daily fixed doses. We have used GH-deficient dwarf rats to determine whether variable GH dose regimens promote growth more effectively than fixed doses. Animals were treated with saline or 4.

Genetic regulation of pituitary gland development in human and mouse.

Normal hypothalamopituitary development is closely related to that of the forebrain and is dependent upon a complex genetic cascade of transcription factors and signaling molecules that may be either intrinsic or extrinsic to the developing Rathke's pouch. These factors dictate organ commitment, cell differentiation, and cell proliferation within the anterior pituitary. Abnormalities in these processes are associated with congenital hypopituitarism, a spectrum of disorders that includes syndromic disorders such as septo-optic dysplasia, combined pituitary hormone deficiencies, and isolated hormone deficiencies, of which the commonest is GH deficiency.

Regulation of rapid signal transducer and activator of transcription-5 phosphorylation in the resting cells of the growth plate and in the liver by growth hormone and feeding.

GH has physiological functions in many tissues, but the cellular targets for direct effects of GH remain ill defined in complex tissues such as the growth plate in which the contribution of direct vs. indirect actions of GH remains controversial. The Janus kinase (Jak)-signal transducer and activator of transcription (STAT)-5 pathway is activated by GH, so we developed a method to visualize nuclear Stat5b and phosphorylated Stat5 in single cells in response to a pulse of GH.

The circadian clock components CRY1 and CRY2 are necessary to sustain sex dimorphism in mouse liver metabolism.

In mammals, males and females exhibit anatomical, hormonal, and metabolic differences. A major example of such sex dimorphism in mouse involves hepatic drug metabolism, which is also a noticeable target of circadian timekeeping. However, whether the circadian clock itself contributes to sex-biased metabolism has remained unknown, although several daily output parameters differ between sexes in a number of species, including humans.

Somatostatin secreted by islet delta-cells fulfills multiple roles as a paracrine regulator of islet function.

Objective: Somatostatin (SST) is secreted by islet delta-cells and by extraislet neuroendocrine cells. SST receptors have been identified on alpha- and beta-cells, and exogenous SST inhibits insulin and glucagon secretion, consistent with a role for SST in regulating alpha- and beta-cell function. However, the specific intraislet function of delta-cell SST remains uncertain.

SOX2-expressing progenitor cells generate all of the major cell types in the adult mouse pituitary gland.

The pituitary gland adapts the proportion of each of its endocrine cell types to meet differing hormonal demands throughout life. There is circumstantial evidence that multipotent adult progenitor cells contribute to this plasticity, but these cells have not been identified. Here, we describe a small (<0.

SOX2 plays a critical role in the pituitary, forebrain, and eye during human embryonic development.

Context: Heterozygous, de novo mutations in the transcription factor SOX2 are associated with bilateral anophthalmia or severe microphthalmia and hypopituitarism. Variable additional abnormalities include defects of the corpus callosum and hippocampus.

Objective: We have ascertained a further three patients with severe eye defects and pituitary abnormalities who were screened for mutations in SOX2.

Rescue of pituitary function in a mouse model of isolated growth hormone deficiency type II by RNA interference.

Splicing mutations in the human GH (hGH) gene (GH-1) that cause skipping of exon 3 result in a form of GH deficiency termed isolated GH deficiency type II (IGHD II). The GH-1 gene contains five exons; constitutive splicing produces the wild-type 22-kDa hormone, whereas skipping of exon 3 results in transcripts encoding a 17.5-kDa isoform that acts as a dominant-negative to block secretion of the wild-type hormone.

Selective alteration at the growth-hormone- releasing-hormone nerve terminals during aging in GHRH-green fluorescent protein mice.

Growth hormone (GH) secretion decreases spontaneously during lifespan, and the resulting GH deficiency participates in aging-related morbidity. This deficiency appears to involve a defect in the activity of hypothalamic GH-releasing hormone (GHRH) neurons. Here, we investigated this hypothesis, as well as the underlying mechanisms, in identified GHRH neurons from adult ( approximately 13 weeks old) and aged ( approximately 100 weeks old) transgenic GHRH-green fluorescent protein mice, using morphological, biochemical and electrophysiological methods.

Dual-level afferent control of growth hormone-releasing hormone (GHRH) neurons in GHRH-green fluorescent protein transgenic mice.

The organization of the peptidergic neurons of the hypothalamic arcuate nucleus is not fully understood. These include growth hormone-releasing hormone (GHRH) neurons involved in growth and metabolism. We studied identified GHRH neurons of GHRH-green fluorescent protein transgenic mice using patch-clamp methods and focused on gender differences, which govern the physiological patterns of GHRH release.

Multiple co-localizations in arcuate GHRH-eGFP neurons in the mouse hypothalamus.

In the present work, we took advantage of a recently described model of GHRH-enhanced green fluorescent protein (eGFP) transgenic mice to evaluate the extent of co-localization of GHRH neurons with galanin (GAL), neurotensin (NT) and tyrosine hydroxylase (TH) in 3- and 8-month-old male and female mice. The total number of GHRH-eGFP neurons along the rostro-caudal axis of the arcuate nucleus did not differ according to gender or age. GAL-immunoreactivity was present in 40-44% of 3-month-old GHRH-eGFP neurons in male and female arcuate nucleus, respectively, but only 25-22% in 8-month-old mice.

Evolution of gonadotropin deficiency in a patient with type II autosomal dominant GH deficiency.

Background: Type II isolated GH deficiency (IGHD type II) is caused by dominant negative splicing or point mutations of the GH-1 gene. Studies have suggested that dominant mutant GH forms prevent the secretion of wild-type GH, resulting in eventual cell death; surprisingly, some patients with these GH mutations develop other hormonal deficiencies (ACTH, TSH).

Subjects: The proband presented at the age of 2.

Isolated autosomal dominant growth hormone deficiency: stimulating mutant GH-1 gene expression drives GH-1 splice-site selection, cell proliferation, and apoptosis.

The majority of mutations that cause isolated GH deficiency type II (IGHD II) affect splicing of GH-1 transcripts and produce a dominant-negative GH isoform lacking exon 3 resulting in a 17.5-kDa isoform, which further leads to disruption of the GH secretory pathway. A clinical variability in the severity of the IGHD II phenotype depending on the GH-1 gene alteration has been reported, and in vitro and transgenic animal data suggest that the onset and severity of the phenotype relates to the proportion of 17.

Mutations within Sox2/SOX2 are associated with abnormalities in the hypothalamo-pituitary-gonadal axis in mice and humans.

The transcription factor SOX2 is expressed most notably in the developing CNS and placodes, where it plays critical roles in embryogenesis. Heterozygous de novo mutations in SOX2 have previously been associated with bilateral anophthalmia/microphthalmia, developmental delay, short stature, and male genital tract abnormalities. Here we investigated the role of Sox2 in murine pituitary development.

Sexually dimorphic distribution of sst2A somatostatin receptors on growth hormone-releasing hormone neurons in mice.

The pulsatile pattern of GH secretion exhibits sexual dimorphism that is likely to depend on somatostatin (SRIH) effects on somatoliberin (GHRH) neurons in the hypothalamus. Using transgenic GHRH-enhanced green fluorescent protein (eGFP) mice, no difference in the total number of GHRH-eGFP neurons or change in somatostatin receptor sst2 and SRIH mRNA levels in ventromedial hypothalamic nucleus-arcuate nucleus and periventricular nucleus regions and GHRH mRNA levels in the ventromedial hypothalamic-arcuate region were observed between male and female mice. However, the percentage of GHRH-eGFP neurons bearing sst2A receptors reached 78% in female vs.

Variability of isolated autosomal dominant GH deficiency (IGHD II): impact of the P89L GH mutation on clinical follow-up and GH secretion.

Objective: Four distinct familial types of isolated GH deficiency (IGHD) are classified, of which type II, IGHD II, is the autosomal dominant inherited form. Based on clinical data, it became evident that there is a wide variability in phenotype among the various GH-1 gene alterations leading to the disorder. As subjects suffering from IGHD II caused by the specific missense mutated P89L GH (C6129T) have never been reported in detail, the aim was to analyse the impact of this mutated GH form on its clinical follow-up as well as to study its effect at the cellular level in comparison with the most common missense mutation R183H GH (G6664A).