The Growth Hormone Receptor: Mechanism of Receptor Activation, Cell Signaling, and Physiological Aspects

Novel perspectives on growth hormone regulation of ovarian function: mechanisms, formulations, and therapeutic applications

Delayed childbearing has led to a continuous rise in the incidence of infertility because of social development and the evolving roles of women. Assisted reproductive technology (ART) has provided new opportunities for infertility treatment, such as the application of growth hormone (GH). GH regulates ovarian function through multiple pathways, improving follicular development and hormone secretion. However, traditional GH therapy is limited by issues such as low bioavailability and insufficient delivery efficiency. In recent years, drug delivery systems based on novel biomaterials have provided breakthrough solutions for the innovative application of GH in ART. This review summarizes the mechanisms by which GH affects ovarian endocrine function and focuses on the cutting-edge advancements in GH delivery systems with examination of the innovative applications of composite biomaterials in enhancing the therapeutic efficacy of GH. By analyzing the pharmacokinetic properties of novel formulations, the safety and long-term efficacy of their clinical applications can be evaluated. GH delivery systems based on novel biomaterials considerably improve the bioavailability and targeting of GH and could lead to innovative therapeutic strategies for preventing and treating ovarian dysfunction and related diseases. By integrating multidisciplinary research findings, we provide new insights into the field of reproductive medicine that could lead to theoretical and practical importance for promoting the innovative development of ART.

Invited Review: Somatotropin and Lactation Biology

Purpose of this review is to update the human and animal safety findings on bovine somatotropin (bST) since 1993 as well as to discuss ST action and its impacts on sustainability. Bovine somatotropin (bST) is a naturally produced hormone which is a key regulator of growth and milk production. Beginning in the 1930s and continuing until today, investigations have examined bST's impact on animal related factors such as nutrition, bioenergetics, metabolism, health, and well-being, and consumer related issues such as product safety, milk quality, and manufacturing characteristics. Overall, bST homeorhetically orchestrates (both directly and indirectly) the coordination of key physiological processes involved in lactation. Bovine somatotropin's direct effects involve adaptations in a variety tissues, and altered metabolism of all nutrient classes - water, carbohydrates, lipids, protein, and minerals. Mechanistically, this includes modifying key enzymes, intracellular signal transduction systems, tissue response to homeostatic signals and diversity of receptor subtypes. Indirect effects are mediated by the insulin-like growth factor (IGF) system. Collectively, IGF governs cellular changes within the mammary gland resulting in increased rates of milk synthesis and enhanced maintenance of secretory cells. The responses to bST are modulated by environmental and management factors, especially an animal's nutritional plane. This modulation is a principal component in allowing bST to play a key role in regulating nutrient utilization across a range of physiological states. Recombinant bST (rbST) was developed in the early 1980s and commercial rbST use in the United States began in 1994. Utilizing rbST markedly increases milk yield and improves feed efficiency and farm income; thus, it was rapidly adopted by many dairy producers. Despite reducing the environmental footprint of milk production and having no impact on cow health in well-managed dairies, milk consumption or human safety concerns, many within the processing, grocery and retailer industries began labeling and promoting "rbST-free" dairy products as a marketing strategy. The FDA was concerned this represented an implied health issue, so they required products labeled as "rbST-free" to also include the statement that "no significant difference has been shown between milk derived from rbST treated and non-rbST treated cows." Many Cooperatives had an aggressive strategy to market "rbST-free" milk to compete with "organic" milk and suggested producers would receive higher milk prices if they voluntarily stopped using rbST. The net effect was American farmers ceased using the technology. However, rbST continues to safely increase farmer revenue and to minimize the carbon footprint of dairy production in many parts of Asia, Africa, and South America. Overall, bST is a homeorhetic control which orchestrates metabolic processes affecting nutrient partitioning and animal productivity, and it is naturally higher in genetically superior animals. The intrinsic biology of endogenous bST can be harnessed with the use of exogenous rbST to safely and sustainably improve animal performance.

GH-Releasing Hormone Neurons Regulate the Hypothalamic-Pituitary-Somatotropic Axis via Short-Loop Negative Feedback

Growth hormone (GH)-releasing hormone (GHRH) neurons are master regulators of GH secretion. However, the role of these cells in controlling pituitary GH secretion through short-loop negative feedback has not yet been fully clarified. Thus, GHRH-specific GH receptor (GHR) knockout (GHRHΔGHR) mice were generated, and possible consequences on GH secretion and body growth were determined. Approximately 60% of arcuate nucleus GHRH neurons exhibited GH-induced STAT5 phosphorylation, a marker of GHR-expressing cells. This response was practically eliminated in GHRHΔGHR mice. GHR ablation in GHRH-expressing cells increased body weight, lean mass, and naso-anal length in male and female mice without affecting fat mass. The higher body growth of GHRHΔGHR mice was associated with increases in GH secretion, mainly via higher pulsatile GH secretion and GH pulse amplitude. GHRHΔGHR female mice also showed increased GH pulse frequency and basal (non-pulsatile) secretion compared to control females. Liver Igf1 expression was increased only in GHRHΔGHR male mice. Mice carrying ablation of the insulin-like growth factor-1 (IGF-1) receptor (IGF1R) or both GHR and IGF1R in GHRH-expressing cells were generated. The increases in body growth and serum IGF-1 levels were significantly higher in GHRHΔGHR/IGF1R mice compared to GHRHΔGHR mice but similar to levels observed in GHRHΔIGF1R mice. Electrophysiological experiments showed no acute changes in the activity of GHRH neurons after GH or IGF-1 exposure. In conclusion, GH feeds back on GHRH cells to control the hypothalamic-pituitary-somatotropic axis. However, IGF1R signaling prevails over GHR as the primary signal sensed by GHRH neurons to regulate GH secretion.

The intersection of endocrine signaling and neuroimmune communication regulates muscle inflammation-induced nociception in neonatal mice

Neonatal pain is a significant clinical issue but the mechanisms by which pain is produced early in life are poorly understood. Our recent work has linked the transcription factor serum response factor downstream of local growth hormone (GH) signaling to incision-related hypersensitivity in neonates. However, it remains unclear if similar mechanisms contribute to inflammatory pain in neonates. We found that local GH treatment inhibited neonatal inflammatory myalgia but appeared to do so through a unique signal transducer and activator of transcription (STAT) dependent pathway within sensory neurons. The STAT1 transcription factor appeared to regulate peripheral inflammation itself by modulation of monocyte chemoattractant protein 1/C-C motif chemokine ligand 2 (MCP1/CCL2) release from sensory neurons. Data suggests that STAT1 upregulation, downstream of GH signaling, contributes to neonatal nociception during muscle inflammation through a novel neuroimmune loop involving chemokine release from primary afferents. Results could uncover new ways to treat muscle pain and inflammation in neonates.

Growth hormone signaling and clinical implications: from molecular to therapeutic perspectives

Growth hormone (GH) is a key polypeptide hormone secreted by somatotroph cells in the anterior pituitary gland, essential for postnatal growth, metabolism, and systemic homeostasis. Its secretion is regulated by hypothalamic neuropeptides, including GH-releasing hormone and somatostatin. GH exerts effects through direct interaction with the growth hormone receptor and indirect pathways mediated by the GH-IGF-I axis. GHR activation triggers signaling pathways, such as JAK-STAT, PI3K/AKT, and MAPK, promoting cellular proliferation, differentiation, and metabolic balance. The GH-IGF-I axis is critical for bone growth, lipid and carbohydrate metabolism, and organ-specific physiological functions. Dysregulation of GH results in diverse disorders. Congenital deficiencies, like isolated GH deficiency and syndromic conditions (e.g., Turner syndrome), stem from genetic mutations. Acquired deficiencies arise from trauma, tumors, infections, or autoimmune damage, while GH overproduction causes gigantism in children and acromegaly in adults, often due to pituitary adenomas. Idiopathic deficiencies, lacking identifiable causes, complicate management further. Advances in therapy have transformed outcomes for GH disorders. Recombinant human growth hormone provides effective replacement therapy for deficiencies. Somatostatin analogs, dopamine receptor agonists, and GH receptor antagonists are pivotal for managing GH excess. Surgical and radiotherapeutic interventions remain essential for pituitary adenomas. However, GH therapy requires close monitoring to prevent side effects like insulin resistance and metabolic complications. This review provides a comprehensive evaluation of the molecular mechanisms underlying GH action, its physiological roles, GH-related disorders, and therapeutic approaches to optimize patient outcomes.

Evaluation of Prenatal Transportation Stress on DNA Methylation (DNAm) and Gene Expression in the Hypothalamic-Pituitary-Adrenal (HPA) Axis Tissues of Mature Brahman Cows

Background/Objectives: The experience of prenatal stress results in various physiological disorders due to an alteration of an offspring's methylome and transcriptome. The objective of this study was to determine whether PNS affects DNA methylation (DNAm) and gene expression in the stress axis tissues of mature Brahman cows. Methods: Samples were collected from the paraventricular nucleus (PVN), anterior pituitary (PIT), and adrenal cortex (AC) of 5-year-old Brahman cows that were prenatally exposed to either transportation stress (PNS, n = 6) or were not transported (Control, n = 8). The isolated DNA and RNA samples were, respectively, used for methylation and RNA-Seq analyses. A gene ontology and KEGG pathway enrichment analysis of each data set within each sample tissue was conducted with the DAVID Functional Annotation Tool. Results: The DNAm analysis revealed 3, 64, and 99 hypomethylated and 2, 93, and 90 hypermethylated CpG sites (FDR < 0.15) within the PVN, PIT, and AC, respectively. The RNA-Seq analysis revealed 6, 25, and 5 differentially expressed genes (FDR < 0.15) in the PVN, PIT, and AC, respectively, that were up-regulated in the PNS group relative to the Control group, as well as 24 genes in the PIT that were down-regulated. Based on the enrichment analysis, several developmental and cellular processes, such as maintenance of the actin cytoskeleton, cell motility, signal transduction, neurodevelopment, and synaptic function, were potentially modulated. Conclusions: The methylome and transcriptome were altered in the stress axis tissues of mature cows that had been exposed to prenatal transportation stress. These findings are relevant to understanding how prenatal experiences may affect postnatal neurological functions.

Ligand-induced receptor multimerization achieves specificity enhancement of kinetic proofreading without associated costs

Kinetic proofreading (KPR) is a commonly invoked mechanism for specificity enhancement of receptor signaling. However, specificity enhancement comes at a cost of nonequilibrium energy input and signal attenuation. We show that ligand-induced multimeric receptor assembly can enhance receptor specificity to the same degree as KPR, yet without the need for out-of-equilibrium energy expenditure and signal loss. We show how multimeric receptor specificity enhancement arises from the amplification of affinity differences via sequential progression down a free energy landscape. We also show that multimeric receptor ligand recognition is more robust to stochastic fluctuations and molecular noise than KPR receptors. Finally, we show that multimeric receptors perform signaling tasks beyond specificity enhancement like absolute discrimination and aspects of ligand antagonism. Our results suggest that multimeric receptors may serve as a potent mechanism of ligand discrimination comparable to and potentially with more advantages than traditional proofreading.

Targeting ROR2 homooligomerization disrupts ROR2-dependent signaling and suppresses stem-like cell properties of human breast adenocarcinoma

Breast cancer stem-like cells (CSCs) are enriched following treatment with chemotherapy, and posited as having a high level of plasticity and enhanced tumor-initiation capacity, which can enable cancer relapse. Here, we show that such features are shared by breast cancer (BCA) cells that express receptor tyrosine kinase-like orphan receptor (ROR2), which is expressed primarily during embryogenesis and by various cancers. We find that Wnt5a can induce ROR2 homooligomerization to activate noncanonical Wnt signaling and enhance tumor-initiation capacity of BCA cells. Molecular analysis reveals that the cysteine-rich domain and transmembrane domain are required for ROR2 homooligomerization to activate ROR2. Treatment with a newly generated monoclonal antibody (mAb) specific for ROR2 can block Wnt5a-induced ROR2 homooligomerization, ROR2-dependent noncanonical Wnt signaling, and impair the capacity of BCA patient-derived xenografts to initiate tumor in immune-deficient mice. Collectively, these results indicate that targeting ROR2 (e.g., using mAb) suppresses BCA stemness and, thereby, may prevent BCA relapse.

GDNF family receptor alpha-like (GFRAL) expression is restricted to the caudal brainstem

OBJECTIVE

Growth differentiation factor 15 (GDF15) acts on the receptor dimer of GDNF family receptor alpha-like (GFRAL) and Rearranged during transfection (RET). While Gfral-expressing cells are known to be present in the area postrema and nucleus of the solitary tract (AP/NTS) located in the brainstem, the presence of Gfral-expressing cells in other sites within the central nervous system and peripheral tissues is not been fully addressed. Our objective was to thoroughly investigate whether GFRAL is expressed in peripheral tissues and in brain sites different from the brainstem.

METHODS

From Gfral:eGFP mice we collected tissue from 12 different tissues, including brain, and used single molecule in-situ hybridizations to identify cells within those tissues expressing Gfral. We then contrasted the results with human Gfral-expression by analyzing publicly available single-cell RNA sequencing data.

RESULTS

In mice we found readably detectable Gfral mRNA within the AP/NTS but not within other brain sites. Within peripheral tissues, we failed to detect any Gfral-labelled cells in the vast majority of examined tissues and when present, were extremely rare. Single cell sequencing of human tissues confirmed GFRAL-expressing cells are detectable in some sites outside the AP/NTS in an extremely sparse manner. Importantly, across the utilized methodologies, smFISH, genetic Gfral reporter mice and scRNA-Seq, we failed to detect Gfral-labelled cells with all three.

CONCLUSIONS

Through highly sensitive and selective technologies we show Gfral expression is overwhelmingly restricted to the brainstem and expect that GDF15 and GFRAL-based therapies in development for cancer cachexia will specifically target AP/NTS cells.

Growth Hormone, Hypothalamic Inflammation, and Aging

While inflammation is a crucial response in injury repair and tissue regeneration, chronic inflammation is a prevalent feature in various chronic, non-communicable diseases such as obesity, diabetes, and cancer and in cardiovascular and neurodegenerative diseases. Long-term inflammation considerably affects disease prevalence, quality of life, and longevity. Our research indicates that the growth hormone/insulin-like growth factor 1 (GH/IGF-1) axis is a pivotal regulator of inflammation in some tissues, including the hypothalamus, which is a key player in systemic metabolism regulation. Moreover, the GH/IGF-1 axis is strongly linked to longevity, as GH- or GH receptor-deficient mice live approximately twice as long as wild-type animals and exhibit protection against aging-induced inflammation. Conversely, GH excess leads to increased neuroinflammation and reduced longevity. Our review studies the associations between the GH/IGF-1 axis, inflammation, and aging, with a particular focus on evidence suggesting that GH receptor signaling directly induces hypothalamic inflammation. This finding underscores the significant impact of changes in the GH axis on metabolism and on the predisposition to chronic, non-communicable diseases.

Beyond Calories: Individual Metabolic and Hormonal Adaptations Driving Variability in Weight Management-A State-of-the-Art Narrative Review

The global rise in obesity underscores the need for effective weight management strategies that address individual metabolic and hormonal variability, moving beyond the simplistic "calories in, calories out" model. Body types-ectomorph, mesomorph, and endomorph-provide a framework for understanding the differences in fat storage, muscle development, and energy expenditure, as each type responds uniquely to caloric intake and exercise. Variability in weight outcomes is influenced by factors such as genetic polymorphisms and epigenetic changes in hormonal signaling pathways and metabolic processes, as well as lifestyle factors, including nutrition, exercise, sleep, and stress. These factors impact the magnitude of lipogenesis and myofibrillar protein synthesis during overfeeding, as well as the extent of lipolysis and muscle proteolysis during caloric restriction, through complex mechanisms that involve changes in the resting metabolic rate, metabolic pathways, and hormonal profiles. Precision approaches, such as nutrigenomics, indirect calorimetry, and artificial-intelligence-based strategies, can potentially leverage these insights to create individualized weight management strategies aligned with each person's unique metabolic profile. By addressing these personalized factors, precision nutrition offers a promising pathway to sustainable and effective weight management outcomes. The main objective of this review is to examine the metabolic and hormonal adaptations driving variability in weight management outcomes and explore how precision nutrition can address these challenges through individualized strategies.

Effects of lactose content in milk replacer on apparent digestibility, growth, liver messenger RNA expression, and blood parameters related to metabolism of dairy calves

Even with the same energy supply, differences in energy sources may affect calf growth and metabolism. In this study, we evaluated the effects of feeding 3 different milk replacers (MR) with different lactose supplies under isoenergetic conditions on calf digestibility, growth, and metabolism-related markers. Fifteen Holstein bull calves were randomly assigned to one of 3 MR feeding treatments: low lactose (L: 38%), medium lactose (M: 41%), or high lactose (H: 46%). After birth, calves were provided colostrum, and treatment MR were fed from 1 d of age and gradually increased to a maximum feeding rate at 20 d of age (L: 1.16 kg/d, M: 1.21 kg/d, H: 1.26 kg/d DM) without feeding solid feeds during the experimental period. Blood samples were temporarily collected weekly to assess blood concentrations of metabolites and hormones. From 30 to 36 d of age, the calves were euthanized and liver samples were collected to determine growth-related mRNA expression. The L calves showed a greater body length than H calves and the highest growth hormone receptor (GHR) mRNA expression. Plasma concentrations of total cholesterol, urea nitrogen, total protein, albumin, insulin, and IGF-1 were not different, but plasma concentrations of triglycerides were greater in order H, M, and L. These results showed that the difference in lactose content in the MR affected calf metabolism, and the L-MR was suggested to be more likely to enhance growth into the peripheral tissues.

Long-term efficacy and safety of PEGylated recombinant human growth hormone in treating Chinese children with growth hormone deficiency: a 5-year retrospective study

OBJECTIVES

The study endeavored to evaluate the prolonged efficacy and safety of PEGylated rhGH (PEG-rhGH) administration in Chinese children diagnosed with growth hormone deficiency (GHD) over a 5-year period.

METHODS

A retrospective analysis was conducted on children with GHD, who received a 0.2 mg/kg/week dose of PEG-rhGH between 2016 and 2023 in our department.

RESULTS

The height standard deviation score (Ht SDS) exhibited a marked elevation post-PEG-rhGH administration (p<0.001), sustaining this enhancement beyond year 3, with increments recorded at 0.94±0.37, 1.49±0.48, 1.77±0.51, 2.12±0.65, and 2.15±0.58 across 5 years. Similarly, the height velocity (HV), insulin-like growth factor-1 standard deviation score (IGF-1 SDS), and bone age to chronological age ratio (BA/CA ratio) underwent significant augmentations (p<0.01). Remarkably, no signs of rapid bone maturation were detected during the 5-year observation. Among the participants, 31 patients (59.62 %) experienced adverse events, of which eight instances (15.38 %) were classified as treatment-related adverse events, but none were severe or unexpected. Additionally, high-density lipoprotein (HDL) levels rose while low-density lipoprotein (LDL) levels fell, both remaining within the standard range throughout the treatment phase.

CONCLUSIONS

Administering PEG-rhGH at a dosage of 0.2 mg/kg/week proved both effective and well-tolerated in treating prepubertal children with GHD. This regimen also demonstrated positive impacts on lipid metabolism over an extended treatment period.

IGF1 drives Wnt-induced joint damage and is a potential therapeutic target for osteoarthritis

Osteoarthritis is the most common joint disease and a global leading cause of pain and disability. Current treatment is limited to symptom relief, yet there is no disease-modifying therapy. Its multifactorial etiology includes excessive activation of Wnt signaling, but how Wnt causes joint destruction remains poorly understood. Here, we identify that Wnt signaling promotes the transcription of insulin-like growth factor 1 (IGF1) in articular chondrocytes and that IGF1 is a major driver of Wnt-induced joint damage. Male mice with cartilage-specific Igf1 deficiency are protected from Wnt-triggered joint disease. Mechanistically, Wnt-induced IGF1 transcription depends on β-catenin and binding of Wnt transcription factor TCF4 to the IGF1 gene promoter. In a clinically relevant mouse model of post-traumatic osteoarthritis, cartilage-specific deletion of Igf1 protects against the disease in male mice. IGF1 silencing in chondrocytes from patients with osteoarthritis restores a healthy molecular profile. Our findings reveal that reducing Wnt-induced IGF1 is a potential therapeutic strategy for osteoarthritis.

Can the reduced GH, IGF-1, and ovarian steroids concentrations be considered as suspected biomarkers of age-associated functional deficit in mares?

In humans' and experimental animals' components of the somatotropic axis, such as growth hormone (GH) and insulin-like growth factor 1 (IGF-1) concentrations, decrease with advancing age. Although there is evidence regarding IGF-1, the effect of age on GH in mares, as well as the relationships between both parameters, have not yet been elucidated. On the other hand, although GH and IGF-1 are related to follicular development, it is unknown if they could be correlated with the circulating concentrations of ovarian steroids in mares, as occurs in other species. The hypothesis of this study was that both GH and IGF-1 could experience physiological changes with advancing age also in mares, and that both GH/IGF-1 could be correlated with oestradiol-17β (E2) and progesterone (P4), as recorded for other species. Hence, the objective of this study was to evaluate the concentrations of GH, IGF-1, E2, and P4 in mares, according to the different ages. Blood samples were drawn from 56 healthy cyclic Spanish Purebred mares belonging to four different age groups: 6-9 years, 10-13 years, 14-16 years and >16 years. Mares aged 6-9 years and 10-13 years showed higher GH concentrations (P < 0.05) than mares of 14-16 and >16 years; and mares aged 14-16 showed higher GH concentrations (P < 0.05) than >16 years (P < 0.05). Mares aged >16 years showed lower IGF-1 concentrations (P < 0.05) than mares of 6-9, 10-13 and 14-16 years (P < 0.05). The concentrations of E2 and P4 showed no significant differences among different age groups. Both GH and IGF-1 were not correlated with each other or with E2 and P4. The concentrations of E2 and P4 did not change with age. Advancing age leads to a decrease in the activity of the somatotropic axis in physiological cyclic mares, represented by a significant GH reduction, which, however, was ascribed for IGF-1 exclusively to mares over 16 years of age, without alterations in steroid hormone patterns.

Alternate-day fasting delays pubertal development in normal-weight mice but prevents high-fat diet-induced obesity and precocious puberty

BACKGROUND/OBJECTIVES

Childhood obesity, particularly in girls, is linked to early puberty onset, heightening risks for adult-onset diseases. Addressing childhood obesity and precocious puberty is vital to mitigate societal burdens. Despite existing costly and invasive medical interventions, introducing lifestyle-based alternatives is essential. Our study investigates alternate-day fasting's (ADF) impact on pubertal development in normal-weight and high-fat diet (HFD)-induced obese female mice.

METHODS

Four groups of female mice were utilized, with dams initially fed control chow during and before pregnancy. Post-parturition, two groups continued on control chow, while two switched to an HFD. Offspring diets mirrored maternal exposure. One control and one HFD group were subjected to ADF. Morphometry and hormone analyses at various time points were performed.

RESULTS

Our findings demonstrate that ADF in normal-weight mice led to reduced body length, weight, uterine, and ovarian weights, accompanied by delayed puberty and lower levels of sex hormones and growth hormone (GH). Remarkably, GH treatment effectively prevented ADF-induced growth reduction but did not prevent delayed puberty. Conversely, an HFD increased body length, induced obesity and precocious puberty, and altered sex hormones and leptin levels, which were counteracted by ADF regimen. Our data indicate ADF's potential in managing childhood obesity and precocious puberty.

CONCLUSIONS

ADF reduced GH and sex hormone levels, contributing to reduced growth and delayed puberty, respectively. Therefore, parents of normal-weight children should be cautious about prolonged overnight fasting. ADF prevented HFD-induced obesity and precocious puberty, offering an alternative to medical approaches; nevertheless, further studies are needed for translation into clinical practice.

The intersection of endocrine signaling and neuroimmune communication regulates neonatal nociception

Neonatal pain is a significant clinical issue but the mechanisms by which pain is produced early in life are poorly understood. Our recent work has linked the transcription factor serum response factor downstream of local growth hormone (GH) signaling to incision-related hypersensitivity in neonates. However, it remains unclear if similar mechanisms contribute to inflammatory pain in neonates. We found that local GH treatment inhibited neonatal inflammatory myalgia but appeared to do so through a unique signal transducer and activator of transcription (STAT) dependent pathway within sensory neurons. The STAT1 transcription factor appeared to regulate peripheral inflammation itself by modulation of monocyte chemoattractant protein 1 (MCP1) release from sensory neurons. Data suggests that STAT1 upregulation, downstream of GH signaling, contributes to neonatal nociception during muscle inflammation through a novel neuroimmune loop involving cytokine release from primary afferents. Results could uncover new ways to treat muscle pain and inflammation in neonates.

The protection role of human growth hormone on skin cells following ultraviolet B exposure

BACKGROUND

Ultraviolet-B (UVB) radiation is the leading environmental cause of skin damage and photoaging. The epidermis and dermis layers of the skin mainly absorb UVB. UVB stimulates apoptosis, cell cycle arrest, generation of reactive oxygen species, and degradation of collagen and elastin fibers.

OBJECTIVE

This study investigated the potential of human growth hormone (hGH) in protecting the skin fibroblasts and keratinocytes (HFFF-2 and HaCaT cell lines) from UVB-induced damage.

METHODS

The MTT assay was performed to evaluate UVB-induced mitochondrial damage via assessing the mitochondrial dehydrogenase activity, and flow cytometry was carried out to investigate the effects of UVB and hGH on the cell cycle and apoptosis of UVB-irradiated cells. In addition, the fold change mRNA expression levels of Type I collagen and elastin in HFFF-2 cells were evaluated using the qRT-PCR method following UVB exposure.

RESULTS

We observed that treatment of cells with hGH before UVB exposure inhibited UVB-induced loss of mitochondrial dehydrogenase activity, apoptosis, and sub-G1 population formation in both cell lines. We also found that hGH-treated HFFF-2 cells showed up-regulated mRNA expression of Type I collagen, elastin, and IGF-1 in response to UVB irradiation.

CONCLUSION

These findings suggest hGH as a potential anti-UVB compound that can protect skin cells from UVB-induced damage. Our findings merit further investigation and can be used to better understand the role of hGH in skin photoaging.

Plasma proteomic analysis reveals key pathways associated with divergent residual body weight gain phenotype in beef steers

We utilized plasma proteomics profiling to explore metabolic pathways and key proteins associated with divergent residual body weight gain (RADG) phenotype in crossbred (Angus × Hereford) beef steers. A group of 108 crossbred growing beef steers (average BW = 282.87 ± 30 kg; age = 253 ± 28 days) were fed a high-forage total mixed ration for 49 days in five dry lot pens (20-22 beef steers per pen), each equipped with two GrowSafe8000 intake nodes to determine their RADG phenotype. After RADG identification, blood samples were collected from the beef steers with the highest RADG (most efficient; n = 15; 0.76 kg/d) and lowest RADG (least efficient; n = 15; -0.65 kg/d). Plasma proteomics analysis was conducted on all plasma samples using a nano LC-MS/MS platform. Proteins with FC ≥ 1.2 and false-discovery rate-adjusted p-values (FDR) ≤ 0.05 were considered significantly differentially abundant. The analysis identified 435 proteins, with 59 differentially abundant proteins (DAPs) between positive and negative-RADG beef steers. Plasma abundance of 38 proteins, such as macrophage stimulating 1 and peptidase D was upregulated (FC ≥ 1.2, FDR ≤ 0.05) in positive-RADG beef steers, while 21 proteins, including fibronectin and ALB protein were greater (FC < 1.2, FDR ≤ 0.05) in negative-RADG beef steers. The results of the Gene Ontology (GO) analysis of all the DAPs showed enrichment of pathways such as metabolic processes, biological regulation, and catalytic activity in positive-RADG beef steers. Results of the EuKaryotic Orthologous Groups (KOG) analysis revealed increased abundance of DAPs involved in energy production and conversion, amino acid transport and metabolism, and lipid transport and metabolism in positive-RADG beef steers. The results of this study revealed key metabolic pathways and proteins associated with divergent RADG phenotype in beef cattle which give more insight into the biological basis of feed efficiency in crossbred beef cattle.

Fasting and prolonged food restriction differentially affect GH secretion independently of GH receptor signaling in AgRP neurons

Growth hormone (GH) receptor (GHR) is abundantly expressed in neurons that co-release the agouti-related protein (AgRP) and neuropeptide Y (NPY) in the arcuate nucleus of the hypothalamus (ARH). Since ARHAgRP/NPY neurons regulate several hypothalamic-pituitary-endocrine axes, this neuronal population possibly modulates GH secretion via a negative feedback loop, particularly during food restriction, when ARHAgRP/NPY neurons are highly active. The present study aims to determine the importance of GHR signaling in ARHAgRP/NPY neurons on the pattern of GH secretion in fed and food-deprived male mice. Additionally, we compared the effect of two distinct situations of food deprivation: 16 h of fasting or four days of food restriction (40% of usual food intake). Overnight fasting strongly suppressed both basal and pulsatile GH secretion. Animals lacking GHR in ARHAgRP/NPY neurons (AgRP∆GHR mice) did not exhibit differences in GH secretion either in the fed or fasted state, compared to control mice. In contrast, four days of food restriction increased GH pulse frequency, basal GH secretion, and pulse irregularity/complexity (measured by sample entropy), whereas pulsatile GH secretion was not affected in both control and AgRP∆GHR mice. Hypothalamic Ghrh mRNA levels were unaffected by fasting or food restriction, but Sst expression increased in acutely fasted mice, but decreased after prolonged food restriction in both control and AgRP∆GHR mice. Our findings indicate that short-term fasting and prolonged food restriction differentially affect the pattern of GH secretion, independently of GHR signaling in ARHAgRP/NPY neurons.

Growth hormone receptor antagonist pegvisomant and its role in the medical therapy of growth hormone excess

Pegvisomant is a growth-hormone (GH) receptor antagonist that prevents the formation of the active heterotrimer of the dimerised GH receptor and the GH molecule necessary for downstream signal transduction. Over the past 20 years, it has become a key therapeutic option for physicians treating syndromes of GH/IGF-1 excess. Sufficient longitudinal follow-up data suggest that it can be deemed both safe and effective. It is the drug with the greatest potential for achieving an amelioration of the biochemical effects of GH excess with a corresponding normalisation of IGF-1 levels; however, insufficient dose titration has lessened real-world therapeutic outcomes. Theoretical concerns about stimulating tumour growth have been resolved as this has not been observed, while derangement of liver enzymes and local skin-related adverse reactions may occur in a minority of the patients. It may be a particularly impactful medication for the treatment of children, young people, and those with inherited disorders of GH excess, where other treatment modalities often fail. Combination therapy of pegvisomant with first- and second-generation somatostatin receptor ligands or with dopamine agonists remains an ongoing area of interest and research. High cost remains a barrier to the use of pegvisomant in many settings.

Post-natal muscle growth and protein turnover: a narrative review of current understanding

A model explaining the dietary-protein-driven post-natal skeletal muscle growth and protein turnover in the rat is updated, and the mechanisms involved are described, in this narrative review. Dietary protein controls both bone length and muscle growth, which are interrelated through mechanotransduction mechanisms with muscle growth induced both from stretching subsequent to bone length growth and from internal work against gravity. This induces satellite cell activation, myogenesis and remodelling of the extracellular matrix, establishing a growth capacity for myofibre length and cross-sectional area. Protein deposition within this capacity is enabled by adequate dietary protein and other key nutrients. After briefly reviewing the experimental animal origins of the growth model, key concepts and processes important for growth are reviewed. These include the growth in number and size of the myonuclear domain, satellite cell activity during post-natal development and the autocrine/paracrine action of IGF-1. Regulatory and signalling pathways reviewed include developmental mechanotransduction, signalling through the insulin/IGF-1-PI3K-Akt and the Ras-MAPK pathways in the myofibre and during mechanotransduction of satellite cells. Likely pathways activated by maximal-intensity muscle contractions are highlighted and the regulation of the capacity for protein synthesis in terms of ribosome assembly and the translational regulation of 5-TOPmRNA classes by mTORC1 and LARP1 are discussed. Evidence for and potential mechanisms by which volume limitation of muscle growth can occur which would limit protein deposition within the myofibre are reviewed. An understanding of how muscle growth is achieved allows better nutritional management of its growth in health and disease.

New findings on brain actions of growth hormone and potential clinical implications

Growth hormone (GH) is secreted by somatotropic cells of the anterior pituitary gland. The classical effects of GH comprise the stimulation of cell proliferation, tissue and body growth, lipolysis, and insulin resistance. The GH receptor (GHR) is expressed in numerous brain regions. Notably, a growing body of evidence indicates that GH-induced GHR signaling in specific neuronal populations regulates multiple physiological functions, including energy balance, glucose homeostasis, stress response, behavior, and several neurological/cognitive aspects. The importance of central GHR signaling is particularly evident when the organism is under metabolic stress, such as pregnancy, chronic food deprivation, hypoglycemia, and prolonged exercise. These particular situations are associated with elevated GH secretion. Thus, central GH action represents an internal signal that coordinates metabolic, neurological, neuroendocrine, and behavioral adaptations that are evolutionarily advantageous to increase the chances of survival. This review summarizes and discusses recent findings indicating that the brain is an important target of GH, and GHR signaling in different neuronal populations regulates essential physiological functions.

The Pattern of GH Action in the Mouse Brain

GH acts in numerous organs expressing the GH receptor (GHR), including the brain. However, the mechanisms behind the brain's permeability to GH and how this hormone accesses different brain regions remain unclear. It is well-known that an acute GH administration induces phosphorylation of the signal transducer and activator of transcription 5 (pSTAT5) in the mouse brain. Thus, the pattern of pSTAT5 immunoreactive cells was analyzed at different time points after IP or intracerebroventricular GH injections. After a systemic GH injection, the first cells expressing pSTAT5 were those near circumventricular organs, such as arcuate nucleus neurons adjacent to the median eminence. Both systemic and central GH injections induced a medial-to-lateral pattern of pSTAT5 immunoreactivity over time because GH-responsive cells were initially observed in periventricular areas and were progressively detected in lateral brain structures. Very few choroid plexus cells exhibited GH-induced pSTAT5. Additionally, Ghr mRNA was poorly expressed in the mouse choroid plexus. In contrast, some tanycytes lining the floor of the third ventricle expressed Ghr mRNA and exhibited GH-induced pSTAT5. The transport of radiolabeled GH into the hypothalamus did not differ between wild-type and dwarf Ghr knockout mice, indicating that GH transport into the mouse brain is GHR independent. Also, single-photon emission computed tomography confirmed that radiolabeled GH rapidly reaches the ventral part of the tuberal hypothalamus. In conclusion, our study provides novel and valuable information about the pattern and mechanisms behind GH transport into the mouse brain.

Development of nano-liposomal human growth hormone as a topical formulation for preventing uvb-induced skin damage

Due to its involvement in skin maintenance and repair, topical administration of recombinant human growth hormone (rhGH) is an interesting strategy for therapeutic purposes. We have formulated and characterized a topical rhGH-loaded liposomal formulation (rhGH-Lip) and evaluated its safety, biological activity, and preventive role against UVB-induced skin damage. The rhGH-Lip had an average size and zeta potential of 63 nm and -33 mV, respectively, with 70 % encapsulation efficiency. The formulation was stable at 4 °C for at least one year. The SDS-PAGE and circular dichroism results showed no structural alterations in rhGH upon encapsulation. In vitro, studies in HaCaT, HFFF-2, and Ba/F3-rhGHR cell lines confirmed the safety and biological activity of rhGH-Lip. Franz diffusion cell study showed increased rhGH skin permeation compared to free rhGH. Animal studies in nude mice showed that liposomal rhGH prevented UVB-induced epidermal hyperplasia, angiogenesis, wrinkle formation, and collagen loss, as well as improving skin moisture. The results of this study show that rhGH-Lip is a stable, safe, and effective skin delivery system and has potential as an anti-wrinkle formulation for topical application. This study also provides a new method for the topical delivery of proteins and merits further investigation.

Fyn, Blk, and Lyn kinase inhibitors: A mini-review on medicinal attributes, research progress, and future insights

Fyn, Blk, and Lyn are part of a group of proteins called Src family kinases. They are crucial in controlling cell communication and their response to the growth, changes, and immune system. Blocking these proteins with inhibitors can be a way to treat diseases where these proteins are too active. The primary mode of action of these inhibitors is to inhibit the phosphorylation of Fyn, Blk, and Lyn receptors, which in turn affects how signals pass within the cells. This review shows the structural and functional aspects of Fyn, Blk, and Lyn kinases, highlighting the significance of their dysregulation in diseases such as cancer and autoimmune disorders. The discussion encompasses the design strategies, SAR analysis, and chemical characteristics of effective inhibitors, shedding light on their specificity and potency. Furthermore, it explores the progress of clinical trials of these inhibitors, emphasizing their potential therapeutic applications.

Growth Hormone Mediators and Glycemic Control in Youths With Type 2 Diabetes: A Secondary Analysis of a Randomized Clinical Trial

Importance

Youth-onset type 2 diabetes (T2D) has a more aggressive phenotype than adult-onset T2D, including rapid loss of glycemic control and increased complication risk.

Objective

To identify associations of growth hormone mediators with glycemic failure, beta cell function, and insulin sensitivity in youth-onset T2D.

Design, Setting, and Participants

This post hoc secondary analysis of the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) randomized clinical trial, which enrolled participants from July 2004 to February 2009, included 398 participants from 15 university-affiliated medical centers with available plasma samples from baseline and 36 months. Participants were youths aged 10 to 17 years with a duration of T2D of less than 2 years who were randomized to metformin, metformin plus lifestyle intervention, or metformin plus rosiglitazone. Participants were followed up for a mean (SD) of 3.9 (1.5) years during the trial, ending in 2011. Statistical analysis was performed from August 2022 to November 2023.

Exposure

Plasma insulin-like growth factor-1 (IGF-1), growth hormone receptor (GHR), and insulin-like growth factor binding protein 1 (IGFBP-1).

Main Outcomes and Measures

Main outcomes were (1) loss of glycemic control during the TODAY study, defined as hemoglobin A1c (HbA1c) level of 8% or more for 6 months or inability to wean from insulin therapy, and (2) baseline and 36-month measures of glycemia (fasting glucose, HbA1c), insulin sensitivity (1/fasting C-peptide), high-molecular-weight adiponectin, and beta cell function (C-peptide index, C-peptide oral disposition index).

Results

This analysis included 398 participants (mean [SD] age, 13.9 [2.0] years; 248 girls [62%]; 166 Hispanic participants [42%]; 134 non-Hispanic Black participants [34%], and 84 non-Hispanic White participants [21%]). A greater increase in IGF-1 level between baseline and 36 months was associated with lower odds of glycemic failure (odds ratio [OR], 0.995 [95% CI, 0.991-0.997]; P < .001) and higher C-peptide index per 100-ng/mL increase in IGF-1 (β [SE], 0.015 [0.003]; P < .001). A greater increase in log2 GHR level between baseline and 36 months was associated with higher odds of glycemic failure (OR, 1.75 [95% CI, 1.05-2.99]; P = .04) and lower C-peptide index (β [SE], -0.02 [0.006]; P < .001). A greater increase in log2 IGFBP-1 level between baseline and 36 months was associated with higher odds of glycemic failure (OR, 1.37 [95% CI, 1.09-1.74]; P = .007) and higher high-molecular-weight adiponectin (β [SE], 431 [156]; P = .007).

Conclusions and Relevance

This study suggests that changes in plasma growth hormone mediators are associated with loss of glycemic control in youth-onset T2D, with IGF-1 associated with lower risk and GHR and IGFBP-1 associated with increased risk.

Trial Registration

ClinicalTrials.gov Identifier: NCT00081328.

Design, Synthesis and In Vitro Evaluation of Levodopa Stearic Acid Hydrazide Conjugate for the Management of Parkinson's DiseaseNovel Conjugate for Parkinson's Disease

Parkinson's disease is the highest prevalent neurodegenerative disease in elderly individuals after Alzheimer's disease. The pathological identification for Parkinson's disease is loss of dopaminergic neurons in substantia nigra region of the brain that in turn leads to dopamine deficiency that affects the body's normal physiological and neurological disorder. The important drawback in the modality of treatment is levodopa is only supplying depleted dopamine in the brain, it does not affect neurodegeneration. Even though levodopa manages the disease, an alternative treatment strategy is required to stop or prevent further degeneration of neuron. The compound with neuroprotector activity suits the requirement. Of them, stearic acid plays a vital role in protecting neurons against oxidative stress through a Phosphoinositide 3-kinase-dependent mechanism. Hence, our present study aimed to design, synthesize, and characterize the levodopa stearic acid hydrazide conjugate. Additionally, evaluate the cytotoxicity of synthesized compound in SHSY5Y: cell lines. In brief, levodopa was conjugated to the stearic acid successfully and was confirmed with Fourier-transform infrared spectroscopy, Nuclear magnetic resonance, and Mass Spectroscopy. In vitro cell viability study in SHSY5Y: cell lines showed elevated cell viability in 0.134 µm concentration of Conjugate, and 0.563 µm concentration of levodopa. Showing that the synthesized compound could offer an improved treatment strategy for Parkinson's disease.

Food deprivation reduces sensitivity of liver Igf1 synthesis pathways to growth hormone in juvenile gopher rockfish (Sebastes carnatus)

Growth hormone (Gh) regulates growth in part by stimulating the liver to synthesize and release insulin-like growth factor-1 (Igf1), which then promotes somatic growth. However, for fish experiencing food limitation, elevated blood Gh can occur even with low circulating Igf1 and slow growth, suggesting that nutritional stress can alter the sensitivity of liver Igf1 synthesis pathways to Gh. Here, we examined how recent feeding experience affected Gh regulation of liver Igf1 synthesis pathways in juvenile gopher rockfish (Sebastes carnatus) to illuminate mechanisms underlying the nutritional modulation of Igf1 production. Juvenile gopher rockfish were maintained under conditions of feeding or complete food deprivation (fasting) for 14 d and then treated with recombinant sea bream (Sparus aurata) Gh or saline control. Gh upregulated hepatic igf1 mRNA levels in fed fish but not in fasted fish. The liver of fasted rockfish also showed a lower relative abundance of gene transcripts encoding teleost Gh receptors 1 (ghr1) and 2 (ghr2), as well as reduced protein levels of phosphorylated janus tyrosine kinase 2 (pJak2) and signal transducer and activator of transcription 5 (pStat5), which function to induce igf1 gene transcription following Gh binding to Gh receptors. Relative hepatic mRNA levels for suppressors of cytokine signaling (Socs) genes socs2, socs3a, and socs3b were also lower in fasted rockfish. Socs2 can suppress Gh activation of Jak2/Stat5, and fasting-related variation in socs expression may reflect modulated inhibitory control of igf1 gene transcription. Fasted rockfish also had elevated liver mRNA abundances for lipolytic hormone-sensitive lipase 1 (hsl1) and Igf binding proteins igfbp1a, -1b and -3a, reduced liver mRNAs encoding igfbp2b and an Igfbp acid labile subunit-like (igfals) gene, and higher transcript abundances for Igf1 receptors igf1ra and igf1rb in skeletal muscle. Together, these findings suggest that food deprivation impacts liver Igf1 responsiveness to Gh via multiple mechanisms that include a downregulation of hepatic Gh receptors, modulation of the intracellular Jak2/Stat5 transduction pathway, and possible shifts in Socs-inhibitory control of igf1 gene transcription, while also demonstrating that these changes occur in concert with shifts in liver Igfbp expression and muscle Gh/Igf1 signaling pathway components.

Crosstalk Between the Neuroendocrine System and Bone Homeostasis

The homeostasis of bone microenvironment is the foundation of bone health and comprises 2 concerted events: bone formation by osteoblasts and bone resorption by osteoclasts. In the early 21st century, leptin, an adipocytes-derived hormone, was found to affect bone homeostasis through hypothalamic relay and the sympathetic nervous system, involving neurotransmitters like serotonin and norepinephrine. This discovery has provided a new perspective regarding the synergistic effects of endocrine and nervous systems on skeletal homeostasis. Since then, more studies have been conducted, gradually uncovering the complex neuroendocrine regulation underlying bone homeostasis. Intriguingly, bone is also considered as an endocrine organ that can produce regulatory factors that in turn exert effects on neuroendocrine activities. After decades of exploration into bone regulation mechanisms, separate bioactive factors have been extensively investigated, whereas few studies have systematically shown a global view of bone homeostasis regulation. Therefore, we summarized the previously studied regulatory patterns from the nervous system and endocrine system to bone. This review will provide readers with a panoramic view of the intimate relationship between the neuroendocrine system and bone, compensating for the current understanding of the regulation patterns of bone homeostasis, and probably developing new therapeutic strategies for its related disorders.

Evaluation of the anticonvulsant and neuroprotective effect of intracerebral administration of growth hormone in rats

INTRODUCTION

The growth hormone (GH) has been reported as a crucial neuronal survival factor in the hippocampus against insults of diverse nature. Status epilepticus (SE) is a prolonged seizure that produces extensive neuronal cell death. The goal of this study was to evaluate the effect of intracerebroventricular administration of GH on seizure severity and SE-induced hippocampal neurodegeneration.

METHODOLOGY

Adult male rats were implanted with a guide cannula in the left ventricle and different amounts of GH (70, 120 or 220ng/3μl) were microinjected for 5 days; artificial cerebrospinal fluid was used as the vehicle. Seizures were induced by the lithium-pilocarpine model (3mEq/kg LiCl and 30mg/kg pilocarpine hydrochloride) one day after the last GH administration. Neuronal injury was assessed by Fluoro-Jade B (F-JB) staining.

RESULTS

Rats injected with 120ng of GH did not had SE after 30mg/kg pilocarpine, they required a higher number of pilocarpine injections to develop SE than the rats pretreated with the vehicle, 70ng or 220ng GH. Prefrontal and parietal cortex EEG recordings confirmed that latency to generalized seizures and SE was also significantly higher in the 120ng group when compared with all the experimental groups. FJ-B positive cells were detected in the hippocampus after SE in all rats, and no significant differences in the number of F-JB cells in the CA1 area and the hilus was observed between experimental groups.

CONCLUSION

Our results indicate that, although GH has an anticonvulsive effect in the lithium-pilocarpine model of SE, it does not exert hippocampal neuroprotection after SE.

Association of the GHRd3 polymorphism with adult height and type 2 diabetes in a Saudi Arabian population from Jazan Province: A case-control study

Objectives

This study investigated the association of the GHRd3 polymorphism with height and type-2 diabetes mellitus (T2DM) in Saudi Arabia.

Methods

This case-control study included a total of 284 participants, divided into healthy controls (n = 142) and patients with T2DM (n = 142), recruited from Jazan University Hospital, southwest of Saudi Arabia in the period between January to September 2022. The GHRd3 polymorphism was genotyped using multiplex PCR. The correlation between height and genotypes was analyzed using one-way analysis of variance. The association between GHRd3 polymorphism and T2DM was assessed using logistic regression analysis.

Results

The data showed a significant difference between the means of heights associated with each GHRd3 genotype, flfl, fld3, and d3d3. Logistic regression analysis showed no association between GHRd3 variants and T2DM.

Conclusion

Homozygous GHRd3 polymorphism carriers, d3d3 genotype, were taller than fld3 or flfl carriers in our population. None of the GHRd3 variants were associated with T2DM. Thus, the GHRd3 polymorphism has growth-related actions with a minor contribution to T2DM. However, more studies with a larger sample size are required to confirm these findings.

The effects of peripheral hormone responses to exercise on adult hippocampal neurogenesis

Over the last decade, a considerable amount of new data have revealed the beneficial effects of exercise on hippocampal neurogenesis and the maintenance or improvement of cognitive function. Investigations with animal models, as well as human studies, have yielded novel understanding of the mechanisms through which endocrine signaling can stimulate neurogenesis, as well as the effects of exercise on acute and/or chronic levels of these circulating hormones. Considering the effects of aging on the decline of specific endocrine factors that affect brain health, insights in this area of research are particularly important. In this review, we discuss how different forms of exercise influence the peripheral production of specific endocrine factors, with particular emphasis on brain-derived neurotrophic factor, growth hormone, insulin-like growth factor-1, ghrelin, estrogen, testosterone, irisin, vascular endothelial growth factor, erythropoietin, and cortisol. We also describe mechanisms through which these endocrine responses to exercise induce cellular changes that increase hippocampal neurogenesis and improve cognitive function.

WIP1 is a novel specific target for growth hormone action

DNA damage repair (DDR) is mediated by phosphorylating effectors ATM kinase, CHK2, p53, and γH2AX. We showed earlier that GH suppresses DDR by suppressing pATM, resulting in DNA damage accumulation. Here, we show GH acting through GH receptor (GHR) inducing wild-type p53-inducible phosphatase 1 (WIP1), which dephosphorylated ATM and its effectors in normal human colon cells and three-dimensional human intestinal organoids. Mice bearing GH-secreting xenografts exhibited induced colon WIP1 with suppressed pATM and γH2AX. WIP1 was also induced in buffy coats derived from patients with elevated GH from somatotroph adenomas. In contrast, decreased colon WIP1 was observed in GHR-/- mice. WIP1 inhibition restored ATM phosphorylation and reversed GH-induced DNA damage. We elucidated a novel GH signaling pathway activating Src/AMPK to trigger HIPK2 nuclear-cytoplasmic relocation and suppressing WIP1 ubiquitination. Concordantly, blocking either AMPK or Src abolished GH-induced WIP1. We identify WIP1 as a specific target for GH-mediated epithelial DNA damage accumulation.

Short Stature due to Bioinactive Growth Hormone (Kowarski Syndrome)

OBJECTIVE

Bioinactive growth hormone (BGH) is a structurally abnormal, biologically inactive, but immunoreactive form of growth hormone encoded by pathogenic growth hormone 1 gene variants. The underlying cause of the defective physiology is decreased BGH binding affinity to both growth hormone binding proteins and growth hormone receptors (GHRs). GHR cannot dimerize when it is in a quiescent state because BGH cannot activate it. Nondimerized GHR is unable to activate intracytoplasmic signaling pathway molecules such as Janus kinase 2 and signal transducer and activator of transcription, which initiate insulin-like growth factor-1 (IGF-1) transcription. IGF-1 cannot therefore be synthesized and IGF-1 levels in the circulation decrease. In contrast to children with growth hormone insensitivity, children with short stature due to BGH, known as Kowarski syndrome, exhibit an outstanding linear growth response to recombinant growth hormone therapy. For a number of reasons, differential diagnosis presents some difficulties. Similar diseases caused by genetic abnormalities that cause short stature range in severity from minor to severe clinical spectrum. Furthermore, some patients with Kowarski syndrome have previously been diagnosed with familial short stature, constitutional delayed puberty, and idiopathic short stature. This paper aims to review the particular clinical and laboratory findings of BGH.

METHODS

This study collected clinical and laboratory data from KS cases reported in the literature.

RESULTS

This review reports that KS cases have lower SDSs for height and IGF-1 compared to growth hormone deficiency.

CONCLUSION

The diversity of genetic defects underlying Kowarski syndrome (KS) will provide new insights into growth hormone insensitivity. As the availability of genetic analysis, including functional investigations expands, researchers will identify new underlying genetic pathways.

Involvement of Sirtuin 1 in the Growth Hormone/Insulin-like Growth Factor 1 Signal Transduction and Its Impact on Growth Processes in Children

The regulation of growth processes in children depends on the synthesis of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Insulin-like growth factor 1, which is mainly secreted in the liver in response to GH, is the main peripheral mediator of GH action. Newly discovered factors regulating GH secretion and its effects are being studied recently. One of them is sirtuin 1 (SIRT1). This NAD+-dependent deacetylase, by modulating the JAK2/STAT pathway, is involved in the transduction of the GH signal in hepatocytes, leading to the synthesis of IGF-1. In addition, it participates in the regulation of the synthesis of GHRH in the hypothalamus and GH in the somatotropic cells. SIRT1 is suggested to be involved in growth plate chondrogenesis and longitudinal bone growth as it has a positive effect on the epiphyseal growth plate. SIRT1 is also implicated in various cellular processes, including metabolism, cell cycle regulation, apoptosis, oxidative stress response, and DNA repair. Thus, its expression varies depending on the different metabolic states. During malnutrition, SIRT1 blocks GH signal transduction in hepatocytes to reduce the IGF-1 secretion and prevent hypoglycemia (i.e., it causes transient GH resistance). In this review, we focused on the influence of SIRT1 on GH signal transduction and the implications that may arise for growth processes in children.

Developmental impact of peripheral injury on neuroimmune signaling

A peripheral injury drives neuroimmune interactions at the level of the injury and throughout the neuraxis. Understanding these systems will be beneficial in the pursuit to target persistent pain that involves both neural and immune components. In this review, we discuss the impact of injury on the development of neuroimmune signaling, along with data that suggest a possible cellular immune memory. We also discuss the parallel effects of injury in the nervous system and immune related areas including bone marrow, lymph node and central nervous system-related cells. Finally, we relate these findings to patient populations and current research that evaluates human tissue.

Structural Modeling of Cytokine-Receptor-JAK2 Signaling Complexes Using AlphaFold Multimer

Homodimeric class 1 cytokine receptors include the erythropoietin (EPOR), thrombopoietin (TPOR), granulocyte colony-stimulating factor 3 (CSF3R), growth hormone (GHR), and prolactin receptors (PRLR). These cell-surface single-pass transmembrane (TM) glycoproteins regulate cell growth, proliferation, and differentiation and induce oncogenesis. An active TM signaling complex consists of a receptor homodimer, one or two ligands bound to the receptor extracellular domains, and two molecules of Janus Kinase 2 (JAK2) constitutively associated with the receptor intracellular domains. Although crystal structures of soluble extracellular domains with ligands have been obtained for all of the receptors except TPOR, little is known about the structure and dynamics of the complete TM complexes that activate the downstream JAK-STAT signaling pathway. Three-dimensional models of five human receptor complexes with cytokines and JAK2 were generated here by using AlphaFold Multimer. Given the large size of the complexes (from 3220 to 4074 residues), the modeling required a stepwise assembly from smaller parts, with selection and validation of the models through comparisons with published experimental data. The modeling of active and inactive complexes supports a general activation mechanism that involves ligand binding to a monomeric receptor followed by receptor dimerization and rotational movement of the receptor TM α-helices, causing proximity, dimerization, and activation of associated JAK2 subunits. The binding mode of two eltrombopag molecules to the TM α-helices of the active TPOR dimer was proposed. The models also help elucidate the molecular basis of oncogenic mutations that may involve a noncanonical activation route. Models equilibrated in explicit lipids of the plasma membrane are publicly available.

The Exon 3-Deleted Growth Hormone Receptor (d3GHR) Polymorphism-A Favorable Backdoor Mechanism for the GHR Function

Growth hormone (GH) is a peptide hormone that plays a crucial role in controlling growth, development, and lifespan. Molecular regulation of GH is accomplished via the GH receptor (GHR), which is the main factor influencing human development and is essential to optimal functioning of the GH/IGF-I axis. Two GHR isoforms have been studied, according to the presence (flGHR) or absence (d3GHR) of exon 3. The d3GHR isoform, which lacks exon 3 has recently been related to longevity; individuals carrying this isoform have higher receptor activity, improved signal transduction, and alterations in the treatment response and efficacy compared with those carrying the wild type (WT) isoform (flGHR). Further, studies performed in patients with acromegaly, Prader-Willi syndrome, Turner syndrome, small for gestational age (SGA), and growth hormone deficiency (GHD) suggested that the d3GHR isoform may have an impact on the relationship between GH and IGF-I levels, height, weight, BMI, and other variables. Other research, however, revealed inconsistent results, which might have been caused by confounding factors, including limited sample sizes and different experimental methods. In this review, we lay out the complexity of the GHR isoforms and provide an overview of the major pharmacogenetic research conducted on this ongoing and unresolved subject.

The growth hormone receptor interacts with transcriptional regulator HMGN1 upon GH-induced nuclear translocation

Growth hormone (GH) actions are mediated through binding to its cell-surface receptor, the GH receptor (GHR), with consequent activation of downstream signalling. However, nuclear GHR localisation has also been observed and is associated with increased cancer cell proliferation. Here we investigated the functional implications of nuclear translocation of the GHR in the human endometrial cancer cell-line, RL95-2, and human mammary epithelial cell-line, MCF-10A. We found that following GH treatment, the GHR rapidly translocates to the nucleus, with maximal localisation at 5-10 min. Combined immunoprecipitation-mass spectrometry analysis of RL95-2 whole cell lysates identified 40 novel GHR binding partners, including the transcriptional regulator, HMGN1. Moreover, microarray analysis demonstrated that the gene targets of HMGN1 were differentially expressed following GH treatment, and co-immunoprecipitation showed that HMGN1 associates with the GHR in the nucleus. Therefore, our results suggest that GHR nuclear translocation might mediate GH actions via interaction with chromatin factors that then drive changes in specific downstream transcriptional programs.

Resistance exercise stress: theoretical mechanisms for growth hormone processing and release from the anterior pituitary somatotroph

Heavy resistance exercise (HRE) is the most effective method for inducing muscular hypertrophy and stimulating anabolic hormones, including growth hormone, into the blood. In this review, we explore possible mechanisms within the GH secretory pathway of the pituitary somatotroph, which are likely to modulate the flow of hormone synthesis and packaging as it is processed prior to exocytosis. Special emphasis is placed on the secretory granule and its possible role as a signaling hub. We also review data that summarize how HRE affects the quality and quantity of the secreted hormone. Finally, these pathway mechanisms are considered in the context of heterogeneity of the somatotroph population in the anterior pituitary.

Whole-Body and Forearm Muscle Protein Metabolism in Patients With Acromegaly Before and After Treatment

BACKGROUND

Active acromegaly is characterized by increased lean body mass, but the mechanisms underlying the protein anabolic effect are unclear.

AIM

To study if active acromegaly induces reversible changes in whole-body and skeletal muscle protein kinetics.

PATIENTS AND METHODS

Eighteen patients with acromegaly were investigated before and 47 ± 10 weeks after disease control by surgery (n = 8) and/or medical treatment (n = 10). Labeled phenylalanine and tyrosine tracers were employed to assess whole-body and regional forearm muscle protein kinetics. Intramyocellular protein signaling was assessed in skeletal muscle biopsies, and whole-body dual-energy X-ray absorptiometry scan and indirect calorimetry assessed lean body mass (LBM) and resting energy expenditure, respectively.

RESULTS

Disease control induced a 7% decrease in lean body mass (P < .000) and a 14% decrease in LBM-adjusted energy expenditure. Whole-body phenylalanine breakdown decreased after disease control (P = .005) accompanied by a decrease in the degradation of phenylalanine to tyrosine (P = .005) and a decrease in whole-body phenylalanine synthesis (P = .030). Skeletal muscle protein synthesis tended to decrease after disease control (P = .122), whereas the muscle protein breakdown (P = .437) and muscle protein loss were unaltered (P = .371). Unc-51 like autophagy activating kinase 1 phosphorylation, an activator of protein breakdown, increased after disease control (P = .042).

CONCLUSIONS

Active acromegaly represents a reversible high flux state in which both whole-body protein breakdown and synthesis are increased, whereas forearm muscle protein kinetics are unaltered. Future studies are needed to decipher the link between protein kinetics and the structure and function of the associated growth hormone-induced increase in lean body mass.

Case Report: A child with NFKB1 haploinsufficiency explaining the linkage between immunodeficiency and short stature

We report the case of a patient with common variable immunodeficiency (CVID) presenting with short stature and treated with recombinant human growth hormone (rhGH). Whole exome sequencing revealed a novel single-nucleotide duplication in the NFKB1 gene (c.904dup, p.Ser302fs), leading to a frameshift and thus causing NFKB1 haploinsufficiency. The variant was considered pathogenic and was later found in the patient's mother, also affected by CVID. This is the first reported case of a patient with CVID due to NFKB1 mutation presenting with short stature. We analyzed the interconnection between NFKB1 and GH - IGF-1 pathways and we hypothesized a common ground for both CVID and short stature in our patient.

Structure and function of a dual antagonist of the human growth hormone and prolactin receptors with site-specific PEG conjugates

Human growth hormone (hGH) is a pituitary-derived endocrine protein that regulates several critical postnatal physiologic processes including growth, organ development, and metabolism. Following adulthood, GH is also a regulator of multiple pathologies like fibrosis, cancer, and diabetes. Therefore, there is a significant pharmaceutical interest in developing antagonists of hGH action. Currently, there is a single FDA-approved antagonist of the hGH receptor (hGHR) prescribed for treating patients with acromegaly and discovered in our laboratory almost 3 decades ago. Here, we present the first data on the structure and function of a new set of protein antagonists with the full range of hGH actions-dual antagonists of hGH binding to the GHR as well as that of hGH binding to the prolactin receptor. We describe the site-specific PEG conjugation, purification, and subsequent characterization using MALDI-TOF, size-exclusion chromatography, thermostability, and biochemical activity in terms of ELISA-based binding affinities with GHR and prolactin receptor. Moreover, these novel hGHR antagonists display distinct antagonism of GH-induced GHR intracellular signaling in vitro and marked reduction in hepatic insulin-like growth factor 1 output in vivo. Lastly, we observed potent anticancer biological efficacies of these novel hGHR antagonists against human cancer cell lines. In conclusion, we propose that these new GHR antagonists have potential for development towards multiple clinical applications related to GH-associated pathologies.

Reporting a novel growth hormone receptor gene variant in an Iranian consanguineous pedigree with Laron syndrome: a case report

BACKGROUND

Human growth hormone (hGH) plays a crucial role in growth by binding to growth hormone receptor (GHR) in target cells. Binding of GH molecules to their cognate receptors triggers downstream signaling pathways leading to the transcription of several genes, including insulin-like growth factor (IGF)-1. Pathogenic variants in the GHR gene can result in structural and functional defects in the GHR protein, leading to Laron Syndrome (LS) with the primary clinical manifestation of short stature. So far, around 100 GHR variants have been reported, mostly biallelic, as causing LS.

CASE PRESENTATION

We report on three siblings from an Iranian consanguineous family who presented with dwarfism. Whole-exome sequencing (WES) was performed on the proband, revealing a novel homozygous missense variant in the GHR gene (NM_000163.5; c.610 T > A, p.(Trp204Arg)) classified as a likely pathogenic variant according to the recommendation of the American College of Medical Genetics (ACMG). Co-segregation analysis was investigated using Sanger sequencing.

CONCLUSIONS

To date, approximately 400-500 LS cases with GHR biallelic variants, out of them 10 patients originating from Iran, have been described in the literature. Given the high rate of consanguineous marriages in the Iranian population, the frequency of LS is expected to be higher, which might be explained by undiagnosed cases. Early diagnosis of LS is very important, as treatment is available for this condition.

Hypothalamus and Post-Traumatic Stress Disorder: A Review

Humans have lived in a dynamic environment fraught with potential dangers for thousands of years. While fear and stress were crucial for the survival of our ancestors, today, they are mostly considered harmful factors, threatening both our physical and mental health. Trauma is a highly stressful, often life-threatening event or a series of events, such as sexual assault, war, natural disasters, burns, and car accidents. Trauma can cause pathological metaplasticity, leading to long-lasting behavioral changes and impairing an individual's ability to cope with future challenges. If an individual is vulnerable, a tremendously traumatic event may result in post-traumatic stress disorder (PTSD). The hypothalamus is critical in initiating hormonal responses to stressful stimuli via the hypothalamic-pituitary-adrenal (HPA) axis. Linked to the prefrontal cortex and limbic structures, especially the amygdala and hippocampus, the hypothalamus acts as a central hub, integrating physiological aspects of the stress response. Consequently, the hypothalamic functions have been attributed to the pathophysiology of PTSD. However, apart from the well-known role of the HPA axis, the hypothalamus may also play different roles in the development of PTSD through other pathways, including the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-gonadal (HPG) axes, as well as by secreting growth hormone, prolactin, dopamine, and oxytocin. This review aims to summarize the current evidence regarding the neuroendocrine functions of the hypothalamus, which are correlated with the development of PTSD. A better understanding of the role of the hypothalamus in PTSD could help develop better treatments for this debilitating condition.

Structural modeling of cytokine-receptor-JAK2 signaling complexes using AlphaFold Multimer

Homodimeric class 1 cytokine receptors include the erythropoietin (EPOR), thrombopoietin (TPOR), granulocyte colony-stimulating factor 3 (CSF3R), growth hormone (GHR), and prolactin receptors (PRLR). They are cell-surface single-pass transmembrane (TM) glycoproteins that regulate cell growth, proliferation, and differentiation and induce oncogenesis. An active TM signaling complex consists of a receptor homodimer, one or two ligands bound to the receptor extracellular domains and two molecules of Janus Kinase 2 (JAK2) constitutively associated with the receptor intracellular domains. Although crystal structures of soluble extracellular domains with ligands have been obtained for all the receptors except TPOR, little is known about the structure and dynamics of the complete TM complexes that activate the downstream JAK-STAT signaling pathway. Three-dimensional models of five human receptor complexes with cytokines and JAK2 were generated using AlphaFold Multimer. Given the large size of the complexes (from 3220 to 4074 residues), the modeling required a stepwise assembly from smaller parts with selection and validation of the models through comparisons with published experimental data. The modeling of active and inactive complexes supports a general activation mechanism that involves ligand binding to a monomeric receptor followed by receptor dimerization and rotational movement of the receptor TM α-helices causing proximity, dimerization, and activation of associated JAK2 subunits. The binding mode of two eltrombopag molecules to TM α-helices of the active TPOR dimer was proposed. The models also help elucidating the molecular basis of oncogenic mutations that may involve non-canonical activation route. Models equilibrated in explicit lipids of the plasma membrane are publicly available.

Exploring the Therapeutic Potential of Targeting GH and IGF-1 in the Management of Obesity: Insights from the Interplay between These Hormones and Metabolism

Obesity is a growing public health problem worldwide, and GH and IGF-1 have been studied as potential therapeutic targets for managing this condition. This review article aims to provide a comprehensive view of the interplay between GH and IGF-1 and metabolism within the context of obesity. We conducted a systematic review of the literature that was published from 1993 to 2023, using MEDLINE, Embase, and Cochrane databases. We included studies that investigated the effects of GH and IGF-1 on adipose tissue metabolism, energy balance, and weight regulation in humans and animals. Our review highlights the physiological functions of GH and IGF-1 in adipose tissue metabolism, including lipolysis and adipogenesis. We also discuss the potential mechanisms underlying the effects of these hormones on energy balance, such as their influence on insulin sensitivity and appetite regulation. Additionally, we summarize the current evidence regarding the efficacy and safety of GH and IGF-1 as therapeutic targets for managing obesity, including in pharmacological interventions and hormone replacement therapy. Finally, we address the challenges and limitations of targeting GH and IGF-1 in obesity management.

Central growth hormone action regulates neuroglial and proinflammatory markers in the hypothalamus of male mice

Growth hormone (GH) action in specific neuronal populations regulates neuroendocrine responses, metabolism, and behavior. However, the potential role of central GH action on glial function is less understood. The present study aims to determine how the hypothalamic expression of several neuroglial markers is affected by central GH action in male mice. The dwarf GH- and insulin-like growth factor-1 (IGF-1)-deficient Ghrhrlit/lit mice showed decreased mRNA expression of Nes (Nestin), Gfap, Iba1, Adgre1 (F4/80), and Tnf (TNFα) in the hypothalamus, compared to wild-type animals. In contrast, transgenic overexpression of GH led to high serum GH and IGF-1 levels, and increased hypothalamic expression of Nes, Gfap, Adgre1, Iba1, and Rax. Hepatocyte-specific GH receptor (GHR) knockout mice, which are characterized by high serum GH levels, but reduced IGF-1 secretion, showed increased mRNA expression of Gfap, Iba1, Tnf, and Sox10, demonstrating that the increase in GH levels alters the hypothalamic expression of glial markers associated with neuroinflammation, independently of IGF-1. Conversely, brain-specific GHR knockout mice showed reduced expression of Gfap, Adgre1, and Vim (vimentin), indicating that brain GHR signaling is necessary to mediate GH-induced changes in the expression of several neuroglial markers. In conclusion, the hypothalamic mRNA levels of several neuroglial markers associated with inflammation are directly modulated by GHR signaling in male mice.

A systems biology approach for discovering the cellular and molecular aspects of psychogenic non-epileptic seizure

Objectives

Psychogenic non-epileptic seizure (PNES) is the most common non-epileptic disorder in patients referring to epilepsy centers. Contrary to common beliefs about the disease's harmlessness, the death rate of PNES patients is similar to drug-resistant epilepsy. Meanwhile, the molecular pathomechanism of PNES is unknown with very limited related research. Thus, the aim of this in silico study was to find different proteins and hormones associated with PNES via a systems biology approach.

Methods

Different bioinformatics databases and literature review were used to find proteins associated with PNES. The protein-hormone interaction network of PNES was constructed to discover its most influential compartments. The pathways associated with PNES pathomechanism were found by enrichment analysis of the identified proteins. Besides, the relationship between PNES-related molecules and psychiatric diseases was discovered, and the brain regions that could express altered levels of blood proteins were discovered.

Results

Eight genes and three hormones were found associated with PNES through the review process. Proopiomelanocortin (POMC), neuropeptide Y (NPY), cortisol, norepinephrine, and brain-derived neurotrophic factor (BDNF) were identified to have a high impact on the disease pathogenesis network. Moreover, activation of Janus kinase-signaling transducer and activator of transcription (JAK-STAT) and JAK, as well as signaling of growth hormone receptor, phosphatidylinositol 3-kinase /protein kinase B (PI3K/AKT), and neurotrophin were found associated with PNES molecular mechanism. Several psychiatric diseases such as depression, schizophrenia, and alcohol-related disorders were shown to be associated with PNES predominantly through signaling molecules.

Significance

This study was the first to gather the biochemicals associated with PNES. Multiple components and pathways and several psychiatric diseases associated with PNES, and some brain regions that could be altered during PNES were suggested, which should be confirmed in further studies. Altogether, these findings could be used in future molecular research on PNES patients.