Hepatic Growth Hormone Receptor Research Articles

Tmem263 deletion disrupts the GH/IGF-1 axis and causes dwarfism and impairs skeletal acquisition

Genome-wide association studies (GWAS) have identified a large number of candidate genes believed to affect longitudinal bone growth and bone mass. One of these candidate genes, TMEM263, encodes a poorly characterized plasma membrane protein. Single nucleotide polymorphisms in TMEM263 are associated with bone mineral density in humans and mutations are associated with dwarfism in chicken and severe skeletal dysplasia in at least one human fetus. Whether this genotype-phenotype relationship is causal, however, remains unclear. Here, we determine whether and how TMEM263 is required for postnatal growth. Deletion of the Tmem263 gene in mice causes severe postnatal growth failure, proportional dwarfism, and impaired skeletal acquisition. Mice lacking Tmem263 show no differences in body weight within the first 2 weeks of postnatal life. However, by P21 there is a dramatic growth deficit due to a disrupted growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis, which is critical for longitudinal bone growth. Tmem263-null mice have low circulating IGF-1 levels and pronounced reductions in bone mass and growth plate length. The low serum IGF-1 in Tmem263-null mice is associated with reduced hepatic GH receptor (GHR) expression and GH-induced JAK2/STAT5 signaling. A deficit in GH signaling dramatically alters GH-regulated genes and feminizes the liver transcriptome of Tmem263-null male mice, with their expression profile resembling wild-type female, hypophysectomized male, and Stat5b-null male mice. Collectively, our data validates the causal role for Tmem263 in regulating postnatal growth and raises the possibility that rare mutations or variants of TMEM263 may potentially cause GH insensitivity and impair linear growth.

Tmem263 deletion disrupts the GH/IGF-1 axis and causes dwarfism and impairs skeletal acquisition.

Genome-wide association studies (GWAS) have identified a large number of candidate genes believed to affect longitudinal bone growth and bone mass. One of these candidate genes, TMEM263, encodes a poorly characterized plasma membrane protein. Single nucleotide polymorphisms in TMEM263 are associated with bone mineral density in humans and mutations are associated with dwarfism in chicken and severe skeletal dysplasia in at least one human fetus. Whether this genotype-phenotype relationship is causal, however, remains unclear. Here, we determine whether and how TMEM263 is required for postnatal growth. Deletion of the Tmem263 gene in mice causes severe postnatal growth failure, proportional dwarfism, and impaired skeletal acquisition. Mice lacking Tmem263 show no differences in body weight within the first 2 weeks of postnatal life. However, by P21 there is a dramatic growth deficit due to a disrupted growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis, which is critical for longitudinal bone growth. Tmem263-null mice have low circulating IGF-1 levels and pronounced reductions in bone mass and growth plate length. The low serum IGF-1 in Tmem263-null mice is associated with reduced hepatic GH receptor (GHR) expression and GH-induced JAK2/STAT5 signaling. A deficit in GH signaling dramatically alters GH-regulated genes and feminizes the liver transcriptome of Tmem263-null male mice, with their expression profile resembling wild-type female, hypophysectomized male, and Stat5b-null male mice. Collectively, our data validates the causal role for Tmem263 in regulating postnatal growth and raises the possibility that rare mutations or variants of TMEM263 may potentially cause GH insensitivity and impair linear growth.

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.

Deletion of hepatic growth hormone receptor (GHR) alters the mouse gut microbiota by affecting bile acid metabolism

ABSTRACT Both growth hormone (GH) and gut microbiota play significant roles in diverse physiological processes, but the crosstalk between them is poorly understood. Despite the regulation of GH by gut microbiota, study on GH’s influence on gut microbiota is limited, especially on the impacts of tissue specific GH signaling and their feedback effects on the host. In this study, we profiled gut microbiota and metabolome in tissue-specific GHR knockout mice in the liver (LKO) and adipose tissue (AKO). We found that GHR disruption in the liver rather than adipose tissue affected gut microbiota. It changed the abundance of Bacteroidota and Firmicutes at phylum level as well as abundance of several genera, such as Lactobacillus, Muribaculaceae, and Parasutterella, without affecting α-diversity. Moreover, the impaired liver bile acid (BA) profile in LKO mice was strongly associated with the change of gut microbiota. The BA pools and 12-OH BAs/non-12-OH BAs ratio were increased in the LKO mice, which was due to the induction of CYP8B1 by hepatic Ghr knockout. Consequently, the impaired BA pool in cecal content interacted with gut bacteria, which in turn increased the production of bacteria derived acetic acid, propionic acid, and phenylacetic acid that were possible to participate in the impaired metabolic phenotype of the LKO mice. Collectively, our findings suggested that the liver GH signaling regulates BA metabolism by its direct regulation on CYP8B1, which is an important factor influencing gut microbiota. Our study is significant in exploring gut microbiota modification effects of tissue-specific GH signaling as well as its involvement in gut microbiota–host interaction.

Caloric restriction as a possible pitfall for persistent acromegaly follow-up – case report

BackgroundAcromegaly diagnosis is established when plasma levels of IGF-1 are increased and the Oral Glucose Tolerance Test (OGTT) with 75gr of glucose can’t suppress Growth Hormone (GH) levels. These two parameters are also useful during follow-up, after surgical/radiologic therapy and/or during medical therapy.Case presentationA 29-year-old woman was diagnosed with acromegaly after a severe headache. Previous amenorrhea and facial and acral changes were noticed. A pituitary macroadenoma was found, biochemical evaluation was in agreement with the suspected acromegaly and a transsphenoidal adenectomy was performed. As the disease recurred, a surgical reintervention and radiosurgery (Gamma Knife, 22 Gy) were necessary. No normalization of IGF-1 was achieved during three years after radiosurgery. Surprisingly, then, and although clinical features seemed getting worse, IGF-1 levels became consistently controlled to 0.3–0.8 times the upper limit of the reference range. Questioned, the patient referred that she was following an intermittent fasting dietary plan. However, based on the dietary questionnaire, she was found to be under severe caloric restriction. First OGTT (under caloric restriction) showed absence of GH suppression and an IGF-1 value of 234 ng/dL (Reference Range 76–286 ng/mL). A second OGTT, one month after an eucaloric diet was instituted, showed an increased IGF-1 of 294 ng/dL, maintaining an unsuppressed, yet less elevated, GH.ConclusionsGHRH/GH/IGF-1 axis controls somatic growth. Regulation is complex, and nutrition status and feeding pattern have a recognized role. Like systemic inflammation or chronic liver disease, fasting and malnutrition decrease the expression of hepatic GH receptors, with consequent reduction of IGF-1 levels, through resistance to GH. This clinical report shows that caloric restriction may represent a pitfall in acromegaly follow-up.

The Optimum Dietary Phenylalanine Requirement of Hybrid Grouper (Epinephelusfuscoguttatus ♀ × Epinepheluslanceolatus ♂) Juveniles: Effects on Growth Performance, Gut Micromorphology, and Antioxidation.

The optimum phenylalanine (Phe) requirement for hybrid grouper (Epinephelusfuscoguttatus ♀ × Epinepheluslanceolatus ♂) juveniles was determined through an 8-week growth trial. A total of seven isoenergetic (340 kcal per 100 g of dry matter), isonitrogenous, and isolipidic diets were made, containing 8.2 (Phe 8.2), 9.2 (Phe 9.2), 10.1 (Phe 10.1), 11.2 (Phe 11.2), 13.3 (Phe 13.3), 15.2 (Phe 15.2), and 17.3 g/kg (Phe 17.3), respectively. Triplicate tanks of juvenile fish (about 16.7 g/fish) were fed each experimental diet twice daily until apparent satiation. The results indicated that different dietary Phe levels significantly influenced weight gain percentage (WG), feed efficiency (FE), protein efficiency ratio (PER), as well as, productive protein value (PPV). Fish fed Phe 8.2 had the lowest WG or PPV among all experimental treatments. Furthermore, the optimal dietary Phe level increased fold height, width, enterocyte, and microvillus height of fish. The Phe 10.1 group exhibited higher growth hormone (GH) expression in the pituitary compared to other groups. Expression of hepatic insulin-like growth factor-1 (IGF-1) and growth hormone receptor 1 (GHR1) displayed a similar pattern of variation to that of GH. The Phe 13.3 group had lower expression of S6 kinase 1 (S6K1) and target of rapamycin (TOR) than other groups. In addition, fish fed Phe 10.1 had lower levels of nuclear factor erythroid 2 (Nrf2) and heat shock protein 70 (HSP70) in the head kidney, and Cu/Zn-superoxide (Cu/ZnSOD) dismutases in the midgut compared to fish fed other Phe levels. Generally, optimal Phe content in the diet of hybrid grouper was estimated to be 12.7 g/kg of dry matter (27.3 g/kg of dietary protein), and at this level, the feed utilization, gut micromorphology, and immunity of fish were also elevated.

Expression of IGF-1 receptor and GH receptor in hepatic tissue of patients with nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

ObjectiveThe GH and IGF-1 axis is a candidate disease-modifying target in nonalcoholic fatty liver disease (NAFLD) given its lipolytic, anti-inflammatory and anti-fibrotic properties. IGF-1 receptor (IGF-1R) and GH receptor (GHR) expression in adult, human hepatic tissue is not well understood across the spectrum of NAFLD severity. Therefore, we sought to investigate hepatic IGF-1R and GHR expression in subjects with NAFLD utilizing gene expression analysis (GEA) and immunohistochemistry (IHC). DesignGEA (n = 318) and IHC (n = 30) cohorts were identified from the Massachusetts General Hospital NAFLD Tissue Repository. GEA subjects were categorized based on histopathology as normal liver histology (NLH), steatosis only (Steatosis), nonalcoholic steatohepatitis (NASH) without fibrosis (NASH F0), and NASH with fibrosis (NASH F1–4) with GEA by the Nanostring nCounter assay. IHC subjects were matched for age, body mass index (BMI), sex, and diabetic status across three groups (n = 10 each): NLH, Steatosis, and NASH with fibrosis (NASH F1–3). IHC for IGF-1R, IGF-1 and GHR was performed on formalin-fixed, paraffin-embedded hepatic tissue samples. ResultsIGF-1R gene expression did not differ across NAFLD severity while IGF-1 gene expression decreased with increasing NAFLD severity, including when controlled for BMI and age. GHR expression did not differ by severity of NAFLD based on GEA or IHC. ConclusionsIGF-1R and GHR expression levels were not significantly different across NAFLD disease severity. However, expression of IGF-1 was lower with increasing severity of NAFLD. Additional research is needed regarding the contribution of the GH/IGF-1 axis to the pathophysiology of NAFLD and NASH.

Modulating effect of elevated water hardness on growth performance, ammonia dynamics and ion-regulatory capacity in channel catfish (Ictalurus punctatus) following chronic challenge with high environmental ammonia and salinity stress

The aim of this study was to assess whether rearing fish at increased water hardness could assist channel catfish (Ictalurus punctatus) juveniles to efficiently cope with later (sub)lethal ammonia exposure or salinity stress. Fish were subjected to 100, 494 (10% of 96 h-LC50) or 1250 mg/L (25% of 96 h-LC50) CaCO3 water hardness levels for two months. Afterwards, fish were challenged with high environmental ammonia (HEA; 12.2 mg/L total ammonia ~25% of 96 h-LC50 value) or salinity stress (SST;10 ppt) separately for 21 days at their respective water hardness levels. Results show that after two months, weight gain (%), specific growth rate and feed conversion in 1250 mg/L CaCO3 group were markedly worse than 100 and 494 mg/L CaCO3 groups. This finding was accompanied with a down-regulation of hepatic IGF-I and growth hormone receptors (GHR) mRNA levels. During SST, growth was still significantly worse for those at 1250 mg/L CaCO3 (1250SST). However, exposure to HEA inhibited growth for 100HEA and 494HEA relative to 1250HEA. Ammonia excretion rate (Jamm) remained similar at different hardness levels; however, this was strongly inhibited at 100HEA, 494HEA and 100SST. This appeared to align to some degree with high water hardness having a protective effect on the gill histomorphology. In fact, fish at 1250HEA were able to increase Jamm efficiently, which was associated with upregulated branchial expression of ammonia transporters (Rhesus glycoproteins ‘Rhcg’) and Na+/H+ exchanger, as well as augmented gill H+-ATPase activity. These responses prevented a build-up of excess ammonia in plasma. In contrast, both 1250 mg/L CaCO3 and 1250HEA groups displayed inhibited branchial Na+/K+-ATPase activity indicating this unlikely has a major role in ammonia excretion. Gill Ca2+-ATPase activities reduced at the highest hardness (1250 mg/L CaCO3) and 1250HEA groups, likely to prevent hypercalcemia in plasma. No differences among hardness levels were noted for ion-regulation or Ca2+- homeostasis under SST. Overall, findings suggest that although elevated water hardness up to 1250 mg/L CaCO3 adversely affects the growth performance of channel catfish, it can ameliorate the inhibitory growth effects of HEA. This was partly attributed to 1250 mg/L CaCO3 protecting the gills as well as mitigating HEA-induced ammonia excretory and ion-regulatory disruption. However, elevated hardness may not be as effective in alleviating salinity stress in catfish.

The effects of blue and red light color combinations on the growth and immune performance of juvenile steelhead trout, Oncorhynchus mykiss

To examine the growth and immune response of steelhead trout (Oncorhynchus mykiss) under conditions of differing light color, we investigated the effects of different red and blue light color combinations on plasma non-specific immunity, hepatic antioxidant capacity, and GH/IGF-1 axis gene expression in juvenile steelhead trout (initial weight: 34.67 ± 2.69 g). The 16-week trial was set up with six treatments in which light color varied at a constant light intensity of 150 lx: 12 h white light + 12 h dark (12 W), 12 h blue light + 12 h dark (12B), 12 h red light + 12 h dark (12 R), 1.5 h blue light + 9 h red light + 1.5 h blue light + 12 h dark (3B9R), 3 h blue light + 6 h red light + 3 h blue light + 12 h dark (6B6R), total 12 h of blue and red light + 12 h dark (T12BR). The results revealed that the 12B and 3B9R light environments significantly enhanced plasma immunoglobulin M levels in steelhead trout, and that the 3B9R light environment also promoted significant increases in the gene expression of hepatic growth hormone receptor, insulin-like growth factor 1, and insulin-like growth factor-binding protein. The 3B9R light environment was also found enhance the antioxidant capacity of trout by increasing hepatic superoxide dismutase, catalase, and glutathione peroxidase activities. In contrast, trout exposed to the 6B6R light environment showed significant reductions in growth and immune performance, and there were similar reductions in hepatic antioxidant capacity. Furthermore, fish exposed to the 12R light environment were found to be characterized by elevated levels of lipid peroxidation and malondialdehyde, which are indicative of hepatic stress. In addition, we observed that in response to light variation, there were elevations in the activities of glutamic oxaloacetic transaminase and lactic dehydrogenase in the plasma of steelhead trout, thereby indicating an inhibition of cardiomyocyte function. In summary, our findings indicate that a 3B9R light environment simulates the blue-red-blue daily rhythm of light color variation in natural underwater environments, which is beneficial with respect to enhancing the growth and immunity of steelhead trout, and could accordingly be used to provide suitable light conditions in commercial trout production. However, sudden changes in light color should be avoided in the aquaculture of trout.

The Impact of Curcumin on Growth Performance, Growth-Related Gene Expression, Oxidative Stress, and Immunological Biomarkers in Broiler Chickens at Different Stocking Densities.

Simple SummaryThe primary goal of global poultry production is to optimize the amount of chicken produced per square meter of floor area. Consequently, stocking density (SD) and curcumin supplementation on broiler performance were investigated. Our results revealed that supplemental curcumin improved birds’ growth, behaviours, and immunity by lowering oxidative stress, enhancing humoral immune response, and modulating the suppression of growth-related gene expressions in broilers raised in high stocking density circumstances.Curcumin’s antioxidant properties reduce free radicals and may improve broiler growth. Therefore, the influence of stocking density (SD) and administration of curcumin in the diet on broiler performance was explored to clarify the impact of HSD and curcumin on the performance of growth, behavioural patterns, haematological, oxidant/antioxidant parameters, immunity markers, and the growth-related genes expression in broiler chickens. A total of 200 broiler chickens (Cobb 500, 2-weeks old) were allotted into 4 groups; SD (moderate and high) and curcumin (100 and 200 mg/kg diet)-supplemented HSD, respectively. Behavioural observations were performed. After a 28-day experimental period, tissue and blood samples were collected for analysis. Expressions of mRNA for insulin-like growth factor-1 (IGF-1), growth hormone receptor (GHR), myostatin (MSTN), and leptin in liver tissues were examined. HSD birds exhibited lower growth performance measurements, haematological parameters, circulating 3,5,3-triiodothyronine and thyroxine levels, antioxidant activities (GSH-Px, catalase, superoxide dismutase), immunoglobulins (A, G, M), and hepatic GHR and IGF-1 expression values. However, HSD birds even had an increment of serum corticosterone, malondialdehyde, pro-inflammatory cytokine (TNF-a, IL-2, IL-6) levels, hepatic leptin and MSTN expression. Moreover, HSD decreased drinking, feeding, crouching, body care, and increased standing and walking behaviour. The addition of curcumin, particularly at a 200 mg/kg diet, alleviated the effect of HSD through amending growth-related gene expression in the chickens. In conclusion, curcumin can enhance birds’ growth performance, behavioural patterns, and immunity by reducing oxidative stress and up-regulating the growth-related gene expressions of broilers under stressful conditions due to a high stocking density.

KETOgenic diet therapy in patients with HEPatocellular adenoma: study protocol of a matched interventional cohort study

IntroductionHepatocellular adenoma (HCA) is an uncommon, solid and benign liver lesion, mainly occurring in women using oral contraceptives. Patients are advised to stop using oral contraceptives (OC) and, as overweight...

High-throughput mediation analysis of human proteome and metabolome identifies mediators of post-bariatric surgical diabetes control

To improve the power of mediation in high-throughput studies, here we introduce High-throughput mediation analysis (Hitman), which accounts for direction of mediation and applies empirical Bayesian linear modeling. We apply Hitman in a retrospective, exploratory analysis of the SLIMM-T2D clinical trial in which participants with type 2 diabetes were randomized to Roux-en-Y gastric bypass (RYGB) or nonsurgical diabetes/weight management, and fasting plasma proteome and metabolome were assayed up to 3 years. RYGB caused greater improvement in HbA1c, which was mediated by growth hormone receptor (GHR). GHR’s mediation is more significant than clinical mediators, including BMI. GHR decreases at 3 months postoperatively alongside increased insulin-like growth factor binding proteins IGFBP1/BP2; plasma GH increased at 1 year. Experimental validation indicates (1) hepatic GHR expression decreases in post-bariatric rats; (2) GHR knockdown in primary hepatocytes decreases gluconeogenic gene expression and glucose production. Thus, RYGB may induce resistance to diabetogenic effects of GH signaling.Trial Registration: Clinicaltrials.gov NCT01073020.

Growth performance, economic efficiency, meat quality, and gene expression in two broiler breeds fed different levels of tomato pomace.

Male broiler chicks (135 Indian River chicks (IR) and 135 Cobb chicks; n = 270) were weighed, wing banded, and distributed randomly into three iso-energetic and iso-nitrogenous diet groups for each breed (triplicate design, 45 bird/group, 15 bird/replicate). The chicks were fed the diets with levels of 0, 4, or 6% sun-dried tomato pomace (SDTP), respectively, for 42 consecutive days to determine the effect of consuming different levels of SDTP on growth performance, economic efficiency, meat quality, and gene expression in IR and Cobb broiler chickens. The inclusion of up to 6% SDTP in the diet of IR or Cobb chickens had no negative impact on growth performance parameters. Chickens from both the IR and Cobb breeds fed a diet containing 4% or 6% SDTP consumed more feed than those fed a diet containing 0% SDTP. Concomitantly, the groups fed a 6% SDTP diet of IR breed incurred a significantly higher feed cost, total variable cost (TVC), and total cost (TC). The inclusion of up to 6% SDTP in the feed of both breeds resulted in a non-significant increase in return parameters. The ultimate pH decreased as the SDTP concentration increased, with no significant differences in water holding capacity (WHC) or drip loss (48h). No alteration in the mRNA expression of hepatic growth hormone receptor gene (GHR) or insulin like growth factor-1 (IGF-1) was found among the treatments for either the IR or Cobb breeds. Thus, up to 6% SDTP can be added to the diet of IR and Cobb broiler chickens without any adverse effects on the examined parameters.

Treatment of acromegaly by rosiglitazone via upregulating 15-PGDH in both pituitary adenoma and liver

SummaryRosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) ligand, has been reported to reduce growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in 10 patients with acromegaly. However, the mechanisms remain unknown. Here, we reveal that PPARγ directly enhances 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, whose expression is decreased and negatively correlates with tumor size in acromegaly. Rosiglitazone decreases GH production and promotes apoptosis and autophagy in GH3 and primary somatotroph adenoma cells and suppresses hepatic GH receptor (GHR) expression and IGF-1 secretion in HepG2 cells. Activating the PGE2/cAMP/PKA pathway directly increases GHR expression. Rosiglitazone suppresses tumor growth and decreases GH and IGF-1 levels in mice inoculated subcutaneously with GH3 cells. The above effects are all dependent on 15-PGDH expression. Rosiglitazone as monotherapy effectively decreases GH and IGF-1 levels in all nineteen patients with active acromegaly. Evidence suggests that rosiglitazone may be an alternative pharmacological approach for acromegaly by targeting both pituitary adenomas and liver.

Expression of IGF-1, IGF-1 Receptor and Growth Hormone Receptor in Hepatic Tissue in Adults Across the Spectrum of Nonalcoholic Fatty Liver Disease (NAFLD)

Background: Obesity is a state of relative growth hormone (GH) and insulin-like growth factor-1 (IGF-1) deficiency, and the GH/IGF-1 axis has been implicated in the pathophysiology of nonalcoholic fatty liver disease (NAFLD) and the progression to steatohepatitis (NASH) in preclinical models and human studies. GH has both lipolytic and anti-inflammatory properties while IGF-1 has been implicated in reducing hepatic fibrosis and promoting hepatic regeneration. The GH/IGF-1 axis may be a therapeutic target in NAFLD/NASH, however, IGF-1, IGF-1 receptor (IGF-1R) and GH receptor (GHR) expression in adult human hepatic tissue has not been studied across the spectrum of disease severity. Methods: We quantified IGF-1, IGF-1R, and GHR gene expression in hepatic tissue from 318 adults with obesity using the Nanostring nCounter assay. Subjects were classified into four categories of disease severity based on histopathology: normal liver histology (NLH) (n=76, 24%), steatosis only (Steatosis) (n=88, 28%), NASH without fibrosis (NASH F0) (n=72, 23%), and NASH with fibrosis (NASH F1-F4) (n=82, 26%). Gene expression analysis is presented as normalized gene counts by group with p-value of the generalized linear model controlled for age, sex and BMI. Results: Mean (±SD) age (whole cohort 44.0±12 years) and BMI (whole cohort 46.8±7.2 kg/m2) did not differ across groups (p=0.2 for both). ALT was higher with increasing disease severity (NLH 30.1±26.7, Steatosis 31.9±15.7, NASH F0 35.7±16.5, NASH F1-4 48.4±34.9, p<0.001). IGF-1 gene expression was lower in all NAFLD/NASH groups compared to the NLH reference group (NLH 485.4±292.7; Steatosis 396.3±238.0, p=0.04; NASH F0 349.8±220.1, p=0.01 and NASH F1-4 341.2±268.6, p=0.03, all p-values vs NLH). There was no difference in IGF-1R or GHR gene expression across disease severity groups (IGF-1R NLH 43.3±10.2, Steatosis 41.4±11.6, NASH F0 38.8±8.8 and NASH F1-4 39.1±8.1, p>0.05 between any disease state; GHR NLH 6382±2366, Steatosis 6544±2699, NASH F0 7220±2542 and NASH F1-4 5997±2352, p>0.05 between any disease state). Conclusion: We demonstrated that IGF-1 gene expression was lower in liver tissue from patients with NAFLD and NASH than healthy controls. This is consistent with our prior finding that histologic NASH and fibrosis are associated with lower serum IGF-1 levels. Moreover, we demonstrated that hepatic IGF-1R and GHR gene expression is not lower in liver tissue from patients with NAFLD and does not decline across disease severity. This reinforces our prior finding that GHR staining intensity and zonality by immunohistochemistry does not change with increasing disease severity in NAFLD/NASH. These data demonstrate that the GH axis is relatively suppressed but that expression of GHR and IGF-1R receptors is stable with worsening disease severity in NAFLD/NASH, suggesting that GH augmentation may be a viable therapeutic target in NAFLD.

The optimum threonine requirement in diets of juvenile hybrid grouper ( epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂ )

A six-week growth trial was conducted to evaluate the optimum threonine (Thr) requirement in diets of juvenile hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂). Six isoenergetic, isoproteic and isolipidic diets were formulated to contain 5.4, 7.5, 10.3, 11.5, 13.7 and 15.2 g/kg dry matter dietary Thr levels. Results showed that and fish fed 5.4 g/kg dietary Thr had the lowest weight gain percentage (WG%) or protein productive value (PPV) among all experimental treatments. Analysis by the quadratic regression indicated that the optimum Thr requirement for maximum WG% or PPV in diets for hybrid grouper was estimated to be 11.48 or 13.55 g/kg of dry matter. The mRNA expression of hepatic growth hormone receptor 1 (GHR1) in fish fed 11.5 and 13.7 g/kg dietary Thr was higher than that of fish fed other dietary Thr levels. Fish fed 5.4 g/kg dietary Thr had the lowest whole-body protein contents and the lowest expression of hepatic target of rapamycin (TOR), ribosomal protein S6 kinase 1 (S6 K1) among all experimental groups. In conclusion, the optimum dietary Thr requirement for best growth of hybrid grouper was estimated to be 11.48 g/kg dry matter (corresponding to 23.27 g/kg dietary protein).

Growth hormone receptor disrupts glucose homeostasis via promoting and stabilizing retinol binding protein 4.

Rationale: The molecular mechanisms underlying the pathogenesis of systemic insulin resistance in type 2 diabetes remain elusive. Growth hormone receptor (GHR) deficiency has long been known to improved insulin sensitivity. However, whether hepatic GHR overexpression or activation is a cause of insulin resistance is still unknown. The aim of this study was to identify the new role of GHR in systemic insulin resistance and explore the underlying mechanism.Method: Different samples obtained from obese humans, ob/ob mice, db/db mice, high-fat diet (HFD)-fed mice and primary mouse hepatocytes were used to evaluate the correlations between GHR and metabolic disorders. Recombinant adeno-associated viruses encoding GHR and STAT5 and GHR knockout mice were used to investigate the roles of hepatic GHR in glucose homeostasis. Tissue H&E, Oil Red O and PAS staining were performed for histomorphological analysis. Gel filtration chromatography was employed for the separation of serum RBP4-TTR complexes. Plasmids (related to GHR, STAT5 and HIF1α), siRNA oligos (siGHR and siSTAT5), luciferase activity and ChIP assays were used to explore the potential mechanism of hepatic GHR.Results: Here, we found that hepatic GHR expression was elevated during metabolic disorder. Accordingly, hepatic GHR overexpression disrupted systemic glucose homeostasis by promoting gluconeogenesis and disturbing insulin responsiveness in the liver. Meanwhile, hepatic GHR overexpression promoted lipolysis in white adipose tissue and repressed glucose utilization in skeletal muscle by promoting the circulating level of RBP4, which contributed to impaired systemic insulin action. A mechanistic study revealed that hepatic GHR disrupted systemic insulin sensitivity by increasing RBP4 transcription by activating STAT5. Additionally, overexpression of hepatic GHR promoted TTR transcriptional levels by enhancing the expression of HIF1α, which not only increased the protein stability of RBP4 but also inhibited renal clearance of RBP4 in serum.Conclusions: Hepatic GHR overexpression and activation accelerated systemic insulin resistance by increasing hepatic RBP4 production and maintaining circulating RBP4 homeostasis. Our current study provides novel insights into the pathogenesis of type 2 diabetes and its associated metabolic complications.

GH directly inhibits steatosis and liver injury in a sex-dependent and IGF1-independent manner.

A reduction in hepatocyte growth hormone (GH)-signaling promotes non-alcoholic fatty liver disease (NAFLD). However, debate remains as to the relative contribution of the direct effects of GH on hepatocyte function vs indirect effects, via alterations in insulin-like growth factor 1 (IGF1). To isolate the role of hepatocyte GH receptor (GHR) signaling, independent of changes in IGF1, mice with adult-onset, hepatocyte-specific GHR knockdown (aHepGHRkd) were treated with a vector expressing rat IGF1 targeted specifically to hepatocytes. Compared to GHR-intact mice, aHepGHRkd reduced circulating IGF1 and elevated GH. In male aHepGHRkd, the shift in IGF1/GH did not alter plasma glucose or non-esterified fatty acids (NEFA), but was associated with increased insulin, enhanced systemic lipid oxidation and reduced white adipose tissue (WAT) mass. Livers of male aHepGHRkd exhibited steatosis associated with increased de novo lipogenesis, hepatocyte ballooning and inflammation. In female aHepGHRkd, hepatic GHR protein levels were not detectable, but moderate levels of IGF1 were maintained, with minimal alterations in systemic metabolism and no evidence of steatosis. Reconstitution of hepatocyte IGF1 in male aHepGHRkd lowered GH and normalized insulin, whole body lipid utilization and WAT mass. However, IGF1 reconstitution did not reduce steatosis or eliminate liver injury. RNAseq analysis showed IGF1 reconstitution did not impact aHepGHRkd-induced changes in liver gene expression, despite changes in systemic metabolism. These results demonstrate the impact of aHepGHRkd is sexually dimorphic and the steatosis and liver injury observed in male aHepGHRkd mice is autonomous of IGF1, suggesting GH acts directly on the adult hepatocyte to control NAFLD progression.

Cortisol regulates insulin-like growth-factor binding protein (igfbp) gene expression in Atlantic salmon parr

The growth hormone (Gh)/insulin-like growth-factor (Igf)/Igf binding protein (Igfbp) system regulates growth and osmoregulation in salmonid fishes, but how this system interacts with other endocrine systems is largely unknown. Given the well-documented consequences of mounting a glucocorticoid stress response on growth, we hypothesized that cortisol inhibits anabolic processes by modulating the expression of hepatic igfbp mRNAs. Atlantic salmon (Salmo salar) parr were implanted intraperitoneally with cortisol implants (0, 10, and 40 μg g−1 body weight) and sampled after 3 or 14 days. Cortisol elicited a dose-dependent reduction in specific growth rate (SGR) after 14 days. While plasma Gh and Igf1 levels were unchanged, hepatic igf1 mRNA was diminished and hepatic igfbp1b1 and -1b2 were stimulated by the high cortisol dose. Plasma Igf1 was positively correlated with SGR at 14 days. Hepatic gh receptor (ghr), igfbp1a, -2a, -2b1, and -2b2 levels were not impacted by cortisol. Muscle igf2, but not igf1 or ghr, levels were stimulated at 3 days by the high cortisol dose. As both cortisol and the Gh/Igf axis promote seawater (SW) tolerance, and particular igfbps respond to SW exposure, we also assessed whether cortisol coordinates the expression of branchial igfbps and genes associated with ion transport. Cortisol stimulated branchial igfbp5b2 levels in parallel with Na+/K+-ATPase (NKA) activity and nka-α1b, Na+/K+/2Cl--cotransporter 1 (nkcc1), and cystic fibrosis transmembrane regulator 1 (cftr1) mRNA levels. The collective results indicate that cortisol modulates the growth of juvenile salmon via the regulation of hepatic igfbp1s whereas no clear links between cortisol and branchial igfbps previously shown to be salinity-responsive could be established.

SUN-LB52 The Protective Effects of Hepatocyte GH Receptor (GHR) Signaling Against Steatosis and Liver Injury Is Sexually Dimorphic and Autonomous of IGF1

GH dysregulation contributes to the development of non-alcoholic fatty liver disease (NAFLD), however debate remains as to the relative contribution of the direct vs indirect effects of GH, via IGF1. Mouse models with congenital, liver-specific knockout of the GHR, JAK2 or STAT5, as adults exhibit steatosis, glucose intolerance, insulin resistance and white adipose tissue (WAT) lipolysis. It is believed that fatty liver is due to the dramatic reduction in circulating IGF1 altering systemic metabolism, due to loss of the insulin-like effects of IGF1 and the loss of IGF1 negative feedback to the pituitary leading to a rise in GH that promotes systemic insulin resistance and WAT lipolysis shifting the flux of fatty acids to the liver. In addition, low IGF1/high GH alters the development of other metabolically relevant tissues, which could indirectly contribute to the liver phenotype observed with congenital loss of hepatic GH signaling. To directly test the actions of GH on adult hepatocyte function, we developed a mouse model of adult-onset, hepatocyte-specific knockdown of the GHR (aHepGHRkd; 12 week-old, GHRfl/fl mice treated with AAV8-TBGp-Cre). aHepGHRkd enhanced hepatic de novo lipogenesis (DNL), rapidly leading to steatosis in males, but not females. In males, enhanced DNL and steatosis was sustained with age and associated with hepatocyte ballooning, inflammation and mild fibrosis. These changes occurred independent of severe systemic insulin resistance and WAT lipolysis, although the aHepGHRkd mice exhibit low IGF1/high GH similar to that of congenital models. To directly test the role of hepatocyte GHR signaling, independent of changes in IGF1, aHepGHRkd mice were treated with a vector expressing rat IGF1 targeted specifically to hepatocytes (AAV8-TBGp-rIGF1). Mice were fed standard chow diet and tissues collected 8m post-AAV. IGF1 replacement elevated plasma IGF1 in aHepGHRkd mice, resulting in a reduction in plasma GH and pituitary expression of Gh, Ghrhr and Ghsr, indicating negative feedback of IGF1 was restored. In male aHepGHRkd mice, IGF1 replacement reduced insulin and whole body lipid utilization and increased WAT, however it did not reduce steatosis or alter hepatic fatty acid composition indicative of DNL and had minimal effects on liver injury markers. RNAseq analysis of liver extracts showed IGF1 replacement also had no major impact on the differentially expressed genes observed after aHepGHRkd. These results demonstrate that steatosis, DNL and liver injury observed in male aHepGHRkd mice are autonomous of IGF1. Despite the fact that hepatic GHR protein levels were not detectable in both female and male aHepGHRkd mice, females maintained moderate levels of IGF1 and were protected from steatosis. The mechanism by which female mice are protected remains to be elucidated, however is consistent with clinical data indicating pre-menopausal women are resistance to NAFLD.