Downregulation of the GHRH/GH/IGF1 axis in a mouse model of Börjeson-Forssman-Lehman syndrome

Börjeson-Forssman-Lehmann syndrome (BFLS) is an intellectual disability and endocrine disorder caused by plant homeodomain finger 6 (PHF6) mutations. Individuals with BFLS present with short stature. We report a mouse model of BFLS, in which deletion of Phf6 causes a proportional reduction in body size compared with control mice. Growth hormone (GH) levels were reduced in the absence of PHF6. Phf6 ^{- /Y} animals displayed a reduction in the expression of the genes encoding GH-releasing hormone (GHRH) in the brain, GH in the pituitary gland and insulin-like growth factor 1 (IGF1) in the liver. Phf6 deletion specifically in the nervous system caused a proportional growth defect, indicating a neuroendocrine contribution to the phenotype. Loss of suppressor of cytokine signaling 2 (SOCS2), a negative regulator of growth hormone signaling partially rescued body size, supporting a reversible deficiency in GH signaling. These results demonstrate that PHF6 regulates the GHRH/GH/IGF1 axis.

Neuroinflammation is associated with reduced SOCS2 and SOCS3 expression during intracranial HSV-1 infection

Herpes simplex virus type 1 (HSV-1) is the main etiological agent of acute and sporadic encephalitis. Proteins of the suppressor of cytokine signaling (SOCS) family have shown to regulate the inflammation during HSV-1 infection in the brain. However, the effects of SOCS2 and SOCS3 in viral encephalitis remain unclear. The aim of the current study is to investigate the potential association between SOCS2, SOCS3, cytokines, and hippocampal damage, especially neuronal apoptosis, during acute intracranial HSV-1 infection in mice. Male C57BL/6 mice were infected by intracranial route with 10² plaque-forming units (PFU) inoculum of purified HSV-1. At three days post-infection (3 d.p.i.), mice were euthanized and their hippocampi were collected for histopathological analysis, immunohistochemical reaction against active caspase-3 and quantification of SOCS2, SOCS3 and cytokines (tumoral necrosis factor (TNF), interleukin (IL) 1β, IL-6, IL-10; interferon (IFN) -α, IFN-β, IFN-γ) mRNA expression. Infected mice exhibited neuronal loss and hemorrhagic focus in Cornu Ammonis (CA) region. The apoptotic index was higher in infected mice compared to controls. HSV-1 infection was associated with increased hippocampal expression of TNF, IL1-β, IL-6 and IFNα/IFNβ and decreased expression of IL-10, IFN-γ, SOCS2 and SOCS3. Our results suggest that down regulation of SOCS2 and SOCS3 contributes to a pro-inflammatory environment associated with hippocampal damage and neuronal apoptosis during acute HSV-1 infection in mice.

SOCS2 Silencing Improves Somatic Growth without Worsening Kidney Function in CKD

BACKGROUND

Growth hormone (GH) resistance in CKD is partly due to increased expression of SOCS2, a GH signaling negative regulator. In SOCS2 absence, body growth is exaggerated. However, GH overexpression in mice causes glomerulosclerosis. Accordingly, we tested whether lack of SOCS2 improves body growth, but accelerates kidney damage in CKD.

METHODS

Eight-week-old mutant SOCS2-deficient high growth (HG) and normal wild-type mice (N) underwent 5/6 nephrectomy (CKD) or sham operation (C) and were sacrificed after 12 weeks, generating 4 groups: C-N, C-HG, CKD-N, CKD-HG.

RESULTS

Somatic growth, inhibited in CKD-N, increased significantly in CKD-HG. Liver p-STAT5, a key intracellular signal of GH receptor (GHR) activation, was decreased in CKD-N but not in CKD-HG. Serum Cr as well as histopathological scores of renal fibrosis were similar in both CKD groups. Kidney fibrogenic (TGF-β and collagen type IV mRNA) and inflammatory precursors (IL6, STAT3, and SOCS3 mRNA) were similarly increased in C-HG, CKD-HG, and CKD-N versus C-N. Renal GHR mRNA was decreased in C-HG, CKD-HG, and CKD-N versus C-N. Kidney p-STAT5 was decreased in CKD-N but not elevated in CKD-HG.

CONCLUSIONS

CKD-related growth retardation is overcome by SOCS2 silencing, in association with increased hepatic STAT5 phosphorylation. Renal insufficiency is not worsened by SOCS2 absence, as kidney GHR and STAT5 are not upregulated. This may be due to elevated kidney proinflammatory cytokines and their mediators, phospho-STAT3 and SOCS3, which may counteract for the absence in SOCS2 and explain the renal safety of prolonged GH therapy in CKD.

miR-486 is involved in the pathogenesis of acute myeloid leukemia by regulating JAK-STAT signaling

Acute myeloid leukemia (AML) is a widely prevalent disease worldwide and poses a large threat to public health. Previous studies have shown that AML is associated with cytogenetic heterogeneity, complex subtypes, and different therapeutic approaches. In this study, we found that miR-486 was upregulated in AML using both The Cancer Genome Atlas (TCGA) database and patient tissues. After knockdown of miR-486 by short hairpin RNA (shRNA), we discovered that miR-486 was required for cell proliferation. Through miRNA profile analysis and a dual-luciferase reporter assay, suppressor of cytokine signaling 2 (SOCS2) was identified as a direct target of miR-486. Therefore, by silencing SOCS2, a negative regulator of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, miR-486 enhanced JAK-STAT3 activity and promoted cell proliferation. The miR-486-SOCS2-STAT3 proliferation axis is therefore involved in the pathogenesis of AML, providing a novel molecular mechanism and diagnostic and therapeutic clues for AML.

LncRNA SOCS2-AS1 inhibits progression and metastasis of colorectal cancer through stabilizing SOCS2 and sponging miR-1264

Abnormal expression of long noncoding RNA (lncRNA) is involved in human cancers, including colorectal cancer (CRC). However, their functional mechanism is largely unknown. In this study, we explored the roles of lncRNA SOCS2-AS1 in modulating CRC progression. We showed that SOCS2-AS1 was lowly expressed in CRC tissues and cells. SOCS2-AS1 downregulation predicted a poor prognosis in patients with CRC. SOCS2-AS1 overexpression significantly suppressed CRC cell proliferation, colony formation, EdU incorporation, cell-cycle, migration and invasion in vitro while SOCS2-AS1 knockdown led to an opposite phenotype. SOCS2-AS1 overexpression inhibited CRC growth and metastasis in vivo. Mechanistically, we discovered that SOCS2-AS1 was positively correlated with SOCS2 expression in CRC tissues. SOCS2-AS1 contributes to SOCS2 expression through restraining miR-1264. Additionally, we showed that SOCS2 silencing abrogated the suppressive effects of SOCS2-AS1 overexpression. Taken together, our results identified a novel regulatory loop in which SOCS2-AS1/miR-1264/SOCS2 axis suppresses CRC progression.

IL-1β Induces SOCS2 Expression in Human Dendritic Cells

Dendritic cells (DCs) regulate immunity and inflammation and respond to various stimuli, including cytokines. IL-1β is a key cytokine in the course of both acute and chronic inflammatory responses, making it indispensable for protection of the host, but also linking it to several diseases. Thus, IL-1β signaling must be tightly regulated. As suppressor of cytokine signaling (SOCS) proteins effectively control immune responses, we investigated the role of SOCS2 in IL-1β-induced DC activation. Human monocyte-derived DCs were stimulated with IL-1β, and SOCS2 mRNA and protein levels were measured. DC activation was assessed by cytokine secretion and surface marker expression. For functional analysis, small interfering RNA (siRNA)-based SOCS2 silencing was performed. SOCS2 expression was also analyzed in a curated NCBI GEO dataset of myeloid leukemia patients. We found IL-1β to be a potent inducer of SOCS2 expression. By silencing SOCS2, we showed that SOCS2 specifically limits IL-1β-induced IL-8 secretion. Moreover, our analysis revealed that SOCS2 levels are significantly increased in patients with acute and chronic myeloid leukemia, two hematological malignancies where disease progression is closely linked to IL-1β. This study identifies SOCS2 as a novel IL-1β-inducible target gene and points toward a potential role of SOCS2 in IL-1β-mediated DC activation.

SOCS2 modulates adipose tissue inflammation and expansion in mice

INTRODUCTION

Obesity is usually triggered by a nutrient overload that favors adipocyte hypertrophy and increases the number of pro-inflammatory cells and mediators into adipose tissue. These mediators may be regulated by suppressors of cytokine signaling (SOCS), such as SOCS2, which is involved in the regulation of the inflammatory response of many diseases, but its role in obesity is not yet known. We aimed to investigate the role of SOCS2 in metabolic and inflammatory dysfunction induced by a high-refined carbohydrate-containing diet (HC).

MATERIAL AND METHODS

Male C57BL/6 wild type (WT) and SOCS2 deficient (SOCS2^-/-) mice were fed chow or an HC diet for 8 weeks.

RESULTS

In general, SOCS2 deficient mice, independent of the diet, showed higher adipose tissue mass compared with their WT counterparts that were associated with decreased lipogenesis rate in adipose tissue, lipolysis in adipocyte culture and energy expenditure. An anti-inflammatory profile was observed in adipose tissue of SOCS2^-/- by reduced secretion of cytokines, such as TNF and IL-6, and increased M2-like macrophages and regulatory T cells compared with WT mice. Also, SOCS2 deficiency reduced the differentiation/expansion of pro-inflammatory cells in the spleen but increased Th2 and Treg cells compared with their WT counterparts.

CONCLUSION

The SOCS2 protein is an important modulator of obesity that regulates the metabolic pathways related to adipocyte size. Additionally, SOCS2 is an inflammatory regulator that appears to be essential for controlling the release of cytokines and the differentiation/recruitment of cells into adipose tissue during the development of obesity.

Inhibition of lncRNA XIST Improves Myocardial I/R Injury by Targeting miR-133a through Inhibition of Autophagy and Regulation of SOCS2

The objective of this study was to investigate the role of lncRNA XIST and its relationship with miR-133a in myocardial I/R injury. H9C2 cells treated by hypoxia/reoxygenation (H/R) were used to establish an in vitro I/R model. The small interfering RNA (siRNA) for XIST and miR-133 mimics, inhibitor, and suppressor of cytokine signaling (SOCS2) recombinant plasmids were used to transfect the cells. Cell apoptosis was determined by flow cytometry analysis, and cell viability was used for 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, Thiazolyl Blue Tetrazolium Bromide (MTT) assay. The dual-luciferase reporter assay was performed to confirm binding between XIST and miR-133a, as well as miR-133a and SOCS2. To inhibit or overexpress XIST, miR-133a, or SOCS2 in I/R mice, we used recombinant lentivirus vectors and adenovirus vectors for tail vein injection. The expression of XIST, miR-133a, and SOCS2 was determined by quantitative real-time PCR, and LC3 I/II and Beclin1 was determined by western blotting. The expression of XIST and SOCS2 was significantly upregulated, whereas the miR-133a level was remarkably downregulated in both H/R H9C2 cells and I/R mice myocardial tissues. In both H/R H9C2 cells and I/R mice, the inhibition of XIST led to decreased apoptosis and autophagy, and inhibition of miR-133a reversed these effects. Similarly, overexpression of miR-133a resulted in reduced apoptosis and autophagy, which were reversed by overexpression of SOCS2. The inhibition of XIST and overexpression of miR-133a also promote cell viability of H/R cells. The dual-luciferase reporter assay significantly showed that XIST directly targeted on miR-133a, and miR-133a directly targeted on SOCS2. The inhibition of XIST could improve myocardial I/R injury by regulation of the miR-133a/SOCS2 axis and inhibition of autophagy.

LncRNA HIF1A-AS1 contributes to ventricular remodeling after myocardial ischemia/reperfusion injury by adsorption of microRNA-204 to regulating SOCS2 expression

Objectives: Long non-coding RNAs (lncRNAs) serve pivotal roles in heart disease, while the role of lncRNA hypoxia-inducible factor 1α-antisense RNA 1 (HIF1A-AS1) is rarely mentioned. Therefore, the objective of this study was to investigate the mechanism of lncRNA HIF1A-AS1 regulating suppressor of cytokine signaling 2 (SOCS2) expression by adsorption of microRNA-204 (miR-204) on ventricular remodeling after myocardial ischemia-reperfusion (I/R) injury in mice. Methods: The mouse model of I/R was established by left coronary artery occlusion. The expression of HIF1A-AS1, miR-204 and SOCS2 was determined. The mice were injected with HIF1A-AS1-siRNA, miR-204 mimics or their controls to investigate their effects on cardiac function and ventricular remodeling of mice after I/R injury. The binding relationship between HIF1A-AS1 and miR-204 as well as between miR-204 and SOCS2 were verified. Results: HIF1A-AS1 and SOCS2 were upregulated and miR-204 was downregulated in myocardial tissues in mice after I/R injury. LVEDD, LVEDS, LVEDP, LVMI and RVMI expression reduced while LVEF, LVFS, +dp/dt max and - dp/dt max increased through knockdown HIF1A-AS1 and upregulated miR-204. The expression of BNP, cTnI, LDH, CK, TNF-α, IL-1β, IL-6 and β-MHC reduced, and the expression of α-MHC increased when HIF1A-AS1 was poorly expressed and miR-204 was highly expressed. Silencing HIF1A-AS1 and upregulating miR-204 inhibited apoptosis of cells. LncRNA HIF1A-AS1 could act as ceRNA to adsorb miR-204 to suppress miR-204 expression and elevate SOCS2 expression. Conclusion: Our study provides evidence that downregulation of HIF1A-AS1 and upregulation of miR-204 could alleviate ventricular remodeling and improve cardiac function in mice after myocardial I/R injury via regulating SOCS2.

Regulation of murine skeletal muscle growth by STAT5B is age- and sex-specific

Background

Sexually dimorphic growth has been attributed to the growth hormone (GH)/insulin-like growth factor 1 (IGF1) axis, particularly GH-induced activation of the intracellular signal transducer and activator of transcription 5B (STAT5B), because deletion of STAT5B reduces body mass and the mass of skeletal muscles in male mice to that in female mice. However, it remains unclear why these effects are sex- and species-specific, because the loss of STAT5B retards growth in girls, but not in male mice. Our objectives were to determine whether sexually dimorphic growth of skeletal muscle persisted in STAT5B^−/− mice and investigate the mechanisms by which STAT5B regulates sexually dimorphic growth.

Methods

Blood and skeletal muscle were harvested from male and female STAT5B^−/− mice and their wild-type littermates from the onset of puberty to adulthood.

Results

Growth of the skeleton and skeletal muscles was retarded in both sexes of STAT5B^−/− mice, but more so in males. Although reduced, sexually dimorphic growth of skeletal muscle persisted in STAT5B^−/− mice with an oxidative shift in the composition of myofibres in both sexes. Concentrations of IGF1 in blood and skeletal muscle were reduced in male STAT5B^−/− mice at all ages, but only in female STAT5B^−/− mice at the onset of puberty. Expression of androgen receptor (AR) and oestrogen receptor alpha (ERα) mRNA and protein was reduced in skeletal muscles of male and female STAT5B^−/− mice, respectively. Loss of STAT5B abolished the sexually dimorphic expression of myostatin protein and Igf1, Ar, Erα, suppressor of cytokine signalling 2 (Socs2), and cytokine-inducible SH2-containing protein (Cis) mRNA in skeletal muscle.

Conclusions

STAT5B appears to mediate GH signalling in skeletal muscles of male mice at all ages, but only until puberty in female mice. STAT5B also appears to mediate the actions of androgens and oestrogens in both male and female mice, but sexually dimorphic growth persists in STAT5B^−/− mice.

Electronic supplementary material

The online version of this article (10.1186/s13395-019-0204-3) contains supplementary material, which is available to authorized users.

SOCS2 Is Critical for the Balancing of Immune Response and Oxidate Stress Protecting Against Acetaminophen-Induced Acute Liver Injury

Acetaminophen (APAP) is usually safe when administrated in therapeutic doses; however, APAP overdose can lead to severe liver injury. APAP can cause direct hepatocyte damage, and stimulates an inflammatory response leading to oxidative stress. Supressor of Cytokine Signaling (SOCS) 2 modulates cytokine and growth factor signaling, and plays a role in the regulation of hepatic cellular processes. Our study evaluated the role of SOCS2 in APAP liver injury. The administration of a toxic dose (600 mg/kg) of APAP caused significant liver necrosis in WT mice. In SOCS2^−/− mice, there was significantly more necrosis, neutrophil recruitment, and expression of the neutrophil-active chemokine CXCL-1. Expression of proinflammatory cytokines, such as TNF-α and IL-6, was elevated, while expression of anti-inflammatory cytokines, IL-10 and TGF-β, was diminished. In vitro, SOCS2^−/− hepatocytes expressed more p-NF-kB and produced more ROS than WT hepatocytes when exposed to APAP. SOCS2^−/− hepatocytes were more sensitive to cell death in the presence of IL-6 and hydrogen peroxide. The administration of catalase in vitro and in vivo resulted in a pronounced reduction of cells/mice death and necrosis in the SOCS2^−/− group. We have demonstrated that SOCS2 has a protective role in the liver by controlling pro-oxidative and inflammatory mechanisms induced by APAP.

miR-196b is a prognostic factor of human laryngeal squamous cell carcinoma and promotes tumor progression by targeting SOCS2

BACKGROUND

Laryngeal squamous cell carcinoma (LSCC) has the second highest incidence among the head and neck malignancies. Additionally, the incidence of LSCCs has been recently increasing. Therefore, understanding the mechanisms of LSCC tumorigenesis and identifying novel biomarkers to accurately predict and improve the prognosis of patients with LSCC is extremely important.

METHODS

miR-196b and SOCS2 expression was measured by qRT-PCR and western blot. Their correlation was analyzed with the Pearson test. TU212 and TU177 cells were cultured and transfected for MTT, Transwell, and apoptosis assays upon miR-196b knockdown, SOSC2 overexpression or SOCS2 silencing. Dual-luciferase reporter assay were conducted to identify the relationship between miR-196b and SOCS2. Moreover, the correlation between clinicopathological parameters and miR-196b/SOCS2 expression in patients was analyzed. Univariate and multivariate analysis and log-rank tests were used to determine if miR-196 was an independent LSCC prognostic factors.

RESULTS

We reported the aberrant expression and inverse correlation of miR-196b and SOCS2 in LSCC samples. miR-196b promoted LSCC cells proliferation and invasion, and suppressed apoptosis by directly inhibiting SOCS2 expression in vitro. Moreover, we also revealed that miR-196b/SOCS2 expression correlated with T stage and cervical metastasis. miR-196b was demonstrated to be an independent prognostic factor for overall survival of patients with LSCC.

CONCLUSIONS

Overexpression of miR-196b suppresses SOCS2 in human LSCC resulting in tumor progression and poor prognosis. miR-196b is a potential marker for prognosis assessment and targeting miR-196b may be a novel valuable strategy for the treatment of LSCC.

A designed cell-penetrating human SOCS2 protein suppresses GH-dependent cancer cell proliferation

Suppressor of cytokine signaling (SOCS) 2, a negative regulator of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), which is associated with acromegaly and cancers, is a promising candidate molecule for treating various diseases. To facilitate its use in protein therapy, we designed and constructed a human SOCS2 protein containing a membrane-permeable peptide sequence and expressed it in an Escherichia coli system. The partially purified recombinant protein was effectively delivered into several cancer cell lines and inhibited cell growth. Biochemical analysis showed that the recombinant SOCS2 protein interacted with growth hormone receptor (GHR) and downregulated GH-STAT5 signaling target genes. Our results suggest that the designed cell-penetrating SOCS2 protein will be useful in intercellular protein therapy to cure cancers. Abbreviations: SOCS: suppressor of cytokine signaling; GH: growth hormone; GHR: growth hormone receptor; IGF-1: insulin-like growth factor 1; CP: cell-penetrating; STAT: signal transducer and activator of transcription; JAK: Janus kinase; HNF: hepatocyte nuclear factor; MTM: membrane-translocating motif; HIV: human immunodeficiency virus.

Inhibitor of IGF1 receptor alleviates the inflammation process in the diabetic kidney mouse model without activating SOCS2

Objective

To explore the anti-inflammatory mechanism of IGF1R inhibitor in diabetic nephropathy.

Methods

C57/BL6 mice were reared with high-fat diet for 8 weeks, then were injected 30 mg/kg streptozotocin intraperitoneally to induce type 2 diabetes. After 8 weeks, the type 2 diabetes nephropathy model was successfully set up the different drugs were administrated to mice with diabetes (insulin 1-2 U/day, benazepril 10 mg/kg per day intragastrically, IGF-1R inhibitor 30 mg/kg per day intragastrically). After 8 weeks drugs administration, all mice were collected the kidney tissue, measured levels of inflammatory factor (F4/80, TLR4and CD68) and fibrosis markers(αSMA, E-cadherin and SR) using immunohistochemistry and in situ hybridization.

Results

The type 2 diabetes nephropathy model was built successfully, which along with increased urinary protein excretion rate and increased inflammatory infiltration, and the correlation was characterized by increased CD68⁺, F4/80⁺ cells and increased TLR4, αSMA, SR expression. IGF-1R inhibitors reversed this changes, but benazepril and insulin were without significant changes. The insulin decreased the expression level of IGF-1, and increased the levels of suppressor of cytokine signaling 2 (SOCS2). Benazepril and IGF-1R inhibitor were no significant changes like insulin.

Conclusion

Inhibition of IGF1R was a more effective choice for inflammation treatment than Ben or Ins in diabetic kidney disease (DKD). The IGF1R inhibitor blocked pathological changes induced by the over-expression of IGF1 in DKD without up-regulating SOCS2 protein levels.

Tropomyosin-Related Kinase B (TrkB) Regulates Neurite Outgrowth via a Novel Interaction with Suppressor of Cytokine Signalling 2 (SOCS2)

Brain-derived neurotrophic factor (BDNF) is highly expressed in the hippocampus, where it can initiate signalling pathways leading to neurite outgrowth, neuron survival, spine maturation and increased synapse strength. Although suppressor of cytokine signalling 2 (SOCS2) is primarily known to negatively regulate cytokine signalling, it is also highly expressed in the hippocampus and exerts neuron-specific functions in the brain, effecting the length and architecture of neurons. However, little is known about the role of SOCS2 in the hippocampus. In this study, we hypothesised that SOCS2 may have a regulatory role in BDNF-dependent neurite growth and hippocampal neuronal function. Here our data demonstrate that SOCS2 interacts with the kinase domain of the BDNF receptor TrkB. Germline overexpression of SOCS2 results in a BDNF-dependent increase in hippocampal neurite outgrowth, whereas deletion of SOCS2 results in shorter neurite outgrowth. Expression of SOCS2 also results in increased ubiquitination of the juxtamembrane region of TrkB, and alters the trafficking of TrkB into recycling endosomes. Collectively, our data suggest a novel role for SOCS2 in interacting with and regulating the trafficking of TrkB, leading to increased neurite outgrowth in hippocampus neurons.

SOCS-mediated immunomodulation of natural killer cells

Natural killer (NK) cells are innate immune cells with an intrinsic ability to detect and kill infected and cancerous cells. The success of therapies targeting immune checkpoints on CD8 cells has intensified interest in harnessing the cytolytic effector functions of NK cells for new cancer treatments. NK cell development, survival and effector activity is dependent on exposure to the cytokine interleukin (IL)-15. The suppressor of cytokine (SOCS) proteins (CIS; SOCS1-7) are important negative regulators of cytokine signaling, and both CIS and SOCS2 are reported to have roles in regulating NK cell responses. Their immunomodulatory effects on NK cells suggest that these SOCS proteins are promising targets that can potentially form the basis of novel cancer therapies. Here we discuss the role of NK cells in tumor immunity as well as review the role of the SOCS proteins in regulating IL-15 signaling and NK cell function.

Suppressor of cytokine signaling 2 (Socs2) deletion protects bone health of mice with DSS-induced inflammatory bowel disease

Individuals with inflammatory bowel disease (IBD) often present with poor bone health. The development of targeted therapies for this bone loss requires a fuller understanding of the underlying cellular mechanisms. Although bone loss in IBD is multifactorial, the altered sensitivity and secretion of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in IBD is understood to be a critical contributing mechanism. The expression of suppressor of cytokine signaling 2 (SOCS2), a well-established negative regulator of GH signaling, is stimulated by proinflammatory cytokines. Therefore, it is likely that SOCS2 expression represents a critical mediator through which proinflammatory cytokines inhibit GH/IGF-1 signaling and decrease bone quality in IBD. Using the dextran sodium sulfate (DSS) model of colitis, we reveal that endogenously elevated GH function in the Socs2^−/− mouse protects the skeleton from osteopenia. Micro-computed tomography assessment of DSS-treated wild-type (WT) mice revealed a worsened trabecular architecture compared to control mice. Specifically, DSS-treated WT mice had significantly decreased bone volume, trabecular thickness and trabecular number, and a resulting increase in trabecular separation. In comparison, the trabecular bone of Socs2-deficient mice was partially protected from the adverse effects of DSS. The reduction in a number of parameters, including bone volume, was less, and no changes were observed in trabecular thickness or separation. This protected phenotype was unlikely to be a consequence of improved mucosal health in the DSS-treated Socs2^−/− mice but rather a result of unregulated GH signaling directly on bone. These studies indicate that the absence of SOCS2 is protective against bone loss typical of IBD. This study also provides an improved understanding of the relative effects of GH/IGF-1 signaling on bone health in experimental colitis, information that is essential before these drugs are explored as bone protective agents in children and adults with IBD.

Summary: Using a mouse model of inflammatory bowel disease, this article provides an improved understanding of the relative effects of GH/IGF-1 on bone health in experimental colitis.

Natural killer cells and anti-tumor immunity

Immune checkpoint inhibitors harness the power of the immune system to fight cancer. The clinical success achieved with antibodies against the inhibitory T cell receptors PD-1 and CTLA4 has focused attention on the possibility of manipulating other immune cells, in particular those involved in innate immunity. Here we review the role of innate lymphoid cells (ILCs) and their contribution to tumor immunity. As the prototypical ILC, the natural killer (NK) cell has an intrinsic ability to detect and kill cancer cells. NK cells are dependent on the cytokine interleukin (IL)-15 for their development and effector activity. We discuss the role of the Suppressor of cytokine (SOCS) proteins in negatively regulating IL-15 and NK cell responses and the potential for targeting these small intracellular regulators as new immune checkpoints.

Lineage-Specific and Non-specific Cytokine-Sensing Genes Respond Differentially to the Master Regulator STAT5

STAT5, a member of the family of signal transducers and activators of transcription, senses cytokines and controls the biology of cell lineages, including mammary, liver, and T cells. Here, we show that STAT5 activates lineage-specific and widely expressed genes through different mechanisms. STAT5 preferentially binds to promoter sequences of cytokine-responsive genes expressed across cell types and to putative enhancers of lineage-specific genes. While chromatin accessibility of STAT5-based enhancers was dependent on cytokine exposure, STAT5-responsive promoters of widely expressed target genes were generally constitutively accessible. While the contribution of STAT5 to enhancers is well established, its role on promoters is poorly understood. To address this, we focused on Socs2, a widely expressed cytokine-sensing gene. Upon deletion of the STAT5 response elements from the Socs2 promoter in mice, cytokine induction was abrogated, while basal activity remained intact. Our data suggest that promoter-bound STAT5 modulates cytokine responses and enhancer-bound STAT5 is mandatory for gene activation.

Suppressor of cytokine signaling 2-12 regulates antimicrobial peptides and ecdysteroid signaling pathways in Bombyx mori (Dazao)

Suppressors of cytokine signaling (SOCS) are a potent negative regulator of diverse cytokine-related responses to maintain various physiological processes in animals. Here, we obtained the SOCS2-12 gene sequence of Bombyx mori (Dazao) (BmSOCS2-12) from the National Center for Biotechnology Information (NCBI) to study its expression profile in different tissues, as well as in the immune tissues following larval exposure to pathogens. Further, we investigated the role of BmSOCS2-12 in producing antimicrobial peptides (AMPs) and as a regulator of ecdysteroid signaling transduction. The quantitative real-time PCR analysis revealed unequal transcript levels of BmSOCS2-12 in the different tissues, however the gene's expression was highest in those of fat body and hemocyte. The challenge with pathogens significantly upregulated the transcript level of BmSOCS2-12 in both fat body and hemocyte when compared with the control. By contrast, recombinant BmSOCS2-12 protein injections strongly suppressed the expression of AMPs, while the knockdown of BmSOCS2-12 by double-stranded RNA enhanced their production. Administration of 20-hydroxyecdysone significantly downregulated the BmSOCS2-12 expression in fat body, and the depletion of BmSOCS2-12 enhanced the transcript levels of 20-hydroxyecdysone-responsive genes at 48 h. Altogether, BmSOCS2-12 may have multiple functional roles in the physiology of B. mori (Dazao), since it negatively regulates the expression of AMPs and ecdysteroid signaling transduction.

SOCS2 overexpression alleviates diabetic nephropathy in rats by inhibiting the TLR4/NF-κB pathway

Suppressor of cytokine signaling 2 (SOCS2) was reported to be involved in the development of Diabetic Nephropathy (DN). However, its underlying mechanism remains undefined. Western blot was carried out to determine the expressions of SOCS2, Toll-like receptors 4 (TLR4) and nuclear factor kappa B (NF-κB) pathway-related proteins in DN patients, streptozotocin (STZ)-induced DN rats and high glucose (HG)-stimulated podocytes. The effects of SOCS2 overexpression on renal injury, the inflammatory cytokines production, renal pathological changes, apoptosis and the TLR4/NF-κB pathway in DN rats or HG-stimulated podocytes were investigated. TLR4 antagonist TAK-242 and NF-κB inhibitor PDTC were used to confirm the functional mechanism of SOCS2 overexpression in HG-stimulated podocytes. SOCS2 was down-regulated, while TLR4 and NF-κB were up-regulated in renal tissues of DN patients and DN rats. Ad-SOCS2 infection alleviated STZ-induced renal injury and pathological changes and inhibited STZ-induced IL-6, IL-1β and MCP-1 generation and activation of the TLR4/NF-κB pathway in DN rats. SOCS2 overexpression attenuated apoptosis, suppressed the inflammatory cytokines expression, and inactivated the TLR4/NF-κB pathway in HG-stimulated podocytes. Suppression of the TLR4/NF-κB pathway enhanced the inhibitory effect of SOCS2 overexpression on apoptosis and inflammatory cytokines expressions in HG-stimulated podocytes. SOCS2 overexpression alleviated the development of DN by inhibiting the TLR4/NF-κB pathway, contributing to developing new therapeutic strategies against DN.

A herpes simplex virus type 2-encoded microRNA promotes tumor cell metastasis by targeting suppressor of cytokine signaling 2 in lung cancer

Certain viruses use microRNAs to regulate the expression of their own genes, host genes, or both. A number of microRNAs expressed by herpes simplex virus type 2 have been confirmed by previous studies. However, whether these microRNAs play a role in the metastasis of lung cancers and how these viral microRNAs precisely regulated the tumor biological process in lung cancer bone metastasis remain obscure. We recently identified the high expression of an acutely and latently expressed viral microRNA, Hsv2-miR-H9-5p, encoded by herpes simplex virus type 2 latency-associated transcript through microarray and quantitative polymerase chain reaction analyses which compared the expression of microRNAs in bone metastasis from lung cancer with primary lung cancers. We now reported that Hsv2-miR-H9-5p was highly expressed in bone metastasis and closely associated with pathological and metastatic processes of lung cancers. The functions of Hsv2-miR-H9-5p were determined by overexpression which results in an increase in survival, migration, and invasion of lung cancer cells in vitro. We determined that Hsv2-miR-H9-5p directly targeted SOCS2 mechanistically by dual-luciferase reporter assay. Then, we investigated the functions of SOCS2 in the progress of lung cancers. Reduction of SOCS2 dosage by hsv2-miR-H9-5p induced increased migration and invasion of lung cancer cells. Overexpression of SOCS2 inverted these phenotypes generated by hsv2-miR-H9-5p, indicating the potential roles of SOCS2 in Hsv2-miR-H9-5p-driven metastasis in lung cancers. The results highlighted that Hsv2-miR-H9-5p regulated and contributed to bone metastasis of lung cancers. We proposed that Hsv2-miR-H9-5p could be used as a potential target in lung cancer therapy.

SOCS gene family expression profile in the blood of multiple sclerosis patients

Multiple sclerosis (MS) is a chronic autoimmune disease, and the most common cause of nontraumatic disability in young people. The etiology of this disease is not well defined yet. Cytokines play an important role in differentiation, maturation and survival of a wide range of cells, including cells of the immune system. Suppressor of cytokine signaling (SOCS) proteins are the most important regulators of this cytokine signaling pathway. The aim of present study was to compare the expression levels of SOCS1, SOCS2, SOCS3 and SOCS5 genes in the blood of 50 relapsing-remitting MS (RR-MS) patients and 50 healthy controls by Taqman Quantitative Real-Time PCR in patients and healthy control group. We observed that SOCS1 and SOCS5 expression was significantly down-regulated (P=0.045 and P=0.044, respectively); whereas, no significant difference was observed between MS patients and controls for SOCS2 and SOCS3 gene expression (P=0.747 and P=0.439, respectively). In addition, there was no significant correlation between the expression of SOCS1, SOCS2, SOCS3 and SOCS5 genes and clinical findings, such as the level of physical disability in the MS patients according to the Kurtzke Expanded Disability Status Scale (EDSS) criterion and disease duration. However, a significant positive correlation was observed between expression levels of SOCS genes. This study shows that loss of balance among various members of the SOCS family proteins may contribute to pathophysiology of multiple sclerosis.

GLP-1 analogue recovers impaired insulin secretion from human islets treated with palmitate via down-regulation of SOCS2

Elevated circulating palmitate levels have been connected with type 2 diabetes mellitus. GLP-1 has favorable effects on beta-cells function. The aim was to identify mechanisms for decreased GSIS after long-term palmitate exposure and restoration by GLP-1 by analyzing changes in G-protein coupled receptor (GPCR) pathway signaling. Insulin secretory response to 20 mM glucose was attenuated after 7 days in islets exposed to palmitate but inclusion of exendin-4 restored secretion. Palmitate treatment altered genes of several GPCR signaling pathways including inflammatory pathways with up-regulated IL-1B, SOCS1 and SOCS2 transcript levels. Protein level of SOCS2 was also up-regulated by palmitate and accompanied by down-regulation of pAkt(T308), which was restored by exendin-4 treatment. When SOCS2 was knocked down, palmitate-induced down-regulation of IRS-1 and pAkt(T308) was prevented and GSIS, proinsulin to insulin ratio and apoptosis was restored. Long-term palmitate treatment up-regulates SOCS2 and reduces PI3K activity, thereby impairing GSIS. GLP-1 reverts the palmitate-induced effects.

Shrimp with knockdown of LvSOCS2, a negative feedback loop regulator of JAK/STAT pathway in Litopenaeus vannamei, exhibit enhanced resistance against WSSV

JAK/STAT pathway is one of cytokine signaling pathways and mediates diversity immune responses to protect host from viral infection. In this study, LvSOCS2, a member of suppressor of cytokine signaling (SOCS) families, has been cloned and identified from Litopenaeus vannamei. The full length of LvSOCS2 is 1601 bp, including an 1194 bp open reading frame (ORF) coding for a putative protein of 397 amino acids with a calculated molecular weight of ∼42.3 kDa. LvSOCS2 expression was most abundant in gills and could respond to the challenge of LPS, Vibrio parahaemolyticus, Staphhylococcus aureus, Poly (I: C) and white spot syndrome virus (WSSV). There are several STAT binding motifs presented in the proximal promoter region of LvSOCS2 and its expression was induced by LvJAK or LvSTAT protein in a dose dependent manner, suggesting LvSOCS2 could be the transcriptional target gene of JAK/STAT pathway. Moreover, the transcription of DmVir-1, a read out of the activation of JAK/STAT pathway in Drosophila, was promoted by LvJAK but inhibited by LvSOCS2, indicating that LvSOCS2 could be a negative regulator in this pathway and thus can form a negative feedback loop. Our previous study indicated that shrimp JAK/STAT pathway played a positive role against WSSV. In this study, RNAi-mediated knockdown of LvSOCS2 shrimps showed lower susceptibility to WSSV infection and caused lessened virus loads, which further demonstrated that the JAK/STAT pathway could function as an anti-viral immunity in shrimp.