Inhibition of miRNA-222-3p Relieves Staphylococcal Enterotoxin B-Induced Liver Inflammatory Injury by Upregulating Suppressors of Cytokine Signaling 1

PURPOSE: Staphylococcal enterotoxin B (SEB) has been well-documented to induce liver injury. miRNA-222-3p (miR-222-3p) was implicated in SEB-induced lung injury and several liver injuries. This study aimed to explore the role of miR-222-3p in SEB-induced liver injury. MATERIALS AND METHODS: Expression of miR-222-3p and suppressors of cytokine signaling 1 (SOCS1) was detected using real-time quantitative PCR and western blot. Liver injury was determined by levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and inflammatory cytokines, numbers of infiltrating mononuclear cells using AST/ALT assay kit, enzyme-linked immunosorbent assay (ELISA), and hematoxylin-eosin staining, respectively. Target binding between miR-222-3p and SOCS1 was predicted on targetScan software, and confirmed by luciferase reporter assay. RESULTS: SEB induced liver injury in D-galactosamine (D-gal)-sensitized mice, as demonstrated by increased serum levels of AST and ALT, elevated release of interferon-gamma (INF-γ), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-2, and promoted infiltrating immune cells into liver. Expression of miR-222-3p was dramatically upregulated, and SOCS1 was downregulated in SEB-induced liver injury both in mice and splenocytes. Moreover, miR-222-3p knockout (KO) mice exhibited alleviated liver injury accompanied with SOCS1 upregulation. Besides, splenocytes under SEB challenge released less INF-γ, TNF-α, IL-6, and IL-2 during miR-222-3p knockdown. Mechanically, SOCS1 was targeted and downregulated by miR-222-3p. Upregulation of SOCS1 attenuated INF-γ, TNF-α, IL-6, and IL-2 release in SEB-induced splenocytes; downregulation of SOCS1 could block the suppressive role of miR-222-3p knockdown in SEB-induced splenocytes. CONCLUSION: Inhibition of miR-222-3p relieves SEB-induced liver inflammatory injury by upregulating SOCS1, thereby providing the first evidence of miR-222-3p in SEB-induced liver injury.

HOXC10 suppresses browning of white adipose tissues

Given that increased thermogenesis in white adipose tissue, also known as browning, promotes energy expenditure, significant efforts have been invested to determine the molecular factors involved in this process. Here we show that HOXC10, a homeobox domain-containing transcription factor expressed in subcutaneous white adipose tissue, is a suppressor of genes involved in browning white adipose tissue. Ectopic expression of HOXC10 in adipocytes suppresses brown fat genes, whereas the depletion of HOXC10 in adipocytes and myoblasts increases the expression of brown fat genes. The protein level of HOXC10 inversely correlates with brown fat genes in subcutaneous white adipose tissue of cold-exposed mice. Expression of HOXC10 in mice suppresses cold-induced browning in subcutaneous white adipose tissue and abolishes the beneficial effect of cold exposure on glucose clearance. HOXC10 exerts its effect, at least in part, by suppressing PRDM16 expression. The results support that HOXC10 is a key negative regulator of the process of browning in white adipose tissue.

Pancreatic regulation of glucose homeostasis

In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.