Insulin receptor substrate-1 inhibits high-fat diet-induced obesity by browning of white adipose tissue through miR-503.

Genetic variation of insulin receptor substrate 1 (IRS-1) was found to modulate the insulin resistance of adipose tissues, but the underlying mechanism was not clear. To investigate how the IRS-1 was involved in the browning of white adipose tissue through miRNA, we identified a mutated Irs-1 (Irs-1-/- ) mice model and found that this mice had a reduced subcutaneous WAT (sWAT) and increased brown adipose tissue (BAT) in the interscapular region. So we isolated the bone marrow stromal cells and analyzed differentially expressed miRNAs and adipogenesis-related genes with miRNA arrays and PCR arrays. Irs-1-/- mice showed decreased miR-503 expression, but increased expression of its target, bone morphogenetic protein receptor type 1a (BMPR1a). Overexpression of miR-503 in preadipocytes downregulated BMPR1a and impaired adipogenic activity through the phosphotidylinositol 3-kinase (PI3K/Akt) pathway, while the inhibitor had the opposite effect. In both Irs-1-/- and cold-induced models, sWAT exhibited BAT features, and showed tissue-specific increased BMPR1a expression, PI3K expression, and Akt phosphorylation. Thus, our results showed that IRS-1 regulated brown preadipocyte differentiation and induced browning in sWAT through the miR-503-BMPR1a pathway, which played important roles in high-fat diet-induced obesity.

Insulin-like growth factor-1 promotes osteogenic differentiation and collagen I alpha 2 synthesis via induction of mRNA-binding protein LARP6 expression.

This study explored the mechanism underlying the stimulation of collagen synthesis and osteoblastic differentiation by insulin-like growth factor 1 (IGF1) in primary mouse osteoblasts. Primary mouse calvarial osteoblasts were cultured and treated with various doses of IGF1 before transfection with siRNA targeting the collagen type I alpha 2 (Col1a2) or La ribonucleoprotein domain family member 6 (Larp6) genes. Alkaline phosphatase (ALP) activity, osteocalcin staining, alizarin red quantification and the expression level of runt-related transcription factor 2 (RUNX2) were performed to assess the differentiation of pre-osteoblasts. Based on Western blot analysis, IGF1 up-regulated COL1A2 protein expression in the primary osteoblasts in a dose- and time-dependent manner. In addition, Col1a2 interference inhibited the differentiation and mineralization of osteoblasts. IGF1 also stimulated the differentiation of mouse primary osteoblasts and increased LARP6 expression during osteogenic differentiation. RNA-Immunoprecipitation (IP) indicated that LARP6 could bind to Col1a2 mRNA after IGF1 stimulation. However, transfection of Larp6-specific siRNA significantly reduced collagen and ALP secretion, mineralization and inhibited the expression of osteocalcin and RUNX2, indicating that Larp6 interference inhibited the differentiation ability of primary mouse calvarial osteoblasts, and these effects could not be reversed by IGF1. Thus, IGF1 could promote COL1A2 expression and osteoblast differentiation in primary mouse calvarial pre-osteoblasts by increasing LARP6 expression via a posttranscriptional mechanism.

Insulin receptor substrate-1 time-dependently regulates bone formation by controlling collagen Iα2 expression via miR-342.

Insulin promotes bone formation via a well-studied canonical signaling pathway. An adapter in this pathway, insulin-receptor substrate (IRS)-1, has been implicated in the diabetic osteopathy provoked by impaired insulin signaling. To further investigate IRS-1's role in the bone metabolism, we generated Irs-1-deficient Irs-1smla/smla mice. These null mice developed a spontaneous mutation that led to an increase in trabecular thickness (Tb.Th) in 12-mo-old, but not in 2-mo-old mice. Analyses of the bone marrow stromal cells (BMSCs) from these mice revealed their differential expression of osteogenesis-related genes and miRNAs. The expression of miR-342, predicted and then proven to target the gene encoding collagen type Iα2 (COL1A2), was reduced in BMSCs derived from Irs-1-null mice. COL1A2 expression was then shown to be age dependent in osteoblasts and BMSCs derived from Irs-1smla/smla mice. After the induction of osteogenesis in BMSCs, miR-342 expression correlated inversely with that of Col1a2 Further, Col1a2-specific small interfering RNA (siRNA) reduced alkaline phosphatase (ALP) activity and inhibited BMSC differentiation into osteocyte-like cells, both in wild-type (WT) and Irs-1smla/smla mice. Conversely, in Irs-1smla/smla osteocytes overexpressing COL1A2, ALP-positive staining was stronger than in WT osteocytes. In summary, we uncovered a temporal regulation of BMSC differentiation/bone formation, controlled via Irs-1/miR-342 mediated regulation of Col1a2 expression.-Guo, Y., Tang, C.-Y., Man, X.-F., Tang, H.-N., Tang, J., Wang, F., Zhou, C.-L., Tan, S.-W., Feng, Y.-Z., Zhou, H.-D. Insulin receptor substrate-1 time-dependently regulates bone formation by controlling collagen Iα2 expression via miR-342.

Vitamin D, selenium, and antidiabetic drugs in the treatment of type 2 diabetes mellitus with Hashimoto's thyroiditis.

BACKGROUND: Diabetes and thyroiditis are closely related. They occur in combination and cause significant damage to the body. There is no clear treatment for type-2 diabetes mellitus (T2DM) with Hashimoto's thyroiditis (HT). While single symptomatic drug treatment of the two diseases is less effective, combined drug treatment may improve efficacy. AIM: To investigate the effect of a combination of vitamin D, selenium, and hypo-glycemic agents in T2DM with HT. METHODS: This retrospective study included 150 patients with T2DM and HT treated at The Central Hospital of Shaoyang from March 2020 to February 2023. Fifty patients were assigned to the control group, test group A, and test group B according to different treatment methods. The control group received low-iodine diet guidance and hypoglycemic drug treatment. Test group A received the control treatment plus vitamin D treatment. Test group B received the group A treatment plus selenium. Blood levels of markers of thyroid function [free T3 (FT3), thyroid stimulating hormone (TSH), free T4 (FT4)], autoantibodies [thyroid peroxidase antibody (TPOAB) and thyroid globulin antibody (TGAB)], blood lipid index [low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triacylglycerol (TG)], blood glucose index [fasting blood glucose (FBG), and hemoglobin A1c (HbA1c)] were measured pre-treatment and 3 and 6 months after treatment. The relationships between serum 25-hydroxyvitamin D3 [25 (OH) D3] level and each of these indices were analyzed. RESULTS: The levels of 25 (OH) D3, FT3, FT4, and LDL-C increased in the order of the control group, test group A, and test group B (all P < 0.05). The TPOAB, TGAB, TC, TG, FBG, HbA1c, and TSH levels increased in the order of test groups B, A, and the control group (all P < 0.05). All the above indices were compared after 3 and 6 months of treatment. Pre-treatment, there was no divergence in serum 25 (OH) D3 level, thyroid function-related indexes, autoantibodies level, blood glucose, and blood lipid index between the control group, test groups A and B (all P > 0.05). The 25 (OH) D3 levels in test groups A and B were negatively correlated with FT4 and TGAB (all P < 0.05). CONCLUSION: The combination drug treatment for T2DM with HT significantly improved thyroid function, autoantibody, and blood glucose and lipid levels.

Association of Sex Hormones and Fat Distribution in Men with Different Obese and Metabolic Statuses.

PURPOSE: Although several studies have explored the association of sex hormones with glucose metabolism, the association between sex hormones and body fat distribution, which is closely related to insulin resistance, has not been fully elucidated. We have tried to explore the relationship of testosterone (T) and estradiol (E2) with visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) mass in Chinese men with different obese and metabolic statuses. PATIENTS AND METHODS: A total of 128 men from the Health Management Center of the Second Xiangya Hospital, Central South University were collected and grouped in accordance with their obese and metabolic syndrome (MS) statuses: metabolically healthy non-overweight/obese men (MHNO), metabolically healthy overweight/obese men (MHO) and metabolically unhealthy overweight/obese men (MUO). Multiple regression analyses were performed to estimate contributions of sex hormones levels to the variations of body fat distribution and the contributions of body fat distribution to the variations of sex hormone levels. RESULTS: With fat mass parameters as independent variables, SAT had a strong negative association with T in MHNO (ß = -2.772, P = 0.034), VAT was positively correlated with E2 in MHO (ß = 22.269, P = 0.009), and SAT was negatively associated with T in MUO (ß = -3.315, P = 0.010). With sex hormones as independent variables, E2 positively correlated with VAT (ß = -176.259, P = 0.048), while T negatively correlated with VAT in MHO (ß = 183.150, P = 0.029). In MUO, an inverse association of T with SAT was observed (ß = -213.689, P = 0.021). CONCLUSION: E2 and VAT had a mutual influence, thus resulting in a vicious circle, and the negative correlation between T and VAT may be related to the decrease of the MS occurrence in the MHO group. There were bi-directional relationships between sex hormones and fat distribution in men with different obese and metabolic statuses. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR-EOC-16010194. Retrospectively registered.

IRS-2 Partially Compensates for the Insulin Signal Defects in IRS-1-/- Mice Mediated by miR-33.

Insulin signaling is coordinated by insulin receptor substrates (IRSs). Many insulin responses, especially for blood glucose metabolism, are mediated primarily through Irs-1 and Irs-2. Irs-1 knockout mice show growth retardation and insulin signaling defects, which can be compensated by other IRSs in vivo; however, the underlying mechanism is not clear. Here, we presented an Irs-1 truncated mutated mouse (Irs-1-/-) with growth retardation and subcutaneous adipocyte atrophy. Irs-1-/- mice exhibited mild insulin resistance, as demonstrated by the insulin tolerance test. Phosphatidylinositol 3-kinase (PI3K) activity and phosphorylated Protein Kinase B (PKB/AKT) expression were elevated in liver, skeletal muscle, and subcutaneous adipocytes in Irs-1 deficiency. In addition, the expression of IRS-2 and its phosphorylated version were clearly elevated in liver and skeletal muscle. With miRNA microarray analysis, we found miR-33 was down-regulated in bone marrow stromal cells (BMSCs) of Irs-1-/- mice, while its target gene Irs-2 was up-regulated in vitro studies. In addition, miR-33 was down-regulated in the presence of Irs-1 and which was up-regulated in fasting status. What's more, miR-33 restored its expression in re-feeding status. Meanwhile, miR-33 levels decreased and Irs-2 levels increased in liver, skeletal muscle, and subcutaneous adipocytes of Irs-1-/- mice. In primary cultured liver cells transfected with an miR-33 inhibitor, the expression of IRS-2, PI3K, and phosphorylated-AKT (p-AKT) increased while the opposite results were observed in the presence of an miR-33 mimic. Therefore, decreased miR-33 levels can up-regulate IRS-2 expression, which appears to compensate for the defects of the insulin signaling pathway in Irs-1 deficient mice.

Genetic diagnosis and treatment of a Chinese ketosis-prone MODY 3 family with depression.

BACKGROUND: To analyze the gene mutation and mental disorder of a Chinese ketosis-prone diabetes (KPD) family, and to make a precise diagnosis and give a treatment for them. METHODS: We studied a Chinese family with a clinical diagnosis of maturity-onset diabetes of the young (MODY). The clinical data and the blood samples were collected. The promotor and coding regions inclusive intron exon boundaries of the HNF1A, HNF4A were detected by polymerase chain reaction (PCR) and direct sequencing. The missense mutation was also analyzed by bioinformatics. Genetic counseling was performed twice a month to relieve the mental disorder of the persons. RESULTS: The missense mutation c.779 C>T (p.T260M) in exon4 of HNF1A gene was detected, and the symptom heterogenicity among persons in this family were found. All the members were retreated with Gliclazide and stopped to use other medicine, the blood glucose of them were well controlled. We also performed an active genetic counseling to them and the mental disorder of the proband's sister was relieved. CONCLUSIONS: A missense mutation of HNF1A gene was first found in Chinese ketosis-prone MODY family with manifestations heterogenicity among the persons. Sulphonylureas medicine and genetic counseling are efficiency ways to treat MODY 3 and its' mental disorder respectively.

Plasticity of adipose tissue in response to fasting and refeeding in male mice.

BACKGROUND: Fasting is the most widely prescribed and self-imposed strategy for treating excessive weight gain and obesity, and has been shown to exert a number of beneficial effects. The aim of the present study was to determine the exact role of fasting and subsequent refeeding on fat distribution in mice. METHODS: C57/BL6 mice fasted for 24 to 72 h and were then subjected to refeeding for 72 h. At 24, 48 and 72 h of fasting, and 12, 24, 48 and 72 h of refeeding, the mice were sacrificed, and serum and various adipose tissues were collected. Serum biochemical parameters, adipose tissue masses and histomorphological analysis of different depots were detected. MRNA was isolated from various adipose tissues, and the expressions of thermogenesis, visceral signature and lipid metabolism-related genes were examined. The phenotypes of adipose tissues between juvenile and adult mice subjected to fasting and refeeding were also compared. RESULTS: Fasting preferentially consumed mesenteric fat mass and decreased the cell size of mesenteric depots; however, refeeding recovered the mass and morphology of inguinal adipose tissues preferentially compared with visceral depots. Thermogenesis-related gene expression in the inguinal WAT and interscapular BAT were suppressed. Mitochondrial biogenesis was affected by fasting in a depot-specific manner. Furthermore, a short period of fasting led to an increase in visceral signature genes (Wt1, Tcf21) in subcutaneous adipose tissue, while the expression of these genes decreased sharply as the fasting time increased. Additionally, lipogenesis-related markers were enhanced to a greater extent greater in subcutaneous depots compared with those in visceral adipose tissues by refeeding. Although similar phenotypic changes in adipose tissue were observed between juvenile mice and adult mice subjected to fasting and refeeding, the alterations appeared earlier and more sensitively in juvenile mice. CONCLUSIONS: Fasting preferentially consumes lipids in visceral adipose tissues, whereas refeeding recovers lipids predominantly in subcutaneous adipose tissues, which indicated the significance of plasticity of adipose organs for fat distribution when subject to food deprivation or refeeding.

MiR-503 inhibits adipogenesis by targeting bone morphogenetic protein receptor 1a.

Adipogenesis plays a key role in the regulation of whole-body energy homeostasis and is critically related to obesity. To overcome obesity and its associated disorders, it is necessary to elucidate the molecular mechanisms involved in adipogenesis. An adipogenesis-related miRNA array analysis demonstrated that miR-503 was differentially expressed before and after adipocyte differentiation; however, the exact role of miR-503 in adipocyte differentiation is unclear. Thus, the objective of this study was to further examine miR-503 in adipocyte differentiation. We found significantly decreased expression of miR-503 during adipocyte differentiation process. Using bioinformatic analysis, miR-503 was identified as a potential regulator of Bone Morphogenetic Protein Receptor 1a (BMPR1a). We then validated BMPR1a as the target of miR-503 using a dual luciferase assay, and found decreased miR-503 and increased BMPR1a expression during adipogenesis. Overexpression of miR-503 in preadipocytes repressed expression of BMPR1a and adipogenic-related factors such as CCAAT/enhancer binding protein a (C/EBPα), proliferator-activated receptor-gamma (PPARγ), and adipocyte protein 2 (AP2). In addition, miR-503 overexpression impaired the phosphoinositol-3 kinase (PI3K)/Akt pathway. Inhibition of miR-503 had the opposite effect. Additionally, BMPR1a interference by siRNA attenuated adipocyte differentiation and the accumulation of lipid droplets via downregulating the PI3K/Akt signaling pathway. Our study provides the first evidence of the role miR-503 plays in adipocyte differentiation by regulating BMPR1a via the PI3K/Akt pathway, which may become a novel target for obesity therapy.