Effect of sidt2 Gene on Cell Insulin Resistance and Its Molecular Mechanism.

BACKGROUND: Sidt2 (SID1 transmembrane family, member 2) is a multiple transmembrane lysosomal membrane protein newly discovered in our previous study. In the previous study, we used gene targeting technique to make a mouse model of sidt2 gene knockout (sidt2-/-). It was found that sidt2-/- mice showed elevated fasting blood glucose and impaired glucose tolerance, showing a disorder of glucose metabolism, suggesting that sidt2 may be closely related to insulin resistance. We used 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells as subjects to observe the effects of sidt2 on insulin-stimulated glucose uptake and the abovementioned insulin signal transduction pathways, and then to explore the effect of sidt2 on peripheral tissue insulin resistance and its possible molecular mechanism. METHODS: (1) Lentiviruses with sidt2 gene knockout and puromycin resistance were constructed by Crispr/cas9 vector and transfected into 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells to construct sidt2 knockout cell line model. (2) Glucose uptake of 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells stimulated by insulin was detected by glucose detection kit, and the results were analyzed. (3) Sidt2 knockout group and control group of 3T3-L1 adipocytes, C2-C12 myoblast, and HEPA1-6 hepatoma cells were cultured according to the routine method. The total proteins of the above cells were extracted, and the expression of PAKT (thr308), PI3-K, and PIRS-1 (ser307) in the IRS-1 signaling pathway of the three groups was detected by western blot technique. RESULTS: (1) The sidt2 elimination models of 3T3-L1 adipocytes, C2-C12 myoblasts, and HEPA1-6 hepatoma cells were successfully constructed. (2) It was found that the glucose uptake of cells in the sidt2 knockout group was lower than that in normal group under insulin stimulation through the detection of glucose concentration in the cell culture medium. (3) It was found that the expression of PAKT (thr308) and PI3-K protein decreased and the expression of PIRS-1 (ser307) protein increased in sidt2-/- group compared to the control group. CONCLUSIONS: sidt2 knockout can reduce glucose uptake in peripheral tissue under insulin stimulation, which may lead to peripheral tissue insulin resistance by affecting the IRS-1 signal pathway.

The Effects of Sidt2 on the Inflammatory Pathway in Mouse Mesangial Cells.

In patients with chronic kidney disease, the abnormal activation of inflammatory pathways is usually an important factor leading to renal fibrosis and further deterioration of renal function. Finding effective intervention targets of the inflammatory signaling pathway is an important way to treat chronic kidney disease. As a newly discovered lysosomal membrane protein, the correlation between SID1 transmembrane family member 2 (Sidt2) and the inflammatory signaling pathway has not been reported. The aim of this study was to investigate the effect of Sidt2 on inflammation by inhibiting the expression of the Sidt2 gene in a mouse mesangial cell line mediated by a lentiviral CRISPR/Cas9 vector. Hematoxylin and eosin staining and microscopy found that the mesangial cells lost their normal morphology after inhibiting the expression of Sidt2, showing that the cell body became smaller, the edge between the cells was unclear, and part of the nucleus was pyknotic and fragmented, appearing blue-black. The expressions of IKK ß, p-IKK α/ß, NF-κB p65, p-NF-κB p65, p-IκBα, IκBα, and TNF-α in the NF-κB pathway of the Sidt2 -/- group were higher than those of the Sidt2 +/+ group. p-Jak2 and IL6 increased in the Jak/Stat pathway, and p-ERK and p-P38 increased in the MAPK pathway. The expressions of IKK ß, p-IKK α/ß, NF-κB p65, p-NF-κB p65, p-IκBα, IκBα, and TNF-α in the NF-κB pathway of the Sidt2 +/++LPS group were significantly higher than those in the Sidt2 +/+ group. The expressions of IKK ß, p-IKK α/ß, NF-κB p65, p-NF-κB p65, p-IκBα, IκBα, and TNF-α in the Sidt2 -/-+LPS group were higher than those in the Sidt2 -/- group. The expressions of p-IKK α/ß, NF-κB p65, p-NF-κB p65, p-IκBα, IκBα, and TNF-α in the Sidt2 -/-+LPS group were higher than those in the Sidt2 +/++LPS group. In the Jak/Stat pathway, the protein expressions of p-Jak2 and IL6 in the Sidt2 +/++LPS group were higher than those in the Sidt2 +/+ group. The expressions of p-Jak2 and IL6 in the Sidt2 -/-+LPS group were higher than those in the Sidt2 -/- group. The expressions of p-Jak2 and IL6 in the Sidt2 -/-+LPS group were higher than those in the Sidt2 +/++LPS group. The expressions of p-JNK, p-ERK, p-P38, and ERK in the MAPK pathway in the Sidt2 +/++LPS group were higher than those in the Sidt2 +/+ group. The expressions of p-JNK, p-ERK, p-P38, and ERK in the Sidt2 -/-+LPS group were higher than those in the Sidt2 -/- group. The expressions of p-JNK, p-ERK, p-P38, and ERK in the Sidt2 -/-+LPS group were higher than those in the Sidt2 +/++LPS group. These data suggested that deletion of the Sidt2 gene changed the three inflammatory signal pathways, eventually leading to the damage of glomerular mesangial cells in mice.

A single-nucleotide polymorphism C-724 /del in the proter region of the apolipoprotein M gene is associated with type 2 diabetes mellitus.

BACKGROUND: Apolipoprotein M (apoM) was the carrier of the biologically active lipid mediator sphingosine-1-phospate in high density lipoprotein cholesterol (HDL-C) and played a critical role in formation and maturation of prebeta-HDL-C particles. The plasma apoM levels were decreased obviously in patients with type 2 diabetes mellitus (T2DM). A new single-nucleotide polymorphism (SNP) C-724del in apoM promoter was associated with a higher risk for coronary artery diseases (CAD) and myocardial infarction, could reduce promoter activities and apoM expression in vitro. The primary aim of the present case-controls study was to investigate the effect of apoM SNP C-724del on apoM expression in vivo and its association with T2DM susceptibility in an eastern Han Chinese cohort. METHODS: Two hundred and fifty-nine T2DM patients and seventy-six healthy controls were included in this study. Amplifying DNA of apoM proximal promoter region including SNP C-724del by Real-Time Polymerase Chain Reaction (RT-PCR) and amplicons sequencing. The plasma apoM concentrations were assayed by enzyme linked immunosorbentassay (ELISA). RESULTS: Four polymorphic sites, rs805297 (C-1065A), rs9404941 (T-855C), rs805296 (T-778C), C-724del were confirmed. rs805297 (C-1065A) and rs9404941 (T-855C) showed no statistical difference in allele frequencies and genotype distributions between T2DM patients and healthy controls just as previous studies. It's worth noting that the difference of rs805296 (T-778C) between these two groups was not found in this study. In SNP C-724del, the frequency of del allele and mutant genotypes (del/del, C/del) were higher in T2DM patients compared with healthy controls (p = 0.035; P = 0.040, respectively), while the plasma apoM levels of C-724del mutant allele carriers compared with the wide-type homozygotes carriers were not statistically different in T2DM patients (18.20 ± 8.53 ng/uL vs 20.44 ± 10.21 ng/uL, P = 0.245). CONCLUSION: The polymorphism C-724del in the promoter region of the apoM gene could confer the risk of T2DM among eastern Han Chinese. Unfortunately, the lowing of plasma apoM levels of C-724del mutant allele carriers compared with the wide-type homozygotes carriers in T2DM patients was not statistically different in present study, so further researchs were needed by enlarging the sample.

Analysis of alternatives for insulinizing patients to achieve glycemic control and avoid accompanying risks of hypoglycemia.

The aims of the present study were to explore the efficacy of glycemic control and the risks of hypoglycemia with different methods of insulin therapy, and to provide reference data for the clinical treatment of diabetes. In this retrospective study, hospitalized patients diagnosed with type 2 diabetes between March and December 2014, in the Department of Endocrinology in the First Affiliated Hospital of Wannan Medical College, were divided into three groups, including an intensive insulin analogue therapy group, a premixed insulin analogue treatment group and a premixed human insulin therapy group. The efficacy of glycemic control and the incidence of hypoglycemia were determined in each of the insulin treatment groups. Compared with the other treatment groups, the intensive insulin analogue therapy group was associated with superior blood glucose control, shorter time to reach standard insulin regimen, shorter hospitalization time, fewer fluctuations in blood glucose levels and lower insulin dosage on discharge from hospital. However, this treatment was also associated with a high risk of hypoglycemia. In conclusion, when combined with the effective prevention of hypoglycemia and appropriate nursing care (especially in hospital care), intensive insulin analogue therapy may provide the greatest benefit to patients.

Apolipoprotein M: Research progress, regulation and metabolic functions (Review).

Apolipoprotein M (ApoM) is a novel lipoprotein-associated plasma protein of the apolipoprotein family. It is predominantly enriched in high-density lipoprotein (HDL), and is also present in small quantities in low-density lipoprotein (LDL) and in very low-density lipoprotein. Transgenic animal experiments have suggested that ApoM can be transformed into various lipoproteins and may be involved in lipoprotein metabolism. ApoM has five subtypes, however, their biological functions remain to be elucidated. The α-helix, formed by ApoM through hydrophobic signal peptides, is anchored to the phospholipid monomolecular layers of HDL. Hydrophobic domains can associate with small lipophilic ligands and perform biological functions. ApoM may affect HDL metabolism and exhibit anti-atherosclerotic functions. Human HDL, containing ApoM subfractions, can protect LDL from oxidation and regulate cholesterol efflux more effectively than HDL without ApoM. Therefore, it is highly correlated with plasma cholesterol levels in the human body. Although previous studies have reported no difference in ApoM between groups of patients with coronary heart disease (CHD) and a normal control groups, the anti-atherosclerotic effect of ApoM is evident. ApoM is highly expressed in renal proximal tubule cells and is secreted into the urine in tubule cells. However, it is usually reabsorbed by giantin-associated proteins in a process, which is also affected in kidney disease. In addition to liver and kidney cells, low expression levels of ApoM occur in the intestinal tract and are associated with lymph node metastasis of colorectal cancer. ApoM gene polymorphism is associated with CHD, diabetes and other immune-associated diseases. Investigations into the gene regulation of ApoM may assist in further clarifying the role of ApoM in blood glucose and lipid metabolism. Genetic modification of the mouse ApoM gene is an essential technique to investigate the gene expression and regulation of ApoM, and to clarify the potential roles of ApoM in lipoprotein metabolism, atherosclerosis, diabetes and renal diseases.

[Study on reproductive toxicity in male embryo rats with the pregnancy SD rates exposed by nonylphenol].

OBJECTIVE: To investigate the effect of nonylphenol (NP) exposure on the genital development of fetal male rats in pregnant rats, and to measure the mRNA and protein expression of insulin-like factor3 (Insl-3) in the testicular tissue of fetal rats. METHODS: A total of 100 pregnant SD rats were equally assigned to blank control group and four NP treated groups. Each rat in the NP treated groups received intragastric administration of NP at doses of 5, 40, 100, or 200 mg/kg/d from day 14 to 19 of gestation, and the rats in the blank control group received intragastric administration of pure peanut oil. The pregnant rats were sacrificed on day 19 of gestation. The body weight and testicular weight of each fetal rat were measured, and the descent of testis was also observed. The mRNA and protein expression of Insl-3 in the testicular tissue of fetal rats was analyzed by reverse transcription-PCR and Western blot. RESULTS: Compared with the blank control group, the 40, 100, and 200 mg/kg NP treated groups showed significantly decreased body weight and weight coefficient of testis (P < 0.05 or P < 0.01), significantly decreased testicular descent (P < 0.05), and significantly decreased mRNA and protein expression of Insl-3 (P < 0.05 or P < 0.01). CONCLUSION: Exposure to nonylphenol can lead to testicular maldevelopment, incomplete testicular descent, and Insl-3 expression downregulation of fetal male rats in pregnant rats.