葡萄糖转运体4与Ⅱ型糖尿病相互关系的研究进展

葡萄糖转运体4（GLUT4）是转运葡萄糖的重要蛋白质，与Ⅱ型糖尿病（T2DM）密切相关．从GLUT4对骨骼肌、心肌和脂肪组织，以及肾组织的肾小球系膜细胞的影响等方面进行了综述，研究葡萄糖转运体4与Ⅱ型糖尿病相互关系．

Effects of Shikonin on Proliferation, Apoptosis, and Extracellular Matrix of Human Mesangial Cells

Objective:To investigate the effect of shikonin on the proliferation, apoptosis and extracellular matrix (ECM) of human mesangial cells (MC). Methods: MC was cultured in vitro with different concentrations of glucose (30, 50, 80 mmol/L). The cell growth was observed by using MTT method and apoptosis by using an aunexin-V-Fluos. Immunohistochemical studies for Laminin (LN), Fibronectin (FN) and type Ⅳ Collagens (Col Ⅳ) were measured. Results: Shikonin inhibited their growth (P<0.05) and apoptosis in the glycated cultured cells. Shikonin 0.05 mmol/L significantly reduced the secretion of LN, FN and Col Ⅳ from MC (P<0.05) cultured in 30, 50 and 80 mmol/L glucose. Conclusion: Shikonin could prevent or treat diabetic nephropathy (DN) and glomerulosclerosis (GS).

Shp-2／NF-κB Pathway Mediates the Inhibition of Lipoxin A4 onIL-1β-induced Synthesis of IL-6 in Glomerular Mesangial Cells

Objective: To examine whether lipoxin A 4 (LXA 4) has an antagonistic effect on IL-1β-induced synthesis of IL-6 in glomerular mesangial cells, and to explore the molecular mechanisms of signal pathway in LXA 4 actions. Methods: The glomerular mesangial cells of rat were cultured and treated with IL-1β, with or without preincubation with LXA 4 at different concentrations. The amount of IL-6 in the supernatant of cells was analyzed by enzyme-linked immunosorbent assay(ELISA). The expressions of mRNA of IL-6 were determined by RT-PCR. The expressions of Src homology 2(SH 2) containing protein-tyrosine phosphatase 2(Shp-2) were assessed by immunoprecipitation and immunoblotting. Activities of DNA-binding of nuclear factor-kappa B(NF-κB) were measured by electrophoretic mobility shift assay(EMSA). Results: IL-1β-stimulated secretion of protein and expression of mRNA of IL-6 in mesangial cells were inhibited by LXA 4 in a dose-dependent manner. LXA 4 antagonizes the phosphorylation of Shp-2 and activities of NF-κB induced by IL-1β. Conclusion: LXA 4 antagonists IL-1β-induced synthesis of IL-6 in glomerular mesangial cells through the mechanism of Shp-2/NF-κB pathway-dependent signal transduction.

IDENTIFICATION OF GLUCOSE TRANSPORTER- 1 AND ITS FUNCTIONAL ASSAY IN MOUSE GLOMERULAR MESANGIAL CELLS CULTURED IN VITRO

To evaluate the role of glucose transporter- l (GLUT1) in the glucose uptake of glomerular mesangial cells. Methods. Cultured C57/SJL mouse mesangial cells were used in the study. The expression of GLUT1 mRNA was detected by RT- PCR. The expression of GLUT1 protein was detected by immunofluorescence and flow cytometry. The uptake of glucose and its kinetics were determined by 2- deoxy- [3H]- D- glucose uptake. Results. Both GLUT1 mRNA and protein were found in mouse glomerular mesangial cells. 2- deoxy- D- glucose uptake and kinetics assay showed that this glucose transporter had high affinity for glucose and the glucose uptake specificity was further confirmed by phloretin. Conclusion. Functional GLUT1 did present in mouse mesangial cells cultured in vitro and it might be the predominant transporter mediated the uptake of glucose into mesangial cells.

Effects of peripheral blood mononuclear cells from idiopathic nephrotic childr en on cultured rat glomerular epithelial and mesangial cells

Objective To investigate the effect of immune cell from idiopathic nephrotic children on extracellular matrix (ECM) synthesis by cultured rat glomerular epithelial cell (GEC) and on the proliferation of mesangial cell (GMC). Methods Twenty-eight children with idiopathic nephrotic syndrome and 15 age-matched healthy children were randomly selected and divided into 4 groups: Group 1, untreated nephrotic children; Group 2, glucocorticoid treated nephrotic children; Group 3, children undergoing glucocorticoid treatment with negative proteinuria; and Group 4, normal control. The peripheral blood mononuclear cells (PBMC) were collected from these children and PBMC conditioned medium (PBMC-CM) were prepared. The PBMC-CM was co-cultured with GEC and GMC respectively. The concentrations of collagen, laminin, collagen Ⅲ and collagen Ⅳ in the GEC and PBMC-CM co-culture medium were investigated. The GMC proliferation was measured by the 3 H-thymidin incorporation method. Results The 3 H-proline incorporation coefficients of the GEC treated with the PBMC-CM of the 4 groups were 0.93, 1.24, 1.23, and 1.11, respectively. The laminin inhibitory coefficients of the 4 groups were 0.95, 1.02, 1.01, and 1.04, respectively. The inhibitory coefficients of collagen Ⅲ were 0.97, 1.00, 0.99, and 1.01, respectively, for the 4 groups. All these parameters showed a significant difference between Group 1 and the other 3 groups (P<0.05). However, there was no significant difference in the inhibitory coefficient of collagen Ⅳ between each two of the 4 groups (1.04, 1.05, 1.04, 1.08, P>0.05). The 3 H-thymidine incorporation coefficients of GMC responsive to PBMC-CM were 1.21, 1.53, 1.50, and 1.10, respectively, and no significant difference was found between the 4 groups (P>0.05). Conclusion The results suggested that the circulating immune cells from idiopathic nephrotic children have a direct effect on some ECM component synthesis in cultured rat GEC; the bio-activity of immune cells could be neutralized by administering glucocorticoid; and the circulating immune cells of nephrotic children have no direct effect on GMC proliferation.

SREBP-1 is a novel mediator of TGFβ1 signaling in mesangial cells

Glomerular matrix accumulation is a hallmark of diabetic nephropathy. Recent studies showed that overexpression of the transcription factor SREBP-1 induces glomerutoscterosis. TGFI31 is a key profibrotic mediator of glomerutoscterosis, but whether SREBP-1 regulates its effects is unknown. In kidney mesangial cells and in vivo, TGFβI activates SREBP-1. This requires SCAPo SIP0 and PI3K/Akt signaling, but is independent of Smad3. Activation of the TGFβ1-responsive reporter plasmid p3TP-lux requires SREBP-la, but not SREBP-lc, binding to an E-box adjacent to a Smad-binding element. SREBP-la overexpression atone activates p3TP-tux. Smad3 is required for SREBP-la transcriptional activation and TGFβ induces association between the two transcription factors. SREBP-la K333 acetylation by the acetyltransferase CBP is required for Smad3 association and SREBP-1 transcriptional activity, and is also required for Smad3 transcriptional activity. Thus, both Smad3 and SREBP-la activation cooperatively regulate TGFβ transcriptional responses. SREBP-1 inhibition provides a novel therapeutic strategy for diabetic kidney disease.

Effects of Zao Huang Mixture (藻黄合剂) on the Expressions of TGF-β1 and Col IV in Human Glomerular Mesangial Cells Cultured in High Glucose Environment

Objective: To investigate the effect of Zao Huang Mixture (藻黄合剂ZHM) on expressions of growth factor-β1 (TGF-β1) and collagen IV (Col IV) in human glomerular mesangial cells (GMC) cultured in high-glucose environment. Methods: After primary culture of GMC, in vitro culture was carried out in normal group, high glucose group and high glucose medium with ZHM of different concentrations, and the expressions of TGF-β1 and Col IV in the GMC group and in ZHM group were detected at 24 and 48 h respectively. Results: Compared with the normal group, expressions of TGF-β1 and Col IV significantly increased at 24 h, 48 h in the high glucose group (all P<0.01); Compared with the high glucose group, the expressions of TGF-β1 and Col IV in all the ZHM groups significantly decreased at 24 h, 48 h (P<0.05 or P<0.01). Conclusion: ZHM may modulate the process of diabetic nephropathy by changing the expression of TGF-β1 and Col IV in glomerular mesangial cells.

Identification and function of glucose transporter 1 in human mesangial cells

Objective To evaluate the role of glucose transporter 1 (GLUT1) in the glucose uptake of glomerular mesangial cells.Methods Cultured human glomerular mesangial cells were used. The expressions of glucose transporter 1 mRNA and protein were detected with reverse transcription-polymerase chain reaction (RT-PCR), flow cytometry and immunofluorescence staining. Glucose uptake was determined with 2-deoxy-［3H］-D-glucose uptake assay.Results The expressions of GLUT1 mRNA and proteins were detected in human mesangial cells. Glucose uptake and its kinetics assay showed that GLUT1 is a functional glucose transporter in cultured human mesangial cells, and that its function could be inhibited by the specific inhibitor, Phloretin. Conclusion GLUT1 is the predominant glucose transporter in human mesangial cells, which has the kinetic characteristics of high affinity and low capacity for D-glucose. This suggests that in order for mesangial cells to take up excessive quantities of glucose, as in diabetes, changes in glucose transporter expression, translocation or activity may be required.