Objective To construct human surfactant protein B (SP-B) gene promoter luciferase reporter plasmids and detect their transcriptional activities in H441 cells.Methods (1)The fragment of SP-B promoter (-218/+ 435 bp) was acquired from human genome DNA by polymerase chain reaction (PCR) amplification and then was inserted into pGM-T vector by the T4 DNA ligase.The vector was transfected into TOP10 E.coli.The positive clone was identified by DNA sequencing.The identified target SP-B promoter sequence was cloned into pGL3-basic vector to construct the recombinant vector pGL3-basic-SP-B-promoter and was identified by enzyme digestion and sequencing; (2)The pGL3-basic-SP-B-promoter vector was converted into pGL4.17-SP-B-promoter vector through enzyme digestion.The identified recombinant vectors and control plasmid pRL-TK were transfected into H441 cells by lipofectamine 2000,and luciferase assays was performed using the dual-luciferase reporter assay system.Results The sequences of SP-B promoter in the recombinant luciferase reporter plasmids were consistent with the one published on Genebank.The firefly/renilla luciferase activity ratio of pGL3-basic/pGL4.17-SP-B-promoter vector (2.8 ± 1.1,66.5±3.8) was significantly higher than pGL3-Basic,pGL4.17 control vector (0.2 ±0.1,4.3 ±0.4) with statistical significance (t =4.182,27.419,P =0.000),respectively.The SP-B promoter activity of pGL4.17-SP-B-promoter vector was significantly higher than pGL3-basic-SP-B-promoter vector (t =27.712,P =0.000).Conclusions The pGL3-basic/pGL4.17-SP-B-promoter vectors are successfully constructed with SP-B promoter activity in H441 cells and pGL4.17-SP-B-promoter vector is the better choice for further study with higher luciferase activity.

OBJECTIVETo analyze the biochemical and pathological changes in mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet combined with low-dose streptozotocin (STZ) injections.

METHODSC57BL/6J mice were divided randomly into normal control group (NC group), high-fat diet group (HC group) and high-fat diet plus STZ group (HC+STZ group). The mice were fed on normal chow or a high-fat diet for 1 month before two introperitoneal injections of STZ (40 mg/kg) or citrate buffer with an interval of 24 h as appropriate. Fasting blood glucose (FBG) was detected every week for 4 weeks, and oral glucose tolerance test (OGTT) was performed one month after the injections, after which the biochemical profiles, islet and liver were evaluated by immunohistochemical and pathological analysis.

RESULTSIn HC+STZ group, FBG was above the cutoff value (13.89 mmol/L) in 75% of the mice at 1 week after STZ injections and in all the mice at two weeks except for the death of 1 mouse, with a success rate of modeling of 91.3%. FBG in HC group, though slightly higher than that in NC group, remained normal (6.8 mmol/L). The body weight in HC+STZ and HC groups was significantly higher than that in NC group after feeding but without obvious increases after the injections (P<0.01). Blood glucose in HC+STZ group at 0.5 to 2 h after OGTT and the area under curve (AUC) were higher than those in NC and HC groups (P<0.01); the AUC in HC group was a also higher than that in NC group (P<0.05). Plasma creatinine was significantly higher in HC+STZ group than in NC (P<0.01) and HC (P<0.05) groups. Insulin secretion by the islets decreased obviously in HC+STZ and HC group. The mice in HC+STZ group showed atrophy, fibrosis, and vacuolization in the islets with mild fatty liver but no visible renal pathologies.

CONCLUSIONHigh-fat diet and low-dose STZ injections can induce T2DM in mice with very similar biochemical and pathological changes to human T2DM and with such complications as fatty liver.

Animals ; Blood Glucose ; Body Weight ; Diabetes Mellitus, Type 2 ; physiopathology ; Diet, High-Fat ; Fatty Liver ; physiopathology ; Glucose Tolerance Test ; Insulin ; Insulin Resistance ; Islets of Langerhans ; pathology ; Kidney ; pathology ; Mice ; Mice, Inbred C57BL ; Streptozocin