肝脏特异性CD36基因敲除小鼠的制备及鉴定

目的:运用Cre/Loxp重组酶系统构建肝脏特异性CD36基因敲除小鼠并进行鉴定和验证,为研究CD36的生物学功能奠定基础。方法:构建CD36打靶载体,电转转染胚胎干细胞,通过长链PCR筛选出正确同源重组的阳性克隆,阳性胚胎干细胞克隆经扩增后,注射入C57BL/6J小鼠的囊胚中,获得嵌合小鼠,再与Flp小鼠交配筛选获得Flox杂合子小鼠,该小鼠与引进的Alb-Cre小鼠交配,在F3代获得CD36fl/fl:Alb-Cre+基因型小鼠,即为肝脏特异性CD36敲除小鼠。采用PCR鉴定小鼠基因型,PCR、实时荧光定量PCR和Western blot验证小鼠肝脏CD36敲除效果,Western blot检测小鼠肾脏、脂肪和心肌组织CD36表达情况,HE染色观察小鼠肝脏形态学改变。结果:建立了CD36基因的Flox杂合子小鼠,与Alb-Cre小鼠交配后,在F3代筛选出CD36fl/fl:AlbCre-和CD36fl/fl:Alb-Cre+基因型小鼠,DNA水平证实CD36fl/fl:Alb-Cre+基因型小鼠肝脏CD36基因通过Cre/Loxp重组酶系统被敲除。与CD36fl/fl:Alb-Cre-基因型小鼠相比,CD36fl/fl:Alb-Cre+基因型小鼠肝脏CD36mRNA和蛋白表达水平显著降低,肾脏、脂肪和心肌组织CD36蛋白表达无差别,肝脏形态学特征无明显差异。结论:通过Cre/Loxp重组酶系统成功构建了肝脏特异性CD36基因敲除小鼠,为研究CD36在肝脏代谢和肝脏疾病中的功能提供了动物模型。     

Primary Spermatocyte-Specific Cre Recombinase Activity in Transgenic Mice

We have evaluated the specificity of Cre recombinase activity in transgenic mice expressing Cre under the control of the synatonemal complex protein 1 (Sycp1) gene promoter. Sycp1Cre mice were crossed with the ROSA26 reporter line R26R, to monitor the male germ cell stage-specificity of Cre activity as well as to verify that Cre was not active previously during development of other tissues. X-gal staining detected Cre-mediated recombination only in testis. Detailed histological examination indicated that weak Cre-mediated recombination occurred as early as in zygotene spermatocytes at stage XI of the cycle of the seminiferous epithelium. Robust expression of X-gal was detected in early to mid-late spermatocytes at stages V-VIII. We conclude that this transgenic line is a powerful tool for deleting genes of interest specifically during male meiosis.     

Fate mapping using Cited1-CreERT2 mice demonstrates that the cap mesenchyme contains self-renewing progenitor cells and gives rise exclusively to nephronic epithelia

Classic tissue recombination and in vitro lineage tracing studies suggest that condensed metanephric mesenchyme (MM) gives rise to nephronic epithelium of the adult kidney. However, these studies do not distinguish between cap mesenchyme and pre-tubular aggregates comprising the condensed MM, nor do they establish whether these cells have self-renewing capacity. To address these questions, we generated Cited1-CreER^T2 BAC transgenic mice, which express tamoxifen-regulated Cre recombinase exclusively in the cap mesenchyme. Fate mapping was performed by crossing these mice with the Rosa26R^LacZ reporter line and evaluating the location and cellular characteristics of LacZ positive cells at different time points following tamoxifen injection. These studies confirmed expected results from previous in vitro analysis of MM cell fate, and provide in vivo evidence that the cap mesenchyme does not contribute to collecting duct epithelium in the adult. Furthermore, by exploiting the temporally regulated Cre recombinase, these studies show that nephronic epithelium arising at different stages of nephrogenesis has distinct spatial distribution in the adult kidney, and demonstrate for the first time that the cap mesenchyme includes a population of self-renewing epithelial progenitor cells.     

BMP ligands act redundantly to pattern the dorsal telencephalic midline

The embryonic telencephalon is patterned into several areas that give rise to functionally distinct structures in the adult forebrain. Previous studies have shown that BMP4 and BMP2 can induce features characteristic of the telencephalic midline in cultured explants, suggesting that the normal role of BMP4 in the forebrain is to pattern the medial lateral axis of the telencephalon by promoting midline cell fates. To test this hypothesis directly in vivo, the Bmp4 gene was efficiently disrupted in the telencephalon using a CRE/loxP approach. Analysis of Bmp4-deficient telencephalons fails to reveal a defect in patterning, cell proliferation, differentiation, or apoptosis. The absence of a phenotype in the Bmp4-deficient telencephalon along with recent genetic studies establishing a role for a BMP4 receptor, BMPRIA, in telencephalic midline development, demonstrate that loss of Bmp4 function in the telencephalon can be compensated for by at least one other Bmp gene, the identity of which has not yet been determined.     

肾康灵调控系膜细胞炎性反应因子的机制研究

目的：观察氧化低密度脂蛋白（Oxidized Low-Density Lipoprotein,ox-LDL）对系膜细胞（Mesangial Cells,MCs）分泌炎性反应递质功能的影响,并从细胞分子生物学水平阐明肾康灵的作用机制。方法：采用肾康灵干预增殖的系膜细胞,并利用分子生物学技术检测CXCL16、CD36、IFN-γ、IL6、TNF-α含量或基因水平。结果：利用ox-LDL诱导大鼠系膜细胞增殖并加入CXCR6受体后,CXCL16、CD36、IFN-γ、IL6、TNF-α的含量或基因水平显著升高,肾康灵呈浓度依赖性降低其表达水平。结论：ox-LDL诱导系膜细胞增殖时通过CXCR6介导,可促进CXCL16、CD36、IFN-γ、IL6、TNF-α等炎性反应递质的释放,中药肾康灵可通过抑制炎性反应递质的释放,保护系膜细胞的功能。     

Mdm2 is required for maintenance of the nephrogenic niche

The balance between nephron progenitor cell (NPC) renewal, survival and differentiation ultimately determines nephron endowment and thus susceptibile to chronic kidney disease and hypertension. Embryos lacking the p53-E3 ubiquitin ligase, Murine double minute 2 (Mdm2), die secondary to p53-mediated apoptosis and growth arrest, demonstrating the absolute requirement of Mdm2 in embryogenesis. Although Mdm2 is required in the maintenance of hematopoietic stem cells, its role in renewal and differentiation of stem/progenitor cells during kidney organogenesis is not well defined. Here we examine the role of the Mdm2-p53 pathway in NPC renewal and fate in mice. The Six2-GFP::Cre^tg/+ mediated inactivation of Mdm2 in the NPC (NPC^Mdm2^−/−) results in perinatal lethality. NPC^Mdm2^−/− neonates have hypo-dysplastic kidneys, patchy depletion of the nephrogenic zone and pockets of superficially placed, ectopic, well-differentiated proximal tubules. NPC^Mdm2−/− metanephroi exhibit thinning of the progenitor GFP⁺/Six2⁺ population and a marked reduction or loss of progenitor markers Amphiphysin, Cited1, Sall1 and Pax2. This is accompanied by aberrant accumulation of phospho-γH2AX and p53, and elevated apoptosis together with reduced cell proliferation. E13.5–E15.5 NPC^Mdm2−/− kidneys show reduced expression of Eya1, Pax2 and Bmp7 while the few surviving nephron precursors maintain expression of Wnt4, Lhx1, Pax2, and Pax8. Lineage fate analysis and section immunofluorescence revealed that NPC^Mdm2−/− kidneys have severely reduced renal parenchyma embedded in an expanded stroma. Six2-GFP::Cre^tg/+; Mdm2^f/f mice bred into a p53 null background ensures survival of the GFP-positive, self-renewing progenitor mesenchyme and therefore restores normal renal development and postnatal survival of mice. In conclusion, the Mdm2-p53 pathway is essential to the maintenance of the nephron progenitor niche.     

肾上腺素对THP-1巨噬细胞TGF-β1、SR-A1和CD36表达的影响

目的:探讨肾上腺素对THP-1巨噬细胞TGF-β1、SR-A1和CD36表达的影响。方法:不同浓度肾上腺素处理THP-1巨噬细胞24h,运用逆转录多聚酶链反应检测其TGF-β1、SR-A1和CD36的mRNA表达,酶联免疫吸附试验检测TGF-β1蛋白的表达,Westem-blotting检测SR-A1蛋白的表达。结果:100nmol/L及1μmol/L的肾上腺素作用THP-1巨噬细胞,引起TGF-β1 mR- NA和蛋白表达下调(p<0.05),SR-A1 mRNA和蛋白表达上调(P<0.05),1pmol/L～1μmol/L的肾上腺素处理后,各组CD36 mRNA水平无显著性变化(p>0.05)。结论:应激浓度的肾上腺素可能通过影响TGF-β1和SR-A1的表达而参与和/或促进AS的发生发展。