Grx-1基因敲除鼠的繁殖及子代基因型鉴定

目的探讨glutaredoxin-1(Grx-1)基因敲除小鼠的优化繁殖及子代鼠的鉴定方法,为进一步研究Grx-1在支气管肺发育不良(BPD)中的作用奠定基础。方法将从美国哈佛医学院引进的纯合子Grx-1基因敲除小鼠与野生型小鼠进行交配后得到的子一代小鼠同代间相互交配,繁殖出的子二代中将出现纯合子、杂合子以及野生型3种基因型。从出生起观察其生长发育情况,2周龄时剪尾提取基因组DNA,用PCR方法扩增目的基因片段,琼脂糖凝胶电泳结果判定基因型。结果 Grx-1纯合子小鼠的饲养繁殖取得成功,获得了一批Grx-1基因敲除纯合子小鼠。结论正确的饲养繁殖以及鉴定方法是获得Grx-1基因敲除纯合子小鼠的有效途径,为相关研究提供动物实验模型奠定了基础。     

DDR2基因缺失小鼠的繁育及子代基因型的鉴定

目的：探讨盘状结构域受体2（DDR2）基因缺失小鼠的优化繁殖方法与子代小鼠DDR2基因型的鉴定方法,建立DDR2基因缺失小鼠模型,为进一步研究DDR2分子在肿瘤、肺纤维化、类风湿性关节炎等复杂疾病中的功能以及作用机制奠定基础。方法：将从美国JAX实验室引进的三对杂合子小鼠进行饲养并交配繁殖,繁殖成功后其子代中将会出现野生型、杂合子以及纯合子3种基因型。用基因组提取试剂盒试剂盒提取子鼠鼠尾的基因组DNA,经紫外分光光度计定量后,采用Taqman qPCR的方法准确鉴定出小鼠的基因型,同时观察子代小鼠各基因型的比例,并通过小鼠体态观察,进一步证实Taqman qPCR鉴定方法的可靠性。结果：DDR2基因杂合子小鼠互交繁殖可得到DDR2野生型小鼠、DDR2纯合子小鼠以及DDR2杂合子小鼠三种基因型小鼠,所得子代基本符合孟德尔遗传规律,且雌性和雄性DDR2纯合子小鼠体长均较DDR2野生型小鼠和DDR2杂合子小鼠小,鼻子也较其它基因型小鼠明显变短,无繁殖能力。依据Taqman qPCR的结果所得出的纯合子小鼠体貌特征与文献报道一致,证实了Taqman qPCR结果的可靠性。结论：雌、雄性DDR2杂合子小鼠交配可有效获得DDR2基因缺失小鼠;实验所用Taqman qPCR方法能够准确鉴定子代小鼠的基因型,DDR2纯合子小鼠的获得为后续实验的提供了较理想的动物模型。     

限制性内切酶策略鉴定CRISPR/Cas9介导的Chrm3基因敲除小鼠

CRISPR/Cas9技术是近年发展起来的快速基因编辑技术。通过该技术已对多种生物的基因组进行了编辑。由此产生的基因编辑动物的建系与鉴定是随之而来较为繁琐的工作。单导向RNA(single-guide RNA, sgRNA)靶序列的设计和确定不仅影响后续靶向基因组的效率,还可作为优化鉴定、筛选方法的参考。本研究在选取sgRNA靶序列时,不仅依据软件的评分,还分析了sgRNA靶序列是否含有酶切位点,以便对后续纯合子/杂合子进行鉴定。结果显示,以特异引物扩增的野生型小鼠Chrm3基因片段可被限制性内切酶BanⅡ切为两个片段;而纯合子小鼠“丢失”该酶切位点,其PCR产物不能被切开;杂合子小鼠PCR产物被不完全切开,凝胶电泳结果可见三条带。本研究结果提示该策略可有效简化基因编辑动物建系鉴定工作,提高鉴定效率及改善阳性动物辨识效果。     

Caveolin-1基因敲除小鼠子代基因型的鉴定及繁育方法

目的探讨小凹蛋白-1(caveolin-1)基因敲除小鼠的鉴定方法与最优繁育方式,为深入研究caveolin-1在脑缺血损伤修复中的作用提供理想的动物模型。方法将引进的caveolin-1基因敲除小鼠饲养于SPF级实验室,煮沸裂解法提取鼠尾组织基因组DNA,根据美国杰克逊实验室(Jackson Laboratory)提供的引物序列进行PCR反应检测其基因型,采用caveolin-1~(+/-)杂合子互交、杂合子与caveolin-1~(-/-)纯合子杂交(正交及反交)、纯合子互交4种不同的交配方式,观察亲代小鼠的受孕率、子代小鼠的外形特征及纯合率。结果琼脂糖凝胶电泳显示PCR产物分子量大小约200 bp和661 bp,与预期的目的基因片段分子量大小一致,成功鉴定了caveolin-1基因敲除小鼠的不同基因型;不同交配方式的繁殖结果基本符合孟德尔遗传规律,且雌性、雄性caveolin-1~(-/-)纯合鼠具有一定的繁殖能力,三种不同基因型小鼠的外形特征无明显差异。结论煮沸裂解法提取基因组DNA、PCR法能够快速可靠鉴定caveolin-1基因敲除小鼠的基因型;caveolin-1杂合子小鼠互交与纯合子互交相结合的繁育方法可能是短期内获得足量纯合子子鼠与同源野生子鼠的较好方式。     

Smad3基因剔除小鼠的繁殖与基因型鉴定

目的为进一步深入研究Smad3基因在脊椎动物发育中的重要作用,对Smad3基因剔除小鼠进行保种和繁育研究.方法采用基因剔除杂合子小鼠进行保种,通过PCR和Southern杂交对杂合子小鼠交配所产生的后代进行基因型鉴定,纯合子小鼠和野生型小鼠用于表型分析,杂合子小鼠用于留种和繁殖生产.结果采用PCR方法对278只子代小鼠进行了基因型鉴定,83只为野生型,133只为杂合子,62只为纯合子.结论Smad3基因剔除突变能稳定遗传.采用杂合子小鼠保种,子代小鼠三种基因型比例符合孟德尔遗传定律.     

Alpha珠蛋白基因片段表达载体的构建

目的：构建alpha珠蛋白基因片段反义表达载体,抑制重型beta地贫患者alpha珠蛋白基因的过量表达,为重型beta地贫基因治疗打下基础。方法：采用PCR扩增alpha珠蛋白基因片段807bp,反应条件94℃ 30s,68℃ 1min,72℃ 2min,35个循环,然后将所扩增片段用Klenow大片段酶补平PCR产物末端,另外用HindⅢ酶切pLNSX,用Klenow补平后,与补平末段的PCR产物平端连接,转化用CaCl2制备的感受态细胞受体DH5α,用碱法提取所得克隆子质粒,电泳比较质粒大小,再用PCR初筛,最后用双酶切进行鉴定。结果：经过质粒大小比较,PCR初筛,双酶切鉴定,得到6个正向插入重组子。     

乳腺上皮细胞特异性敲除Scrib基因杂合子小鼠的制作与鉴定

目的利用Cre．LoxP重组酶系统构建乳腺上皮细胞特异性敲除Serib基因杂合子小鼠,并进行鉴定,为进一步在动物整体水平研究Scrib基因在乳腺癌中的作用提供研究平台。方法将Scrib条件敲除杂合子小鼠（Scrib＋/ft小鼠）进行繁殖并鉴定,然后将鉴定结果为阳性的子代Scrib＋/ft小鼠与乳腺上皮细胞特异性表达Cre重组酶的MMTV．Cre纯合子小鼠进行杂交,鉴定其子代小鼠的基因型。结果成功繁育Scrib条件敲除小鼠和MMTV．Cre小鼠,并通过鉴定得到Scrib＋/ft小鼠,与MMTV-Cre小鼠杂交并繁殖,获得基因型为Scrib＋/ft;MMTVCre＋/-小鼠5只。结论本研究利用Cre．LoxP重组酶系统成功构建了乳腺上皮细胞特异性敲除Scrib基因杂合子小鼠,为进一步研究极性蛋白Scrib表达下调在乳腺癌发生中的作用提供了良好的动物模型。     

Presenilin-1/Presenilin-2双基因敲除小鼠的繁育及基因型鉴定

目的:繁殖及鉴定Presenilins双基因敲除小鼠,为进一步研究阿尔茨海默症(AD)奠定基础。方法:将引进的野生型及PS1/PS2双基因敲除小鼠进行饲养并繁殖,繁殖成功的子代小鼠基因型有野生型、杂合子和纯合子3种。提取子代小鼠鼠尾基因组DNA,用PCR法和琼脂糖凝胶电泳鉴定基因类型。结果:PS1/PS2双基因敲除小鼠的饲养和繁殖均获得成功,繁殖结果符合孟德尔遗传规律,同时获得更多基因型小鼠和Presenilins双基因敲除小鼠。结论:正确的饲养繁殖以及鉴定方法是获得PS1/PS2双基因敲除小鼠的有效途径。     

肺炎支原体P1蛋白羧基端基因片段在大肠杆菌中克隆的研究

在大肠杆菌中克隆肺炎支原体P1蛋白羧基端基因片段,为P1蛋白基因片段的扩增、表达及探讨羧基端基因片段功能打基础.采用PCR扩增方法获取P1结构基因.扩增产物用SalI和EcoRI酶切消化,回收1kb大小的DNA片段并与pUC19DNA连接,转入大肠杆菌JM109菌株.用X-gal平板及质粒图谱分析方法筛选重组克隆株,再用限制性核酸内切酶酶切图谱分析鉴定.经PCR扩增MPDNA获得1条5.0kbDNA片段.重组质粒限制性内切酶指纹图谱显示出2条带,1条为pUC19载体DNA带,另1条是1kb的插入片段.实验获得肺炎支原体P1蛋白结构基因及含P1蛋白羧基端DNA片段的重组克隆株.     

利用HRM技术区分ob糖尿病小鼠不同基因型

ob/ob小鼠是糖尿病相关研究中使用最广泛的动物模型之一,近年来,市场需求呈上升趋势。与野生型小鼠相比,其瘦素蛋白基因105号密码子发生CT点突变,导致不能产生正常的瘦素蛋白。该模型4周前外观表型与野生型无异,而ob/ob纯合子不育,因而在繁殖建系过程中,需要通过基因型鉴定纯合、杂合和野生三种基因型。该文建立了基于高分辨率溶解曲线分析(high resolution melting analysis,HRM)的基因型鉴定方法,基因型分型结果与常规PCR加酶切方法一致,也与DNA测序结果吻合;通过该方法分型后获得纯合子小鼠外观表型、血糖浓度参数符合预期。该方法较常规方法省时、高效、节省实验成本,可用于大规模ob小鼠繁殖中的基因型鉴定。     

Expression of the matricellular protein SPARC in murine lens: SPARC is necessary for the structural integrity of the capsular basement membrane.

SPARC (Secreted Protein, Acidic and Rich in Cysteine) is a matricellular glycoprotein that modulates cell proliferation, adhesion, migration, and extracellular matrix (ECM) production. Although SPARC is generally abundant in embryonic tissues and is diminished in adults, we have found that the expression of SPARC in murine lens persists throughout embryogenesis and adulthood. Our previous studies showed that targeted ablation of the SPARC gene in mice results in cataract formation, a pathology attributed partially to an abnormal lens capsule. Here we provide evidence that SPARC is not a structural component of the lens capsule. In contrast, SPARC is abundant in lens epithelial cells, and newly differentiated fiber cells, with stable expression in wild-type mice up to 2 years of age. Pertubation of the lens capsule in animals lacking SPARC appears to be a consequence of the invasion of the lens cells situated beneath the capsule. Immunoreactivity for SPARC in the lens cells was uneven, with minimal reactivity in the epithelial cells immediately anterior to the equator. These epithelial cells appeared essentially noninvasive in SPARC-null mice, in comparison to the centrally located anterior epithelial cells, in which strong labeling by anti-SPARC IgG was observed. The posterior lens fibers exhibited cytoplasmic extensions into the posterior lens capsule, which was severely damaged in SPARC-null lenses. The expression of SPARC in wild-type lens cells, together with the abnormal lens capsule in SPARC-null mice, indicated that the structural integrity of the lens capsule is dependent on the matricellular protein SPARC. The effects of SPARC in the lens appear to involve regulation of lens epithelial and fiber cell morphology and functions rather than deposition as a structural component of the lens capsule.     

SPARC mediates early extracellular matrix remodeling following myocardial infarction

Secreted protein, acidic, and rich in cysteine (SPARC) is a matricellular protein that functions in the extracellular processing of newly synthesized collagen. Collagen deposition to form a scar is a key event following a myocardial infarction (MI). Because the roles of SPARC in the early post-MI setting have not been defined, we examined age-matched wild-type (WT; n=22) and SPARC-deficient (null; n=25) mice at day 3 post-MI. Day 0 WT (n=28) and null (n=20) mice served as controls. Infarct size was 52 ± 2% for WT and 47 ± 2% for SPARC null (P=NS), indicating that the MI injury was comparable in the two groups. By echocardiography, WT mice increased end-diastolic volumes from 45 ± 2 to 83 ± 5 μl (P < 0.05). SPARC null mice also increased end-diastolic volumes but to a lesser extent than WT (39 ± 3 to 63 ± 5 μl; P < 0.05 vs. day 0 controls and vs. WT day 3 MI). Ejection fraction fell post-MI in WT mice from 57 ± 2 to 19 ± 1%. The decrease in ejection fraction was attenuated in the absence of SPARC (65 ± 2 to 28 ± 2%). Fibroblasts isolated from SPARC null left ventricle (LV) showed differences in the expression of 22 genes encoding extracellular matrix and adhesion molecule genes, including fibronectin, connective tissue growth factor (CTGF; CCN2), matrix metalloproteinase-3 (MMP-3), and tissue inhibitor of metalloproteinase-2 (TIMP-2). The change in fibroblast gene expression levels was mirrored in tissue protein extracts for fibronectin, CTGF, and MMP-3 but not TIMP-2. Combined, the results of this study indicate that SPARC deletion preserves LV function at day 3 post-MI but may be detrimental for the long-term response due to impaired fibroblast activation.     

The Expression of SPARC in Adipose Tissue and Its Increased Plasma Concentration in Patients with Coronary Artery Disease

Objective: Adipocytes secrete various cytokines and matrix proteins. Several of them precipitate in obesity‐associated diseases, including atherosclerosis. In the current study, we have examined the expression of secreted protein, acidic and rich in cysteine (SPARC) in adipose tissue and its significance in obesity and coronary artery disease (CAD). Research Methods and Procedures: The SPARC mRNA expressions both in vivo and in vitro were detected by Northern blot analysis. Plasma SPARC concentrations were measured by enzyme immunosorbent assay. First, we investigated the plasma SPARC levels of 88 unrelated adult Japanese subjects (62 men and 26 women; average age: [± SD] 50 ± 12 years; body mass index [BMI]: 16 to 46 kg/m²). Additionally 31 subjects with CAD diagnosed by coronary angiography (20 men and 11 women) were also investigated. Results: Human adipose tissues expressed abundant SPARC mRNA. SPARC expression in adipose tissues was upregulated in obese db/db mice. Markedly enhanced expression of SPARC mRNA was observed in 3T3‐L1 fibroblasts during adipocyte differentiation. Consistent with these results, plasma SPARC levels proved a positive correlation with BMI in humans (r = 0.27; p < 0.01). Interestingly, plasma SPARC concentrations were significantly elevated in age‐ and BMI‐matched subjects with CAD (p < 0.05). Discussion: SPARC was expressed in adipose tissues and its expression was enhanced in obese mice. In human, plasma SPARC levels were elevated in obesity and CAD patients. This elevated SPARC may be involved in the progression of CAD.     

Hippocampal SPARC regulates depression‐related behavior

SPARC (secreted protein acidic and rich in cysteine) is a matricellular protein highly expressed during development, reorganization and tissue repair. In the central nervous system, glial cells express SPARC during development and in neurogenic regions of the adult brain. Astrocytes control the glutamate receptor levels in the developing hippocampus through SPARC secretion. To further characterize the role of SPARC in the brain, we analyzed the hippocampal‐dependent adult behavior of SPARC KO mice. We found that SPARC KO mice show increased levels of anxiety‐related behaviors and reduced levels of depression‐related behaviors. The antidepressant‐like phenotype could be rescued by adenoviral vector‐mediated expression of SPARC in the adult hippocampus, but anxiety‐related behavior persisted in these mice. To identify the cellular mechanisms underlying these behavioral alterations, we analyzed neuronal activity and neurogenesis in the dentate gyrus (DG). SPARC KO mice have increased levels of neuronal activity, evidenced as more neurons that express c‐Fos after a footshock. SPARC also affects cell proliferation in the subgranular zone of the DG, although it does not affect maturation and survival of new neurons. SPARC expression in the adult DG does not revert the proliferation phenotype in KO mice, but our results suggest a role of SPARC in limiting the survival of new neurons in the DG. This work suggests that SPARC could affect anxiety‐related behavior by modulating neuronal activity, and that depression‐related behavior is dependent upon the adult expression of SPARC, which affects adult brain function by mechanisms that need to be elucidated.     

Chaperone-like activity revealed in the matricellular protein SPARC

SPARC (Secreted Protein, Acidic and Rich in Cysteine) is a matricellular glycoprotein that modulates cell proliferation, adhesion, migration, and extracellular matrix (ECM) production. In this report chaperone-like activity of SPARC was identified in a thermal aggregation assay in vitro. Ultraviolet circular dichroism (UVCD) spectroscopy determined that SPARC was stable at temperatures up to 50 degrees C. Unfolding and aggregation of the chaperone target protein, alcohol dehydrogenase (ADH), were initiated at 50 degrees C. SPARC inhibited the thermal aggregation of ADH in a concentration-dependent manner, with maximal inhibition at a 1:4 molar ratio of SPARC:ADH. Synergy between the chaperone-like activities of SPARC and alphaB-crystallin, a small heat shock protein and molecular chaperone in the lens, was observed in SPARC-alphaB-crystallin double -/- mice.     

The role of SPARC in extracellular matrix assembly

SPARC is a collagen-binding matricellular protein. Expression of SPARC in adult tissues is frequently associated with excessive deposition of collagen and SPARC-null mice fail to generate a robust fibrotic response to a variety of stimuli. This review summarizes recent advancements in the characterization of the binding of SPARC to collagens and describes the results of studies that implicate a function for SPARC in the regulation of the assembly of basal lamina and fibrillar collagen in the ECM. Potential cellular mechanisms that underlie SPARC activity in ECM deposition are also explored.     

The matricellular protein SPARC/osteonectin as a newly identified factor up-regulated in obesity

Alterations in the expression level of genes may contribute to the development and pathophysiology of obesity. To find genes differentially expressed in adipose tissue during obesity, we performed suppression subtractive hybridization on epididymal fat mRNA from goldthioglucose (GTG) obese mice and from their lean littermates. We identified the secreted protein acidic and rich in cysteine (SPARC), a protein that mediates cell-matrix interactions and plays a role in modulation of cell adhesion, differentiation, and angiogenesis. SPARC mRNA expression in adipose tissue was markedly increased (between 3- and 6-fold) in three different models of obesity, i.e. GTG mice, ob/ob mice, and AKR mice, after 6 weeks of a high fat diet. Immunoblotting of adipocyte extracts revealed a similar increase in protein level. Using a SPARC-specific ELISA, we demonstrated that SPARC is secreted by isolated adipocytes. We found that insulin administration to mice increased SPARC mRNA in the adipose tissue. Food deprivation had no effect on SPARC expression, but after high fat refeeding SPARC mRNA levels were significantly increased. Our results reveal both hormonal and nutritional regulation of SPARC expression in the adipocyte, and importantly, its alteration in obesity. Finally, we show that purified SPARC increased mRNA levels of plasminogen activator inhibitor 1 (PAI-1) in cultured rat adipose tissue suggesting that elevated adipocyte expression of SPARC might contribute to the abnormal expression of PAI-1 observed in obesity. We propose that SPARC is a newly identified autocrine/paracrine factor that could affect key functions in adipose tissue physiology and pathology.