转基因小鼠和基因敲除小鼠

能够把基因功能作为生物体表现来观察的改变了基因的小鼠。即使在基因组信息泛滥的今天,这也是最重要的工具之一,基本原理的研究虽然很早,但目前仍在进行改良法的开发工作。本文由基因控制株式会社的三谷匡董事予以阐述。[编者按]     

FSP27基因敲除小鼠——初步揭开白色脂肪细胞单房油滴之谜

脂肪组织储存甘油三酯等中性脂质,维持能量平衡,在肥胖、胰岛素抵抗和2型糖尿病研究中备受关注,脂肪细胞内油滴也被看成是具有活跃功能的细胞器。众所周之,哺乳动物白色脂肪细胞,胞浆部分95％以上空间被一个单房的大油滴（直径10～200μm不等）所占据;棕色脂肪细胞内含丰富的线粒体和多房的小油滴;其它组织,如肝脏、心肌、肾脏等细胞胞浆内含有多房且体积很小的油滴,提示白色脂肪细胞内单房大油滴是甘油三酯储存的主要形式。     

基因敲除技术及其在JNK-2研究中的应用

基因敲除技术,是利用同源重组的基因打靶技术,将打靶构建物与野生型的等位基因同源重组并交叉互换,经筛选得到所需的某一目的基因缺失的DNA片段,并创建出表达特异性状的动物模型.由于干细胞培养和稳定转染技术的发展,使基因敲除在JNK-2的基因功能、酶学功能研究中的作用日益受到重视.本文就该技术及其在JNK-2研究中的应用、进展及存在的问题做一综述.     

β2m基因敲除小鼠构建

β2m (Beta-2-microglobulin)基因编码一个非糖基化蛋白,作为主要组织相容性复合体1类 (MHCⅠ) 的重要组分,发挥抗原递呈的作用。为了避免免疫介导的清除,人类肿瘤和病原体采取了不同的策略,其中包括MHCⅠ表达的丢失。合适的动物模型对于评估和开发肿瘤及其他疾病的临床治疗新方法,以及阐明目前临床有效治疗方法的机制至关重要。利用CRISPR/Cas9基因编辑、显微注射等方法构建了β2m基因敲除小鼠。随后,通过PCR鉴定、qPCR、流式分析等实验技术进行基因型和表型鉴定。基因型鉴定结果显示在该品系小鼠中,目的基因编码区目标区域缺失。qPCR检测发现,β2m的mRNA水平发生显著的下调。流式结果显示,在不同的免疫组织和器官中,CD8+杀伤性T细胞显著减少。综上,成功构建β2m基因敲除小鼠,为后续体内研究β2m基因的功能奠定了基础。     

Mdr2基因敲除小鼠建立原发性肝癌模型观察

目的 观察C57BL/6背景的Mdr2基因敲除小鼠自发肝肿瘤形成情况。方法 (11.3±4.2)周龄Mdr2基因敲除C57BL/6-Abcb4^tm1小鼠9只和野生型C57BL/6小鼠5只,连续饲养65周后处死小鼠,留取血清及肝标本。检测血清ALT、AST、AFP水平,肝组织石蜡切片做HE、天狼猩红染色,免疫组织化学检测肿瘤及肿瘤旁组织CK-7、CK-19表达情况。结果 9只Mdr2基因敲除小鼠均自发形成肝肿瘤,血清ALT、AST、AFP水平均显著高于野生型小鼠(P<0.01),Mdr2基因敲除小鼠肝肿瘤CK-7、CK-19染色均为阴性。结论 Mdr2基因敲除小鼠连续饲养至(76.3±4.2)周龄时均自发形成肝肿瘤,其病理组织分型为肝细胞癌。     

基因敲除动物的研究和应用

目的基因敲除动物是近十几年来发展起来的在个体水平上研究基因功能的一类实验动物,它以基因敲除技术和胚胎干细胞技术为基础,在生命科学研究的各个领域得到了广泛应用。最近两年发展起来的RNA干扰技术仍然不能代替它。本文综述了基因敲除动物在各医学生物领域的研究与应用、浅谈其与RNA干扰技术的比较及其发展前景。     

EERα基因敲除小鼠的繁育及子代小鼠基因型的鉴定

目的 探讨雌激素受体α(ERα)基因敲除小鼠的优化繁育方法及ERα基因敲除小鼠子代鼠的鉴定方法,建立ERα基因敲除小鼠模型,为进一步研究ERα蛋白的功能奠定基础.方法 用4种不同的交配方式观察子代鼠的各表型比率及雌、雄性ERα基因突变纯合子小鼠的繁殖能力;从子鼠鼠尾中提取基因组DNA,用PCR方法扩增ERα基因片段,琼脂糖凝胶电泳后观察结果.HE染色观察雌、雄性ERα<'-/->小鼠生殖系统表型变化.结果 WT、ERα<'+/->、ERα<'-/->各表型小鼠互交繁殖结果基本符合孟德尔遗传规律,且雌、雄性ERα<'-/->小鼠无繁殖能力.与WT比较,雄性ERα<'-/->小鼠睾丸脏器系数降低,睾丸病理变化表现为生精小管管腔膨胀,生精细胞层变薄,且排列不规则;雌性ERα<'-/->小鼠子宫脏器系数降低,子宫和卵巢病变明显,表现为:子宫浆膜、肌层、内膜层细胞排列不规则,卵巢有囊性病变、充血,无黄体.结论 雌、雄性ERα<'+/->小鼠交配是繁育ERα<'-/->小鼠的较好方法;实验所用PCR方法能够精确鉴定ERα<'-/->小鼠,ERα<'-/->小鼠的获得为ERα蛋白功能的实验研究提供了较理想的动物模型.     

ERα基因敲除小鼠的繁育及子代小鼠基因型的鉴定

目的探讨雌激素受体α(ERα)基因敲除小鼠的优化繁育方法及ERα基因敲除小鼠子代鼠的鉴定方法,建立ERα基因敲除小鼠模型,为进一步研究ERα蛋白的功能奠定基础。方法用4种不同的交配方式观察子代鼠的各表型比率及雌、雄性ERα基因突变纯合子小鼠的繁殖能力;从子鼠鼠尾中提取基因组DNA,用PCR方法扩增ERα基因片段,琼脂糖凝胶电泳后观察结果。HE染色观察雌、雄性ERα-/-小鼠生殖系统表型变化。结果 WT、ERα+/-、ERα-/-各表型小鼠互交繁殖结果基本符合孟德尔遗传规律,且雌、雄性ERα-/-小鼠无繁殖能力。与WT比较,雄性ERα-/-小鼠睾丸脏器系数降低,睾丸病理变化表现为生精小管管腔膨胀,生精细胞层变薄,且排列不规则;雌性ERα-/-小鼠子宫脏器系数降低,子宫和卵巢病变明显,表现为:子宫浆膜、肌层、内膜层细胞排列不规则,卵巢有囊性病变、充血,无黄体。结论雌、雄性ERα+/-小鼠交配是繁育ERα-/-小鼠的较好方法;实验所用PCR方法能够精确鉴定ERα-/-小鼠,ERα-/-小鼠的获得为ERα蛋白功能的实验研究提供了较理想的动物模型。     

Lats1基因敲除小鼠保种的研究

目的　以Lats1基因敲除小鼠为例 ,研究国家遗传工程小鼠资源库遗传小鼠的保种技术路线及方法。方法　采用了胚胎移植 ,目的基因检测 ,胚胎冷冻等技术。结果　在库内得到 2 4只Lats+ -小鼠 ,扩群后 ,冷冻保存 110枚胚胎。结论　上述方法能确保Lats1基因敲除小鼠资源库保种成功。     

间隙连接功能多样性:连接蛋白基因敲除研究

编码细胞间间隙连接通道结构蛋白的基因是称为连接蛋白(connexin,Cx)基因的多基因家族;间隙连接蛋白基因有20种,且多数细胞同时表达多种连接蛋白,其功能研究较为复杂;小鼠7种连接蛋白基因的敲除为研究连接蛋白功能多样性提供了良好模型,并揭示了不同连接蛋白在维持不同组织正常发育和代谢中的重要作用.     

Transgenic and knock out mice in skeletal research. Towards a molecular understanding of the mammalian skeleton

Our understanding of the biology of the skeleton, like that of virtually every other subject in biology, has been transformed by recent advances in human and mouse genetics. Among mammals, mice are the most promising animals for this experimental work. Because extensive genetic information exists, many mouse mutations are known, and cells from early mouse developmental stages are accessible, scientists have developed transgenic mice - mice in which a gene is introduced or ablated in the germ line. Thus far, we have analyzed more than 100 different transgenic and knock out models with various skeletal phenotypes, covering the major aspects of both skeletal development and skeletal maintenance. Based on these results we here present a first perspective on transgenic and gene knock out animals in skeletal research, including insights in signaling pathways controlling endochondral bone formation, in the regulation of osteoblast function, osteoclastic bone resorption and in bone tumorigenesis, as well as the central control of bone formation. The use of transgenic mice to dissect and analyze regulatory mechanisms in bone cell physiology and the pathogenesis of human bone diseases is an extremely powerful experimental tool. The data presented here demonstrate that the successful convergence of novel genetic approaches with the established and fundamental knowledge of bone biology has made a beginning.     

Mutagenesis and carcinogenesis in nucleotide excision repair-deficient XPA knock out mice

Mice with a defect in the xeroderma pigmentosum group A (XPA) gene have a complete deficiency in nucleotide excision repair (NER). As such, these mice mimic the human XP phenotype in that they have a >1000-fold higher risk of developing UV-induced skin cancer. Besides being UV-sensitive, XPA^−/− mice also develop internal tumors when they are exposed to chemical carcinogens. To investigate the effect of a total NER deficiency on the induction of gene mutations and tumor development, we crossed XPA^−/− mice with transgenic lacZ/pUR288 mutation-indicator mice. The mice were treated with various agents and chemicals like UV-B, benzo[a]pyrene and 2-aceto-amino-fluorene. Gene mutation induction in several tumor target- and non-target tissues was determined in both the bacterial lacZ reporter gene and in the endogenous Hprt gene. Furthermore, alterations in the p53- and ras genes were determined in UV-induced skin tumors of XPA^−/− mice. In this work, we review these results and discuss the applicability and reliability of enhanced gene mutant frequencies as early indicators of tumorigenesis.     

Chronic hepatotoxicity of carbon tetrachloride in hsp-70 knock out mice.

The chronic hepatotoxic effects of carbon tetrachloride (CCl(4)) in heat-shock protein (HSP) 70 knock out (HSP70-/-) mice were examined. After repeated intraperitoneal injections of CCl(4) for six weeks, the level of ALT and weight ratio of the liver to body were lower in HSP70-/- mice than in the control (WT) mice. The levels of HSP25 and HSP47 were lowered in HSP70-/- mice as compared with WT mice. The grades of hepatic necrosis and neutrophil infiltration were not significantly different between HSP70-/- and WT mice. The collagen content was not affected significantly by CCl(4) treatment.     

Dietary fats modulate neuroinflammation in mucin 2 knock out mice model of spontaneous colitis

Specific diets regulate neuroimmune responses and modify risk of inflammatory bowel diseases, including ulcerative colitis. A link between gut and brain inflammation is also emerging. We hypothesized that adjusting dietary fatty acid composition modulates the neuroimmune responses in the mucin 2 knock out mice model of spontaneous colitis. Mice were randomly divided into three groups and fed isocaloric diets that only differed in their fatty acid composition. Diets enriched with anhydrous milk fat, corn oil, or Mediterranean diet fats were used. After nine weeks, brain and serum concentrations of ten inflammatory cytokines were measured. Three of these cytokines, including interleukin (IL)-2, IL-12 p70 and interferon-γ, were differentially expressed in the brains of animals from the three diet groups while there were no differences in the serum concentrations of these cytokines. Since only limited information is available about the functions of IL-2 in the central nervous system, in vitro experiments were performed to assess its effects on microglia. IL-2 had no effect on the secretion of neurotoxins and nitric oxide by microglia-like cells, but it selectively regulated phagocytic activity and reactive oxygen species production by stimulated microglia-like cells. Modulation of microglial reactive oxygen species through altered brain IL-2 concentrations could be one of the mechanisms linking diets with modified risk of neuroimmune disorders including Parkinson's disease.     

Impact of Ataxin-2 knock out on circadian locomotor behavior and PER immunoreaction in the SCN of mice

In Drosophila melanogaster, Ataxin-2 is a crucial activator of Period and is involved in the control of circadian rhythms. However, in mammals the function of Ataxin-2 is unknown despite its involvement in the inherited neurogenerative disease Spinocerebellar Ataxia type 2 in humans. Therefore, we analyzed locomotor behavior of Atxn2-deficient mice and their WT littermates under entrained- and free-running conditions as well as after experimental jet lag. Furthermore, we compared the PER1 and PER2 immunoreaction (IR) in the SCN. Atxn2^?/? mice showed an unstable rhythmicity of locomotor activity, but the level of PER1 and PER2 IR in the SCN did not differ between genotypes.     

PS1基因突变敲入小鼠B免疫记忆细胞功能变化

探讨PS1基因突变敲入小鼠B免疫记忆细胞功能变化。OVA免疫PS1基因突变敲入小鼠,通过ELISA抗体检测观察B细胞免疫记忆功能;分离小鼠脾淋巴细胞,检测脾淋巴细胞增殖实验、B细胞表面抗原表达情况。痘苗病毒免疫正常和基因突变敲入小鼠两次,在免疫后的一年进行痘病毒腹腔攻毒实验,观察PS1基因突变敲入小鼠存活情况。通过分离中枢和外周淋巴细胞进行体外功能检测表明,PS1基因突变敲入小鼠细胞增殖功能明显降低(P0.0001);B记忆细胞表面蛋白表达有差异(P=0.045);痘苗攻毒实验结果表明,PS1基因突变敲入小鼠死亡率明显增高(P0.0001)。研究结果表明,PS1基因在调控B记忆细胞功能方面发挥重要作用,但是通过调控T细胞功能而发挥间接还是直接针对B细胞发挥调控作用,还需要进一步研究结果确认。     

AAV1-LPL(S447X) gene therapy reduces hypertriglyceridemia in apoE2 knock in mice

Intramuscular (IM) application of adeno-associated virus serotype 1 (AAV1) for the delivery of human lipoprotein lipase (hLPL) was previously shown efficacious in mice with chylomicronemia. The current study addresses whether AAV1-LPL(S447X) can reduce elevated triglyceride (TG) levels in mice with attenuated clearance of TG-rich remnant particles. METHODS: Female mice, expressing human apoE2 but deficient for endogenous apoE (apoE2KI) received IM injections of AAV1-LPL(S447X) (n=6; 8 x 10(12) gc/kg; 4-sites) or PBS (n=5). Following lipid monitoring, the mice were challenged with intravenous Intralipid injections, and sacrificed 3 months after treatment. RESULTS: In the mice that received LPL gene therapy, a marked increase of post-heparin hLPL protein levels (averaging 517+/-277 ng/mL vs. 4+/-3 ng/mL in apoE2KI-untreated) induced 20% reductions of fasting plasma TG levels (p<0.05). This was accompanied by two-fold increased TG clearance rates after Intralipid administration at 6 weeks after treatment (p<0.05). Post-mortem analyses revealed increased levels of TG (2-fold, p<0.005) and cholesterol (1.7-fold, p<0.001) in the treated muscles. CONCLUSIONS: IM application of AAV1-LPL(S447X) is effective in reducing TG levels in a mouse model for type III dyslipidemia. Thus, hypertriglyceridemia caused by attenuated uptake of TG-rich lipoproteins can be alleviated by increasing lipolytic function of the skeletal muscle tissue.     

CART knock out mice have impaired insulin secretion and glucose intolerance, altered beta cell morphology and increased body weight

CART peptides are anorexigenic and are widely expressed in the central and peripheral nervous systems, as well as in endocrine cells in the pituitary, adrenal medulla and the pancreatic islets. To study the role of CART in islet function, we used CART null mutant mice (CART KO mice) and examined insulin secretion in vivo and in vitro, and expression of islet hormones and markers of beta-cell function using immunocytochemistry. We also studied CART expression in the normal pancreas. In addition, body weight development and food intake were documented. We found that in the normal mouse pancreas, CART was expressed in numerous pancreatic nerve fibers, both in the exocrine and endocrine portion of the gland. CART was also expressed in nerve cell bodies in the ganglia. Double immunostaining revealed expression in parasympathetic (vasoactive intestinal polypeptide (VIP)-containing) and in fewer sensory fibers (calcitonin gene-related peptide (CGRP)-containing). Although the expression of islet hormones appeared normal, CART KO islets displayed age dependent reduction of pancreatic duodenal homeobox 1 (PDX-1) and glucose transporter-2 (GLUT-2) immunoreactivity, indicating beta-cell dysfunction. Consistent with this, CART KO mice displayed impaired glucose-stimulated insulin secretion both in vivo after an intravenous glucose challenge and in vitro following incubation of isolated islets in the presence of glucose. The impaired insulin secretion in vivo was associated with impaired glucose elimination, and was apparent already in young mice with no difference in body weight. In addition, CART KO mice displayed increased body weight at the age of 40 weeks, without any difference in food intake. We conclude that CART is required for maintaining normal islet function in mice.