GENETIC AND DEVELOPMENTAL ANALYSIS OF MECHANISMS UNDERLYING TERATOCARCINOGENESIS IN THE MOUSE GERM CELLS.

睾丸畸胎瘤是由睾丸内各种组织和胚胎全能干细胞组成的先天性肿瘤。在自发性睾丸畸胎瘤（STT）易感的129/Sv株中，这些干细胞来源于胎儿睾丸中的原始生殖细胞（PGC）。胚胎睾丸的睾丸内移植是分化的实验性睾丸畸胎瘤（ETT）。卵巢畸胎瘤（SOT）在易感菌株如LT和LTXBJ中来源于卵巢卵泡中孤雌生殖激活的卵子。最近在PTEN基因敲除（KO）小鼠中检测到STT和SOT。然后，为了阐明生殖细胞正常发育和致畸癌发生的机制，我们检查了易感小鼠品系和各种KO小鼠。所得结果总结如下1)。通过微卫星DNA图谱1-19号染色体上ETT发生率的品系差异与SSLP的连锁检验，寻找与ETT形成有关的候选基因。新的候选区域Ett1，Ett2（实验性睾丸畸胎瘤1,2）被定位。新基因Ka （Kasumi）在精子发生、卵子发生、黑色素生成和红细胞生成中诱导干细胞缺乏。已经建立了其同源菌株129/Sv-Ka/+和LTXBJ-Ka/+， Ka突变分别刺激STT的形成和抑制SOT的形成。在PTEN KO雄性中，STT发育，P13K/Akt信号的激活在PGCs中诱导了全能性。抑制Wnt/ β -catenin信号在PGC增殖中起重要作用。在卵母细胞特异性PTEN KO中，女性SOT从未被识别。因此，我们认为雌性PGCs和成熟卵子之间可能通过不同的机制产生SOT。Tact1、Tact2基因和Oxct2a、Oxct2b基因是睾丸单倍体生殖细胞特异性基因。Tact1/Actl7b基因是睾丸生殖细胞特异性的无内含子基因，其开放阅读框中CpG二核苷酸的甲基化抑制其在体细胞中的表达。用体内电穿孔法对小鼠鸟氨酸脱羧酶抗酶单倍体特异性启动子进行瞬时表达分析。己烯雌酚诱导鱼卵母细胞成熟。少

Testicular teratomas are congenital tumors composed of various kinds of tissues and embryonic totipotent stem cells in testes. In the 129/Sv strains susceptible to spontaneous testicular teratomas (STT), these stem cells are derived from primordial germ cells (PGC) in the fetal testes. Intra-testicular grafts of their fetal testes are differentiated experimental testicular teratomas (ETT). Ovarian teratomas (SOT) in the susceptible strains such as LT and LTXBJ are derived from the eggs that are activated parthenogenetically in ovarian follicles. Recently STT and SOT have been detected in PTEN knockout (KO) mice.Then, in order to clarify mechanisms underlying normal development and teratocarcinogenesis in germ cells, we have examined susceptible mouse strains and various KO mice. Results obtained were summarized below.1).The candidate genes responsible for ETT formation were searched by linkage tests between the strain differences of ETT incidence and SSLP of micro-satellite DNA map-mar … More kers on the 1-19 chromosomes. Novel candidate regions Ett1,Ett2 (experimental testicular teratomas 1,2) were mapped.2).Novel gene Ka (Kasumi) inducing stem cell deficiency in spermatogenesis and oogenesis, melanogenesis and erythrogenesis, was detected. Its congenic strains, 129/Sv-Ka/+ and LTXBJ-Ka/+, have been established and Ka mutation stimulated STT formation and inhibited SOT formation, respectively.3).In the PTEN KO males STT was developed and activation of P13K/Akt signaling was observed in induction of totipotency in PGCs. Inhibition of Wnt/beta-catenin signaling played important role in PGC proliferation. In oocyte specific PTEN KO females SOT was never recognized. Thus, it is suggested that SOT might be produced by different mechanisms between female PGCs and matured eggs.4).Tact1,Tact2 genes and Oxct2a,Oxct2b genes are the testis haploid germ cell-specific. Tact1/Actl7b geneis a testicular germ cell-specific intronless gene and methylation of CpG dinucleotides in its open reading frame represses its expression in somatic cells. Transient expression analysis of the mouse ornithine decarboxylase antizyme haploid- specific promorter was performed using in vivo electroporation.5).Diethylstilbestrol induces fish oocyte maturation. Less