Overexpression of mouse follistatin causes reproductive defects in transgenic mice
Overexpression of mouse follistatin causes reproductive defects in transgenic mice
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DOI：
10.1210/mend.12.1.0053
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发表时间：
1998-01-01
影响因子：
--
通讯作者：
Matzuk, MM
中科院分区：
文献类型：
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作者：
Guo, QX;Kumar, TR;Matzuk, MM
卵泡抑素是一种激活素结合蛋白，在体外可作为激活素拮抗剂。卵泡抑素还结合硫酸肝素蛋白聚糖，并可作为体内激活素的储库。在小鼠中，卵泡抑素mRNA首先在胚胎第5.5天的蜕膜中检测到，然后在发育中的后脑、体节、触须、牙齿、表皮和肌肉中检测到。我们以前已经证明，卵泡抑素缺乏的小鼠有许多胚胎缺陷，包括光泽，紧绷的皮肤，生长迟缓，腭裂导致出生后几小时内死亡。为了进一步确定卵泡抑素在哺乳动物生殖和发育过程中的作用，我们创建了功能获得性突变小鼠，其中小鼠卵泡抑素过表达。将小鼠金属硫蛋白（MT）-I启动子置于六外显子小鼠卵泡抑素（FS）基因的上游。为了区分野生型和转基因卵泡抑素mRNA，将小鼠卵泡抑素基因的3 '非翻译区替换为SV 40非翻译和polyA序列。产生了三只雄性和两只雌性创始转基因小鼠，它们是可生育的，并将转基因传递给后代。北方印迹分析表明，转基因mRNA在5个转基因品系中的4个的后代的肝脏中以不同的水平表达，并且在所有5个品系的睾丸中表达。在MT-FS系4中，其在肝脏中具有最高的转基因mRNA表达，转基因转录物也存在于多种其他组织中。从表型上看，MT-FS转基因品系在睾丸、卵巢和毛发中存在缺陷。来自MT-FS系7和10的小鼠睾丸尺寸略微减小，而来自系4、5和9的小鼠睾丸小得多，皮毛有光泽，有些不规则。5号和9号系雄性动物的成年睾丸组织学分析显示不同程度的间质细胞增生、精子发生停滞和生精小管变性，导致不育。来自品系4和品系9的雌性转基因小鼠由于在不同阶段的卵泡发生受阻而具有薄的子宫和小的卵巢。许多第9系雌性小鼠最终变得不育，并且所有第4系雌性小鼠都不育。仅在4号系转基因雄性和雌性小鼠中观察到血清FSH水平受抑制，该系具有广泛的转基因表达。血清FSH水平没有显着不同的性腺切除野生型和5号线转基因雄性小鼠，尽管高水平的卵泡抑素转基因mRNA在这些转基因小鼠的肝脏。这些结果表明卵泡抑素在性腺和垂体水平发挥其作用，作为激活素和可能的其他转化生长因子-β家族成员的局部调节剂。
Follistatin is an activin-binding protein that can act as an activin antagonist in vitro. Follistatin also binds heparin sulfate proteoglycans and may function as a reservoir for activins in vivo. In the mouse, follistatin mRNA is first detected in the deciduum on embryonic day 5.5 and later in the developing hindbrain, somites, vibrissae, teeth, epidermis, and muscle. We have previously shown that follistatin-deficient mice have numerous embryonic defects including shiny, taut skin, growth retardation, and cleft palate leading to death within hours of birth. To further define the roles of follistatin during mammalian reproduction and development, we created gain-of-function mutant mice in which mouse follistatin is overexpressed. The mouse metallothionein (MT)-I promoter was placed upstream of the six-exon mouse follistatin (FS) gene. To distinguish wild-type and transgenic follistatin mRNA, the 3'-untranslated region of the mouse follistatin gene was replaced with the SV40 untranslated and polyA sequences. Three male and two female founder transgenic mice were produced, were fertile, and transmitted the transgene to offspring. Northern blot analysis demonstrated that the transgene mRNA was expressed at varying levels in the livers of offspring from four of five of the transgenic lines and was expressed in the testes in all five lines. In MT-FS line 4, which had the highest expression of the transgene mRNA in the liver, the transgene transcripts were also present in multiple other tissues. Phenotypically, the MT-FS transgenic lines had defects in the testis, ovary, and hair. Mice from MT-FS lines 7 and 10 had slightly decreased testis size, whereas mice from lines 4, 5, and 9 had much smaller testes and shiny, somewhat irregular, fur. Histological analysis of the adult testes from line 5 and 9 males showed variable degrees of Leydig cell hyperplasia, an arrest of spermatogenesis, and seminiferous tubular degeneration leading to infertility. Female transgenic mice from lines 4 and 9 had thin uteri and small ovaries due to a block in folliculogenesis at various stages. Many of the line 9 female mice eventually became infertile, and all of the line 4 female mice were infertile. Suppressed serum FSH levels were seen in only the line 4 transgenic male and female mice, the line with widespread expression of the transgene. Serum FSH levels were not significantly different in gonadectomized wild-type and line 5 transgenic male mice despite high levels of the follistatin transgene mRNA in the liver of these transgenic mice. These results suggest that follistatin exerts its effects at the levels of the gonads and pituitary as a local regulator of activin and possibly other transforming growth factor-beta family members.