HIGH-LEVELS OF METALLOTHIONEIN MESSENGER-RNAS IN MALE GERM-CELLS OF THE ADULT-MOUSE
HIGH-LEVELS OF METALLOTHIONEIN MESSENGER-RNAS IN MALE GERM-CELLS OF THE ADULT-MOUSE
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DOI：
10.1210/mend-5-5-628
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发表时间：
1991-05-01
影响因子：
--
通讯作者：
ANDREWS, GK
中科院分区：
文献类型：
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作者：
DE, SK;ENDERS, GC;ANDREWS, GK
采用Northern杂交、原位杂交和寡脱氧核苷酸过量溶液杂交法对小鼠睾丸中金属硫蛋白-I(MT-I)和金属硫蛋白-II(MT-II)的mRNAs进行定量。来自性成熟成人的睾丸含有高水平的MT mRNAs(大约是对照成人肝脏的10倍)。睾丸MT基因表达水平与年龄相关，出生后2周较低，之后缓慢升高，成年后(出生后9周)达到最高水平。在成人睾丸中，原位杂交显示只有在曲细精管的腺体间室内的细胞(生殖细胞)含有高水平的MT mRNA。在发育过程中含有高水平MT mRNA的细胞的出现从精子发生开始就被推迟了。原位杂交结果表明，MT基因在初级精母细胞分化后积累，并维持在精子细胞中。从成人睾丸分离的粗线精母细胞(PSC)和圆形精子细胞(RTD)含有MT-I和MT-II的mRNAs，其水平与锌处理的肝细胞相当，而分离的Sertoli细胞(ST)的MT mRNA量很低。原位杂交显示，在所有发育阶段的间质、精原细胞和成熟精子细胞中，MT mRNA仅存在于基础水平。Northern杂交和原位杂交结果表明，1周龄小鼠睾丸中SGP-2的表达水平较高，成年后逐渐降低。该基因的原位检测与ST在睾丸中的定位一致。SGP-2mRNA在ST中表达丰富，在PSC和RTD中表达稀少。对分离的PSC和RTD的脉冲标记蛋白分析表明，这些细胞活跃地合成MT-I和MT-II。全身注射镉、锌或细菌脂多糖后，成年大鼠睾丸中MT基因的高水平并未显著增加。与之形成鲜明对比的是，这些治疗导致肝脏和卵巢MT基因水平显著升高。这项研究证实，MT基因在小鼠的雄性生殖细胞中以发育调节的方式活跃地表达。这表明MT在精子发生过程中起着重要作用。
Northern blotting, in situ hybridization, and oligodeoxyribonucleotide excess solution hybridization were used to quantitate metallothionein-I (MT-I) and MT-II mRNAs in mouse testes. Testes from sexually mature adults contained high levels of both MT mRNAs (approximately 10-fold higher than those in control adult liver). Testicular MT mRNA levels were age dependent, being low the first 2 weeks after birth and increasing slowly thereafter to maximal levels in the adult (by 9 weeks after birth). In the adult testis, in situ hybridization indicated that only cells within the adluminal compartment (germ cells) of the seminiferous tubules contain high levels of MT mRNA. The appearance of cells containing elevated levels of MT mRNA during development was delayed from the onset of spermatogenesis. In situ hybridization suggested that MT mRNA accumulates after the initial differentiation of primary spermatocytes and is maintained in spermatids. Pachytene spermatocytes (PSC) and round spermatids (RTD) isolated from adult testes contained both MT-I and MT-II mRNAs in levels equivalent to those found in zinc-treated hepatocytes, whereas very low levels of MT mRNA were detected in isolated Sertoli cells (ST). In situ hybridization suggested that MT mRNA was present at only basal levels in interstitial, spermatogonial, and mature sperm cells at all developmental stages examined. Northern blot and in situ hybridization to sulfated glycoprotein-2 (SGP-2) mRNA, a ST-specific transcript, showed that SGP-2 mRNA is high in the testis of 1-week-old mice and decreases gradually to a lower level in the adult. In situ detection of this mRNA was consistent with the location of ST in the testis. SGP-2 mRNA was abundant in ST and rare in PSC and RTD preparations. Analysis of pulse-labeled proteins from isolated PSC and RTD indicated that these cells actively synthesize MT-I and MT-II. The high levels of MT mRNA in adult testes were not increased substantially after systemic injection of cadmium, zinc, or bacterial lipopolysaccharide. In marked contrast, these treatments led to dramatically increased levels of hepatic and ovarian MT mRNA. This study establishes that the MT genes are actively expressed in a developmentally regulated fashion in the male germ cells of the mouse. This suggests a role for MT in the process of spermatogenesis.