Chen C C, Johnson P A
Department of Animal Science, Cornell University, Ithaca, New York 14853, USA.
Biol Reprod. 1996 Feb;54(2):429-35. doi: 10.1095/biolreprod54.2.429.
A chicken inhibin/activin beta A-subunit cDNA clone has been isolated and used to detect the beta A-subunit mRNA in the hen. A cDNA library of the hen granulosa layer was screened with a rat inhibin beta A-subunit cDNA probe, and a cDNA of 1540 bp was cloned and sequenced. The clone contains the entire open reading frame of 1272 nucleotides encoding 424 amino acids. It shows 78% nucleotide identity (85% in deduced amino acids) in the full-length coding region and 85% nucleotide identity (98% in deduced amino acids) in the 116-amino acid C-terminal mature region to the rat beta A-subunit cDNA clone. The predicted positions of one N-linked glycosylation site and all cysteine residues are fully conserved as well. Northern blot analysis showed that the major 8.4-kb inhibin/activin beta A-mRNA band was primarily expressed in the granulosa layer of the preovulatory follicles. It was also detected in much less abundance in the theca layer, thyroid gland, heart, muscle, intestine, adrenal gland, liver, lung, spinal cord, and spleen. When a chicken inhibin alpha-subunit cDNA probe was used, the 1.7-kb major band of the inhibin alpha-subunit mRNA was detected most strongly in the granulosa layer and less abundantly in the postovulatory follicle, theca layer, testis, heart, and adrenal gland. Moreover, a distinct 1.3-kb alpha-mRNA was detected in the muscle and lung. The present cloning study extends our understanding of the inhibin/activin beta A-subunit cDNA from studied species to the chicken and shows that the beta A-subunit is highly conserved during evolution. Our data indicate that the mRNAs for inhibin/activin alpha- and beta A-subunits are widely present in a variety of chicken tissues but that the granulosa layer of large preovulatory follicles is the primary site of expression. The present study also suggests that both inhibin and activin may serve as local factors to regulate cell function in chicken tissues.
已分离出鸡抑制素/激活素βA亚基的cDNA克隆，并用于检测母鸡体内的βA亚基mRNA。用大鼠抑制素βA亚基cDNA探针筛选母鸡颗粒层的cDNA文库，克隆并测序了一个1540 bp的cDNA。该克隆包含1272个核苷酸的完整开放阅读框，编码424个氨基酸。在全长编码区，它与大鼠βA亚基cDNA克隆的核苷酸同一性为78%（推导氨基酸的同一性为85%），在116个氨基酸的C末端成熟区，核苷酸同一性为85%（推导氨基酸的同一性为98%）。一个N-连接糖基化位点和所有半胱氨酸残基的预测位置也完全保守。Northern印迹分析表明，主要的8.4 kb抑制素/激活素βA-mRNA条带主要在排卵前卵泡的颗粒层中表达。在卵泡膜层、甲状腺、心脏、肌肉、肠道、肾上腺、肝脏、肺、脊髓和脾脏中也检测到少量表达。当使用鸡抑制素α亚基cDNA探针时，抑制素α亚基mRNA的1.7 kb主要条带在颗粒层中检测到的信号最强，在排卵后卵泡、卵泡膜层、睾丸、心脏和肾上腺中的表达较少。此外，在肌肉和肺中检测到一条明显的1.3 kbα-mRNA。目前的克隆研究将我们对抑制素/激活素βA亚基cDNA的理解从已研究的物种扩展到了鸡，并表明βA亚基在进化过程中高度保守。我们的数据表明，抑制素/激活素α和βA亚基的mRNA广泛存在于各种鸡组织中，但大型排卵前卵泡的颗粒层是主要的表达部位。本研究还表明，抑制素和激活素都可能作为局部因子来调节鸡组织中的细胞功能。
