NOVEL VASOPRESSIN GENE-RELATED TRANSCRIPTS IN RAT TESTIS
NOVEL VASOPRESSIN GENE-RELATED TRANSCRIPTS IN RAT TESTIS
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DOI：
10.1210/mend-5-5-645
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发表时间：
1991-05-01
影响因子：
--
通讯作者：
ZINGG, HH
中科院分区：
文献类型：
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作者：
LEFEBVRE, DL;ZINGG, HH
尽管精氨酸抗利尿激素（AVP）基因主要在特定的下丘脑神经元中表达，但免疫反应性AVP （irAVP）也在包括睾丸在内的外周组织中被发现。为了确定下丘脑和睾丸的iravp是否来自相同或不同的转录本，我们通过Northern blot分析、聚合酶链反应（PCR）和RNase作图检测了睾丸AVP基因相关转录本。我们发现睾丸含有三种不同的AVP基因相关转录本，分别为0.67、0.83和2.0千碱基（kb），其大小与下丘脑0.81 kb的AVP mRNA不同。正如死基化所证明的那样，这种尺寸的异质性不是由于聚(A)尾部长度的差异。通过使用外显子特异性探针，我们确定0.67 kb和0.83 kb的转录本包含外显子B和C，但不包含a。相反，2 kb的转录本是唯一包含外显子a相关序列的睾丸转录本。通过应用PCR技术，我们证实存在外显子B和C拼接在一起的睾丸转录本，但外显子A被排除在外。我们的研究结果表明，0.67 kb和0.83 kb的mRNA来自于排除外显子a的不同剪接事件，而2 kb的mRNA可能来自于avp相关基因的表达。由于非肽AVP是由外显子A编码的，睾丸irAVP不能由任何含有外显子B和C的转录本的翻译产生，并且迄今为止AVP外显子C探针鉴定的任何mRNA都与AVP免疫反应产物的生物合成无关。因此，我们目前对不同转录本的外显子a和外显子B相关序列分离的证明，为解决为什么携带外显子B突变的Brattleboro突变大鼠能够在外周组织中产生irAVP而不能在大脑中产生irAVP的问题提供了关键。目前对不同睾丸AVP基因相关mrna的鉴定将允许研究这些转录物的调控和可能的生物学功能。
Although the arginine vasopressin (AVP) gene is predominantly expressed in specific hypothalamic neurons, immunoreactive AVP (irAVP) has also been identified in peripheral tissues, including testis. To determine whether hypothalamic and testicular irAVPs derive from the same or different transcripts, we examined testicular AVP gene-related transcripts by Northern blot analysis, polymerase chain reaction (PCR), and RNase mapping. We show that the testis contains three distinct AVP gene-related transcripts of 0.67, 0.83, and 2.0 kilobases (kb) which differ in size from the 0.81-kb hypothalamic AVP mRNA. As demonstrated by deadenylation, this size heterogeneity is not due to differences in the length of the poly(A) tails. By the use of exon-specific probes we determined that the 0.67- and the 0.83-kb transcripts contain exons B and C, but not A. In contrast, the 2-kb transcript is the only testicular transcript that contains an exon A-related sequence. By application of the PCR technique, we confirm the existence of testicular transcripts in which exons B and C are spliced together, but exon A is excluded.Our findings indicate that the 0.67- and 0.83-kb mRNA result from a differential splicing event that excludes exon A and that the 2-kb mRNA probably originates from the expression of an AVP-related gene. Since the nonapeptide AVP is encoded by exon A, testicular irAVP cannot arise from the translation of any of the exon B- and C-containing transcripts, and any mRNA that has so far been identified by AVP exon C probes is unrelated to the biosynthesis of AVP-immunoreactive products. As a corollary, our present demonstration of a segregation of exon A- and exon B-related sequences to different transcripts provides the key for solving the problem of why the Brattleboro mutant rat, which carries a mutation in exon B, is able to produce irAVP in peripheral tissues but not in brain. The present identification of distinct testicular AVP gene-related mRNAs will now allow studies of the regulation and possible biological function of these transcripts.