Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An isogene of the E1 alpha subunit of the mouse pyruvate dehydrogenase complex was shown in a previous study to map to chromosome 19. Here we demonstrate using Northern blot analysis that this gene is expressed in a testis-specific fashion. Two testis-specific E1 alpha transcripts were detected: (1) a 2.0-kb transcript that is abundant in pachytene cells but also detectable during earlier stages of spermatogenesis, and (2) a shorter 1.7-kb transcript detectable only in round spermatids. Analysis of both transcripts following RNase H digestion revealed that the smaller message is not derived from the shortening of the poly(A) tail and most likely results from the alternate use of two polyadenylation signals. Finally, analysis of polysomes isolated from 20- and 80-day-old mouse testes demonstrated that the 2.0-kb transcript is associated with the polysomal fraction, suggesting that this message is transcribed and actively translated at the same time. We conclude from these results that expression of the testis-specific E1 alpha is initially expressed during the meiotic prophase stage of spermatogenesis and not under any apparent post-transcriptional regulation.
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PMID:Transcriptional expression of a testis-specific variant of the mouse pyruvate dehydrogenase E1 alpha subunit. 163 47

The micropia transposable element of Drosophila hydei is a long terminal repeat-containing retrotransposon present in both the autosomes and the Y chromosome. micropia expression gives rise to a complex set of sense and antisense RNAs transcribed primarily during spermatogenesis. The most abundant sense RNAs constitute an assortment of heterogeneous high-molecular-weight transcripts expressed as constituents of the Y-chromosomal lampbrush loops of primary spermatocytes. In addition, micropia encodes a full-length RNA that extends between the two long terminal repeats of the element. The major 1.0-kb antisense RNA characterized is complementary to the reverse transcriptase and RNase H coding regions of micropia. It is expressed from a testis-specific promoter during the primary spermatocyte stages and is detectable until spermatid elongation stages. Sequence comparison of this promoter with the 5' region of other testis-specific genes allows the conception of a conserved sequence that is responsible for this pattern of expression. A 284-bp fragment containing this sequence is able to drive testis-specific expression of the Escherichia coli lacZ gene in Drosophila melanogaster. This sequence is conserved in the micropia elements present in other Drosophila species that also encode an antisense RNA. The evolutionary conservation of micropia antisense RNA expression and the sequences responsible for its testis-specific transcription suggests a role for this antisense RNA in the control of germ line expression of the full-length transcript or transposon-encoded proteins.
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PMID:The Drosophila micropia retrotransposon encodes a testis-specific antisense RNA complementary to reverse transcriptase. 750 47

The experiments presented in this study show that the testis-specific expression of the murine Hoxa-4 (formerly Hox-1.4) gene is likely to be achieved through a variety of regulatory mechanisms operating on several levels. S1 mapping analysis suggested the possibility of multiple testicular transcripts arising from alternative splicing events. Analysis of cDNA and genomic sequences revealed the presence of two polyadenylation signals: the canonical AATAAA and further 3', an ATTAAA. Primer extension analysis to determine the start site of the testicular transcripts and nuclear run-on analysis suggested the use of a more upstream promoter than the one previously identified. The nuclear run-on analysis further suggested that Hoxa-4 is under posttranscriptional control. RNase H analysis showed that the size difference between the two testicular Hoxa-4 transcripts of 1.35 and 1.45 kb was due to a postmeiotic increase in poly(A) tail length. Only a proportion of the Hoxa-4 mRNA in germ cells was found to be associated with polysomes, suggesting that translational regulation may also operate as a means of control of Hoxa-4 expression in this adult lineage.
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PMID:Multiple levels of regulation exist for expression of the Hoxa-4 (Hox-1.4) gene in the mouse testis. 790 2

The differential regulation of somatic and testis-specific cytochromes c during spermatogenesis in the mouse is accompanied by changes in mRNA length (Hake, L. E., Alcivar, A. A., and Hecht, N. B. (1990) Development 110, 249-257). In spermatogenic stem cells through early meiotic cells, we detect four somatic cytochrome c (cyt cs) mRNAs of 1.3, 1.1, and 0.7-0.5 kilobases (kb), whereas in postmeiotic cells we detect a larger cyt cs mRNA of 1.7 kb. Oligonucleotide-directed RNase H cleavage of cyt cs mRNA revealed that the 1.7-kb mRNA contains over 1 kb of 5'-untranslated region which is not present in the four shorter cyt cs mRNAs. RNase protection assays indicate that this additional sequence arises from the utilization of an alternative transcription initiation site of the functional cyt cs gene which is 1085 base pairs upstream of the initiation site for the four shorter cyt cs mRNAs. To analyze the promoter for the 1.7-kb mRNA, a genomic clone containing the cyt cs gene and 5 kb of 5'-flanking DNA was isolated. Sequence comparison of the putative promoter region with promoters of other postmeiotically expressed genes reveals several conserved regions. Utilization of this alternative initiation site may be involved in the down-regulation of cytochrome cs during spermatogenesis.
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PMID:Utilization of an alternative transcription initiation site of somatic cytochrome c in the mouse produces a testis-specific cytochrome c mRNA. 838 25

Hormone-sensitive lipase (HSL) catalyses the rate-limiting step of adipose tissue lipolysis. The human HSL gene is composed of nine exons encoding the adipocyte form and a testis-specific coding exon. Northern blot analyses showed that human adipocytes express a 2.8 kb HSL mRNA, suggesting the presence of a short (20-150 bp) 5' untranslated region (5'-UTR). A single 5'-UTR of approx. 70 nt was detected in RNase H mapping experiments. Two 5'-UTRs of 70 and 170 nt respectively were obtained by rapid amplification of cDNA ends and cDNA library screenings. RNase protection experiments, with probes derived from the two products, showed that human adipocyte HSL mRNA contains only the 70 nt product. Primer extension analysis mapped the transcriptional start site 74 nt upstream of the start codon. In HT29, a human cell line expressing HSL, the presence of the short or the long 5'-UTR is mutually exclusive. The short and long 5'-UTR exons were located 1.5 and approx. 13 kb respectively upstream of the first coding exon. Various portions of the 5'-flanking region upstream of the short product exon were linked to the luciferase gene and transfected into cells that express HSL (HT29 cells and rat adipocytes) and do not express HSL (HeLa cells). High luciferase activity was found for constructs containing the sequence between nt -2400 and -86, but not for shorter constructs. An analysis of 14 kb of genomic sequence revealed the presence of five DNase I hypersensitive sites associated with active gene transcription. Three of the sites are located in the vicinity of the transcriptional start site and could be linked to the minimal promoter activity. Two of the sites are located downstream of the exon containing the start codon, suggesting the presence of intronic regulatory elements.
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PMID:Characterization of the promoter of human adipocyte hormone-sensitive lipase. 937 1