Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The structure of the mouse neurotrophin-3 (NT-3) gene has been analysed using genomic cloning and the rapid amplification of cDNA ends (RACE) method. The gene consists of two small upstream exons (exons IA and IB) and a larger downstream exon (exon II) that encodes the mature protein. Two classes of NT-3 transcripts, termed transcripts A and B, are generated by alternative splicing of exon IA or exon IB to the common exon II. The NT-3 gene also contains several transcription start sites in both upstream exons, and three different polyadenylation sites in exon II, as shown by RNase protection assays and by RACE, giving rise to multiple NT-3 mRNA variants of slightly different lengths. Cerebellar granule neurons express both classes of NT-3 transcripts, but only transcript B is regulated by tri-iodothyronine (T3) in these neurons. The effect of T3 on NT-3 mRNA is primarily due to transcription enhancement, as shown in nuclear run-on experiments. The levels of NT-3 mRNA are much lower in cultured mouse astrocytes and are undetectable in the human neuroblastoma cell line IMR 32. A TATA box is present in the upstream region of exon IB but not in that of exon IA. Promoter analysis using the chloramphenicol acetyltransferase reporter gene fused to different NT-3 upstream regions showed the presence of two active NT-3 promoters in cerebellar granule neurons. However, in IMR 32 cells, NT-3 promoter activity decreased dramatically with increasing length of the 5' flanking region. This suggests that expression of the NT-3 gene is regulated both by positive influences, such as T3, and by negative silencing elements present in the upstream regions of the NT-3 promoter.
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PMID:Two promoters direct transcription of the mouse NT-3 gene. 795 96

The 5'-flanking region of the human neurotrophin-3 (NT-3) gene was isolated from a human placental genomic library using the oligonucleotide corresponding to the 5'-noncoding region of the NT-3 cDNA as a probe. A 3.8 kbp genomic fragment containing the 5'-flanking region, the first exon and a portion of the first intron was isolated and sequenced. The transcriptional initiation site, identified by S1 nuclease mapping, was located 27 bp downstream from the TATA-like sequence. Several plasmids, in which the NT-3 promoter regions were fused to the chloramphenicol acetyltransferase (CAT) gene, were constructed. Transient expression in human glioma Hs683 cells demonstrated that a fragment of about 0.1 kbp from the transcriptional initiation site was sufficient for promoter activity. While, in human plasma cell leukemia ARH77 cells, in which NT-3 mRNA was not detected, the region upstream from -65 functioned to silence CAT activity. It is suggested that this region contains the transcriptional regulatory element for the specific expression of the NT-3 gene.
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PMID:Identification of the functional regulatory region of the neurotrophin-3 gene promoter. 838 96

To examine the tissue and cell type specificity of the human neurotrophin-3 (NT-3) promoter, we generated transgenic mice bearing the 3.3 kbp upstream region of the human NT-3 gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene as a reporter. Eight independent founders of transgenic mice were obtained, and four of them transmitted the transgene to their offsprings. Among three lines of four transgenic mice at 6 weeks of age, a high level of production of CAT protein was detected in the spleen and a low level in the brain. By in situ hybridization analysis, CAT gene expression was detected in the hippocampal neurons and in the cerebellar granular neurons of the transgenic mouse brain. These results suggest that the 3.3 kbp 5' flanking region of the human NT-3 gene has adequate promoter activity in vivo and that its expression pattern resembles the endogenous gene.
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PMID:Tissue and cell type specificity of the human neurotrophin-3 promoter region in transgenic mice. 972 20