Human beta 1-integrin gene expression is regulated by two promoter regions.
We report the cloning of two full-length cDNAs coding for the human beta 1-integrin which diverge from each other for their 5'-untranslated sequences. Characterization of a genomic clone containing these two sequences showed that they are contiguous, spaced by 261 nucleotides, and both followed by donor splice sites. Analysis by primer extension and transient transfection in a human osteogenic sarcoma cell line (MG-63) demonstrated the existence of two independent promoters for transcription initiation. The two promoter regions are very G+C-rich, and lack both a TATA box and a CAAT box. Northern blot analysis showed that transcripts starting from the distal promoter (with respect to the first coding exon) are at least 20-fold more abundant than transcripts originating from the proximal one. The levels of both transcripts increase after transforming growth factor-beta 1 induction, however, mRNAs originating from the proximal promoter increase at an higher extent. Reverse transcriptase/polymerase chain reaction analysis performed on different human tissues and cell lines revealed that, while the distal promoter is ubiquitously active, the proximal promoter is not. These findings suggest a possible complex pattern for regulation of the human beta 1-integrin gene expression.
Cervella
P
P
Dipartimento di Genetica, Biologia e Chimica Medica, Università di Torino, Italy.
Silengo
L
L
Pastore
C
C
Altruda
F
F
D001483:Base Sequence; D015152:Blotting, Northern; D004247:DNA; D005786:Gene Expression Regulation; D006801:Humans; D016023:Integrins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D016023:Integrins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D004247:DNA