ALTERNATIVE 5' SPLICE-SITE SELECTION INDUCED BY HEAT-SHOCK

The mouse HSP47 gene consists of six exons separated by five introns. Three HSP47 cDNAs differing only in their 5' noncoding regions have be en reported. One of these alternatively spliced mRNAs was detected onl y after heat shock, which caused an alternative 5' splice donor site s election. Other stress inducers, including an amino acid analog and so dium arsenite, had no effect on the alternative splicing. The alternat ively spliced mRNA, which was 169 nucleotides longer in the 5' noncodi ng region compared to mRNA transcribed in non-heat shock conditions, w as efficiently translated under heat shock conditions. This novel find ing that alternative splicing is caused by artificial treatment like h eat shock will provide a useful in vivo model for understanding the ex on-intron recognition mechanism as well as heat shock-induced alterati ons in gene expression.