Tissue-specific alternative splicing of the CSE1L/CAS (cellular apoptosis susceptibility) gene.

CSE1L/CAS (CAS) is a nuclear transport factor that plays a role in proliferation and apoptosis. The CAS gene consists of 25 exons. mRNA homologous over its entire length to the yeast homologue CSE1 is the predominant transcript in proliferating tissues. Additional mRNAs are generated by alternative splicing in a tissue-specific manner. An extended 3'-end is found in fetal and adult brain. A mRNA containing the 5'-end of CAS up to position 690 and an alternative 3'-end is expressed in trachea and encodes a truncated Ran-binding domain. Fetal liver expresses a mRNA with deletions of a central portion of CAS and additional sequences encoded by the last intron. SW480 colon cancer cells express another approximately 1500-base mRNA. Western blot analyses of various human tissues and immunohistology of mouse embryos show a correlation of CAS transcripts and CAS protein in different tissues. CAS isoforms may control nuclear transport of tissue-specific proteins.