The Diverse Roles of Spliceosomal Proteins in the Regulation of Cell Processes

The spliceosome is necessary for the removal of intron sequences in transcribed pre-mRNA in eukaryotic cells. More than 200 proteins are involved in the process of pre-mRNA splicing; they coordinate the alternative splicing of most eukaryotic genes, which participate in the regulation of a variety of important cellular processes. However, a growing number of studies demonstrate the functions of spliceosomal proteins that are not directly related to the splicing process, such as (1) R-loop formation, (2) DNA repair, (3) telomere elongation, (4) M phase regulation, and (5) mRNA export from the nucleus. In this review, we summarize the data on the noncanonical functions of the spliceosomal proteins. Taking into account the fact that mutations in spliceosomal genes are commonly found in tumor cells, a careful study of noncanonical functions of spliceosomal proteins may provide new insights into the development of effective methods of cancer treatment and design of drugs for delaying cell aging.