Mutation in the prp12 + gene encoding a homolog of SAP130/SF3b130 causes differential inhibition of pre-mRNA splicing and arrest of cell-cycle progression in Schizosaccharomyces pombe

Abstract

ABSTRACTprp12-1 is one of the mutants defective in pre-mRNA splicing at a nonpermissive temperature in Schizosaccharomyces pombe. We found that the prp12 + gene encodes a protein highly homologous with a human splicing factor, SAP130/SF3b130, a subunit of a U2 snRNP-associated complex SF3b. Prp12p was shown to interact genetically with Prp10p that is a homolog of SAP155/SF3b155, another subunit in SF3b, suggesting that Prp12p is a functional homolog of human SAP130/SF3b130. Prp12p tagged with GFP is uniformly localized in the nuclear DNA region. In addition to pre-mRNA splicing defects, the prp12-1 mutant produced elongated cells, a typical phenotype of cell division cycle (cdc) mutants, suggesting a possible link between pre-mRNA splicing and cell-cycle progression. We examined kinetics of splicing defects in prp12-1 and several other prp mutants using northern blot hybridization and found that, among all the tested pre-mRNAs, only TfIId + pre-mRNA with low splicing efficiency showed detectable splicing defects at the nonpermissive temperature in prp12-1. In addition, we found that other prp mutants with the cdc phenotype also showed differential splicing defects in tested pre-mRNAs at the nonpermissive temperature. On the other hand, prp mutants that do not exhibit the cdc phenotype showed a rapid and complete block of pre-mRNA splicing in all the tested pre-mRNAs at the nonpermissive temperature, indicating that prp mutants with weak splicing defects have a tendency to exhibit the cdc phenotype. These results suggest that the cdc phenotype in prp12-1 is caused by a selective reduction of spliced transcripts encoding a protein (or proteins) required for G2/M transition.

A novel RING-finger-like protein Ini1 is essential for cell cycle progression in fission yeast

“…These include the mutants cdc5, cdc28 and prp12, all of which appear to arrest in G2 upon shift to the restrictive temperature (Burns et al, 1999;Habara et al, 2001;Ohi et al, 1994). It has also been reported that cdc5 mutants, in the absence of Wee1, undergo mitotic catastrophe similar to what we observe following depletion of Ini1 (Ohi et al, 1994).…”

“…At least three of these genes, cdc5, cdc28 and prp12 + are required for cell viability and cell cycle progression (Habara et al, 2001;Lundgren et al, 1996;Ohi et al, 1994). Furthermore, a Saccharomyces cerevisiae homologue of ini1 + is present in purified preparations of the yeast U2/U5/U6 snRNP complex, which is required for pre-mRNA splicing (K. Gould, personal communication).…”

“…Cell cycle arrest required the activity of the Wee1 protein kinase, a negative regulator of mitosis, but not Rad3, a kinase required for the G2-M checkpoint control. Therefore, the DNA damage checkpoint is not involved in the cell cycle delay.Some of the characteristics of the ini1 + gene and the phenotype of the ∆ini1 mutant were reminiscent of a collection of cdc/prp genes that have been shown to be required for normal pre-mRNA splicing in yeast (Burns et al, 1999;Habara et al, 2001;Lundgren et al, 1996;Ohi et al, 2002;Potashkin et al, 1998;Potashkin et al, 1989;Urushiyama et al, 1996). At least three of these genes, cdc5, cdc28 and prp12 + are required for cell viability and cell cycle progression (Habara et al, 2001;Lundgren et al, 1996;Ohi et al, 1994).…”

The Prp4 Kinase: Its Substrates, Function and Regulation in Pre-mRNA Splicing

“…There are introns which are spliced independently of the large subunit of the U2 auxiliary factor (U2AF 59 ). Noteworthy here, U2AF 59 is essential for growth [56][57][58]. Moreover, there is some evidence that the recruitment of U2AF 59 to auxiliary factor dependent introns might be mediated by the SR protein Srp2, which has been shown above to be an in vitro substrate of Prp4 kinase [26].…”

Suppressors of the cdc-25.1(gf)-associated intestinal hyperplasia reveal important maternal roles for prp-8 and a subset of splicing factors in C. elegans

“…Links between splicing events and cell cycle regulation that involve Prp8 and other splicing components have been reported in budding and fission yeast, while in Drosophila, orthologs of the splicing factors that suppress cdc-25.1(rr31) affect cell growth, supporting the idea that the links between splicing and cell cycle control may have been conserved from yeast to higher eukaryotes (Shea et al 1994;Lundgren et al 1996;Potashkin et al 1998;Ben-Yehuda et al 2000a,b;Russell et al 2000;Habara et al 2001;Coelho et al 2005).…”