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

Abstract

The maternal contribution of gene products enables embryos to initiate their developmental program in the absence of zygotic gene expression. In Caenorhabditis elegans, maternal CDC-25.1 levels are tightly regulated to promote early cell divisions, while stabilization of this phosphatase by gain-of-function mutations gives rise to intestinal-specific hyperplasia. To identify regulators of CDC-25.1 levels and/or function, we performed a modifier screen of the cdc-25.1(gf)-dependent hyperplasia. One of the isolated suppressor mutants possesses a donor splice site mutation in prp-8, a key splicing factor of the U5-specific snRNP. prp-8(rr40) produces aberrant prp-8 splice variants that generate C-terminal truncations at the expense of wild-type prp-8. Levels of maternal transcripts are reduced, including cdc-25.1, while zygotic transcripts appear unperturbed, suggesting a germline-specific role for this splicing factor in regulating the splicing, and consequently, the steady-state levels of maternal transcripts. Using a novel feeding RNAi strategy we found that only a subset of splicing factors suppress cdc-25.1(gf), suggesting that they too may play specific roles in germ-line spliceosome function. In humans, mutations in the corresponding hPrp8 Cterminal domain result in retinitis pigmentosa, a retinal-specific disorder. Intriguingly, despite affecting the general splicing apparatus, both human and C. elegans show tissue-specific defects resulting from mutations in this key splicing component. Our findings suggest that in addition to its important regulatory function in the C. elegans germ line, prp-8(rr40) may provide further insight into the etiology of this splicing-associated human disorder.

Regulation of miRNA abundance by RNA binding protein TOUGH in Arabidopsis

“…in genome-wide RNAi screens (31)(32)(33), consistent with the role of miRNA in regulating developmental processes of plants and animals.…”

A mutation in teg-4, which encodes a protein homologous to the SAP130 pre-mRNA splicing factor, disrupts the balance between proliferation and differentiation in the C. elegans germ line

“…In C. elegans, another cell cycle regulator, CDC-25.1, is necessary for proliferation and maintenance of the germ line (Ashcroft and Golden, 2002). Reduction in the functions of a subset of splicing factors, including teg-4, is able to suppress intestinal hyperplasia caused by a cdc-25.1 gain-of-function allele, presumably by decreasing proper splicing of cdc-25 (Hebeisen et al, 2008). We have shown that a decrease in TEG-4 activity, in an otherwise wild-type background, results in decreased germline proliferation.…”

Modeling of autosomal-dominant retinitis pigmentosa in Caenorhabditis elegans uncovers a nexus between global impaired functioning of certain splicing factors and cell type-specific apoptosis

“…As an example of such co-transcriptional splicing in a developing multicellular animal, our laboratory demonstrated that RSR-2 interacts with PRP-8 and the RNA polymerase II (RNAPII) in C. elegans, and that the impairment of RSR-2 functions results in a lower transcriptional efficiency (Fontrodona et al 2013). Consistent with this second hypothesis, the mutant allele prp-8(rr40), which reduces the levels of wild-type PRP-8, diminishes the production of highly expressed germline transcripts, but it does not affect the splicing reaction (Hebeisen et al 2008).…”