Poster abstracts

Poster number 90 submitted by Shaokun Li

Dissecting the role of CLP1 in RNA maturation and alternative polyadenylation through the R140H mutation

Shaokun Li (Department of Neurosciences, Case Western Reserve University), Ashleigh Schaffer (Department of Genetics and Genome Sciences, Case Western Reserve University)

Abstract:
CLP1 is a multifunctional RNA kinase essential for the maturation of both tRNA and mRNA. The CLP1 R140H mutation causes pontocerebellar hypoplasia type 10 (PCH10), a severe neurodegenerative disorder. Patients with PCH10 exhibit mild atrophy of the cerebellum, pons, and corpus callosum, along with progressive microcephaly and severe axonal sensorimotor neuropathies. Previous studies have demonstrated that the R140H mutation in CLP1 impairs its kinase activity and its interactions with the TSEN complex, which is involved in tRNA maturation, as well as the CPA complex, which regulates mRNA alternative polyadenylation (APA). However, only defects in mRNA processing have been observed in motor neurons derived from PCH10 patients. Specifically, mRNAs in these neurons preferentially use distal polyadenylation sites, generating longer isoforms, which is opposite of the pattern observed in CLP1 KO motor neurons. Thus, we hypothesize that the CLP1 R140H mutation confers a gain-of-function effect, resulting in an APA shift toward distal sites to cause the pathogenesis of PCH10. Our data indicates that overexpression of CLP1R140H, but not wild-type CLP1, in motor neuron progenitors recapitulated the phenotypes observed in motor neurons derived from PCH10 patients. To further investigate the underlying mechanism of PCH10, we propose to utilize CLIP-seq and BioID/AP-mass spectrometry to characterize the RNA and protein interactomes of both wild-type CLP1 and the CLP1R140H. Additionally, we will perform transient transcriptome sequencing to identify the primary RNA targets of CLP1 and CLP1R140H. The outcomes of our research will provide profound insight into the mechanism by which the cleavage site is selected from multiple possible elements.

Keywords: alternative polyadenylation, neurodegenerative disorders, motor neurons