GSE203520
Matrin3 regulates mitotic spindle dynamics by controlling alternative splicing of CDC14B [PAR-CLIP]
Purpose: Matrin3 (MATR3) is a DNA and RNA-binding protein and one of the major components of the nuclear matrix. Matrin3 is upregulated in colorectal cancer (CRC) compared to normal tissues, indicating potential oncogenic function in CRC. We found that depletion of Matrin3 results in decreased proliferation and colony formation in two CRC cell lines. To understand the molecular mechanism(s) by which Matrin3 mediates these effects, we aimed to find Matrin3 direct RNA targets and the effects of Matrin3 on them. Methods: We performed PAR-CLIP for endogenous Matrin3 and RNA-seq after Matrin3 silencing in HCT116 cells, a colorectal cancer cell line. Results: We uncovered Matrin3-mediated regulation of spindle dynamics in colorectal cancer (CRC) cells. We identified bound and regulated Matrin3 target RNAs transcriptome-wide in CRC cells, and found that Matrin3 broadly regulates alternative splicing. Among the top Matrin3 targets, we focused on CDC14B and found that Matrin3 loss resulted in misprocessing of the CDC14B transcript that has a premature termination codon and simultaneous down-regulation of the standard CDC14B transcript in our model. Selective knockdown of the CDC14B standard variant phenocopied the loss of Matrin3 and resulted in reduced CRC cell proliferation, stabilized microtubules, and defects in mitotic spindle formation with tumbled mitotic spindles, suggesting that CDC14B is a key downstream effector of Matrin3. Conclusions: Our data show that by regulating the abundance of CDC14B standard variant, Matrin3 contributes to maintenance of microtubules dynamics, spindle morphology and proper mitotic spindle orientation and suggest that defects in this pathway may contribute to the reduced proliferation of cells after depletion of Matrin3. Overall design: RNA binding profile of Matrin3