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bioRxiv · 10.1101/2024.08.18.608437

DNA polymerase kappa stabilized by PTBP2 interacts with MRE11 and promotes genomic instability in leukemia cells

Lama, S.·Barik, B.·I.S., S.·Sarkar, T.·Chanda, S.·Behera, M.·Behera, S. P.·Biswas, S.·Mohapatra, S.·Biswas, G.·Chakraborty, S.
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Abstract

Polypyrimidine tract binding protein 2 (PTBP2) is an RNA-binding protein that controls alternative splicing in neuronal, muscle, and Sertoli cells. Our study unveils a novel role of PTBP2 in promoting the excessive production of the DNA polymerase kappa (Pol{kappa}) by stabilizing its 3UTR. We observed an association between its increased expression and the upregulation of PTBP2 in clinical samples of Chronic Myeloid Leukemia (CML). Ptbp2 knock-out CML cell lines and patient samples treated with hydroxyurea presented with increased DNA damage, as evidenced by long comet tails and higher levels of the DNA damage marker, {gamma}H2AX foci, however overexpression of Pol{kappa} in the Ptbp2-KO cells restored normal phenotype. The deregulation of the DNA repair pathway is a defining feature of malignancies and is closely associated with genomic instability. POLK was found to interact with MRE11 of the MRN complex, thereby governing the activation of ATM-CHK2. Cells with elevated levels of Ptbp2 and Pol{kappa} demonstrated increased sister chromatid exchange and BrdU incorporation in ex-vivo assays, while multinucleated cells with multipolar spindles were observed in in-vivo assays. Our findings confirm the critical role of the PTBP2-POLK axis in driving genomic instability and bolstering the viability of cells with increased malignancy.

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Lama, S., Barik, B., I.S., S., Sarkar, T., Chanda, S., Behera, M., Behera, S. P., Biswas, S., Mohapatra, S., Biswas, G., Chakraborty, S.. 2024-08-19. DNA polymerase kappa stabilized by PTBP2 interacts with MRE11 and promotes genomic instability in leukemia cells. https://doi.org/10.1101/2024.08.18.608437

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