Biology subjects

Arfelli, V. C.

Publications and source records attributed to Arfelli, V. C..

3 recordsLinked to original sources

bioRxiv2025

Loss of PIMREG impairs double-strand break signaling and repair

Glioblastoma (GBM) is the most common primary brain tumor in adults. It is an aggressive type of tumor with an average overall survival of 12-15 months post-diagnosis. Standard treatment involves surgical resection, followed by radiotherapy and chemotherapy with temozolomide (TMZ). However, resistance to treatment is frequently observed. PIMREG is a marker of proliferation highly expressed across different tumor types, with particularly elevated levels in GBM. Our previous study revealed that PIMREG silencing sensitizes GBM cells to TMZ treatment and affects ATM activation, a key apical kinase involved in DNA damage signaling. Given the emerging significance of PIMREG in the DNA damage response, we sought to explore PIMREGs role in DNA damage repair and signaling in GBM cells exposed to genotoxic agents. Here we assessed the functionally enriched pathways associated with high PIMREG expression in GBM patient samples, analyzed the interactome of PIMREG upon treatment of GBM cells with TMZ and evaluated the impact of PIMREG loss on DNA damage signaling, DNA break formation and the repair of double-strand breaks. Our findings reveal that PIMREG functions as a direct substrate for ATM/ATR kinases, interacts with key DNA repair proteins upon TMZ treatment and actively facilitates the cellular response to chemotherapy- and radiotherapy-induced DNA damage. Taken together, PIMREG may function in the DNA damage response, particularly in the signaling and repair of double strand breaks via homologous recombination in GBM cells. In all, our data suggested high PIMREG expression may affect resistance of GBM cells to treatment.

cancer biology↗

bioRxiv2022

UHMK1 is a novel splicing regulatory kinase

The U2AF Homology Motif Kinase 1 (UHMK1) is the only kinase that contains the U2AF homology motif (UHM), a common protein interaction domain among splicing factors. Through this motif, UHMK1 interacts with the splicing factors SF1 and SF3B1, known to participate in the 3 splice site recognition during the early steps of spliceosome assembly. Although UHMK1 phosphorylates these splicing factors in vitro, the involvement of UHMK1 in RNA processing has not previously been demonstrated. Here, we identify novel putative substrates of this kinase and evaluate UHMK1 contribution to overall gene expression and splicing, by integrating global phosphoproteomics, RNA-seq, and bioinformatics approaches. Upon UHMK1 modulation, 163 unique phosphosites were differentially phosphorylated in 117 proteins, of which 106 are novel potential substrates of this kinase. Gene Ontology (GO) analysis showed enrichment of terms previously associated with UHMK1 function, such as mRNA splicing, cell cycle, cell division and microtubule organization. The majority of the annotated RNA-related proteins are components of the spliceosome, but are also involved in several steps of gene expression. Comprehensive analysis of splicing showed that UHMK1 affected over 200 alternative splicing events. Moreover, splicing reporter assay further supported UHMK1 function on splicing. Overall, RNA-seq data demonstrated that UHMK1 knockdown had a minor impact on gene expression and pointed to UHMK1 function in epithelial-mesenchymal transition. Finally, the functional assays demonstrated that UHMK1 modulation affects proliferation, colony formation, and migration of the cells. Taken together, our data implicate UHMK1 as a splicing regulatory kinase, connecting protein regulation through phosphorylation and gene expression in key cellular processes.

molecular biology↗

bioRxiv2017

The U2AF homology motif kinase 1 (UHMK1) is upregulated upon hematopoietic cell differentiation

UHMK1 (KIS) is a nuclear serine/threonine kinase that possesses a U2AF homology motif and phosphorylates and regulates the activity of the splicing factors SF1 and SF3b155. Mutations in these components of the spliceosome machinery have been recently implicated in leukemogenesis. The fact that UHMK1 regulates these factors suggests that UHMK1 might be involved in RNA processing and perhaps leukemogenesis. Here we analyzed UHMK1 expression in normal hematopoietic and leukemic cells as well as its function in leukemia cell line.\n\nIn the normal hematopoietic compartment, markedly higher levels of transcripts were observed in differentiated lymphocytes (CD4+, CD8+ and CD19+) compared to the progenitor enriched subpopulation (CD34+) or leukemia cell lines. UHMK1 expression was upregulated in megakaryocytic-, monocytic-and granulocytic-induced differentiation of established leukemia cell lines and in erythrocytic-induced differentiation of CD34+ cells. No aberrant expression was observed in patient samples of myelodysplastic syndrome (MDS), acute myeloid (AML) or lymphoblastic (ALL) leukemia. Nonetheless, in MDS patients, increased levels of UHMK1 expression positively impacted event free and overall survival.\n\nLentivirus mediated UHMK1 knockdown did not affect proliferation, cell cycle progression, apoptosis or migration of U937 leukemia cells, although UHMK1 silencing strikingly increased clonogenicity of these cells. Thus, our results suggest that UHMK1 plays a role in hematopoietic cell differentiation and suppression of autonomous clonal growth of leukemia cells.

cancer biology↗