JAK2V617F+ single-stranded DNA modulates exosome complex activity and DNA-sensing pathways in myeloproliferative neoplasms.

Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPNs) are characterized by excessive myeloid cell proliferation due to mutations in hematopoietic stem/progenitor cells, most notably JAK2V617F mutation. This mutation leads to persistent JAK2 activation, driving genomic instability and accumulation of single-stranded DNA (ssDNA) fragments in the cytoplasm. The RNA-exosome complex, a critical ribonuclease complex, plays a key role in maintaining genomic stability by degrading damaged RNAs and processing ssDNA. In this study, we examined the effects of JAK2V617F+ ssDNA on the DNA-sensing pathways and exosome complex activity in healthy and Ph-MPN-derived cells. Using an in vitro model, we cultured cord blood mononuclear cells with ssDNA isolated from the Ph-MPN cell lines. Our findings revealed that Ph-MPN-derived cells release JAK2V617F+ ssDNA, which upregulates exosome complex components, including EXOSC1, and activates DNA-sensing pathways such as cGAS-STING and TLR9 in healthy cells without inducing apoptosis. Additionally, JAK2 wild-type ssDNA stimulates DIS3 expression, highlighting its regulatory role in inflammation and RNA metabolism. These results demonstrated that ssDNA derived from JAK2V617F+ cells can alter RNA-exosome complex gene expression and nucleic acid-sensing pathways, contributing to chronic inflammation in MPNs. This study provides novel insights into the interplay between ssDNA, exosome complex, and inflammatory signaling and offers potential therapeutic targets to modulate inflammation and genomic instability in MPNs.