Biology subjects

Bektash, A.

Publications and source records attributed to Bektash, A..

2 recordsLinked to original sources

bioRxiv2026

MCM10 and RECQL4 have cooperative and redundant roles in activating the CMG helicase during the replication initiation

DNA replication initiation requires activation of the CMG helicase to establish the replisome. This process involves the extrusion of single-stranded DNA (ssDNA) from the central channel of MCM double hexamers, allowing the two CMG helicases to pass each other; however, the factors that mediate this process in human cells remain unclear. We show that degron-mediated depletion of either MCM10 or RECQL4 alone causes only mild replication defects, whereas simultaneous depletion of both proteins completely blocks CMG activation. ChIP-seq analyses demonstrate that RECQL4 localises to replication initiation zones (IZs) independently of MCM10, whereas MCM10 recruitment to IZs is enhanced upon RECQL4 depletion, suggesting RECQL4 primarily functions in CMG activation, and MCM10 acts as a backup or supporting factor. Rescue experiments further indicate that RECQL4 cooperates with MCM10 through direct interaction, and that their ssDNA-binding activity underlies their functional overlap. We propose MCM10 and RECQL4 act cooperatively and redundantly to promote CMG activation.

molecular biology↗

bioRxiv2025

Highly active chromosome regions preferentially associate with two perispeckle networks that partition the interchromatin space

A subset of highly active chromosomal "hot zones" reproducibly positions adjacent to nuclear speckles (NS). Genes within these regions amplify their expression only with NS contact. However, gene expression differences inversely correlate with differences in NS distance, genome-wide. We hypothesized the existence of additional gene expression "niches" away from, but spatially correlated with, NS. Here we report the identification of two dynamic perispeckle patterns of protein concentrations extending outwards from NS and persisting even after NS are eliminated. Highly active chromosome regions which weakly associate with NS instead show close, NS-independent association with these perispeckle patterns. Additionally, transcripts from model intron-containing versus intronless genes associate differentially with these two patterns. While genes within NS-associated genomic regions are predominantly downregulated upon NS depletion, genes associated with perispeckle patterns are biased towards upregulation. We suggest the interchromatin space is partitioned into additional gene expression "niches"- surrounding and extending from NS - that may be involved in mRNA and gene dynamics.

cell biology↗