Research Paper Volume 16, Issue 20 pp 12977—13011
Werner syndrome RECQ helicase participates in and directs maintenance of the protein complexes of constitutive heterochromatin in proliferating human cells
- 1 Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA 98195, USA
- 2 Present address: Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
- 3 Present address: Parse Biosciences, Seattle, WA 98109, USA
Received: February 21, 2024 Accepted: September 6, 2024 Published: October 17, 2024
https://doi.org/10.18632/aging.206132How to Cite
Copyright: © 2024 Lazarchuk et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Werner syndrome of premature aging is caused by mutations in the WRN RECQ helicase/exonuclease, which functions in DNA replication, repair, transcription, and telomere maintenance. How the loss of WRN accelerates aging is not understood in full. Here we show that WRN is necessary for optimal constitutive heterochromatin levels in proliferating human fibroblasts. Locally, WRN deficiency derepresses SATII pericentromeric satellite repeats but does not reduce replication fork progression on SATII repeats. Globally, WRN loss reduces a subset of protein-protein interactions responsible for the organization of constitutive heterochromatin in the nucleus, namely, the interactions involving Lamin B1 and Lamin B receptor, LBR. Both the mRNA level and subcellular distribution of LBR are affected by WRN deficiency, and unlike the former, the latter phenotype does not require WRN catalytic activities. The phenotypes of heterochromatin disruption seen in WRN-deficient proliferating fibroblasts are also observed in WRN-proficient fibroblasts undergoing replicative or oncogene-induced senescence. WRN interacts with histone deacetylase 2, HDAC2; WRN/HDAC2 association is mediated by heterochromatin protein alpha, HP1α, and WRN complexes with HP1α and HDAC2 are downregulated in senescing cells. The data suggest that the effect of WRN loss on heterochromatin is separable from senescence program, but mimics at least some of the heterochromatin changes associated with it.
Abbreviations
CH: constitutive heterochromatin; INM: inner nuclear membrane; MSC: mesenchymal stem cell; maRTA: microfluidics-assisted replication track analysis; MFI: mean fluorescence intensity; NHDF: normal human dermal fibroblast; NPC: nuclear pore complex; OIS: oncogene-induced senescence; ORF: open reading frame; PCH: pericentric heterochromatin; PLA: proximity ligation assay; PDL: population doubling level; RS: replicative senescence; RLFS: R-loop forming site; SAHF: senescence-associated heterochromatin foci.