Lamin A/C depletion enhances DNA damage-induced stalled replication fork arrest.

Abstract

The human LMNA gene encodes the essential nuclear envelope proteins lamin A and C (lamin A/C). Mutations in LMNA result in altered nuclear morphology, but how this impacts the mechanisms that maintain genomic stability is unclear. Here, we report that lamin A/C-deficient cells have a normal response to ionizing radiation but are sensitive to agents that cause interstrand cross-links (ICLs) or replication stress. In response to treatment with ICL agents (cisplatin, camptothecin, and mitomycin), lamin A/C-deficient cells displayed normal γ-H2AX focus formation but a higher frequency of cells with delayed γ-H2AX removal, decreased recruitment of the FANCD2 repair factor, and a higher frequency of chromosome aberrations. Similarly, following hydroxyurea-induced replication stress, lamin A/C-deficient cells had an increased frequency of cells with delayed disappearance of γ-H2AX foci and defective repair factor recruitment (Mre11, CtIP, Rad51, RPA, and FANCD2). Replicative stress also resulted in a higher frequency of chromosomal aberrations as well as defective replication restart. Taken together, the data can be interpreted to suggest that lamin A/C has a role in the restart of stalled replication forks, a prerequisite for initiation of DNA damage repair by the homologous recombination pathway, which is intact in lamin A/C-deficient cells. We propose that lamin A/C is required for maintaining genomic stability following replication fork stalling, induced by either ICL damage or replicative stress, in order to facilitate fork regression prior to DNA damage repair.

• Authors: Mayank Singh, Clayton R Hunt, Raj K Pandita, Rakesh Kumar, Chin-Rang Yang, Nobuo Horikoshi, Robert Bachoo, Sara Serag, Michael D Story, Jerry W Shay, Simon N Powell, Arun Gupta, Jessie Jeffery, Shruti Pandita, Benjamin P C Chen, Dorothee Deckbar, Markus Löbrich, Qin Yang, Kum Kum Khanna, Howard J Worman, Tej K Pandita
• Journal: Molecular and cellular biology (Mol Cell Biol) Vol. 33 Issue 6 Pg. 1210-22 (Mar 2013) ISSN: 1098-5549 [Electronic] United States
• PMID: 23319047 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• FANCD2 protein, human
• Fanconi Anemia Complementation Group D2 Protein
• H2AX protein, human
• Histones
• LMNA protein, human
• Lamin Type A
• Hydroxyurea

Topics

• Animals
• Cell Line
• Cell Line, Tumor
• Chromosome Aberrations
• DNA Damage
• DNA Repair (genetics)
• DNA Replication
• Fanconi Anemia Complementation Group D2 Protein (genetics, metabolism)
• Fibroblasts (metabolism)
• Gene Expression (genetics)
• HEK293 Cells
• Histones (genetics, metabolism)
• Homologous Recombination (genetics)
• Humans
• Hydroxyurea (metabolism)
• Lamin Type A (deficiency, genetics, metabolism)
• MCF-7 Cells
• Mice
• Radiation, Ionizing
• Signal Transduction (genetics)