Expression of disease-causing lamin A mutants impairs the formation of DNA repair foci.
A-type lamins are components of the nuclear lamina. Mutations in the gene encoding lamin A are associated with a range of highly degenerative diseases termed laminopathies. To evaluate sensitivity to DNA damage, GFP-tagged lamin A cDNAs with disease-causing mutations were expressed in HeLa cells. The inner nuclear membrane protein emerin was mislocalised upon expression of the muscular dystrophy mutants G232E, Q294P or R386K, which aberrantly assembled into nuclear aggregates, or upon expression of mutants causing progeria syndromes in vivo (lamin A del50, R471C, R527C and L530P). The ability of cells expressing these mutants to form DNA repair foci comprising phosphorylated H2AX in response to mild doses of cisplatin or UV irradiation was markedly diminished, unlike the nearly normal response of cells expressing wild-type GFP-lamin A or disease-causing H222P and R482L mutants. Interestingly, mutants that impaired the formation of DNA repair foci mislocalised ATR (for ;ataxia telangiectasia-mutated and Rad3-related') kinase, which is a key sensor in the response to DNA damage. Our results suggest that a subset of lamin A mutants might hinder the response of components of the DNA repair machinery to DNA damage by altering interactions with chromatin.
Manju
Kaliyaperumal
K
Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India.
Muralikrishna
Bhattiprolu
B
Parnaik
Veena K
VK
D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D004260:DNA Repair; D049914:DNA Repair-Deficiency Disorders / Q000378:metabolism*; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D034904:Lamin Type A / Q000235:genetics* / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism*; D009687:Nuclear Proteins; D011371:Progeria / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D013946:Thymopoietins / Q000378:metabolism; D014018:Tissue Distribution; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; C468783:H2AX protein, human; D006657:Histones; D034904:Lamin Type A; D008565:Membrane Proteins; D050505:Mutant Proteins; D009687:Nuclear Proteins; D013946:Thymopoietins; C092710:emerin; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D002945:Cisplatin