Knockdown of αII spectrin in normal human cells by siRNA leads to chromosomal instability and decreased DNA interstrand cross-link repair

Nonerythroid alpha-spectrin (alpha IISp) is a structural protein involved in repair of DNA interstrand cross-links and is deficient in cells from patients with Fanconi anemia (FA), which are defective in ability to repair cross-links. In order to further demonstrate the importance of the role that alpha IISp plays in normal human cells and in the repair defect in FA, alpha IISp was knocked down in normal cells using siRNA. Depletion of alpha IISp in normal cells by siRNA resulted in chromosomal instability and cellular hypersensitivity to DNA interstrand cross-linking agents. An increased number of chromosomal aberrations were observed and, following treatment with a DNA interstrand cross-linking agent, mitomycin C, cells showed decreased cell growth and survival and decreased formation of damage-induced alpha IISp and XPF nuclear foci. Thus depletion of alpha IISp in normal cells leads to a number of defects observed in FA cells such as, chromosome instability and a deficiency in cross-link repair. (c) 2009 Elsevier Inc. All rights reserved.