A novel radiosensitive SCID patient with a pronounced G(2)/M sensitivity

作者：Wiegant Wouter W; Meyers Matty; Verkaik Nicole S; van der Burg Mirjam; Darroudi Firouz; Romeijn Ron; Bernatowska Ewa; Wolska Kusnierz Beata; Mikoluc Bozena; Jaspers Nicolaas G J; Vreeken Cees; Ijspeert Hanna; Esveldt van Lange Rebecca E E; Friedl Anna A; de Villartay Jean Pierre; Mullenders Leon H F; van Dongen Jacques J M; van Gent Dik C; Pastink Albert^*; Zdzienicka Malgorzata Z

来源：DNA Repair, 2010, 9(4): 365-373.

DOI：10.1016/j.dnarep.2009.12.004

• Immunodeficiency
• X-ray sensitivity
• Repair defect

V(D)J rearrangement in lymphoid cells involves repair of double-strand breaks (DSBs) through nonhomologous end joining (NHEJ). Defects in this process lead to increased radiosensitivity and severe combined immunodeficiency (RS-SCID). Here, a SCID patient, M3, is described witha-T-B+NK+ phenotype but without causative mutations in CD3 delta, epsilon, zeta or IL7R alpha, genes specifically involved in T cell development. Clonogenic survival of M3 fibroblasts showed an increased sensitivity to the DSB-inducing agents ionizing radiation and bleomycin, as well as the crosslinking compound, mitomycin C. We did not observe inactivating mutations in known NHEJ genes and results of various DSB-repair assays in G(1) M3 cells were indistinguishable from those obtained with normal cells. However, we found increased chromosomal radiosensitivity at the G(2) phase of the cell cycle. Checkpoint analysis indicated functional G(1)/S and intra-S checkpoints after irradiation but impaired activation of the "early" G(2)/M checkpoint. Together these results indicate a novel class of RS-SCID patients characterized by the specific absence of T lymphocytes and associated with defects in G(2)-specific DSB repair. The pronounced G(2)/M radiosensitivity of the RS-SCID patient described here, suggests a defect in a putative novel and uncharacterized factor involved in cellular DNA damage responses and T cell development.

• 出版日期2010-4-4