Ricerc@Sapienza

AKTIP is a lamin-interacting factor essential for cell survival, implicated in telomeric metabolism and DNA replication. Four main observations link AKTIP to HGPS: i) AKTIP impairment recapitulates HGPS phenotype in vitro; ii) AKTIP impairment recapitulates HGPS phenotype in mice; iii) AKTIP partially co-localizes with lamins, and iv) AKTIP is mislocalized in patient-derived HGPS cells. In addition, we have observed a direct interaction of AKTIP with the replication factor PCNA. We postulate the hypothesis that an AKTIP complex enriched at the nuclear periphery including the replication factor PCNA, lamins and DNA acts as a checkpoint for challenging replicative events, e.g. replication fork stalling at telomeres. We expect that in HGPS cells this checkpoint is compromised, which, in turn, may contribute to the HGPS phenotype. We propose to extensively analyze AKTIP function in vitro, in patient-derived HGPS cells, and in LV-progerin infected human fibroblasts. We will use multiple AKTIP-tag fusions, advanced microscopy and ChIP-seq. To investigate the role of AKTIP in vivo, we will study mouse derived mesenchymal stem cells and produce stroma-targeted depletion of the mouse orthologue of AKTIP, Ft1. We expect that this research will give new insights into the connection between progerin and telomere dysfunction through AKTIP, along with information on the role of DNA replication impairment as a potential driver mechanism in progeria. Given that the knowledge of the determinants and driver mechanisms of HGPS etiology has not been yet fully acquired, we believe that studies on new lamin-interacting players, as AKTIP, will be instrumental to dissect the mechanistic bases of HGPS and to open the path to therapeutic strategies.