Ricerc@Sapienza

Nuclear envelope (NE) ruptures are doubly linked to cancer: they create chromatin herniations and genome instability and favor cancer cell diffusion in confined spaces. Endosomal sorting complexes required for transport (ESCRT) machinery is associated with membrane sealing at trafficking vesicles and at the midbody in cytokinesis and also controls NE integrity and completion of NE reorganization after mitosis. AKTIP (Ft1 in mouse) is a new factor enriched at the NE, controlling telomere function, genome stability and nuclear envelope integrity. AKTIP has multiple striking similarities with ESCRTs. It interacts with vesicle factors, it is enriched at the NE and at the midbody, and is structurally similar to the ESCRT-I TSG101. Along with this, Ft1 is a concausal element in the diffusion of lymphomas in mice and AKTIP reduction in human lymphoma has been reported.
We hypothesize that AKTIP/Ft1 depletion would impinge on NE and chromatin organization. Deriving fragile nuclei and DNA damage would contribute to diffusion of lymphomas.
On these premises, in this study we aim at dissecting the role of AKTIP/Ft1 in nuclear integrity and ESCRT activity, along with defining the contribution of Ft1-linked NE alterations to lymphoma diffusion.
We will use 3D SIM to better understand AKTIP NE localization. We will study in vivo AKTIP dynamics by imaging of CRISPR/Cas9 AKTIP-GFP edited cells. We will define whether, in the absence of AKTIP, ESCRT activity at the NE is impaired and we will monitor NE integrity. We will analyze DNA damage markers on cells with reduced AKTIP/Ft1 expression combined with modulation of ESCRTs or lamins. Finally, we will monitor nature of lymphomas in Ft1 mutant mice injected with lentivectors expressing hairpin RNAs directed to ESCRT factors.
We believe that this study will give relevant insights into the role of NE and NE sealing factors in genome stability, telomere function, which interrelate with cancer aggressiveness and metastatic behavior.