Unraveling stress-related pathogenetic pathways involving LMNA and POLD1 genes in premature ageing: focus on adipocyte dysfunction (ADIPOAGE)

Premature ageing syndromes are rare diseases that recapitulate many aspects of normal ageing including lipodystrophy, skin and bone deterioration and cardiovascular disorders. In particular, lipodystrophy and lipoatrophy are phenotypes shared by several progeroid syndromes, including progeroid laminopathies and MDPL (Mandibular Hypoplasia Deafness Progeroid Features and Lipodystrophy syndrome). In that context, it is becoming clear that adipose tissue loss acts as a main determinant of the whole premature ageing pathology, rather than being a mere effect of organismal ageing. Our preliminary data obtained by profiling gene expression and the secretome of progeroid cells show that defects in pathways and molecules involved in adipocyte determination and those triggered by mature adipocyte activity are evidenced under stress conditions. This is not surprising as proteins involved in MDPL, MADA (Mandibuloacral dysplasia) and HGPS (Hutchinson Gilford progeria), which are investigated in our research, play a key role in stress response. The POLD1 product, Pol-delta, mutated in MDPL, participates in DNA damage repair; lamin A/C, mutated in HGPS and MADA, cooperates to recruitment of DNA damage response factors and regulation of p21 during repair progression. Impairment of these processes, associated with altered telomere dynamics and mitochondrial activity, have been observed in HGPS, MADA and MDPL. Despite the clear pathogenetic role of the lamin A precursor, which is accumulated as wild-type, mutated or alternatively spliced prelamin A (progerin) in MDPL, MADA and HGPS respectively, there is a missing link between cellular defects and specific pathogenetic pathways affecting tissue homeostasis. Moreover, it is not clear how mutations in LMNA or POLD1 cause such overlapping phenotypes, particularly in adipose tissue, while knowledge of the interplay between those gene products may help explaining downstream effects on cell proliferation, survival or differentiation. IN THIS PROJECT, WE WILL INVESTIGATE THESE EFFECTS IN ADIPOCYTES WITH THE MAIN AIM OF IDENTIFYING PATHOGENETIC MECHANISMS LEADING TO ADIPOSE TISSUE DETERIORATION.By focusing our research on DNA damage response pathways in LMNA and POLD1-mutated adipocytes versus CRISPR/Cas gene corrected cells and healthy controls, we expect to identify THERAPEUTIC TARGETS FOR PREMATURE AGEING DISEASES AND AGEING-RELATED ADIPOSE TISSUE DETERIORATION. The whole experimental plan is feasible and realistic thanks to different and complementary expertise in partner laboratories including genetics (long-lasting expertise in LMNA and POLD1 gene analysis, NGS and other high throughput technologies, UNIT 2), molecular biology (CRISPR/Cas9 technology and other gene editing technologies, UNIT 3) and cell biology (long lasting expertise in the study of laminopathic cells, cellular differentiation and protein interactions, UNIT 1) and availability of in vitro preclinical models (UNIT 1 and UNIT 2).