Characterization of the nuclear envelope alterations during ageing

• Autor(a) principal: Sousa, Jéssica Fabiana Moreira de
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/25139
• topic: Ageing; Senescence; Nuclear functions; Nuclear envelope proteins; Protein-protein interaction; Aged mice; Human fibroblasts

Ageing is characterized by an overall organismal fitness decrease across lifespan. Hence, the risk of developing complex diseases as neuropathologic disorders, diabetes, cancer and cardiovascular diseases increases with age. Despite a huge effort to determine the underlying molecular and cellular changes, the precise molecular mechanisms that regulate the ageing process remain elusive. Although, in the last few years, the protein regulation at the nuclear periphery, particularly of the nuclear lamina and lamina-associated proteins, has been pointed out as a major contributor to the ageing process. In fact, in premature ageing models, some nuclear envelope proteins have been mentioned to be altered. In this work, we performed a bioinformatic analysis that allowed us to develop an intricate study of the ageing process. Briefly, we assembled a list of age-related genes by combining the data of two public databases. Remarkably, the analysis of the data places the nucleus in the spotlight of the ageing process, given that almost half of the age-related genes are associated to nuclear functions. Moreover, protein-protein interaction network construction led us to the identification of prominent age-related functional clusters related with transcription regulation and chromatin remodelling, and DNA metabolic process and DNA repair. Further, in order to unravel the nuclear envelope proteins alterations during ageing, we performed immunoblotting and immunocytochemistry analysis in mice tissues and human fibroblasts. Our results clearly indicate that lamin A/C and SUN1 protein levels increases during ageing in both human and mice models. Moreover, nesprin-2, emerin, LAP1, and lamin B1 protein levels increase with age in mice models, whereas lamin B1, NUP133 and NUP93 protein levels decreases with age in human fibroblasts. Moreover, in aged human fibroblasts it is observable a loss of the nuclear integrity, combined with a decrease of the nucleocytoplasmic fraction of lamin A/C. Also, an increase of emerin nuclear speckles is noticeable in aged fibroblasts. To conclude, the nuclear architecture and the nuclear envelope proteins seems to be affected during the ageing process and further studies should be performed in order to elucidate their relative contribution to ageing