Isolated fusion polypeptide comprising a first amino acid sequence characterized by at least (≥)85% sequence identity to SEQ ID NO 01 -SEQ NO 04, SEQ ID 23 or SEQ ID 08 said first amino acid sequence and/or said isolated fusion protein having an NAD+-dependent deacetylase function identical to SIRT1 isoform 1, isoform 2, isoform b or isoform c or the catalytic domain thereof, said first amino acid sequence being directly or indirectly chemically linked to at least one of second amino acid sequence comprising a fragment crystallizable (Fc) region or an albumin, or a post- translationally modified derivative thereof, for use in a method of treatment amelioration, mitigation, slowing, arresting, reversing or prevention of an age-related diseases or of a condition selected from the group consisting of: mitochondrial-related diseases/disorders, metabolic disorders, neurodegenerative diseases, polyglutamine diseases, anticoagulation and antithrombotic conditions, allergies and respiratory conditions, autoimmune diseases, vision impairment, but also dyslipidemia, hyperlipidemia, diabetes, metabolic syndrome, inflammation, apoptosis, neurodegeneration, cancer, hypercholesterolemia, atherosclerosis, cardiovascular disease (CVD), steatohepatitis (fatty liver disease), pancreatitis, renal lipid deposition, and obesity-related conditions.La présente invention concerne un polypeptide de fusion isolé qui comprend une première séquence d'acides aminés caractérisée par au moins (≥) 85 % d'identité de séquence à SEQ ID NO 01 - SEQ NO 04, SEQ ID 23 ou SEQ ID 08, ladite première séquence d'acides aminés et/ou ladite protéine de fusion isolée ayant une fonction désacétylase dépendante de NAD+ identique à l'isoforme 1 de SIRT1, l'isoforme 2, l'isoforme b ou l'isoforme c ou son domaine catalytique, ladite première séquence d'acides aminés étant directement ou indirectement liée chimiquement à au moins une seconde séquence d'acides aminés comprenant un fragment d'une région (Fc) cristalli
