Aging of connective tissues: from genetic to epigenetic mechanisms

The mechanisms of aging and of age-dependentpathologies can be studied at the tissue level. Suchstudies concern cell aging within tissues, where cellsare surrounded by their matrix. Matrix componentsundergo post-synthetic modifications such as theMaillard reaction and proteolytic degradations.Finally, cell matrix interactions, mediated by cellmembrane receptors also undergo age-dependentmodifications. These three aspects of tissue-aging arediscussed succinctly in this review with severalexamples, as the age-dependent increase of fibronectinand the potential harmful effects of its degradationproducts and the age-dependent degradation of elastinand the harmful effects of elastin peptides mediatedby the elastin-laminin receptor. These examplesclearly show the intricate cooperation ofgene-mediated processes (increased expression offibronectin and some elastolytic enzymes) and ofpost-synthetic processes as the novel properties offibronectin and elastin derived peptides. Suchepigenetic mechanisms appear to play a crucial role inage-dependent tissue alterations and pathologies.