Aging of connective tissues: from genetic to epigenetic mechanisms.
The mechanisms of aging and of age-dependent pathologies can be studied at the tissue level. Such studies concern cell aging within tissues, where cells are surrounded by their matrix. Matrix components undergo post-synthetic modifications such as the Maillard reaction and proteolytic degradations. Finally, cell matrix interactions, mediated by cell membrane receptors also undergo age-dependent modifications. These three aspects of tissue-aging are discussed succinctly in this review with several examples, as the age-dependent increase of fibronectin and the potential harmful effects of its degradation products and the age-dependent degradation of elastin and the harmful effects of elastin peptides mediated by the elastin-laminin receptor. These examples clearly show the intricate cooperation of gene-mediated processes (increased expression of fibronectin and some elastolytic enzymes) and of post-synthetic processes as the novel properties of fibronectin and elastin derived peptides. Such epigenetic mechanisms appear to play a crucial role in age-dependent tissue alterations and pathologies.
Robert
L
L
Laboratoire d'Ophtalmologie, Hôtel Dieu, 1 Place du Parvis Notre Dame, 75181 Paris, France.
Labat-Robert
J
J
D000375:Aging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D016922:Cellular Senescence; D003238:Connective Tissue / Q000378:metabolism* / Q000473:pathology; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology; D006801:Humans