Aging of Long‐Lived Proteins: Extracellular Matrix (Collagens, Elastins, Proteoglycans) and Lens Crystallins

Exploring the Interplay between Polyphenols and Lysyl Oxidase Enzymes for Maintaining Extracellular Matrix Homeostasis

Collagen, the most abundant structural protein found in mammals, plays a vital role as a constituent of the extracellular matrix (ECM) that surrounds cells. Collagen fibrils are strengthened through the formation of covalent cross-links, which involve complex enzymatic and non-enzymatic reactions. Lysyl oxidase (LOX) is responsible for catalyzing the oxidative deamination of lysine and hydroxylysine residues, resulting in the production of aldehydes, allysine, and hydroxyallysine. These intermediates undergo spontaneous condensation reactions, leading to the formation of immature cross-links, which are the initial step in the development of mature covalent cross-links. Additionally, non-enzymatic glycation contributes to the formation of abnormal cross-linking in collagen fibrils. During glycation, specific lysine and arginine residues in collagen are modified by reducing sugars, leading to the creation of Advanced Glycation End-products (AGEs). These AGEs have been associated with changes in the mechanical properties of collagen fibers. Interestingly, various studies have reported that plant polyphenols possess amine oxidase-like activity and can act as potent inhibitors of protein glycation. This review article focuses on compiling the literature describing polyphenols with amine oxidase-like activity and antiglycation properties. Specifically, we explore the molecular mechanisms by which specific flavonoids impact or protect the normal collagen cross-linking process. Furthermore, we discuss how these dual activities can be harnessed to generate properly cross-linked collagen molecules, thereby promoting the stabilization of highly organized collagen fibrils.

Molecular Age-Related Changes in the Anterior Segment of the Eye

Purpose

To examine the current knowledge about the age-related processes in the anterior segment of the eye at a biological, clinical, and molecular level.

Methods

We reviewed the available published literature that addresses the aging process of the anterior segment of the eye and its associated molecular and physiological events. We performed a search on PubMed, CINAHL, and Embase using the MeSH terms “eye,” “anterior segment,” and “age.” We generated searches to account for synonyms of these keywords and MESH headings as follows: (1) “Eye” AND “ageing process” OR “anterior segment ageing” and (2) “Anterior segment” AND “ageing process” OR “anterior segment” AND “molecular changes” AND “age.” Results. Among the principal causes of age-dependent alterations in the anterior segment of the eye, we found the mutation of the TGF-β gene and loss of autophagy in addition to oxidative stress, which contributes to the pathogenesis of degenerative diseases.

Conclusions

In this review, we summarize the current knowledge regarding some of the molecular mechanisms related to aging in the anterior segment of the eye. We also introduce and propose potential roles of autophagy, an important mechanism responsible for maintaining homeostasis and proteostasis under stress conditions in the anterior segment during aging.

Genetic analysis of ageing: role of oxidative damage and environmental stresses

Evolutionary theory predicts substantial interspecific and intraspecific differences in the proximal mechanisms of ageing. Our goal here is to seek evidence for common ('public') mechanisms among diverse organisms amenable to genetic analysis. Oxidative damage is a candidate for such a public mechanism of ageing. Long-lived strains are relatively resistant to different environmental stresses. The extent to which these stresses produce oxidative damage remains to be established.