Gap junctions (GJ) are specialized cell-cell contacts formed by connexins (Cxs), which provide direct communication between adjacent cells. Cx43 ubiquitination has been suggested to induce the internalization of GJs, as well as the recruitment of the autophagy receptor p62 to mediate binding to LC3B and degradation by macroautophagy. In this report, we describe a functional LC3 interacting region (LIR), present in the amino terminal of most Cx protein family members, which can mediate the autophagy degradation of Cx43 without the need of ubiquitin. Mutation of the LIR motif on Cx37, Cx43, Cx46 and Cx50 impairs interaction with LC3B and GABARAP without compromising protein ubiquitination. Through in vitro protein-protein interaction assays, we demonstrate that this LIR motif is required for the binding of Cx43 to LC3B and GABARAP. Overall, our findings describe an alternative mechanism whereby Cxs interact with LC3/GABARAP proteins, envisioning a new model for the autophagy degradation of connexins.

Aging is a risk factor for cardiovascular diseases. Through aging, blood vessels become stiffer, less elastic and, thus, with less ability to contract. The objectives of this chapter are to review (i) recent progresses in the characterization of physiological and pathological vascular aging and (ii) in vitro platforms to study vascular aging. Initially, we will discuss the causes and biomarkers of vascular aging. Then we will discuss the main characteristics related to physiological and pathological aging including (i) altered ECM remodeling (e.g. composition, mechanical properties, degradation, calcification of the ECM during aging), (ii) enhanced fibrosis (e.g. causes and mechanisms), (iii) vascular cell dysfunction triggered by chronic oxidative stress, inflammation or senescence, and (iv) altered responses of vascular cells to flow shear stress. Finally, we will discuss in vitro systems to study vascular aging, particularly the effect of biomechanics in aged cells as well as the effect of drugs during vascular aging.