Knockdown of paraoxonase 1 expression influences the ageing of human dermal microvascular endothelial cells

Abstract

Skin is one of the most commonly studied tissues for microcirculation research owing to its close correlation of cutaneous vascular function, ageing and age-related cardiovascular events. To elucidate proteins that determine this correlation between endothelial cell function and ageing in the vascular environment of the skin, we performed a proteomic analysis of plasma samples from six donors in their 20s (young) and six donors in their 60s (old). Among identified proteins, paraoxonase 1 (PON1) was selected in this study. To elucidate the role of PON1 on skin ageing and determine how it controls cellular senescence, the characteristics of PON1 in human dermal microvascular endothelial cells (HDMECs) were determined. When the expression of endogenous PON1 was knocked-down by small interfering RNA (siRNA) targeting PON1, HDMECs showed characteristic features of cellular senescence such as increases in senescence-associated β-galactosidase stained cells and enlarged and flattened cell morphology. At 48 h post-transfection, the protein expression of p16 in PON1 siRNA-treated HDMECs was higher than that in scrambled siRNA-treated HDMECs. In addition, the expressions of moesin and rho GTP dissociation inhibitor, additional age-related candidate biomarkers, were decreased by PON1 knock-down in HDMECs. In conclusion, these results suggest that PON1 functions as an ageing-related protein and plays an important role in the cellular senescence of HDMECs.

Human paraoxonase-1 (PON1): Gene structure and expression, promiscuous activities and multiple physiological roles

“…The use of different assay systems also makes comparisons between studies almost impossible. A number of relatively non-toxic substrates have been developed in Seattle [140] which could be used until a definitive PON1 substrate is developed.…”

Impaired vascular function with age and RhoGTPase

“…Paraoxonase 1 protects against ROS, vascular aging, and senescence in endothelial cells. Paraoxonase 1 knockdown decreases levels of RhoGDI and increases levels of senescence marker β-galactosidase [6]. SIRT1, an HDAC, reduces endothelial senescence by increasing eNOS and Foxo1 and decreasing RhoA-ROCK signaling.…”

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

“…The association between PON-1 enzyme and cell aging was evidenced by Lee et al, [98]. PON-1 gene expression of human microvascular endothelial cells in culture was inhibited with interfering RNA.…”

“…Another important result was the high increase of protein hydroperoxides. Protein hydroperoxides inhibit thiol-dependent cysteine proteases and protein tyrosine phosphases [98]. These proteases break down proteins damaged by oxidative stress in cells, tissues and plasma, and participate in the activation and propagation in signaling pathways of the redox system.…”

“…These proteases break down proteins damaged by oxidative stress in cells, tissues and plasma, and participate in the activation and propagation in signaling pathways of the redox system. Therefore, when these proteases are decreased, the oxidative signaling is increased, contributing to the triggering of the aging process [98].…”