Purpose of review: The paraoxonase (PON) gene family includes three members, PON1, PON2, and PON3. In-vitro and mouse studies have demonstrated that all three PONs are atheroprotective. Some, but not all, human epidemiologic studies have observed associations between PON gene polymorphisms and risk of cardiovascular disease (CVD). In this review, we summarize studies published within the last year, elucidating involvement of PON1 and PON2 in oxidative stress, CVD, and innate immune responses.
Recent findings: In a prospective study, the PON1 192QQ genotype and low PON1 activity were associated with increased systemic oxidative stress and increased risk for CVD. PON1 expression protected against Pseudomonas aeruginosa lethality in Drosophila, suggesting that PON1 can interfere with quorum sensing in vivo. PON2 attenuated macrophage triglyceride accumulation via inhibition of diacylglycerol acyltransferase 1. Overexpression of PON2 protected against endoplasmic reticulum stress-induced apoptosis when the stress was induced by interference with protein modification but not when endoplasmic reticulum stress was induced by Ca2+ deregulation.
Summary: Both mouse and human studies have demonstrated the antioxidative and atheroprotective effects of PON1. The mechanisms by which PON2 exerts its atheroprotective effects are emerging. Large-scale epidemiologic studies are needed to further examine the relationship between PON2 genetic polymorphisms and risk for CVD. Elucidation of the physiologic substrates of the PON proteins is of particular importance to further advance this field.