Will the real angiotensin converting enzyme please stand up?

Osthole Alleviates Bleomycin-Induced Pulmonary Fibrosis via Modulating Angiotensin-Converting Enzyme 2/Angiotensin-(1-7) Axis and Decreasing Inflammation Responses in Rats

Studies have shown that angiotensin-converting enzyme 2 (ACE2) plays modulating roles in lung pathophysiology, including pulmonary fibrosis (PF) and acute lung injury. Pulmonary fibrosis is a common complication in these interstitial lung diseases, and PF always has a poor prognosis and short survival. To date, there are few promising methods for treating PF, and they are invariably accompanied by severe side effects. Recent studies have showed that the traditional Chinese herbal extract, osthole, had beneficial effects on lipopolysaccharide (LPS) induced acute lung injury (ALI) via an ACE2 pathway. Here we further investigated the protective effects of osthole on bleomycin induced pulmonary fibrosis and attempted to determine the underlying mechanism. PF mode rats were induced by bleomycin (BLM) and then subsequently administered osthole. Histopathological analyses were employed to identify PF changes. The results showed that BLM resulted in severe PF and diffuse lung inflammation, together with significant elevation of inflammatory factors and a marked increase in expression of angiotensin II (ANG II) and transforming growth factor-beta 1 (TGF-β1). ACE2 and angiotensin-(1-7) [ANG-(1-7)] were both greatly reduced after BLM administration. Meanwhile, osthole treatment attenuated BLM induced PF and inflammation, decreased the expression of these inflammatory mediators, ANG II, and TGF-β1, and reversed ACE2 and ANG-(1-7) production in rat lungs. We conclude that osthole may exert beneficial effects on BLM induced PF in rats, perhaps via modulating the ACE2/ANG-(1-7) axis and inhibiting lung inflammation pathways.

ACE for all - a molecular perspective

Angiotensin-I converting enzyme (ACE, EC 3.4.15.1) is a zinc dependent dipeptidyl carboxypeptidase with an essential role in mammalian blood pressure regulation as part of the renin-angiotensin aldosterone system (RAAS). As such, it has long been targeted in the treatment of hypertension through the use of ACE inhibitors. Although ACE has been studied since the 1950s, only recently have the full range of functions of this enzyme begun to truly be appreciated. ACE homologues have been found in a host of other organisms, and are now known to be conserved in insects. Insect ACE homologues typically share over 30 % amino acid sequence identity with human ACE. Given that insects lack a mammalian type circulatory system, they must have crucial roles in other physiological processes. The first ACE crystal structures were reported during the last decade and have enabled these enzymes to be studied from an entirely different perspective. Here we review many of these key developments and the implications that they have had on our understanding of the diverse functions of these enzymes. Specifically, we consider how structural information is being used in the design of a new generation of ACE inhibitors with increased specificity, and how the structures of ACE homologues are related to their functions. The Anopheles gambiae genome is predicted to code for ten ACE homologues, more than any genome studied so far. We have modelled the active sites of some of these as yet uncharacterised enzymes to try and infer more about their potential roles at the molecular level.