N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a ubiquitous molecule generated in all mammalian
tissues from the N-terminal sequence of thymosin 4 (T4) by the action of propyl oligopeptidase. Ac-SDKP is an
alternative substrate for angiotensin converting enzyme (ACE).
There are several indications that Ac-SDKP may be protective in the cardiovascular system. First, the level of Ac-
SDKP in plasma and tissues is reduced in some cardiovascular pathologies such as hypertension. Second, an administration
of Ac-SDKP to rodents attenuates inflammation, cell differentiation, proliferation, and migration resulting in a reduction of
fibrosis in the heart, vessels and kidneys in conditions of their disorders. Third, the treatment with ACE-inhibitors is associated with a reduced
degradation and hence increased levels of Ac-SDKP, while a simultaneous treatment with monoclonal antibodies against Ac-
SDKP partly counteracts the benefit of ACE-inhibition. Since Ac-SDKP fails to reduce blood pressure and left ventricular hypertrophy
(LVH), its potential structural benefit is obviously mediated by direct action on tissue in preventing or reversing excessive fibrosis.
The protection by ACE-inhibition seems to be partly mediated by increased availability of Ac-SDKP. Thus, it is to suppose that harvesting
the knowledge on the role of Ac-SDKP in cardiovascular physiology and pathology could deepen our insight into the mechanisms of
action of the renin-angiotensin system (RAS) as well as agents interfering with this system. The exciting protective potential of Ac-SDKP
suggests that this compound could be a focused drug target not only in animal experiments but also in the clinical cardio-pharmacologic
research in the near future.