Vasoinhibitory activity of synthetic peptides from the amino terminus of chromogranin A

Abstract

Naturally occurring amino terminal fragments of chromogranin A (CGA), the calcium-binding protein found in all endocrine secretory vesicles, have vasoinhibitory activity when tested in isolated segments of the endothelium-denuded human saphenous vein. Synthetic peptides corresponding to sequences within the first 76 residues of chromogranin A have been made and tested for biological activity. Full length vasostatin I (CGA1-76) (40 nM), but not the truncated vasostatin I, CGA1-40 (100 nM) mimics natural chromogranin A fragments in its inhibition of contractions induced by endothelin-1 (ET-1) in calcium containing medium. CGA1-40 (100 nM) mimics the inhibitory effect of the vasostatins on the contractions induced in the absence of extracellular calcium by high potassium and noradrenaline, but not by ET-1. The iodinated peptides both exhibit saturable binding in an aortic smooth muscle cell line, indicative of a single class of high affinity binding protein ('receptor' with an apparent KD of approximately 45 nM. This binding is not affected by endothelin-1. Iodinated peptides can be crosslinked to a single polypeptide in binding experiments performed on intact calf aortic smooth muscle cells.

Endothelium-derived nitric oxide mediates the antiadrenergic effect of human vasostatin-1 in rat ventricular myocardium

“…The present results, demonstrating that the antiadrenergic effect induced by VS-1 is due to a Ca 2ϩ -independent PI3K-dependent endothelial release of NO, rather than a direct action on cardiac cells, provide an unifying working hypothesis to explain at the cellular level the mechanism of the cardiac inotropic effect of VS-1 and the vasodilator effects observed in some vascular preparations (1)(2)(3)5).…”

Chromogranin A: current status as a precursor for bioactive peptides and a granulogenic/sorting factor in the regulated secretory pathway

“…In future it will be necessary to establish the presence and concentration of candidate peptides in paracrine/autocrine target cells, and characterize their receptors. The lack of a single receptor-binding assay for a CGA-derived peptide is a major impediment to further progress in the field at this time, although preliminary characterization of high-affinity vasostatin binding sites in vascular tissue has been reported [145]. Peptides such as WE-14 and GE-25 (Table 2) are likely candidates for bioactive peptides and will require screening for biological activity in diverse bioassays.…”

“…Aardel and co-workers have demonstrated specific binding of vasostatin to endothelial tissue on which it exerts a modulatory action, but full characterization of a receptor for vasostatin is lacking. Initial cross-linking experiments done with vascular smooth muscle cells responsive to vasostatin indicate that this receptor has a molecular weight of about 78,000 [145]. Establishing a quantitative receptor-binding assay for the density and presence of receptors in various tissues will be required, along with physiological and biochemical characterization of CGA-derived peptides, to make a convincing case for their status as CGAderived biologically active peptides (neuropeptides).…”

Characterisation of N-terminal chromogranin A and chromogranin B in mammals by region-specific radioimmunoassays and chromatographic separation methods

“…Furthermore, both proteins have been postulated to serve as pro-hormones for biologically active peptides (Eiden 1987, Helle & Angeletti 1994. Some specific domains of the molecules have been assigned with different biological activity.…”