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

Abstract

Chromogranin A (CgA) and chromogranin B (CgB) are acidic proteins stored in and released from hormone granules in endocrine and neuroendocrine tissue. The chromogranins are postulated to serve as pro-hormones to generate biologically active peptides, which may influence hormonal release and vascular functions or have antibacterial functions. Although N-terminal and C-terminal regions show some species amino acid homology, the chromogranins as a whole display considerable interspecies differences, which prevents their use in comparative studies of biological functions.We present four new radioimmunoassays for the measurement of defined N-terminal regions of CgA and CgB. A new radioimmunoassay for measurement of intact bovine CgA has also been developed. With these assays and two previously published ones, we have compared the cross-reactivity of chromogranins from man, cattle, sheep, goat, pig and horse and compared adrenomedullar content and serum levels of CgA from these species. We have also studied the influence of peptide concentrations and the ionic strength of the mobile phase on molecular weight estimations.Assays with antibodies directed against the N-terminal parts of CgA and CgB showed sufficient interspecies cross-reactivity to allow comparative quantification of the circulating levels in man, cattle, sheep, goat, pig and horse. Assays measuring the intact human or bovine CgA were not suitable for comparative purposes in samples from sheep, goat, pig and horse. Molecular interactions between vasostatin immunoreactive material and intact bovine CgA were demonstrated in gel permeation studies, suggesting that conclusions about the degree of N-terminal processing from elution profiles should be made with caution.Reliable interspecies comparison of chromogranins is difficult, but measurements with region-specific assays may be helpful to study concentrations of chromogranins and chromogranin-related peptides.

Structural and Biological Characterization of Chromofungin, the Antifungal Chromogranin A-(47–66)-derived Peptide

“…In addition, the processing of CGA and CGB has been shown to be cell-and tissue-specific (41,42), giving rise to the release of multiple peptides recovered in blood and lymph circulations but also in biological fluids such as salivary (43), synovial, milk, and cerebrospinal fluids. 40) with a unique affinity constant close to 50 nM (47). The role of vasostatin-I in stress response could represent an important biological function in addition to that of catecholamines on regulating blood circulation.…”

“…1 H NMR Analysis of Synthetic Peptide CGA- (47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63)(64)(65)(66))-A lyophilized sample of 4 mg of CGA-(47-66) was dissolved in 600 l of aqueous 20 mM sodium acetate-d 6 buffer (pH 5.0), 50 mM KCl with the addition of deuterated trifluoroethanol (TFE-d 3 ) to yield 50% (v/v) solution. The final peptide concentration was 3 mM.…”

Prognostic Factors and Survival in 324 Patients with Pancreatic Endocrine Tumor Treated at a Single Institution

“…Data regarding plasma chromogranin A were retrieved from patient charts, and reported as times upper normal limit at the time of diagnosis. Blood from fasting subjects had been drawn into chilled tubes containing sodium heparin and 400 units/mL kallikrein inhibitory aprotinin, and centrifuged at 4jC, before measurement by RIA, as previously described (21,22).…”

Chromogranin A Regulates Renal Function by Triggering Weibel–Palade Body Exocytosis

“…The CHGA RIA has been described in detail elsewhere. [35][36][37] Healthy Individuals: Twin and Sibling Pairs There were 690 individuals: 176 males and 514 females; 458 white, 62 black, and 270 of other ethnicities; 516 twins (176 monozygotic pairs and 82 dizygotic pairs) and 174 siblings of twins or members of other sibships. Ages were 15 to 84 yrs old.…”