Selective Localization of the Parathyroid Secretory Protein-I/Adrenal Medulla Chromogranin A Protein Family in a Wide Variety of Endocrine Cells of the Rat*

Abstract

Secretory protein-I (SP-I) of parathyroid glands and chromogranin A ( CGA ) of adrenal medullary chromaffin cells are chemically similar if not identical proteins. Both proteins are contained within secretory granules and appear to be cosecreted with granule contents, for example, in the parathyroid with PTH and in the adrenal with epinephrine and dopamine beta-hydroxylase. Antisera to bovine SP-I and porcine CGA , together with antisera to a variety of peptide hormones, were used in an immunofluorescence study of rat tissues in order to determine the probable distribution and cellular localization of these proteins. In addition to their previously demonstrated presence in parathyroid and adrenal cells, the SP-I/ CGA protein family was detected in cells of the thyroid that contained calcitonin and often SRIF but not thyroglobulin; in cells of the anterior pituitary staining for the alpha-subunit of TSH/FSH/LH but not in cells staining for GH, PRL, ACTH, or beta-endorphin; in pancreatic islet cells staining for SRIF and pancreatic polypeptide-related peptides, but not for insulin or glucagon; in the celiac and mesenteric ganglia in cells some of which contained SRIF; and in the gastric antrum in cells containing SRIF, but not gastrin. SP-I/ CGA was not detected in cells of the liver, kidney, parotid gland, or acinar pancreas or in the intermediate or posterior lobes of the pituitary. These results suggest that this protein family enjoys a widespread but highly restricted distribution in many different endocrine-peptide cells of the rat, many that are believed to be of the APUD cell series. The possibility is raised that SP-I/ CGA plays some physiological role in the secretory process or exerts an effect of its own in the periphery after secretion.

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

“…Similar work was carried out with a monoclonal antibody to human CGA in human tissues by Wilson and Lloyd [18]. Several laboratories soon established that CGA was ubiquitous to neuroendocrine tissues in which hormones were stored in secretory granules, and absent from endocrine tissues such as the adrenal cortex in which hormone secretion occurs immediately upon biosynthesis without intervening storage in and exocytosis from, secretory granules [9,16,17]. Chromogranin B and secretogranin II were subsequently shown to have a similar, but somewhat more restricted distribution compared to that of CGA [19,20].…”

“…Exonic organization of the CGA genes of human, cow and mouse. Schematic representation of bovine [25], human [26], and mouse [24] The granins are found, along with various peptides derived from them by proteolytic processing, in secretory granules throughout the diffuse neuroendocrine system [2,[8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The granin proteins have been variously considered for a number of intracellular and extracellular roles in neuroendocrine function because of their ubiquity and abundance.…”

The Role of Hoxa3 Gene in Parathyroid Gland Organogenesis of the Mouse

“…Secretory protein-1 (SP-1) coexists with parathormone (PTH) in secretory granules of the parathyroid chief cells (Cohn et al 1984). SP-1 and chromogranin A are chemically similar if not identical proteins (Cohn et al 1982).…”

Production of monoclonal antibodies against a novel glycoprotein synthesized and secreted by dog thyroid C-cells.

“…Secretory protein I extracted from parathyroid glands is a very similar to chromogranin A, if not identical, in its size, amino acid and carbohydrate composition, partial amino acid sequence, immunological crossreactivity, and physical properties (Cohn et al, 1982). Subpopulations of rat thyroid C-cells have been reported to show immunoreactivity for chromogranin A and secretory protein I (Cohn et al, 1984). NSE is an isoenzyme of the glycolytic enzyme enolase, which is an energy-providing enzyme of the glycolytic path- way.…”