Chromogranin A Biosynthetic Cell Populations in Bovine Endocrine and Neuronal Tissues: Detection byin SituHybridization Histochemistry

Abstract

Chromogranin A is a highly acidic protein that is found in the secretory granules of many endocrine and neuronal cells. To localize bovine cell populations involved in chromogranin A biosynthesis, the distribution of the mRNA encoding this protein was determined with in situ hybridization histochemistry. In the adrenal gland, the mRNA was found in the chromaffin cells of the medulla but was absent from the cortex. The distribution of the mRNA in the medulla was uneven; cells located at the periphery were more heavily labeled than those in the center of the gland. Because the adrenal medulla is composed of several cell types, the chromogranin A-containing cells were further characterized for the presence of neuropeptide and adrenergic markers. Adjacent sections were examined for the mRNAs encoding enkephalin and phenylethanolamine N-methyltransferase (PNMT), the enzyme that catalyzes the formation of epinephrine from norepinephrine. Both mRNAs were present in a narrow band of cells at the periphery of the medulla. However, in contrast to the distribution of chromogranin A mRNA, the enkephalin and PNMT mRNAs were detected in only a small number of cells in the inner medullary region. The difference in the distribution of the enkephalin and PNMT mRNAs from that of chromogranin A suggests that the expression of these genes is differentially regulated. In addition to the adrenal gland, chromogranin A mRNA is expressed by many other tissues. In the parathyroid gland, which is rich in the mRNA but exhibits little chromogranin A-like immunoreactivity, the message was present in most cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of Xenin-immunoreactive Cells in the Duodenal Mucosa of Humans and Various Mammals

“…CgA is an established marker for neuroendocrine cells and a pan-neuronal marker (Facer et al 1985;Siegel et al 1988;Schäfer et al 1994). It is clear that CgA is localized at the soluble cores of peptide hormone storage vesicles (O'Connor 1983).…”

Disruption of target interactions prevents the development of enkephalin immunoreactivity in sympathetic neurons

“…While there was a correlation between Enk-IR and proenkephalin A mRNA during the first 3 postnatal weeks, the proportion of neurons with proenkephalin A mRNA did not decrease after P2 1 and there was only a small decrease in the amount of mRNA per neuron (see also Watanabe et al, 1991). Discrepancies in Enk protein and proenkephalin A mRNA have been reported previously (Livett et al, 1982;Kilpatrick et al, 1985Kilpatrick et al, , 1987Pittius et al, 1985;Howells et al, 1986;Siegel et al, 1988;Stachowiak et al, 1988). The difference between the levels of Enk-IR and proenkephalin A in the adult could reflect increased stability of proenkephalin A mRNA, decreased translation of Figure II.…”