Immunocytochemical evidence of intragranular acetylation of ?-MSH in the melanotrophic cells of the rabbit

Stoeckel, M. E.; Schimchowitsch, Sarah; Garaud, Jean-Claude; Schmitt, Gisela; Vaudry, Hubert; Porte, A

doi:10.1007/bf00216197

Cited by 8 publications

(2 citation statements)

References 12 publications

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“…Since the axonal transport of the neurohypophysial peptides occurs exclu sively within neurosecretory vesicles, these data strongly in dicated that the neurosecretory vesicles contained the me chanisms for post-translational processing of precursors. Further experimental work supporting this view of the role of secretory vesicles in precursor processing can be found in various studies of proinsulin [21,22,47,80,91] and POMC [31,36,58,93] processing. In some cases (e.g., for parathyroid hormone processing [38], the interpretation is that precursor processing can occur in the Golgi complex.…”

Section: The Secretory Vesicle Hypothesismentioning

confidence: 76%

The Enzymology and Intracellular Organization of Peptide Precursor Processing: The Secretory Vesicle Hypothesis

1985

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The ‘secretory vesicle hypothesis of precursor processing’ states that the initial endopeptidase cleavages which excise the nascent, biologically active peptides from their protein precursors occur primarily in secretory vesicles (or granules). Hence, all the processing steps subsequent to these cleavages must also occur within these organelles. Two types of evidence are presented in support of this view: (1) cell biological studies which implicate the secretory vesicle as the site of precursor conversion to peptides, and (2) enzymological studies which locate and characterize putative processing enzymes in secretory vesicles. The processing enzymes reviewed include the ‘prohormone-converting enzymes’ which cleave at pairs of basic amino acids, other endopeptidases, carboxypeptidase-B-like enzymes and aminopeptidase, and N-acetylation and α-amidation enzymes. The properties of these enzymes in relation to the nature of the processing micro-environment in the secretory vesicles is discussed.

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Section: The Secretory Vesicle Hypothesismentioning

confidence: 76%

The Enzymology and Intracellular Organization of Peptide Precursor Processing: The Secretory Vesicle Hypothesis

1985

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“…Immunohistochemical studies showed a co-localized distribution of two or more of the POMC-derived peptides in the same corticotropic and melanotropic cells of the anterior and intermediate lobe of the pituitary, and in the POMC neurons in the basal hypothalamus, at the light and electron microscopical level (Akil et al, 1978;Bloch et al, 1978Bloch et al, , 1979Crine et al, 1978;Dub6 et al, 1978;Sofroniew, 1979;Weber et al, 1979;Chatelain et al. 1979;Nilaver et al, 1979;Vaudri et al, 1980;Guy et al, 1980;Loh et al, 1982;Cantin et al, 1983;Stoeckel et al, 1983Stoeckel et al, , 1985Mains et al, 1983;Tanaka and Kurosumi, 1986;Powel and Baker, 1987;Kantin et al, 1988). Pelletier and Leclerc (1979) have shown at the ultrastructural level that ACTH is present in dense-core secretory granules in the brain.…”

Section: Co-localization Of Pomc Derived Peptidesmentioning

confidence: 99%

Ultrastructural Characterization of Adrenocorticotrope Hormone (ACTH) Immunoreactive Fibres in the Mesencephalic Central Grey Substance of the Rat

Buma

Veening

Nieuwenhuys

1989

Eur J of Neuroscience

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The fine structural localization of fibres immunoreactive for the adrenocorticotrope hormone (ACTH) was studied in the mesencephalic central grey substance (MCG) of the male Wistar rat. Light microscopically, varicose ACTH-immunoreactive fibres were found throughout the MCG in a dorsal, lateral and ventral, periventricular position. Electron microscopically, the immunoreactivity was most prominent in the direct vicinity of electron-dense secretory granules in axonal varicosities, and, although to a lower degree, around other cytoplasmic organelles such as electron-lucent synaptic vesicles, mitochondria and microtubules. With serial section analysis two types of ACTH-immunoreactive varicosity were discerned. The first type is large, contains many, small electron-lucent synaptic vesicles, that are located in the vicinity of a morphologically well-defined synaptic contact. In this type of varicosity, large dense-core secretory granules are scarce. Immunoreactivity is low or absent, particularly near the active zone. The second type is strongly immunoreactive. It always contains many large, dense-core secretory granules; electron-lucent vesicles are rare. The smaller varicosities of this type never make synaptic contacts, but a few of the larger varicosities have synaptic contacts with dendrites of MCG cells.

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Immunocytochemical evidence for intragranular processing of pro-opiomelanocortin in the melanotropic cells of the rabbit

Stoeckel¹,

Schimchowitsch²,

Garaud

et al. 1985

Cell Tissue Res.

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The immunogold technique, employing antisera with clear-cut specificities, was used to localise different processing stages of pro-opiomelanocortin (POMC) in rabbit melanotropic cells. While the antiserum against gamma 3-MSH labelled all the secretory granules including intrasaccular condensations in the Golgi apparatus, antisera against alpha-MSH only labelled extra-Golgi secretory vesicles (SV). All extra-Golgi SV were likewise labelled with the three antisera against alpha-MSH used, despite their different specificities for the deacetylated, N-acetylated or C-amidated forms of the peptide. The antibody against beta-endorphin also labelled the extra-Golgi SV, while only some SV were labelled with the antibody against gamma-endorphin. These results correlate with biochemical data in favour of mainly--if not exclusively--intragranular processing of POMC. Except for gamma 3-MSH, the cleavage of which could coincide with Golgi packaging of secretory material, other post-translational modifications of the precursor seem to occur when SV are discharged outside the Golgi area. The cleavage of gamma-endorphin appears to be a later step in POMC processing, occurring in some mature SV.

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Immunocytochemical evidence of intragranular acetylation of ?-MSH in the melanotrophic cells of the rabbit

Cited by 8 publications

References 12 publications

The Enzymology and Intracellular Organization of Peptide Precursor Processing: The Secretory Vesicle Hypothesis

The Enzymology and Intracellular Organization of Peptide Precursor Processing: The Secretory Vesicle Hypothesis

Ultrastructural Characterization of Adrenocorticotrope Hormone (ACTH) Immunoreactive Fibres in the Mesencephalic Central Grey Substance of the Rat

Immunocytochemical evidence for intragranular processing of pro-opiomelanocortin in the melanotropic cells of the rabbit

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