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Comparative fine structural distribution of endopeptidase 24.15 (EC3.4.24.15) and 24.16 (EC3.4.24.16) in rat brain

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Fontenele-Neto, José Domingues ; Massarelli, Eduardo Ernst ; Garrido, Paula Amaral Gurgel ; Beaudet, Alain ; Ferro, Emer Suavinho [5]
Número total de Autores: 5
Tipo de documento: Artigo Científico
Fonte: JOURNAL OF COMPARATIVE NEUROLOGY; v. 438, n. 4, p. 399-410, Oct. 2001.
Área do conhecimento: Ciências Biológicas - Morfologia
Assunto(s):Neuropeptídeos   Endopeptidases   Proteínas nucleares   Imuno-histoquímica

Endopeptidase 24.15 (EP24.15) and 24.16 (EP24.16) are closely related metalloendopeptidases implicated in the metabolism of several neuropeptides and widely expressed in mammalian brain. To gain insight into the functional role of these two enzymes in the central nervous system, we examined their cellular and subcellular distribution in rat brain by using electron microscopic immunogold labeling. In all areas examined, EP24.15 and EP24.16 immunoreactivity were observed in selective subpopulations of neuronal and glial cells. Subcellular localization of EP24.15 in neurons revealed that this enzyme was predominantly concentrated in the nucleus, whereas EP24.16 was almost exclusively cytoplasmic. The amount of EP24.15 found in the nucleus was inversely correlated with that found in the cytoplasm, suggesting that the enzyme could be mobilized from one compartment to the other. Within the cytoplasm, EP24.15 and EP24.16 immunoreactivity showed comparable distributional patterns. Both enzymes were detected throughout perikarya and dendrites, as well as within axons and axon terminals. In all neuronal compartments, EP24.15 and EP24.16 showed a major association with membranes of neurosecretory elements, including Golgi cisternae, tubulovesicular organelles, synaptic vesicles, and endosomes. However, whereas EP24.15 always faced the cytoplasmic face of the membranes, EP24.16 was observed on both cytoplasmic and luminal sides, suggesting that the latter was more likely to contribute to the processing of peptides or to the degradation of internalized ligands. Taken together, the present results suggest that EP24.15 could play a major role in the hydrolysis of intranuclear substrates, whereas EP24.16 would be predominantly involved in the processing and inactivation of signaling peptides. (AU)

Processo FAPESP: 99/01983-9 - Bases moleculares e celulares da biologia da peptidases: projeto ii do laboratorio de comunicacao celular
Beneficiário:Emer Suavinho Ferro
Linha de fomento: Auxílio à Pesquisa - Regular