Immunocytochemical localization of cathepsins B and H in corticotrophs and melanotrophs of rat pituitary gland.
We examined by immunocytochemistry the localization of cathepsins B and H in corticotrophs and melanotrophs in anterior and intermediate lobes of rat pituitary gland, using monospecific antibodies to cathepsins B and H. In serial semithin sections, immunodeposits for cathepsin H were detected throughout the cytoplasm of cells immunoreactive for ACTH and alpha-MSH in anterior and intermediate pituitary. Granular immunodeposits for cathepsin B were demonstrated in anterior and intermediate cells. Double immunostaining colocalized immunogold particles for cathepsin H and ACTH or alpha-MSH in secretory granules of corticotrophs or melanotrophs, whereas those for cathepsin B were detected only in their lysosomes. Enzyme assay demonstrated cathepsin B activity in both anterior and intermediate pituitary tissue, but did not detect cathepsin H activity in the intermediate pituitary. Western blotting, however, revealed the presence of cathepsin H and cystatin beta in intermediate pituitary. These results suggest that cathepsin B plays a role in protein degradation in lysosomes of corticotrophs and melanotrophs. Moreover, the presence of cathepsin H in secretory granules of the cells may indicate that the enzyme participates in the activation of secretory products.
Uchiyama
Y
Y
Department of Anatomy, University of Tsukuba, Ibaraki-Ken, Japan.
Nakajima
M
M
Muno
D
D
Watanabe
T
T
Ishii
Y
Y
Waguri
S
S
Sato
N
N
Kominami
E
E
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D002401:Cathepsin B / Q000378:metabolism*; D056655:Cathepsin H; D002403:Cathepsins / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D015151:Immunoblotting; D007150:Immunohistochemistry; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D014018:Tissue Distribution
D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; D056655:Cathepsin H; C534128:Ctsh protein, rat