Unstimulated amylase secretion is proteoglycan-dependent in rat parotid acinar cells.
It is well-known that amylase is secreted in response to extracellular stimulation from the acinar cells. However, amylase is also secreted without stimulation. We distinguished vesicular amylase as a newly synthesized amylase from the accumulated amylase in secretory granules by short time pulse and chased with (35)S-amino acid. The newly synthesized amylase was secreted without stimulation from secretory vesicles in rat parotid acinar cells. The secretion process did not include microtubules, but was related to microfilaments. p-Nitrophenyl beta-xyloside, an inhibitor of proteoglycan synthesis, inhibited the newly synthesized amylase secretion. This indicated that the newly synthesized amylase was secreted from secretory vesicles, not via the constitutive-like secretory route, which includes the immature secretory granules, and that proteoglycan synthesis was required for secretory vesicle formation.
Nashida
Tomoko
T
Department of Biochemistry, School of Life Dentistry at Niigata, The Nippon Dental University, 1-8 Hamaura-cho, Niigata 951-8580, Japan. nashida@ngt.ndu.ac.jp
Imai
Akane
A
Shimomura
Hiromi
H
Yoshie
Sumio
S
Yokosuka
Hiroyuki
H
Kumakura
Masahiko
M
D000681:Amylases / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D020126:Brefeldin A / Q000494:pharmacology; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D006027:Glycosides / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010306:Parotid Gland / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism*; D051381:Rats
D006027:Glycosides; D011509:Proteoglycans; C008646:4-nitrophenyl beta-D-xyloside; D020126:Brefeldin A; D000681:Amylases