Expression of Ca2+-dependent synaptotagmin isoforms in mouse and rat parotid acinar cells.
Synaptotagmin is a Ca2+ sensing protein, which triggers a fusion of synaptic vesicles in neuronal transmission. Little is known regarding the expression of Ca2+-dependent synaptotagmin isoforms and their contribution to the release of secretory vesicles in mouse and rat parotid acinar cells. We investigated a type of Ca2+-dependent synaptotagmin and Ca2+ signaling in both rat and mouse parotid acinar cells using RT-PCR, microfluorometry, and amylase assay. Mouse parotid acinar cells exhibited much more sensitive amylase release in response to muscarinic stimulation than did rat parotid acinar cells. However, transient [Ca2+]i increases and Ca2+ influx in response to muscarinic stimulation in both cells were identical, suggesting that the expression or activity of the Ca2+ sensing proteins is different. Seven Ca2+-dependent synaptotagmins, from 1 to 7, were expressed in the mouse parotid acinar cells. However, in the rat parotid acinar cells, only synaptotagmins 1, 3, 4 and 7 were expressed. These results indicate that the expression of Ca2+-dependent synaptotagmins may contribute to the release of secretory vesicles in parotid acinar cells.
Jo
Hae
H
Department of Oral Biology, Yonsei University College of Dentistry, Seodaemun-gu, Seoul 120-752, Korea.
Byun
Hae Mi
HM
Kim
Jong-Hoon
JH
Kim
Min Seuk
MS
Kim
Seung-Hyeoi
SH
Hong
Jeong Hee
JH
Seo
Jeong Taeg
JT
Lee
Syng-Ill
SI
Shin
Dong Min
DM
Son
Heung-Kyu
HK
D000681:Amylases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D051379:Mice; D018721:Muscarinic Agonists / Q000494:pharmacology; D010306:Parotid Gland / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D050857:Synaptotagmins / Q000378:metabolism*
D018721:Muscarinic Agonists; D020033:Protein Isoforms; D050857:Synaptotagmins; D002217:Carbachol; D000681:Amylases; D002118:Calcium