VAMP8/endobrevin as a general vesicular SNARE for regulated exocytosis of the exocrine system.
The molecular mechanism governing the regulated secretion of most exocrine tissues remains elusive, although VAMP8/endobrevin has recently been shown to be the major vesicular SNARE (v-SNARE) of zymogen granules of pancreatic exocrine acinar cells. In this article, we have characterized the role of VAMP8 in the entire exocrine system. Immunohistochemical studies showed that VAMP8 is expressed in all examined exocrine tissues such as salivary glands, lacrimal (tear) glands, sweat glands, sebaceous glands, mammary glands, and the prostate. Severe anomalies were observed in the salivary and lacrimal glands of VAMP8-null mice. Mutant salivary glands accumulated amylase and carbonic anhydrase VI. Electron microscopy revealed an accumulation of secretory granules in the acinar cells of mutant parotid and lacrimal glands. Pilocarpine-stimulated secretion of saliva proteins was compromised in the absence of VAMP8. Protein aggregates were observed in mutant lacrimal glands. VAMP8 may interact with syntaxin 4 and SNAP-23. These results suggest that VAMP8 may act as a v-SNARE for regulated secretion of the entire exocrine system.
Wang
Cheng-Chun
CC
Institute of Molecular and Cell Biology, Singapore 138673, Singapore.
Shi
Hong
H
Guo
Ke
K
Ng
Chee Peng
CP
Li
Jie
J
Gan
Bin Qi
BQ
Chien Liew
Hwee
H
Leinonen
Jukka
J
Rajaniemi
Hannu
H
Zhou
Zhi Hong
ZH
Zeng
Qi
Q
Hong
Wanjin
W
D000818:Animals; D005088:Exocrine Glands / Q000166:cytology / Q000378:metabolism*; D005089:Exocytosis; D007765:Lacrimal Apparatus / Q000166:cytology / Q000648:ultrastructure; D008297:Male; D051379:Mice; D020836:Protein Structure, Quaternary; D011506:Proteins / Q000737:chemistry; D050683:R-SNARE Proteins / Q000172:deficiency / Q000378:metabolism*; D050600:SNARE Proteins / Q000378:metabolism*; D012469:Salivary Glands / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D022142:Secretory Vesicles / Q000648:ultrastructure
D011506:Proteins; D050683:R-SNARE Proteins; D050600:SNARE Proteins; C491831:Vamp8 protein, mouse