Multiple transcripts of anoctamin genes expressed in the mouse submandibular salivary gland.
OBJECTIVE
Salivary fluid formation is primarily driven by Ca(2+)-activated, apical efflux of chloride into the lumen of the salivary acinus. The anoctamin1 protein is an anion channel with properties resembling the endogenous calcium-activated chloride channels. In order to better understand the role of anoctamin proteins in salivary exocrine secretion, the expression of the ten members of the anoctamin gene family in the mouse submandibular gland was studied.


METHODS
Total RNA extracted from mouse submandibular salivary glands was reverse transcribed using primer pairs to amplify the full-length coding regions of each anoctamin gene and was subcloned into plasmid vectors for DNA sequencing. Alternative splice variants were also screened by polymerase chain reaction using primer pairs that amplified six overlapping regions of the complementary DNA of each anoctamin gene, spanning multiple exons.


RESULTS
Multiple anoctamin transcripts were found in the mouse submandibular salivary gland, including full-length transcripts of anoctamin1, anoctamin3, anoctamin4, anoctamin5, anoctamin6, anoctamin9, and anoctamin10. Exon-skipping splicing in the N-terminal exons of the anoctamins1, anoctamin5, and anoctamin6 genes resulted in multiple alternative splice variants. No expression of anoctamin2, anoctamin7, or anoctamin8 was found.


CONCLUSIONS
The predominant anoctamin transcript expressed in the mouse submandibular gland is anoctamin1ac. The chloride channel protein produced by anoctamin1ac is likely responsible for the Ca(2+)-activated chloride efflux, which is the rate-limiting step in salivary exocrine secretion.
Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
Ji-Hye
0000-0003-3661-9596
JH
Han
Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
Hye-Mi
0000-0002-2327-2143
HM
Kim
Department of Conservative Dentistry, Seoul National University School of Dentistry, Seoul, Korea.
Deog-Gyu
0000-0002-0160-6317
DG
Seo
Department of Oral Biochemistry, Seoul National University School of Dentistry, Seoul, Korea.
Gene
0000-0002-8213-9916
G
Lee
Laboratory of Veterinary Biochemistry and Molecular Biology, Chungbuk National University College of Veterinary Medicine, Cheongju, Korea.
Eui-Bae
0000-0001-8936-916X
EB
Jeung
Program in Neurobiology, Seoul National University School of Dentistry and Dental Research Institute, Seoul, Korea.
Frank H
0000-0001-9306-1731
FH
Yu
Alternative splicing; Chloride channels; Submandibular gland