Open AccessExpression patterns of l-amino acid receptors in the murine STC-1 enteroendocrine cell line
Author(s) -
Hongxia Wang,
Karnam S. Murthy,
John R. Grider
Publication year - 2019
Publication title -
cell and tissue research/cell and tissue research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.64
H-Index - 137
eISSN - 1432-0878
pISSN - 0302-766X
DOI - 10.1007/s00441-019-03074-y
Subject(s) - receptor , enteroendocrine cell , biology , metabotropic glutamate receptor , gpr120 , umami , cell culture , medicine , endocrinology , microbiology and biotechnology , biochemistry , glutamate receptor , g protein coupled receptor , taste , endocrine system , genetics , hormone
Regulation of gut function depends on the detection and response to luminal contents. Luminal L-amino acids (L-AA) are detected by several receptors including metabotropic glutamate receptors 1 and 4 (mGluR1 and mGluR4), calcium-sensing receptor (CaSR), GPRC family C group 6 subtype A receptor (GPRC6A) and umami taste receptor heterodimer T1R1/T1R3. Here, we show that murine mucosal homogenates and STC-1 cells, a murine enteroendocrine cell line, express mRNA for all L-AA receptors. Immunohistochemical analysis demonstrated the presence of all L-AA receptors on STC-1 with CaSR being most commonly expressed and T1R1 least expressed (35% versus 15% of cells); mGluRs and GPRC6a were intermediate (~ 20% of cells). Regarding coexpression of L-AA receptors, the mGluRs and T1R1 were similarly coexpressed with CaSR (10-12% of cells) whereas GPRC6a was coexpressed least (7% of cells). mGluR1 was coexpressed with GPRC6a in 11% of cells whereas coexpression between other receptors was less (2-8% of cells). CaSR and mGluR1 were coexpressed with glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) in 20-25% of cells whereas T1R1 and GPRC6a were coexpressed with GLP-1 and PYY less (8-12% of cells). Only mGluR4 showed differential coexpression with GLP-1 (13%) and PYY (21%). L-Phenylalanine (10 mM) caused a 3-fold increase in GLP-1 release, which was strongly inhibited by siRNA to CaSR indicating functional coupling of CaSR to GLP-1 release. The results suggest that not all STC-1 cells express (and coexpress) L-AA receptors to the same extent and that the pattern of response likely depends on the pattern of expression of L-AA receptors.