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Cell Tissue Res. 2019 Dec;378(3):471-483. doi: 10.1007/s00441-019-03074-y. Epub 2019 Aug 13.

Expression patterns of L-amino acid receptors in the murine STC-1 enteroendocrine cell line.

Author information

1
Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences (VPENS), Virginia Commonwealth University, Box 908551, Richmond, VA, 23298, USA.
2
Department of Physiology and Biophysics, VCU Program in Enteric Neuromuscular Sciences (VPENS), Virginia Commonwealth University, Box 908551, Richmond, VA, 23298, USA. John.Grider@vcuhealth.org.

Abstract

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.

KEYWORDS:

Enteroendocrine cells; L-Amino acid receptors; Neurohumoral peptides; STC-1 cells; Taste receptors

PMID:
31410629
PMCID:
PMC6872933
[Available on 2020-12-01]
DOI:
10.1007/s00441-019-03074-y

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