Subscribe to RSS
DOI: 10.1055/s-0034-1372100
TAAR expression in thyroid epithelial cell lines as to establish an in vitro-model for signalling analysis
Objectives: Trace amine-associated receptors (TAARs) comprise a sub-class of G protein-coupled receptors that are suspected to become activated by thyronamines, i.e. endogenous metabolites of the classical thyroid hormones (TH) that functionally antagonise the effect of their precursors. Accordingly, the potential signalling of thyronamines through TAARs is suspected to be involved in the auto-regulation of the thyroid gland and, consequently, the regulation of TH delivery to target tissue. Previous results have shown TAAR1 to be expressed in mouse thyroid tissue and to be trafficked to the surface of thyroid epithelial cells. The current study focuses on investigating the sub-cellular localisation of TAARs in vitro, using Fischer rat thyroid cells, FRT and FRTL-5, to model TAAR over-expression.
Methods: TAAR over-expression was performed by single or co-transfections of FRT cells with vectors coding for haemaglutinin-, rhodopsin-, or eGFP-tagged TAARs. The expressing cells were also subjected to immunofluorescence analysis and confocal microscopy.
Results: Single expression of mouse mTAAR1-eGFP and mTAAR5-eGFP showed localisation confined to the nuclear envelope and the ER lumen of FRT cells. Interestingly, co-transfections with a variety of different TAAR-encoding vectors enabled trafficking to the cell surface along the secretory route.
Conclusion: Our data suggests that TAARs require [hetero]dimerisation in order to pass the ER quality control and enter the secretory pathway to reach the surface of thyroid epithelial cells.
Supported by Deutsche Forschungsgemeinschaft, SPP 1629, BR 1308/11 – 1.