Functional expression of SLC15 peptide transporters in rat thyroid follicular cells

• Published in: Molecular and cellular endocrinology 2010-02, Vol.315 (1), p.174-181
• Main Authors: Romano, A., Barca, A., Kottra, G., Daniel, H., Storelli, C., Verri, T.
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Dipeptides - chemistry; Dipeptides - genetics; Dipeptides - metabolism; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; PC Cl3 cells; Peptide Transporter 1; Protein Isoforms - genetics; Protein Isoforms - metabolism; Rats; Rats, Sprague-Dawley; RNA, Messenger - genetics; RNA, Messenger - metabolism; SoLute Carrier 15 family; Symporters - genetics; Symporters - metabolism; Thyroglobulin; Thyroid follicular cell (thyrocyte); Thyroid Gland - cytology; Thyroid Gland - metabolism; Thyrotropin - metabolism; β-Ala-Lys-N ɛ-7-amino-4-methyl-coumarin-3-acetic acid
• ISSN: 0303-7207; 1872-8057; 0303-7207
• DOI: 10.1016/j.mce.2009.11.002

Peptide transport and expression of SoLute Carrier 15 (SLC15) peptide transporters was assessed in rat thyroid tissue and a rat thyroid cell line (PC Cl3 cells). Peptide transport was studied by monitoring the uptake of the fluorophore-conjugated dipeptide β-Ala-Lys-N ɛ-7-amino-4-methyl-coumarin-3-acetic acid (Ala-Lys-AMCA). Expression of SLC15-specific mRNA transcripts was analyzed by RT-PCR. Of the two SLC15 transporters expressed in thyroid follicular cells, namely PEPT2 (SLC15A2) and PHT1 (SLC15A4), only PEPT2 was involved in peptide transport at the plasma membrane, with PHT1 most likely being intracellular. Interestingly, at the mRNA level PEPT2 was up-regulated under TSH stimulation. These findings represent the first evidence that peptide transport occurs in thyroid follicular cells. SLC15 transporters could participate to recycling of peptides derived from extracellular and lysosomal thyroglobulin proteolysis, both essential steps for thyroid hormone synthesis.