title: Ca(2+)-binding protein expression in primary human thyrocytes.
abstract: We recently identified several Ca(2+)-binding proteins (CaBP) from the S100 and annexin family to be regulated by TSH in FRTL-5 cells. Here, we study the regulation of S100A4, S100A6 and ANXA2 in primary human thyrocytes (PHT) derived from surrounding tissues (ST), cold benign thyroid nodules (CTN) and autonomously functioning thyroid nodules (AFTN). We investigated the expression and regulation of CaBP and the effect of their expression on Ca(2+) and TSHR signaling. We used an approach that accounts for the potential of an individual PHT culture to proliferate or to express thyroid differentiation features by assessing the expression of FOS and TPO. We found a strong correlation between the regulation of CaBP and the proliferation-associated transcription factor gene FOS. PKA and MEK1/2 were regulators of ANXA2 expression, while PI3-K and triiodothyronine were additionally involved in S100 regulation. The modulated expression of CaBP was reflected by changes in ATP-elicited Ca(2+) signaling in PHT. S100A4 increased the ratio of subsequent Ca(2+) responses and showed a Ca(2+) buffering effect, while ANXA2 affected the first Ca(2+) response to ATP. Overexpression of S100A4 led to a reduced activation of NFAT by TSH. Using S100A4 E33Q, D63N, F72Q and Y75K mutants we found that the effects of S100A4 expression on Ca(2+) signaling are mediated by protein interaction. We present evidence that TSH has the ability to fine-tune Ca(2+) signals through the regulation of CaBP expression. This represents a novel putative cross-regulating mechanism in thyrocytes that could affect thyrocyte signaling and physiology.
authors.affiliation: Department for Internal Medicine, Clinic for Endocrinology and Nephrology, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany; Interdisciplinary Center for Clinical Research, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Lorenz
authors.affiliation: Research Laboratories, Clinic for Visceral, Thoracic, Vascular and Transplant Surgery, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Aust
authors.affiliation: Interdisciplinary Center for Clinical Research, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany. Electronic address: krok@medizin.uni-leipzig.de.
authors.forename: K
authors.initials: K
authors.lastname: Krohn
mesh_terms: D017306:Annexin A2 / Q000235:genetics / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D020832:EF Hand Motifs; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D050505:Mutant Proteins / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D055503:Protein Multimerization / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011989:Receptors, Thyrotropin / Q000378:metabolism; D000075383:S100 Calcium Binding Protein A6; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013961:Thyroid Gland / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: C472822:ANXA2 protein, human; D017306:Annexin A2; D015415:Biomarkers; D018797:Cell Cycle Proteins; D050505:Mutant Proteins; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D011989:Receptors, Thyrotropin; D000075383:S100 Calcium Binding Protein A6; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; D018808:Transcription Factor AP-1; D014284:Triiodothyronine; C055351:S100A6 protein, human; C077591:S100A4 protein, human; D013972:Thyrotropin; D002118:Calcium
keywords: AFTN; Annexin; CTN; CaBP; Calcium-binding protein; PHT; S100 protein; ST; Thyroid cancer; Thyroid physiology; Thyroid signal transduction; autonomously functioning thyroid nodule; calcium binding protein; cold benign thyroid nodule; primary human thyrocytes; surrounding tissue