International audienceSphingosine 1-phosphate (S1P) receptor expression and the effects of S1P on migration were studied in one papillary (NPA), two follicular (ML-1, WRO) and two anaplastic (FRO, ARO) thyroid cancer cell lines, as well as in human thyroid cells in primary culture. Additionally, the effects of S1P on proliferation, adhesion and calcium signalling were addressed in ML-1 and FRO cells. All cell types expressed multiple S1P receptors. S1P evoked intracellular calcium signalling in primary cultures, ML-1 cells and FRO cells. Neither proliferation nor migration was affected in primary cultures, whereas S1P partly inhibited proliferation in ML-1 and FRO cells. Low nanomolar concentrations of S1P inhibited migration in FRO, WRO and ARO cells, but stimulated ML-1 cell migration. Consistently, S1P 1} and S1P 3}, which mediate migratory responses, were strongly expressed in ML-1 cells and S1P 2}, which inhibits migration, was the dominating receptor in the other cell lines. The migratory effect in ML-1 cells was mediated by G i} and phosphatidylinositol 3-kinase. Both S1P and the S1P 1}-specific agonist SEW-2871 induced Akt phosphorylation at Ser-473. However, SEW-2871 failed to stimulate migration, whereas the S1P 1}/S1P 3} antagonist VPC 23019 inhibited S1P-induced migration. The results implicate that aberrant S1P receptor expression may enhance thyroid cancer cell migration and thus contribute to the metastatic behaviour of some thyroid tumours

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Recently a role of adipose tissue as an endocrine organ secreting factors involved in the regulation of whole-body energy homeostasis has emerged. Preadipocytes in different fat depots have distinct adipogenic potential and the metabolic activity differs between mature adipocytes of different depot origins. Here we describe the proliferation and differentiation of stromal-vascular cells derived from subcutaneous and visceral fat depots of adult pigs. We demonstrate that subcutaneous porcine preadipocytes proliferate more actively and that individual subcutaneous adipocytes have a more rapid accumulation of triacylglycerols than visceral cells. During differentiation, subcutaneous and visceral preadipocytes showed similar gene expression patterns with increased expression of adiponectin (APM1), adipocyte-specific fatty acid binding protein (FABP4), catalase (CAT), and peroxisome proliferator-activated receptor gamma 2 (PPARG2). Furthermore, initial data showing depot-originated effects on the expression of CAT, carnitine palmitoyl transferase 1B (CPT1B) and FABP4 suggest possible depot specific differences in the function and metabolism of mature porcine adipocytes.

Delta-like 1 (DLK1) belongs to the epidermal growth factor-like transmembrane protein family and is involved in the regulation of adipogenesis. Several splice variants of DLK1 have been identified in various species, of which two have been previously identified in pig. Here, we present two novel porcine DLK1 splice variants DLK1A and DLK1C. The gene expression profile of these variants together with the previously described DLK1B and DLK1C2 variants was studied in adipose tissue depots of pigs and during adipocyte differentiation in vitro. The short DLK1C and DLK1C2 transcripts were most abundantly expressed and their expression was reduced during porcine adipogenesis.

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