Background: 3-iodothyronamine (T1AM) is an endogenous messenger chemically related to thyroid hormone. Among its functional effects a shift from carbohydrates to lipids as principal energy resource has been observed. Recent results indicate significant transcriptional effects of chronic T1AM administration involving genes of the sirtuin family. Sirtuins regulate important metabolic pathways involved in apoptosis, stress resistance, energy metabolism. Therefore the aim of this work was to compare the effect of T1AM and T3 chronic treatment on mammalian sirtuin expression in hepatoma cells (HepG2) and isolated hepatocytes. Methods:. Isolated hepatocytes were obtained by liver in-situ collagenase perfusion. Sirtuin expression was evaluated by Western Blot analysis in cells treated for 24h with 1-20µM T1AM or T3. In addition, cell viability was evaluated by MTT test upon 24h treatment with 0.5nM to 20µM T1AM or T3. Results: Protein expression: In HepG2, T1AM significantly reduced SIRT1 and SIRT4 expression at 20µM while T3 strongly decreased the expression of SIRT1 (20µM), and SIRT2 (any concentration tested). In primary rat hepatocytes T1AM decreased SIRT4 expression (10-20µM) whether T3 decreased SIRT2 at 10µM. Cell viability: T1AM caused a moderate but significant reduction in the number of viable cells particularly in HepG2 cells in which the effect occurred at concentration starting from 5nM that did not caused any change in sirtuin expression. T3 did not affect cell viability in both HepG2 and isolated hepatocytes. Conclusions: T1AM and T3 differently affect sirtuin expression in hepatocytes. Since SIRT1 and SIRT4 are important regulator of lipid and glucose metabolism, whereas SIRT2 has a key role in regulating cell cycle and genomic integrity, our observations are consistent with the shift from carbohydrates to lipids induced by T1AM. T1AM has also a moderate effect on cell viability in HepG2 cells which seems however independent from sirtuin modulation.
Effects of thyroid hormones and 3-iodothyronamine on sirtuin expression in hepatocytes
ZUCCHI, RICCARDO;GHELARDONI, SANDRA
2016-01-01
Abstract
Background: 3-iodothyronamine (T1AM) is an endogenous messenger chemically related to thyroid hormone. Among its functional effects a shift from carbohydrates to lipids as principal energy resource has been observed. Recent results indicate significant transcriptional effects of chronic T1AM administration involving genes of the sirtuin family. Sirtuins regulate important metabolic pathways involved in apoptosis, stress resistance, energy metabolism. Therefore the aim of this work was to compare the effect of T1AM and T3 chronic treatment on mammalian sirtuin expression in hepatoma cells (HepG2) and isolated hepatocytes. Methods:. Isolated hepatocytes were obtained by liver in-situ collagenase perfusion. Sirtuin expression was evaluated by Western Blot analysis in cells treated for 24h with 1-20µM T1AM or T3. In addition, cell viability was evaluated by MTT test upon 24h treatment with 0.5nM to 20µM T1AM or T3. Results: Protein expression: In HepG2, T1AM significantly reduced SIRT1 and SIRT4 expression at 20µM while T3 strongly decreased the expression of SIRT1 (20µM), and SIRT2 (any concentration tested). In primary rat hepatocytes T1AM decreased SIRT4 expression (10-20µM) whether T3 decreased SIRT2 at 10µM. Cell viability: T1AM caused a moderate but significant reduction in the number of viable cells particularly in HepG2 cells in which the effect occurred at concentration starting from 5nM that did not caused any change in sirtuin expression. T3 did not affect cell viability in both HepG2 and isolated hepatocytes. Conclusions: T1AM and T3 differently affect sirtuin expression in hepatocytes. Since SIRT1 and SIRT4 are important regulator of lipid and glucose metabolism, whereas SIRT2 has a key role in regulating cell cycle and genomic integrity, our observations are consistent with the shift from carbohydrates to lipids induced by T1AM. T1AM has also a moderate effect on cell viability in HepG2 cells which seems however independent from sirtuin modulation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
