Implications of altered sirtuins in metabolic regulation and oral cancer.

Sirtuins (SIRTs 1-7) are a group of histone deacetylase enzymes with a wide range of enzyme activities that target a range of cellular proteins in the nucleus, cytoplasm, and mitochondria for posttranslational modifications by acetylation (SIRT1, 2, 3, and 5) or ADP ribosylation (SIRT4, 6, and 7). A variety of cellular functions, including mitochondrial functions and functions in energy homeostasis, metabolism, cancer, longevity and ageing, are regulated by sirtuins. Compromised sirtuin functions and/or alterations in the expression levels of sirtuins may lead to several pathological conditions and contribute significantly to alterations in metabolic phenotypes as well as oral carcinogenesis. Here, we describe the basic characteristics of seven mammalian sirtuins. This review also emphasizes the key molecular mechanisms of sirtuins in metabolic regulation and discusses the possible relationships of sirtuins with oral cancers. This review will provide novel insight into new therapeutic approaches targeting sirtuins that may potentially lead to effective strategies for combating oral malignancies.

Role of Magnesium Transporter Subtype 1 (MagT1) in the Osteogenic Differentiation of Rat Bone Marrow Stem Cells.

In the present study, we investigated the role of magnesium transporter subtype 1 (MagT1), a selective Mg transporter protein, in the osteogenic differentiation of rat bone marrow stem cells (rBMSCs). Osteogenic differentiation was monitored by the expressions of alkaline phosphatase (ALP), osteocalcin (OCN), collagen-1 (COL-1) and runt-related transcription factor 2 (RUNX2), and extracellular matrix mineralization of rBMSCs. The expression of MagT1 increased with osteogenic differentiation of rBMSCs, suggesting the importance of intracellular Mg homeostasis to cell differentiation. Alteration of intracellular Mg homeostasis by culture condition with low extracellular Mg significantly reduced the osteogenic differentiation markers ALP, OCN, COL-1, and RUNX2 gene expressions. MagT1 knockdown during the differentiation period also reduced osteogenic differentiation and the extent of matrix mineralization of rBMSCs. In conclusion, our results indicate that Mg and MagT1 play an important role in osteogenic differentiation of rBMSCs and may be involved in the bone regeneration.