Generation of two isogenic human induced pluripotent stem cell lines from a 15 year-old female patient with MERRF syndrome and A8344G mutation of mitochondrial DNA.

MERRF syndrome is predominantly caused by A8344G mutation in the mitochondrial DNA (mtDNA), affecting MT-TK gene, which impairs the mitochondrial electron transport chain function. Here, we report the generation of two isogenic induced pluripotent stem cell (iPSC) lines, TVGH-iPSC-MRF-M and TVGH-iPSC-MRF-M, from the skin fibroblasts of a female MERRF patient harboring mtDNA A8344G mutation by using retrovirus transduction system. Both cell lines share the same genetic background except containing different proportions of mtDNA with the A8344G mutation.

Impaired ROS Scavenging System in Human Induced Pluripotent Stem Cells Generated from Patients with MERRF Syndrome.

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a mitochondrial disorder characterized by myoclonus epilepsy, generalized seizures, ataxia and myopathy. MERRF syndrome is primarily due to an A to G mutation at mtDNA 8344 that disrupts the mitochondrial gene for tRNA(Lys). However, the detailed mechanism by which this tRNA(Lys) mutation causes mitochondrial dysfunction in cardiomyocytes or neurons remains unclear.

Mitochondrial resetting and metabolic reprogramming in induced pluripotent stem cells and mitochondrial disease modeling.

Background: Nuclear reprogramming with pluripotency factors enables somatic cells to gain the properties of embryonic stem cells. Mitochondrial resetting and metabolic reprogramming are suggested to be key early events in the induction of human skin fibroblasts to induced pluripotent stem cells (iPSCs).

Scope Of Review: We review recent advances in the study of the molecular basis for mitochondrial resetting and metabolic reprogramming in the regulation of the formation of iPSCs.

The emerging role of SOX2 in cell proliferation and survival and its crosstalk with oncogenic signaling in lung cancer.

Tumor cells have long been observed to share several biological characteristics with normal stem/progenitor cells; however, the oncogenic mechanisms underlying the lung stem/progenitor cell signaling remain elusive. Here, we report that SOX2, a self-renewal factor in lung stem/progenitor cells, is highly expressed in a subclass of lung cancer cells, the proliferation, survival, and chemoresistance of which are dependent on SOX2 signaling. Overexpression of SOX2 promotes oncogenic phenotypes in lung cancer cells; knockdown of SOX2 attenuated cell proliferation.

Inhibitory effects of hypoxia on metabolic switch and osteogenic differentiation of human mesenchymal stem cells.

We previously demonstrated that metabolic switch and mitochondrial activation are required for osteogenic differentiation of human mesenchymal stem cells (hMSCs). However, stem cells in niches or transplanted into injured tissues constantly encounter hypoxic stress that hinders aerobic metabolism. Therefore, we investigated the effects of oxygen tension (1% vs.

Mitochondrial bioenergetic function and metabolic plasticity in stem cell differentiation and cellular reprogramming.

Background: The self-renewal ability and pluripotent differentiation potential of stem cells hold great promise for regenerative medicine. Many studies focus on the lineage-specific differentiation and expansion of stem cells, but little is known about the regulation of glycolysis and mitochondrial biogenesis and function during these processes. Recent studies have demonstrated a strong correlation between cellular metabolism and the pluripotency and differentiation potential of stem cells, which indicates the importance of bioenergetic function in the regulation of stem cell physiology.

Determination of the minimal melatonin exposure required to induce osteoblast differentiation from human mesenchymal stem cells and these effects on downstream signaling pathways.

The purpose of this study was to determine the critical time periods of melatonin treatment required to induce human mesenchymal stem cells (hAMSCs) into osteoblasts and to determine which osteogenic genes are involved in the process. The study design consisted of adding melatonin for different times (2, 5, 10, 14 or 21 days) toward the end of a 21-day treatment containing osteogenic (OS+) medium or at the beginning of the 21-day treatment and then withdrawn. The results show that a 21-day continuous melatonin treatment was required to induce both alkaline phosphatase (ALP) activity and calcium deposition and these effects were mediated through MT₂Rs.

Upregulation of mitochondrial function and antioxidant defense in the differentiation of stem cells.

Stem cell research has received increasing attention due to their invaluable potentials in the clinical applications to cure degenerative diseases, genetic disorders and even cancers. A great number of studies have been conducted with an aim to elucidate the molecular mechanisms involved in the regulation of self-renewal of stem cells and the mysterious circuits guiding them to differentiate into all kinds of progenies that can replenish the cell pools. However, little effort has been made in studying the metabolic aspects of stem cells.

Analysis of the nucleoside triphosphatase, RNA triphosphatase, and unwinding activities of the helicase domain of dengue virus NS3 protein.

The helicase domain of dengue virus NS3 protein (DENV NS3H) contains RNA-stimulated nucleoside triphosphatase (NTPase), ATPase/helicase, and RNA 5'-triphosphatase (RTPase) activities that are essential for viral RNA replication and capping. Here, we show that DENV NS3H unwinds 3'-tailed duplex with an RNA but not a DNA loading strand, and the helicase activity is poorly processive. The substrate of the divalent cation-dependent RTPase activity is not restricted to viral RNA 5'-terminus, a protruding 5'-terminus made the RNA 5'-triphosphate readily accessible to DENV NS3H.

Differentiation of apoptosis from necrosis by dynamic changes of reduced nicotinamide adenine dinucleotide fluorescence lifetime in live cells.

Direct monitoring of cell death (i.e., apoptosis and necrosis) during or shortly after treatment is desirable in all cancer therapies to determine the outcome.

Reduced nicotinamide adenine dinucleotide fluorescence lifetime separates human mesenchymal stem cells from differentiated progenies.

The metabolic changes of human mesenchymal stem cells (hMSCs) during osteogenic differentiation were accessed by reduced nicotinamide adenine dinucleotide (NADH) fluorescence lifetime. An increase in mean fluorescence lifetime and decrease in the ratio between free NADH and protein-bound NADH correlated with our previously reported increase in the adenosine triphosphate (ATP) level of hMSCs during differentiation. These findings suggest that NADH fluorescence lifetime may serve as a new optical biomarker for noninvasive selection of stem cells from differentiated progenies.

Stem cell therapy for liver disease: parameters governing the success of using bone marrow mesenchymal stem cells.

Background & Aims: Liver transplantation is the primary treatment for various end-stage hepatic diseases but is hindered by the lack of donor organs and by complications associated with rejection and immunosuppression. There is increasing evidence to suggest the bone marrow is a transplantable source of hepatic progenitors. We previously reported that multipotent bone marrow-derived mesenchymal stem cells differentiate into functional hepatocyte-like cells with almost 100% induction frequency under defined conditions, suggesting the potential for clinical applications.

Coordinated changes of mitochondrial biogenesis and antioxidant enzymes during osteogenic differentiation of human mesenchymal stem cells.

The multidifferentiation ability of mesenchymal stem cells holds great promise for cell therapy. Numerous studies have focused on the establishment of differentiation protocols, whereas little attention has been paid to the metabolic changes during the differentiation process. Mitochondria, the powerhouse of mammalian cells, vary in their number and function in different cell types with different energy demands, but how these variations are associated with cell differentiation remains elusive.