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ABSTRACT: An important question about adipogenesis is how master adipogenesis factors (defined as being able to initiate adipogenesis when expressed alone) peroxisome proliferator-activated receptor (PPAR) initiate adipogenesis only in differentiating preadipocytes. The objective of our research was to find previously unidentified factors that are unique or highly enriched in cells of the adipocyte lineage during adipogenesis that may provide functional tissue specificity to preadipocytes. We reasoned that such factors may alter expression profile specifically in obese individuals. Omental adipose tissues were obtained from obese and non-obese male patients undergoing emergency abdominal surgery. mRNAs extracted from either group were used for suppression subtraction hybridization (SSH). Genes corresponding to mRNAs enriched in obese versus non-obese patients were identified through sequencing and further analyzed for tissue distribution. Out of ~20 genes, we found several that showed clear fat cell specific expression patterns. In this study, we functionally studied one of these genes, previously designated as open reading frame C10orf116. Our data demonstrated that C10orf116 is highly expressed in adipose tissue and is localized primarily within the nucleus. Over-expression studies in 3T3-L1 cells indicated that it up-regulates the levels of CCAAT/enhancer binding protein α (C/EBPα) and PPARγ and promotes adipogenic differentiation starting from the early stage of adipogenesis. Over-expressed in omental tissues from obese patients, C10orf16 manifested the characteristics of an adipocyte lineage-specific nuclear factor that can modulate the master adipogenesis transcription factors early during differentiation. Further studies of this factor should help reveal tissue-specific events leading to fat cell development at the transcriptional level.
Journal of Bioenergetics 12/2012; · 2.81 Impact Factor
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ABSTRACT: Uncoupling proteins, a family of proton carriers located in the inner mitochondrial membrane, have important functions in energy metabolism and free radical generation that are relevant to mitochondrial function. Five family members have been identified, UCP1-5, that have distinct tissue distributions, and differences and similarities in physiological function. Uncoupling protein 4 (UCP4) is highly expressed and has a unique function in brain. UCP4 appears to be involved with metabolism in neurons and adipocytes, but conclusions on this protein have been controversial. Here, we used Caenorhabditis elegans to explore the functions of ucp-4, particularly in fat metabolism. Our results showed that UCP4 knockdown induced an obese phenotype and impaired the insulin-like pathway, possibly via oxidative stress in C. elegans. This highlights the importance of studying the role of ucp-4 in fat metabolism.
Gene 01/2012; 491(2):158-64. · 2.34 Impact Factor
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ABSTRACT: The therapeutic promise of induced pluripotent stem cells (iPSCs) has spurred efforts to circumvent genome alteration when reprogramming somatic cells to pluripotency. Approaches based on episomal DNA, Sendai virus, and messenger RNA (mRNA) can generate "footprint-free" iPSCs with efficiencies equaling or surpassing those attained with integrating viral vectors. The mRNA method uniquely affords unprecedented control over reprogramming factor (RF) expression while obviating a cleanup phase to purge residual traces of vector. Currently, mRNA-based reprogramming is relatively laborious due to the need to transfect daily for ~2 weeks to induce pluripotency, and requires the use of feeder cells that add complexity and variability to the procedure while introducing a route for contamination with non-human-derived biological material. We accelerated the mRNA reprogramming process through stepwise optimization of the RF cocktail and leveraged these kinetic gains to establish a feeder-free, xeno-free protocol which slashes the time, cost and effort involved in iPSC derivation.
Scientific Reports 01/2012; 2:657.
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ABSTRACT: To investigate the relationship between resistin (a potential link between obesity and type 2 diabetes) and preadipocyte differentiation.
A rat resistin expression vector was transfected into 3T3-L1 preadipocytes and differentiation was compared between normal 3T3-L1 cells, rat resistin-transfected cells and non-transfected cells grown in conditioned medium taken from resistin-expressing cultures.
The rat resistin gene was inserted into the pDual GC and pEFGP-N2 expression vectors for examination of the effects of resistin overexpression in 3T3-L1 cells before and after differentiation was stimulated with 3-isobutyl-1-methyxanthine (MIX), insulin and dexamethasone (DEX). Smaller conserved fragments were inserted into short interference RNA (siRNA) expression vectors, for examination of the effect of targeted resistin inhibition on differentiation of resistin-overexpressing 3T3-L1 cells.
Prior to stimulation, the resistin-transfected 3T3-L1 cells contained many more small lipid droplets than did non-transfected 3T3-L1 cells. Following stimulation, differentiation in the resistin-transfected 3T3-L1 cells was dramatically promoted, especially in the early stages. Stimulation of differentiation was also observed in non-transfected 3T3-L1 cells grown in resistin protein-containing conditioned medium. The expression of adipocyte differentiation-associated markers such as CCAAT enhancer binding protein (C/EBPalpha), retinoid X receptor (RXRalpha) and lipoprotein lipase (LPL) was upregulated in resistin-overexpressing cells, whereas expression of preadipocyte factor-1 (Pref-1), an inhibitor of preadipocyte differentiation, was downregulated. In addition, expression of two of the three tested siRNAs inhibited the adipoconversion process, providing further evidence that resistin promotes the differentiation of preadipocytes to adipocytes.
Resistin can promote preadipocyte differentiation. Based on this, we propose that resistin may be an important candidate mediator of obesity-induced insulin resistance.
European Journal of Endocrinology 07/2004; 150(6):885-92. · 3.42 Impact Factor
