The transcription factor SOX6 contributes to the developmental origins of obesity by promoting adipogenesis

10.1242/dev.131573Development (Cambridge, England)1436950-961GUSTO (Growing up towards Healthy Outcomes

Enhanced triacylglycerol catabolism by carboxylesterase 1 promotes aggressive colorectal carcinoma

The ability to adapt to low-nutrient microenvironments is essential for tumor cell survival and progression in solid cancers, such as colorectal carcinoma (CRC). Signaling by the NF-κB transcription factor pathway associates with advanced disease stages and shorter survival in patients with CRC. NF-κB has been shown to drive tumor-promoting inflammation, cancer cell survival, and intestinal epithelial cell (IEC) dedifferentiation in mouse models of CRC. However, whether NF-κB affects the metabolic adaptations that fuel aggressive disease in patients with CRC is unknown. Here, we identified carboxylesterase 1 (CES1) as an essential NF-κB–regulated lipase linking obesity-associated inflammation with fat metabolism and adaptation to energy stress in aggressive CRC. CES1 promoted CRC cell survival via cell-autonomous mechanisms that fuel fatty acid oxidation (FAO) and prevent the toxic build-up of triacylglycerols. We found that elevated CES1 expression correlated with worse outcomes in overweight patients with CRC. Accordingly, NF-κB drove CES1 expression in CRC consensus molecular subtype 4 (CMS4), which is associated with obesity, stemness, and inflammation. CES1 was also upregulated by gene amplifications of its transcriptional regulator HNF4A in CMS2 tumors, reinforcing its clinical relevance as a driver of CRC. This subtype-based distribution and unfavorable prognostic correlation distinguished CES1 from other intracellular triacylglycerol lipases and suggest CES1 could provide a route to treat aggressive CRC

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Isolation and culture of human adipose-derived stem cells from subcutaneous and visceral white adipose tissue compartments

Human Adipose-derived Stem/Stromal Cells (ASCs) have been widely used in stem cell and obesity research, as well as clinical applications including cell-based therapies, tissue engineering and reconstruction. Compared with mesenchymal stem cells (MSCs) derived from other tissues such as umbilical cord and bone marrow, isolation of ASCs from human white adipose tissue (WAT) has great advantages due to its rich tissue source and simple surgical procedure. In this detailed protocol we describe a protocol to isolate and characterize ASCs from human WAT. Molecular characterization of isolated ASCs was performed through surface marker expression profiling using flow cytometry. Adipogenic capacity of the isolated ASCs was confirmed through inducing adipogenic differentiation and Oil Red O staining of lipid. This protocol provides researchers with the tools to culture and assess purity and adipogenic differentiation capacity of human ASCs, which can then be utilized for required downstream in vitro applications. This protocol has been modified from Baglioni et al. (2009), Baglioni et al. (2012), and van Harmelen et al. (2005) to describe in detail a complete technique to isolate and subsequently characterize human ASCs from human WAT biopsies. This protocol has been utilized to isolate and characterize human ASCs from both subcutaneous and visceral WAT. The isolated human ASCs show high purity and demonstrate adipogenic differentiation capacity in vitro

Isolation and culture of human adipose-derived stem cells from subcutaneous and visceral white adipose tissue compartments

Human Adipose-derived Stem/Stromal Cells (ASCs) have been widely used in stem cell and obesity research, as well as clinical applications including cell-based therapies, tissue engineering and reconstruction. Compared with mesenchymal stem cells (MSCs) derived from other tissues such as umbilical cord and bone marrow, isolation of ASCs from human white adipose tissue (WAT) has great advantages due to its rich tissue source and simple surgical procedure. In this detailed protocol we describe a protocol to isolate and characterize ASCs from human WAT. Molecular characterization of isolated ASCs was performed through surface marker expression profiling using flow cytometry. Adipogenic capacity of the isolated ASCs was confirmed through inducing adipogenic differentiation and Oil Red O staining of lipid. This protocol provides researchers with the tools to culture and assess purity and adipogenic differentiation capacity of human ASCs, which can then be utilized for required downstream in vitro applications. This protocol has been modified from Baglioni et al. (2009), Baglioni et al. (2012), and van Harmelen et al. (2005) to describe in detail a complete technique to isolate and subsequently characterize human ASCs from human WAT biopsies. This protocol has been utilized to isolate and characterize human ASCs from both subcutaneous and visceral WAT. The isolated human ASCs show high purity and demonstrate adipogenic differentiation capacity in vitro

Telomerase regulates MYC-driven oncogenesis independent of its reverse transcriptase activity

Constitutively active MYC and reactivated telomerase often coexist in cancers. While reactivation of telomerase is thought to be essential for replicative immortality, MYC, in conjunction with cofactors, confers several growth advantages to cancer cells. It is known that the reactivation of TERT, the catalytic subunit of telomerase, is limiting for reconstituting telomerase activity in tumors. However, while reactivation of TERT has been functionally linked to the acquisition of several “hallmarks of cancer” in tumors, the molecular mechanisms by which this occurs and whether these mechanisms are distinct from the role of telomerase on telomeres is not clear. Here, we demonstrated that first-generation TERT-null mice, unlike Terc-null mice, show delayed onset of MYC-induced lymphomagenesis. We further determined that TERT is a regulator of MYC stability in cancer. TERT stabilized MYC levels on chromatin, contributing to either activation or repression of its target genes. TERT regulated MYC ubiquitination and proteasomal degradation, and this effect of TERT was independent of its reverse transcriptase activity and role in telomere elongation. Based on these data, we conclude that reactivation of TERT, a direct transcriptional MYC target in tumors, provides a feed-forward mechanism to potentiate MYC-dependent oncogenesis

The transcription factor SOX6 contributes to the developmental origins of obesity by promoting adipogenesis

International audienceAn association between impaired fetal growth and the postnatal development of obesity has been established. Here, by comparing adipocytes differentiated from mesenchymal stem cells (MSCs) taken from the umbilical cord and derived from normal and growth-restricted neonates, we identified the transcription factor SOX6 as highly expressed only in growth-restricted individuals. We found that SOX6 regulates adipogenesis in vertebrate species by activating adipogenic regulators including PPARγ, C/EBPα and MEST. We further show that SOX6 interacts with β-catenin in adipocytes, suggesting an inhibition of WNT/β-catenin signaling, thereby promoting adipogenesis. The upstream regulatory region of the MEST gene in MSCs from growth-restricted subjects harbors hypomethylated CpGs next to SOX6 binding motifs, and we found that SOX6 binding is impaired by adjacent CpG methylation. In summary, we report that SOX6 is a novel regulator of adipogenesis synergizing with epigenetic mechanisms

Telomerase regulates MYC-driven oncogenesis independent of its reverse transcriptase activity

10.1172/JCI79134Journal of Clinical Investigation12552109-212

The transcription factor SOX6 contributes to the developmental origins of obesity by promoting adipogenesis

An association between impaired fetal growth and the postnatal development of obesity has been established. Here, by comparing adipocytes differentiated from mesenchymal stem cells (MSCs) taken from the umbilical cord and derived from normal and growth-restricted neonates, we identified the transcription factor SOX6 as highly expressed only in growth-restricted individuals. We found that SOX6 regulates adipogenesis in vertebrate species by activating adipogenic regulators including PPARγ, C/EBPα and MEST. We further show that SOX6 interacts with β-catenin in adipocytes, suggesting an inhibition of WNT/β-catenin signaling, thereby promoting adipogenesis. The upstream regulatory region of the MEST gene in MSCs from growth-restricted subjects harbors hypomethylated CpGs next to SOX6 binding motifs, and we found that SOX6 binding is impaired by adjacent CpG methylation. In summary, we report that SOX6 is a novel regulator of adipogenesis synergizing with epigenetic mechanisms