Social stress, obesity and glucose tolerance: a psychobiological investigation

Social stress, obesity and glucose tolerance: a psychobiological investigation Stress has been associated with changes in eating behavior and food preferences (Dallman et al. 2003). In humans psychosocial and socio-economical challenges have been related with neuroendocrine-autonomic dysregulation followed by visceral obesity and increased in body mass index (BMI) (Van Strien et al. 1986, Rosmond, Dallman and Björntorp 1998). The chronic activation of stress response system, leads to an increase in food intake, especially high palatable food (Dallman et al. 2004, Dallman et al. 2005), obesity and metabolic syndrome (Rosmond et al. 1998, Björntorp 1993, Björntorp 1996a, Tsigos and Chrousos 2002). Altogether these metabolic disorders result in a pre-diabetic state, which may turn in type 2 diabetes (T2D) in susceptible individuals in a nutrional rich environment (Björntorp 1996b, Boden 2002, Chan et al. 1994, Colditz et al. 1990, DeFronzo 2004). In addition, comorbid pathology such as “atypical depression” linked to stress (DSM-IV, American Psychiatric Association, 2000) has been associated to eating disorders-induced obesity.(Mitchell and Mussell 1995, Stein et al. 2007, Stunkard 2011). While several genetic or pharmacological animal models of metabolic syndrome and T2D have been developed, so far there is a paucity of models in which the diseases are triggered by psychogenic stimuli. Aim of the present study is: Chapter One: the original characterization of a mouse models of early metabolic syndrome/T2D onset induced by exposing mice to chronic subordination stress in the presence of high fat diet. Chapter Two: determine if vulnerability to stress induced metabolic disease is status dependent. Specifically we will directly compare the metabolic consequences of being high in rank (dominant) and low in rank (subordinate) in mice exposed to our model of chronic psychosocial stress CPS and HFD Chapter Three: characterized if CPS may be considered a model of stress- induced binge eating disorders (BED) and understand the role of hyperphagia in stressed-induced obesity and T2D using a Pair-feeding protocol

Notch activation is required for downregulation of HoxA3-dependent endothelial cell phenotype during blood formation.

Hemogenic endothelium (HE) undergoes endothelial-to-hematopoietic transition (EHT) to generate blood, a process that requires progressive down-regulation of endothelial genes and induction of hematopoietic ones. Previously, we have shown that the transcription factor HoxA3 prevents blood formation by inhibiting Runx1 expression, maintaining endothelial gene expression and thus blocking EHT. In the present study, we show that HoxA3 also prevents blood formation by inhibiting Notch pathway. HoxA3 induced upregulation of Jag1 ligand in endothelial cells, which led to cis-inhibition of the Notch pathway, rendering the HE nonresponsive to Notch signals. While Notch activation alone was insufficient to promote blood formation in the presence of HoxA3, activation of Notch or downregulation of Jag1 resulted in a loss of the endothelial phenotype which is a prerequisite for EHT. Taken together, these results demonstrate that Notch pathway activation is necessary to downregulate endothelial markers during EHT

Chronic subordination stress selectively downregulates the insulin signaling pathway in liver and skeletal muscle but not in adipose tissue of male mice

Chronic stress has been associated with obesity, glucose intolerance, and insulin resistance. We developed a model of chronic psychosocial stress (CPS) in which subordinate mice are vulnerable to obesity and the metabolic-like syndrome while dominant mice exhibit a healthy metabolic phenotype. Here we tested the hypothesis that the metabolic difference between subordinate and dominant mice is associated with changes in functional pathways relevant for insulin sensitivity, glucose and lipid homeostasis. Male mice were exposed to CPS for four weeks and fed either a standard diet or a high-fat diet (HFD). We first measured, by real-time PCR candidate genes, in the liver, skeletal muscle, and the perigonadal white adipose tissue (pWAT). Subsequently, we used a probabilistic analysis approach to analyze different ways in which signals can be transmitted across the pathways in each tissue. Results showed that subordinate mice displayed a drastic downregulation of the insulin pathway in liver and muscle, indicative of insulin resistance, already on standard diet. Conversely, pWAT showed molecular changes suggestive of facilitated fat deposition in an otherwise insulin-sensitive tissue. The molecular changes in subordinate mice fed a standard diet were greater compared to HFD-fed controls. Finally, dominant mice maintained a substantially normal metabolic and molecular phenotype even when fed a HFD. Overall, our data demonstrate that subordination stress is a potent stimulus for the downregulation of the insulin signaling pathway in liver and muscle and a major risk factor for the development of obesity, insulin resistance, and type 2 diabetes mellitus.Supported by UofMN Medical School start-up funds to AB, Medical Research Council MRC Disease Model Core and British Heart Foundation program grants to AVP, and BIO2011-27069 from the Spanish Ministry of Economy and Competitiveness and PROMETEOII/2014/025 from the GVA-FEDER to JD. VS was supported by a graduate student fellowship of the University of Parma. CC was supported by EU FP7-People Project(ref 316861) "MLPM2012: Machine Learning For Personalized Medicine".This is the final version of the article. It first appeared from Taylor & Francis via http://dx.doi.org/10.3109/10253890.2016.115149

Chronic subordination stress selectively downregulates the insulin signaling pathway in liver and skeletal muscle but not in adipose tissue of male mice.

Chronic stress has been associated with obesity, glucose intolerance, and insulin resistance. We developed a model of chronic psychosocial stress (CPS) in which subordinate mice are vulnerable to obesity and the metabolic-like syndrome while dominant mice exhibit a healthy metabolic phenotype. Here we tested the hypothesis that the metabolic difference between subordinate and dominant mice is associated with changes in functional pathways relevant for insulin sensitivity, glucose and lipid homeostasis. Male mice were exposed to CPS for four weeks and fed either a standard diet or a high-fat diet (HFD). We first measured, by real-time PCR candidate genes, in the liver, skeletal muscle, and the perigonadal white adipose tissue (pWAT). Subsequently, we used a probabilistic analysis approach to analyze different ways in which signals can be transmitted across the pathways in each tissue. Results showed that subordinate mice displayed a drastic downregulation of the insulin pathway in liver and muscle, indicative of insulin resistance, already on standard diet. Conversely, pWAT showed molecular changes suggestive of facilitated fat deposition in an otherwise insulin-sensitive tissue. The molecular changes in subordinate mice fed a standard diet were greater compared to HFD-fed controls. Finally, dominant mice maintained a substantially normal metabolic and molecular phenotype even when fed a HFD. Overall, our data demonstrate that subordination stress is a potent stimulus for the downregulation of the insulin signaling pathway in liver and muscle and a major risk factor for the development of obesity, insulin resistance, and type 2 diabetes mellitus.Supported by UofMN Medical School start-up funds to AB, Medical Research Council MRC Disease Model Core and British Heart Foundation program grants to AVP, and BIO2011-27069 from the Spanish Ministry of Economy and Competitiveness and PROMETEOII/2014/025 from the GVA-FEDER to JD. VS was supported by a graduate student fellowship of the University of Parma. CC was supported by EU FP7-People Project(ref 316861) "MLPM2012: Machine Learning For Personalized Medicine".This is the final version of the article. It first appeared from Taylor & Francis via http://dx.doi.org/10.3109/10253890.2016.115149

Evaluation of commonly used ectoderm markers in iPSC trilineage differentiation.

Patient-derived induced pluripotent stem cells (iPSCs) have become a promising resource for exploring genetics of complex diseases, discovering new drugs, and advancing regenerative medicine. Increasingly, laboratories are creating their own banks of iPSCs derived from diverse donors. However, there are not yet standardized guidelines for qualifying these cell lines, i.e., distinguishing between bona fide human iPSCs, somatic cells, and imperfectly reprogrammed cells. Here, we report the establishment of a panel of 30 iPSCs from CD34+ peripheral blood mononuclear cells, of which 10 were further differentiated in vitro into all three germ layers. We characterized these different cell types with commonly used pluripotent and lineage specific markers, and showed that NES, TUBB3, and OTX2 cannot be reliably used as ectoderm differentiation markers. Our work highlights the importance of marker selection in iPSC authentication, and the need for the field to establish definitive standard assays

Brain transplantation of genetically corrected Sanfilippo type B neural stem cells induces partial cross-correction of the disease

Sanfilippo syndrome type B (mucopolysaccharidosis type IIIB) is a recessive genetic disorder that severely affects the brain due to a deficiency in the enzyme α

Altered cofactor regulation with disease-associated p97/VCP mutations

Dominant mutations in p97/VCP (valosin-containing protein) cause a rare multisystem degenerative disease with varied phenotypes that include inclusion body myopathy, Paget’s disease of bone, frontotemporal dementia, and amyotrophic lateral sclerosis. p97 disease mutants have altered N-domain conformations, elevated ATPase activity, and altered cofactor association. We have now discovered a previously unidentified disease-relevant functional property of p97 by identifying how the cofactors p37 and p47 regulate p97 ATPase activity. We define p37 as, to our knowledge, the first known p97-activating cofactor, which enhances the catalytic efficiency (k_(cat)/K_m) of p97 by 11-fold. Whereas both p37 and p47 decrease the K_m of ATP in p97, p37 increases the k_(cat) of p97. In contrast, regulation by p47 is biphasic, with decreased k_(cat) at low levels but increased k_(cat) at higher levels. By deleting a region of p47 that lacks homology to p37 (amino acids 69–92), we changed p47 from an inhibitory cofactor to an activating cofactor, similar to p37. Our data suggest that cofactors regulate p97 ATPase activity by binding to the N domain. Induced conformation changes affect ADP/ATP binding at the D1 domain, which in turn controls ATPase cycling. Most importantly, we found that the D2 domain of disease mutants failed to be activated by p37 or p47. Our results show that cofactors play a critical role in controlling p97 ATPase activity, and suggest that lack of cofactor-regulated communication may contribute to p97-associated disease pathogenesis

HoxA3 Controls Notch Pathway to Repress Blood Development

Hematopoietic stem cells (HSC) are generated from a specialized subset of endothelial cells, hemogenic endothelium. Previous studies performed by our group showed that HoxA3 restrains the cell at the hemogenic endothelium stage, inhibiting further differentiation toward blood by direct repression of Runx1. Building on our previous work, we show here that overexpression of HoxA3 affects the Notch pathway. Upon HoxA3 upregulation in endothelial cells, Jag1 is induced, Mfng (Manic) and Lfng (Lunatic) fringes are downregulated, and there is a trend towards Notch target gene repression. These data suggest that in the presence of HoxA3, endothelial cells are blocked from receiving Notch signal through ligand cis-inhibition with resulting blood inhibition. In order to test this hypothesis, we evaluated the effect of activation or inhibition of the Notch pathway during blood development. We show here that the number of blood progenitors originating from the hemogenic endothelium is decreased when the Notch pathway is inhibited. Conversely, induction of the pathway by upregulation of NICD (Notch1 Intra Cellular Domain) promotes an increase in the number of blood progenitors originating from hemogenic endothelium. Furthermore, inhibition of the pathway when HoxA3 is upregulated has little or no effect in blood while induction of the pathway in HoxA3 presence in part promotes blood development. Taken together, these results demonstrate that Notch pathway is both sufficient and essential for blood development. Specifically HoxA3 inhibits Notch signal reception in two ways: 1) HoxA3 increases Jag1 ligand expression that acts in cis-inhibition; 2) represses Manic and Lunatic fringes both necessary to increase the affinity of Notch receptors for the Delta ligands. When this blockage is bypassed by NICD upregulation, blood is formed, demonstrating that HoxA3-dependent Notch inhibition results in blood suppression

Genetically Corrected iPSC-Derived Neural Stem Cell Grafts Deliver Enzyme Replacement to Affect CNS Disease in Sanfilippo B Mice

Sanfilippo syndrome type B (mucopolysaccharidosis type IIIB [MPS IIIB]) is a lysosomal storage disorder primarily affecting the brain that is caused by a deficiency in the enzyme α-N-acetylglucosaminidase (NAGLU), leading to intralysosomal accumulation of heparan sulfate. There are currently no treatments for this disorder. Here we report that, ex vivo, lentiviral correction of Naglu−/− neural stem cells derived from Naglu−/− mice (iNSCs) corrected their lysosomal pathology and allowed them to secrete a functional NAGLU enzyme that could be taken up by deficient cells. Following long-term transplantation of these corrected iNSCs into Naglu−/− mice, we detected NAGLU activity in the majority of engrafted animals. Successfully transplanted Naglu−/− mice showed a significant decrease in storage material, a reduction in astrocyte activation, and complete prevention of microglial activation within the area of engrafted cells and neighboring regions, with beneficial effects extending partway along the rostrocaudal axis of the brain. Our results demonstrate long-term engraftment of iNSCs in the brain that are capable of cross-correcting pathology in Naglu−/− mice. Our findings suggest that genetically engineered iNSCs could potentially be used to deliver enzymes and treat MPS IIIB. Keywords: MPS IIIB, lysosomal storage disorder, stem cell therap