Muscle ring finger-3 protects against diabetic cardiomyopathy induced by a high fat diet

CITATION: Quintata, M. T. et al. 2015. Muscle ring finger-3 protects against diabetic cardiomyopathy induced by a high fat diet. BMC Endocrine Disorders, 15:36, doi:10.1186/s12902-015-0028-z.The original publication is available at http://bmcendocrdisord.biomedcentral.comBackground: The pathogenesis of diabetic cardiomyopathy (DCM) involves the enhanced activation of peroxisome proliferator activating receptor (PPAR) transcription factors, including the most prominent isoform in the heart, PPARα. In cancer cells and adipocytes, post-translational modification of PPARs have been identified, including ligand-dependent degradation of PPARs by specific ubiquitin ligases. However, the regulation of PPARs in cardiomyocytes and heart have not previously been identified. We recently identified that muscle ring finger-1 (MuRF1) and MuRF2 differentially inhibit PPAR activities by mono-ubiquitination, leading to the hypothesis that MuRF3 may regulate PPAR activity in vivo to regulate DCM. Methods: MuRF3−/− mice were challenged with 26 weeks 60 % high fat diet to induce insulin resistance and DCM. Conscious echocardiography, blood glucose, tissue triglyceride, glycogen levels, immunoblot analysis of intracellular signaling, heart and skeletal muscle morphometrics, and PPARα, PPARβ, and PPARγ1 activities were assayed. Results: MuRF3−/− mice exhibited a premature systolic heart failure by 6 weeks high fat diet (vs. 12 weeks in MuRF3+/+). MuRF3−/− mice weighed significantly less than sibling-matched wildtype mice after 26 weeks HFD. These differences may be largely due to resistance to fat accumulation, as MRI analysis revealed MuRF3−/− mice had significantly less fat mass, but not lean body mass. In vitro ubiquitination assays identified MuRF3 mono-ubiquitinated PPARα and PPARγ1, but not PPARβ. Conclusions: These findings suggest that MuRF3 helps stabilize cardiac PPARα and PPARγ1 in vivo to support resistance to the development of DCM. MuRF3 also plays an unexpected role in regulating fat storage despite being found only in striated muscle.http://bmcendocrdisord.biomedcentral.com/articles/10.1186/s12902-015-0028-zPublisher's versio

Determining the Appropriate Level of Deference for Domestic Court Reviews of Investor-State Arbitral Awards

Figure S4. Detection of cardiac O-GlcNac Protein modifications in MuRF2-/- mice after 26 weeks HFD challenge. A. Densitometric analysis of O-GlcNac/βactin immunoblot (B). N=3/group. Values expressed as Mean ¹ SE. A one-way ANOVA was performed to determine significance followed by an All Pairwise Multiple Comparison Procedure (Holm-Sidak method). #p<0.05

MuRF2 regulates PPARγ1 activity to protect against diabetic cardiomyopathy and enhance weight gain induced by a high fat diet

CITATION: He, J., et al. 2015. MuRF2 regulates PPARγ1 activity to protect against diabetic cardiomyopathy and enhance weight gain induced by a high fat diet. Cardiovascular Diabetology, 14:97, doi:10.1186/s12933-015-0252-x.The original publication is available at http://cardiab.biomedcentral.comBackground: In diabetes mellitus the morbidity and mortality of cardiovascular disease is increased and represents an important independent mechanism by which heart disease is exacerbated. The pathogenesis of diabetic cardiomyopathy involves the enhanced activation of PPAR transcription factors, including PPARα, and to a lesser degree PPARβ and PPARγ1. How these transcription factors are regulated in the heart is largely unknown. Recent studies have described post-translational ubiquitination of PPARs as ways in which PPAR activity is inhibited in cancer. However, specific mechanisms in the heart have not previously been described. Recent studies have implicated the musclespecific ubiquitin ligase muscle ring finger-2 (MuRF2) in inhibiting the nuclear transcription factor SRF. Initial studies of MuRF2−/− hearts revealed enhanced PPAR activity, leading to the hypothesis that MuRF2 regulates PPAR activity by post-translational ubiquitination. Methods: MuRF2−/− mice were challenged with a 26-week 60% fat diet designed to simulate obesity-mediated insulin resistance and diabetic cardiomyopathy. Mice were followed by conscious echocardiography, blood glucose, tissue triglyceride, glycogen levels, immunoblot analysis of intracellular signaling, heart and skeletal muscle morphometrics, and PPARα, PPARβ, and PPARγ1-regulated mRNA expression. Results: MuRF2 protein levels increase ~20% during the development of diabetic cardiomyopathy induced by high fat diet. Compared to littermate wildtype hearts, MuRF2−/− hearts exhibit an exaggerated diabetic cardiomyopathy, characterized by an early onset systolic dysfunction, larger left ventricular mass, and higher heart weight. MuRF2−/− hearts had significantly increased PPARα- and PPARγ1-regulated gene expression by RT-qPCR, consistent with MuRF2’s regulation of these transcription factors in vivo. Mechanistically, MuRF2 mono-ubiquitinated PPARα and PPARγ1 in vitro, consistent with its non-degradatory role in diabetic cardiomyopathy. However, increasing MuRF2:PPARγ1 (>5:1) beyond physiological levels drove poly-ubiquitin-mediated degradation of PPARγ1 in vitro, indicating large MuRF2 increases may lead to PPAR degradation if found in other disease states. Conclusions: Mutations in MuRF2 have been described to contribute to the severity of familial hypertrophic cardiomyopathy. The present study suggests that the lack of MuRF2, as found in these patients, can result in an exaggerated diabetic cardiomyopathy. These studies also identify MuRF2 as the first ubiquitin ligase to regulate cardiac PPARα and PPARγ1 activities in vivo via post-translational modification without degradation.http://cardiab.biomedcentral.com/articles/10.1186/s12933-015-0252-xPublisher's versio

Evaluation of the Association Between Genetic Variants in Circadian Rhythm Genes and Posttraumatic Stress Symptoms Identifies a Potential Functional Allele in the Transcription Factor

Previous studies suggest that genetic variants within genes affecting the circadian rhythm influence the development of posttraumatic stress symptoms (PTSS). In the present study, we used data from three emergency care-based cohorts to search genetic variants in circadian pathway genes previously associated with neuropsychiatric disorders for variants that influence PTSS severity. The three cohorts used included a discovery cohort of African American men and women enrolled following motor vehicle collision (n = 907) and two replication cohorts: one of multi-ethnic women enrolled following sexual assault (n = 274) and one of multi-ethnic men and women enrolled following major thermal burn injury (n = 68). DNA and RNA were collected from trauma survivors at the time of initial assessment. Validated questionnaires were used to assess peritraumatic distress severity and to assess PTSS severity 6 weeks, 6 months, and 1 year following trauma exposure. Thirty-one genetic variants from circadian rhythm genes were selected for analyses, and main effect and potential gene*stress and gene*sex interactions were evaluated. Secondary analyses assessed whether associated genetic variants affected mRNA expression levels. We found that six genetic variants across five circadian rhythm-associated genes predicted PTSS outcomes following motor vehicle collision (p \u3c 0.05), but only two of these variants survived adjustment for multiple comparisons (False Discovery Rate \u3c 5%). The strongest of these associations, an interaction between the PAR-zip transcription factor, thyrotroph embryonic factor (TEF) variant rs5758324 and peritraumatic distress, predicted PTSS development in all three cohorts. Further analysis of genetic variants in the genetic region surrounding TEFrs5758324 (±125,000 nucleotides) indicated that this allele showed the strongest association. Further, TEF RNA expression levels (determined via RNA-seq) were positively associated with PTSS severity in distressed individuals with at least one copy of the TEFrs5758324 minor allele. These results suggest that rs5758324 genetic variant in TEF, a regulator of clock-controlled genes and key mediator of the core circadian rhythm, influence PTSS severity in a stress-dependent manner

Additional file 2: of MuRF2 regulates PPARÎł1 activity to protect against diabetic cardiomyopathy and enhance weight gain induced by a high fat diet

Figure S2. Histological analysis of MuRF2-/- mice. A. Representative H&E analysis of MuRF2-/- and MuRF2+/+ tissue. B. Single MuRF2+/+ heart from mouse found dead 21 weeks high fat diet reveals amorphous way infiltration (arrows) and rare leukocytes infiltrations (*). C. Analysis of Masson’s Trichrome stained slides of MuRF2+/+ heart revealed ~3% fibrosis

Additional file 3: of MuRF2 regulates PPARγ1 activity to protect against diabetic cardiomyopathy and enhance weight gain induced by a high fat diet

Figure S3. mRNA analysis of cardiac PPAR isoform expression in MuRF2 -/- mice. Quantitative RT qPCR analysis of cardiac A. PPAR∝ mRNA B. PPARβ mRNA and C. PPARγ1 mRNA at baseline and 26 weeks after high fat diet compared to sibling-matched wild type hearts. N=5/group. A one-way ANOVA was performed to determine significance followed by an All Pairwise Multiple Comparison Procedure (Holm-Sidak method). *p<0.001

Additional file 6: of MuRF2 regulates PPARÎł1 activity to protect against diabetic cardiomyopathy and enhance weight gain induced by a high fat diet

Figure S6. Pathway analysis of VIP and t-test significant metabolites found in non-targeted metabolomics analysis of MuRF2-/- hearts after high fat diet. N=3/group

Evaluation of the Association Between Genetic Variants in Circadian Rhythm Genes and Posttraumatic Stress Symptoms Identifies a Potential Functional Allele in the Transcription Factor TEF

Previous studies suggest that genetic variants within genes affecting the circadian rhythm influence the development of posttraumatic stress symptoms (PTSS). In the present study, we used data from three emergency care-based cohorts to search genetic variants in circadian pathway genes previously associated with neuropsychiatric disorders for variants that influence PTSS severity. The three cohorts used included a discovery cohort of African American men and women enrolled following motor vehicle collision (n = 907) and two replication cohorts: one of multi-ethnic women enrolled following sexual assault (n = 274) and one of multi-ethnic men and women enrolled following major thermal burn injury (n = 68). DNA and RNA were collected from trauma survivors at the time of initial assessment. Validated questionnaires were used to assess peritraumatic distress severity and to assess PTSS severity 6 weeks, 6 months, and 1 year following trauma exposure. Thirty-one genetic variants from circadian rhythm genes were selected for analyses, and main effect and potential gene*stress and gene*sex interactions were evaluated. Secondary analyses assessed whether associated genetic variants affected mRNA expression levels. We found that six genetic variants across five circadian rhythm-associated genes predicted PTSS outcomes following motor vehicle collision (p < 0.05), but only two of these variants survived adjustment for multiple comparisons (False Discovery Rate < 5%). The strongest of these associations, an interaction between the PAR-zip transcription factor, thyrotroph embryonic factor (TEF) variant rs5758324 and peritraumatic distress, predicted PTSS development in all three cohorts. Further analysis of genetic variants in the genetic region surrounding TEFrs5758324 (±125,000 nucleotides) indicated that this allele showed the strongest association. Further, TEF RNA expression levels (determined via RNA-seq) were positively associated with PTSS severity in distressed individuals with at least one copy of the TEFrs5758324 minor allele. These results suggest that rs5758324 genetic variant in TEF, a regulator of clock-controlled genes and key mediator of the core circadian rhythm, influence PTSS severity in a stress-dependent manner.</p