Axonal pathology in hPSC-based models of Parkinson's disease results from loss of Nrf2 transcriptional activity at the Map1b gene locus.

While mutations in the SNCA gene (α-synuclein [α-syn]) are causal in rare familial forms of Parkinson's disease (PD), the prevalence of α-syn aggregates in the cortices of sporadic disease cases emphasizes the need to understand the link between α-syn accumulation and disease pathogenesis. By employing a combination of human pluripotent stem cells (hPSCs) that harbor the SNCA-A53T mutation contrasted against isogenic controls, we evaluated the consequences of α-syn accumulation in human A9-type dopaminergic (DA) neurons (hNs). We show that the early accumulation of α-syn in SNCA-A53T hNs results in changes in gene expression consistent with the expression profile of the substantia nigra (SN) from PD patients, analyzed post mortem. Differentially expressed genes from both PD patient SN and SNCA-A53T hNs were associated with regulatory motifs transcriptionally activated by the antioxidant response pathway, particularly Nrf2 gene targets. Differentially expressed gene targets were also enriched for gene ontologies related to microtubule binding processes. We thus assessed the relationship between Nrf2-mediated gene expression and neuritic pathology in SNCA-A53T hNs. We show that SNCA-mutant hNs have deficits in neuritic length and complexity relative to isogenic controls as well as contorted axons with Tau-positive varicosities. Furthermore, we show that mutant α-syn fails to complex with protein kinase C (PKC), which, in turn, results in impaired activation of Nrf2. These neuritic defects result from impaired Nrf2 activity on antioxidant response elements (AREs) localized to a microtubule-associated protein (Map1b) gene enhancer and are rescued by forced expression of Map1b as well as by both Nrf2 overexpression and pharmaceutical activation in PD neurons.

HDAC-regulated myomiRs control BAF60 variant exchange and direct the functional phenotype of fibro-adipogenic progenitors in dystrophic muscles.

Fibro-adipogenic progenitors (FAPs) are important components of the skeletal muscle regenerative environment. Whether FAPs support muscle regeneration or promote fibro-adipogenic degeneration is emerging as a key determinant in the pathogenesis of muscular diseases, including Duchenne muscular dystrophy (DMD). However, the molecular mechanism that controls FAP lineage commitment and activity is currently unknown. We show here that an HDAC-myomiR-BAF60 variant network regulates the fate of FAPs in dystrophic muscles of mdx mice. Combinatorial analysis of gene expression microarray, genome-wide chromatin remodeling by nuclease accessibility (NA) combined with next-generation sequencing (NA-seq), small RNA sequencing (RNA-seq), and microRNA (miR) high-throughput screening (HTS) against SWI/SNF BAF60 variants revealed that HDAC inhibitors (HDACis) derepress a "latent" myogenic program in FAPs from dystrophic muscles at early stages of disease. Specifically, HDAC inhibition induces two core components of the myogenic transcriptional machinery, MYOD and BAF60C, and up-regulates the myogenic miRs (myomiRs) (miR-1.2, miR-133, and miR-206), which target the alternative BAF60 variants BAF60A and BAF60B, ultimately directing promyogenic differentiation while suppressing the fibro-adipogenic phenotype. In contrast, FAPs from late stage dystrophic muscles are resistant to HDACi-induced chromatin remodeling at myogenic loci and fail to activate the promyogenic phenotype. These results reveal a previously unappreciated disease stage-specific bipotency of mesenchimal cells within the regenerative environment of dystrophic muscles. Resolution of such bipotency by epigenetic intervention with HDACis provides a molecular rationale for the in situ reprogramming of target cells to promote therapeutic regeneration of dystrophic muscles.

Comparison of the effects of standard vs low-dose prolonged-release tacrolimus with or without ACEi/ARB on the histology and function of renal allografts.

Targeting the renin-angiotensin system and optimizing tacrolimus exposure are both postulated to improve outcomes in renal transplant recipients (RTRs) by preventing interstitial fibrosis/tubular atrophy (IF/TA). In this multicenter, prospective, open-label controlled trial, adult de novo RTRs were randomized in a 2 × 2 design to low- vs standard-dose (LOW vs STD) prolonged-release tacrolimus and to angiotensin-converting enzyme inhibitors/angiotensin II receptor 1 blockers (ACEi/ARBs) vs other antihypertensive therapy (OAHT). There were 2 coprimary endpoints: the prevalence of IF/TA at month 6 and at month 24. IF/TA prevalence was similar for LOW vs STD tacrolimus at month 6 (36.8% vs 39.5%; P = .80) and ACEi/ARBs vs OAHT at month 24 (54.8% vs 58.2%; P = .33). IF/TA progression decreased significantly with LOW vs STD tacrolimus at month 24 (mean [SD] change, +0.42 [1.477] vs +1.10 [1.577]; P = .0039). Across the 4 treatment groups, LOW + ACEi/ARB patients exhibited the lowest mean IF/TA change and, compared with LOW + OAHT patients, experienced significantly delayed time to first T cell-mediated rejection. Renal function was stable from month 1 to month 24 in all treatment groups. No unexpected safety findings were detected. Coupled with LOW tacrolimus dosing, ACEi/ARBs appear to reduce IF/TA progression and delay rejection relative to reduced tacrolimus exposure without renin-angiotensin system blockade. ClinicalTrials.gov identifier: NCT00933231.

Nitration of microtubules blocks axonal mitochondrial transport in a human pluripotent stem cell model of Parkinson's disease.

Neuronal loss in Parkinson's disease (PD) is associated with aberrant mitochondrial function in dopaminergic (DA) neurons of the substantia nigra pars compacta. An association has been reported between PD onset and exposure to mitochondrial toxins, including the agrochemicals paraquat (PQ), maneb (MB), and rotenone (Rot). Here, with the use of a patient-derived stem cell model of PD, allowing comparison of DA neurons harboring a mutation in the α-synuclein (α-syn) gene ( SNCA-A53T) against isogenic, mutation-corrected controls, we describe a novel mechanism whereby NO, generated from SNCA-A53T mutant neurons exposed to Rot or PQ/MB, inhibits anterograde mitochondrial transport through nitration of α-tubulin (α-Tub). Nitration of α-Tub inhibited the association of both α-syn and the mitochondrial motor protein kinesin 5B with the microtubules, arresting anterograde transport. This was, in part, a result of nitration of α-Tub in the C-terminal domain. These effects were rescued by inhibiting NO synthesis with the NOS inhibitor Nω-nitro-L-arginine methyl ester. Collectively, our results are the first to demonstrate a gene by environment interaction in PD, whereby agrochemical exposure selectively triggers a deficit in mitochondrial transport by nitrating the microtubules in neurons harboring the SNCA-A53T mutation.-Stykel, M. G., Humphries, K., Kirby, M. P., Czaniecki, C., Wang, T., Ryan, T., Bamm, V., Ryan, S. D. Nitration of microtubules blocks axonal mitochondrial transport in a human pluripotent stem cell model of Parkinson's disease.

Myosin phosphatase modulates the cardiac cell fate by regulating the subcellular localization of Nkx2.5 in a Wnt/Rho-associated protein kinase-dependent pathway.

RATIONALE: Nkx2.5 is a transcription factor that regulates cardiomyogenesis in vivo and in embryonic stem cells. It is also a common target in congenital heart disease. Although Nkx2.5 has been implicated in the regulation of many cellular processes that ultimately contribute to cardiomyogenesis and morphogenesis of the mature heart, relatively little is known about how it is regulated at a functional level. OBJECTIVE: We have undertaken a proteomic screen to identify novel binding partners of Nkx2.5 during cardiomyogenic differentiation in an effort to better understand the regulation of its transcriptional activity. METHODS AND RESULTS: Purification of Nkx2.5 from differentiating cells identified the myosin phosphatase subunits protein phosphatase 1ß and myosin phosphatase targeting subunit 1 (Mypt1) as novel binding partners. The interaction with protein phosphatase 1 ß/Mypt1 resulted in exclusion of Nkx2.5 from the nucleus and, consequently, inhibition of its transcriptional activity. Exclusion of Nkx2.5 was inhibited by treatment with leptomycin B and was dependent on an Mypt1 nuclear export signal. Furthermore, in transient transfection experiments, Nkx2.5 colocalized outside the nucleus with phosphorylated Mypt1 in a manner dependent on Wnt signaling and Rho-associated protein kinase. Treatment of differentiating mouse embryonic stem cells with Wnt3a resulted in enhanced phosphorylation of endogenous Mypt1, increased nuclear exclusion of endogenous Nkx2.5, and a failure to undergo terminal cardiomyogenesis. Finally, knockdown of Mypt1 resulted in rescue of Wnt3a-mediated inhibition of cardiomyogenesis, indicating that Mypt1 is required for this process. CONCLUSIONS: We have identified a novel interaction between Nkx2.5 and myosin phosphatase. Promoting this interaction represents a novel mechanism whereby Wnt3a regulates Nkx2.5 and inhibits cardiomyogenesis.

Stem cell models of inherited arrhythmias.

Inherited arrhythmias are a heterogeneous group of conditions that confer risk of sudden death. Many inherited arrhythmias have been linked to pathogenic genetic variants that result in ion channel dysfunction, although current genetic testing panels fail to identify variants in many patients, potentially secondary to their underlying substrates being oligogenic or polygenic. Here we review the current state of knowledge surrounding the cellular mechanisms of inherited arrhythmias generated from stem cell models with a focus on integrating genetic and mechanistic data. The utility and limitations of human induced pluripotent stem cell models in disease modeling and drug development are also explored with a particular focus on examples of pharmacogenetics and precision medicine. We submit that progress in understanding inherited arrhythmias is likely to be made by using human induced pluripotent stem cells to model probable polygenic cases as well as to interrogate the diverse and potentially complex molecular networks implicated by genome-wide association studies.

Testosterone enhances cardiomyogenesis in stem cells and recruits the androgen receptor to the MEF2C and HCN4 genes.

Since a previous study (Goldman-Johnson et al., 2008 [4]) has shown that androgens can stimulate increased differentiation of mouse embryonic stem (mES) cells into cardiomyocytes using a genomic pathway, the aim of our study is to elucidate the molecular mechanisms regulating testosterone-enhanced cardiomyogenesis. Testosterone upregulated cardiomyogenic transcription factors, including GATA4, MEF2C, and Nkx2.5, muscle structural proteins, and the pacemaker ion channel HCN4 in a dose-dependent manner, in mES cells and P19 embryonal carcinoma cells. Knock-down of the androgen receptor (AR) or treatment with anti-androgenic compounds inhibited cardiomyogenesis, supporting the requirement of the genomic pathway. Chromatin immunoprecipitation (ChIP) studies showed that testosterone enhanced recruitment of AR to the regulatory regions of MEF2C and HCN4 genes, which was associated with increased histone acetylation. In summary, testosterone upregulated cardiomyogenic transcription factor and HCN4 expression in stem cells. Further, testosterone induced cardiomyogenesis, at least in part, by recruiting the AR receptor to the regulatory regions of the MEF2C and HCN4 genes. These results provide a detailed molecular analysis of the function of testosterone in stem cells and may offer molecular insight into the role of steroids in the heart.

Emerging Targeted Therapies for Inherited Cardiomyopathies and Arrhythmias.

Inherited cardiomyopathy and arrhythmia syndromes are associated with significant morbidity and mortality, particularly in young people. Medical management of these conditions has primarily been limited to agents previously developed for more common forms of heart disease and not tailored to their distinct pathophysiology. As our understanding of their underlying genetics and disease mechanisms has improved, an era of targeted therapies for these rare conditions has begun to emerge. In recent years, several novel agents have been developed and tested in preclinical models and, in some cases, have advanced to both the clinical trial and clinical approval stages with exciting results. These new treatments are derived from multiple classes of therapeutics, including small molecules, antisense oligonucleotides, small interfering RNAs, adeno-associated virus-mediated gene therapies, and in vivo gene editing. Collectively, they carry the promise of revolutionizing management of affected patients and their families.

A Case of Pericarditis and Pericardial Masses Associated With Mycobacterium Paragordonae.

Tuberculosis is a common cause of pericarditis worldwide and has been associated with pericardial masses. Non-tuberculous mycobacteria are uncommonly associated with cardiac disease, having primarily been described in cases of endocarditis. Here we describe a case of an immunocompetent patient with Mycobacterium paragordonae infection causing pericarditis with a large effusion containing pericardial masses. The patient presented with chest pain, hypoxia and biochemical evidence of inflammation (CRP 216.1 mg/L). This report illustrates a rare case of pericarditis with pericardial masses associated with non-tuberculous mycobacteria and the first example of pericarditis associated with M. paragordonae.

New-Onset Atrial Fibrillation After Transcatheter Aortic Valve Replacement: A Systematic Review and Meta-Analysis.

OBJECTIVES: The authors aimed to identify risk factors and outcomes associated with new-onset atrial fibrillation (NOAF) after transcatheter aortic valve replacement (TAVR). BACKGROUND: NOAF is a common complication after TAVR, although estimates of the precise occurrence are variable. This study sought to quantify the occurrence of NOAF after TAVR and to explore the outcomes and predictors associated with this complication. METHODS: We searched Medline, EMBASE, and the Cochrane database from 2016 to 2020 for articles that reported NOAF after TAVR. We extracted data for studies published before 2016 from a previous systematic review. We pooled data using a random effects model. RESULTS: We identified 179 studies with 241,712 total participants (55,271 participants with pre-existing atrial fibrillation (AF) were excluded) that reported NOAF from 2008 to 2020. The pooled occurrence of NOAF after TAVR was 9.9% (95% CI: 8.1%-12%). NOAF after TAVR was associated with a longer index hospitalization (mean difference = 2.66 days; 95% CI: 1.05-4.27), a higher risk of stroke in the first 30 days (risk ratio [RR]: 2.35; 95% CI: 2.12-2.61), 30-day mortality (RR: 1.76; 95% CI: 1.12-2.76), major or life-threatening bleeding (RR: 1.60; 95% CI: 1.39-1.84), and permanent pacemaker implantation (RR: 1.12; 95% CI: 1.05-1.18). Risk factors for the development of NOAF after TAVR included higher Society of Thoracic Surgeons score, transapical access, pulmonary hypertension, chronic kidney disease, peripheral vascular disease, and severe mitral regurgitation, suggesting that the risk for NOAF is highest in more comorbid TAVR patients. CONCLUSIONS: NOAF is common after TAVR. Whether AF after TAVR is a causal factor or a marker of sicker patients remains unclear.

α-Synuclein mutation impairs processing of endomembrane compartments and promotes exocytosis and seeding of α-synuclein pathology.

Neuronal loss in Parkinson's disease (PD) is associated with impaired proteostasis and accumulation of α-syn microaggregates in dopaminergic neurons. These microaggregates promote seeding of α-synuclein (α-syn) pathology between synaptically linked neurons. However, the mechanism by which seeding is initiated is not clear. Using human pluripotent stem cell (hPSC) models of PD that allow comparison of SNCA mutant cells with isogenic controls, we find that SNCA mutant neurons accumulate α-syn deposits that cluster to multiple endomembrane compartments, specifically multivesicular bodies (MVBs) and lysosomes. We demonstrate that A53T and E46K α-syn variants bind and sequester LC3B monomers into detergent-insoluble microaggregates on the surface of late endosomes, increasing α-syn excretion via exosomes and promoting seeding of α-syn from SNCA mutant neurons to wild-type (WT) isogenic controls. Finally, we show that constitutive inactivation of LC3B promotes α-syn accumulation and seeding, while LC3B activation inhibits these events, offering mechanistic insight into the spread of synucleinopathy in PD.

Prevalence of Frailty in Patients Referred to the Kidney Transplant Waitlist.

Background: Comparisons between frailty assessment tools for waitlist candidates are a recognized priority area for kidney transplantation. We compared the prevalence of frailty using three established tools in a cohort of waitlist candidates. Methods: Waitlist candidates were prospectively enrolled from 2016 to 2020 across five centers. Frailty was measured using the Frailty Phenotype (FP), a 37-variable frailty index (FI), and the Clinical Frailty Scale (CFS). The FI and CFS were dichotomized using established cutoffs. Agreement was compared using κ coefficients. Area under the receiver operating characteristic (ROC) curves were generated to compare the FI and CFS (treated as continuous measures) with the FP. Unadjusted associations between each frailty measure and time to death or waitlist withdrawal were determined using an unadjusted Cox proportional hazards model. Results: Of 542 enrolled patients, 64% were male, 80% were White, and the mean age was 54±14 years. The prevalence of frailty by the FP was 16%. The mean FI score was 0.23±0.14, and the prevalence of frailty was 38% (score of ≥0.25). The median CFS score was three (IQR, 2-3), and the prevalence was 15% (score of ≥4). The κ values comparing the FP with the FI (0.44) and CFS (0.27) showed fair to moderate agreement. The area under the ROC curves for the FP and FI/CFS were 0.86 (good) and 0.69 (poor), respectively. Frailty by the CFS (HR, 2.10; 95% CI, 1.04 to 4.24) and FI (HR, 1.79; 95% CI, 1.00 to 3.21) was associated with death or permanent withdrawal. The association between frailty by the FP and death/withdrawal was not statistically significant (HR, 1.78; 95% CI, 0.79 to 3.71). Conclusion: Frailty prevalence varies by the measurement tool used, and agreement between these measurements is fair to moderate. This has implications for determining the optimal frailty screening tool for use in those being evaluated for kidney transplant.

A quality of life comparison in cyclosporine- and tacrolimus-treated renal transplant recipients across Canada.

BACKGROUND: Many Canadian renal transplant recipients receive either cyclosporine or tacrolimus as a long-term immunosuppressive agent. We investigated the effect of these drugs on quality of life (QoL) in Canadian transplant recipients. METHODS: We included adult single-organ recipients undergoing a transplant between July 1997 and March 2005, whose graft function was =18 months, recruited across 13 Canadian sites including 5 transplant centers (TCs) and 8 satellite centers (SCs). Patients were stratified 3:1 by cyclosporine vs. tacrolimus based on calcineurin inhibitor(s) (CNIs) received at 6 months posttransplant and matched 1:1 by TC vs. SC. Physical (PCS) and mental component summary (MCS) scores measured by the SF-12 scale for cyclosporine- and tacrolimus-treated recipients were compared. Patient opinions about their perceived CNI-related side effects captured by categorical questions or a numerical Likert scale (1-10) were compared by chi-square test or ANOVA, respectively. RESULTS: There were 231 participants (124 cyclosporine, 43 tacrolimus and 64 with dual experience) who responded to both questionnaires. Their SF-12-measured PCS and MCS scores were similar (PCS 42.0, 43.0 and 41.4, p=0.705; MCS 50.3, 47.8 and 47.1, p=0.115; respectively). However, patients receiving tacrolimus more strongly preferred to continue on this CNI than those receiving cyclosporine (67.4% vs. 44.4%, p=0.009), while more patients on cyclosporine wished to stop taking it (23.4 vs. 2.3%, p=0.004). Patient preference for CNI did not differ by center type. CONCLUSION: QoL among Canadian renal transplant recipients receiving cyclosporine or tacrolimus is similar. Although Canadian recipients prefer tacrolimus, CNI type does not significantly affect their QoL.

Frailty and the Kidney Transplant Wait List: Protocol for a Multicenter Prospective Study.

BACKGROUND: Understanding how frailty affects patients listed for transplantation has been identified as a priority research need. Frailty may be associated with a high risk of death or wait-list withdrawal, but this has not been evaluated in a large multicenter cohort of Canadian wait-listed patients. OBJECTIVE: The primary objective is to evaluate whether frailty is associated with death or permanent withdrawal from the transplant wait list. Secondary objectives include assessing whether frailty is associated with hospitalization, quality of life, and the probability of being accepted to the wait list. DESIGN: Prospective cohort study. SETTING: Seven sites with established renal transplant programs that evaluate patients for the kidney transplant wait list. PATIENTS: Individuals who are being considered for the kidney transplant wait list. MEASUREMENTS: We will assess frailty using the Fried Phenotype, a frailty index, the Short Physical Performance Battery, and the Clinical Frailty Scale at the time of listing for transplantation. We will also assess frailty at the time of referral to the wait list and annually after listing in a subgroup of patients. METHODS: The primary outcome of the composite of time to death or permanent wait-list withdrawal will be compared between patients who are frail and those who are not frail and will account for the competing risks of deceased and live donor transplantation. Secondary outcomes will include number of hospitalizations and length of stay, and in a subset, changes in frailty severity over time, change in quality of life, and the probability of being listed. Recruitment of 1165 patients will provide >80% power to identify a relative hazard of ≥1.7 comparing patients who are frail to those who are not frail for the primary outcome (2-sided α = .05), whereas a more conservative recruitment target of 624 patients will provide >80% power to identify a relative hazard of ≥2.0. RESULTS: Through December 2019, 665 assessments of frailty (inclusive of those for the primary outcome and all secondary outcomes including repeated measures) have been completed. LIMITATIONS: There may be variation across sites in the processes of referral and listing for transplantation that will require consideration in the analysis and results. CONCLUSIONS: This study will provide a detailed understanding of the association between frailty and outcomes for wait-listed patients. Understanding this association is necessary before routinely measuring frailty as part of the wait-list eligibility assessment and prior to ascertaining the need for interventions that may modify frailty. TRIAL REGISTRATION: Not applicable as this is a protocol for a prospective observational study.

CONTEXTE: La compréhension de l'incidence de la fragilité sur les patients en attente d'une greffe rénale a été désignée comme un besoin prioritaire de recherche. La fragilité pourrait être associée à un risque élevé de mortalité ou de se voir retiré de la liste d'attente pour une transplantation, mais elle n'a jamais été évaluée dans une vaste cohorte multicentrique de patients canadiens en attente d'une greffe. OBJECTIFS: Le principal objectif consiste à déterminer si la fragilité d'un patient l'expose à un plus grand risque de décès ou de retrait permanent de la liste d'attente pour une greffe. Nous souhaitons également vérifier s'il existe un lien entre la fragilité et le nombre d'hospitalisations, la qualité de vie et la probabilité d'être accepté sur la liste d'attente. TYPE D'ÉTUDE: Étude de cohorte prospective. CADRE: Sept sites disposant d'un programme de transplantation rénale évaluant les patients en vue de leur inscription sur la liste d'attente pour une greffe. SUJETS: Des candidats à la liste d'attente pour une transplantation rénale. MESURES: La fragilité sera évaluée à l'aide du Phénotype de Fried (un indice de la fragilité), du test SPPB (Short Physical Performance Battery) et de l'échelle Clinical Frailty Scale au moment de l'inscription sur la liste d'attente pour une transplantation. Nous mesurerons la fragilité des patients de leur orientation vers le programme jusqu'à leur inscription sur la liste, puis sur une base annuelle après leur inclusion dans un sous-groupe de patients. MÉTHODOLOGIE: Le résultat principal, soit un composite du délai avant le décès ou le retrait permanent de la liste, sera comparé entre les patients fragiles et non fragiles, et tiendra compte des risques concurrents découlant de la transplantation selon que l'organe provient d'un donneur vivant ou décédé. Les résultats secondaires comprendront le nombre d'hospitalisations et leur durée, les variations de la fragilité et de la qualité de vie au fil du temps (pour un sous-groupe de patients), de même que les probabilités d'être inscrit sur la liste d'attente. Le recrutement de 1 165 patients nous permettrait d'obtenir un risque relatif d'au moins 1,7 dans plus de 80 % des cas lors de la comparaison des patients fragiles à ceux qui ne le sont pas pour le résultat principal (double erreur alpha = 0,05), alors que ce risque relatif serait de 2,0 avec un objectif de recrutement plus conservateur de 624 patients. RÉSULTATS: Un total de 665 évaluations de la fragilité (tant pour le résultat primaire que pour les résultats secondaires, y compris les mesures répétitives) a été complété en décembre 2019. LIMITES: Les résultats et leur analyse devront tenir compte des possibles variations entre les différents sites en ce qui concerne les processus d'aiguillage et d'inscription sur les listes d'attente pour une greffe. CONCLUSION: Cette étude fournira une compréhension détaillée de l'association entre la fragilité et les résultats cliniques pour les patients en attente d'une greffe. La compréhension de cette association est nécessaire avant d'inclure systématiquement la mesure de la fragilité au processus d'évaluation de l'admissibilité à la liste d'attente et avant d'établir le besoin de procéder à des interventions susceptibles de modifier la fragilité du patient.

Development of end stage renal disease following an acute cardiac event.

We determined the rate and risk factors for end-stage renal disease (ESRD) in consecutive patients discharged after a cardiac event in a large, unbiased Canadian cohort that receives universal health coverage. A total of 8236 adults hospitalized over a 2 year period were followed for up to 7.5 years and the incidence of ESRD and mortality determined. Of these, 113 reached ESRD (stage 5). Patients with moderate (stage 3) and severe (stage 4) renal insufficiency were more likely to develop ESRD than those patients at stage 1 or 2. However, patients with moderate renal insufficiency were 78.6 times more likely to die than to develop ESRD. Absolute rates of progression to ESRD per 100-patient years were 0.08 at stages 1 and 2, 0.17 at stage 3 and 4.27 at stage 4. Age, diabetes, hypertension and congestive heart failure also predicted ESRD. We found that patients with stage 4 disease are at high risk of ESRD after a cardiac admission while those at stage 3 are far more likely to die than to develop ESRD.

Cardiolipin exposure on the outer mitochondrial membrane modulates α-synuclein.

Neuronal loss in Parkinson's disease (PD) is associated with aberrant mitochondrial function and impaired proteostasis. Identifying the mechanisms that link these pathologies is critical to furthering our understanding of PD pathogenesis. Using human pluripotent stem cells (hPSCs) that allow comparison of cells expressing mutant SNCA (encoding α-synuclein (α-syn)) with isogenic controls, or SNCA-transgenic mice, we show that SNCA-mutant neurons display fragmented mitochondria and accumulate α-syn deposits that cluster to mitochondrial membranes in response to exposure of cardiolipin on the mitochondrial surface. Whereas exposed cardiolipin specifically binds to and facilitates refolding of α-syn fibrils, prolonged cardiolipin exposure in SNCA-mutants initiates recruitment of LC3 to the mitochondria and mitophagy. Moreover, we find that co-culture of SNCA-mutant neurons with their isogenic controls results in transmission of α-syn pathology coincident with mitochondrial pathology in control neurons. Transmission of pathology is effectively blocked using an anti-α-syn monoclonal antibody (mAb), consistent with cell-to-cell seeding of α-syn.

Muscle-relevant genes marked by stable H3K4me2/3 profiles and enriched MyoD binding during myogenic differentiation.

Post-translational modifications of histones play a key role in the regulation of gene expression during development and differentiation. Numerous studies have shown the dynamics of combinatorial regulation by transcription factors and histone modifications, in the sense that different combinations lead to distinct expression outcomes. Here, we investigated gene regulation by stable enrichment patterns of histone marks H3K4me2 and H3K4me3 in combination with the chromatin binding of the muscle tissue-specific transcription factor MyoD during myogenic differentiation of C2C12 cells. Using k-means clustering, we found that specific combinations of H3K4me2/3 profiles over and towards the gene body impact on gene expression and marks a subset of genes important for muscle development and differentiation. By further analysis, we found that the muscle key regulator MyoD was significantly enriched on this subset of genes and played a repressive role during myogenic differentiation. Among these genes, we identified the pluripotency gene Patz1, which is repressed during myogenic differentiation through direct binding of MyoD to promoter elements. These results point to the importance of integrating histone modifications and MyoD chromatin binding for coordinated gene activation and repression during myogenic differentiation.

TBP/TFIID-dependent activation of MyoD target genes in skeletal muscle cells.

Change in the identity of the components of the transcription pre-initiation complex is proposed to control cell type-specific gene expression. Replacement of the canonical TFIID-TBP complex with TRF3/TBP2 was reported to be required for activation of muscle-gene expression. The lack of a developmental phenotype in TBP2 null mice prompted further analysis to determine whether TBP2 deficiency can compromise adult myogenesis. We show here that TBP2 null mice have an intact regeneration potential upon injury and that TBP2 is not expressed in established C2C12 muscle cell or in primary mouse MuSCs. While TFIID subunits and TBP are downregulated during myoblast differentiation, reduced amounts of these proteins form a complex that is detectable on promoters of muscle genes and is essential for their expression. This evidence demonstrates that TBP2 does not replace TBP during muscle differentiation, as previously proposed, with limiting amounts of TFIID-TBP being required to promote muscle-specific gene expression.

Outcomes of acute coronary syndrome in a large Canadian cohort: impact of chronic renal insufficiency, cardiac interventions, and anemia.

BACKGROUND: Chronic renal insufficiency (CRI) has been identified as an important risk factor for cardiac events. Studies in the United States reported decreased survival and decreased use of surgical and medical interventions after myocardial infarction in patients with CRI. METHODS: We studied the impact of renal function on health outcomes in a Canadian cohort of consecutive patients admitted with acute coronary syndrome (ACS) between October 1997 and October 1999. The study design is an observational cohort of 5,549 adult patients who survived to discharge with a discharge diagnosis of ACS. Renal function is classified into 4 levels: (1) normal, glomerular filtration rate (GFR) greater than 80 mL/min/1.73 m2 (>1.33 mL/s); (2) mild CRI, GFR of 60 to 80 mL/min/1.73 m2 (1.00 to 1.33 mL/s); (3) moderate CRI, GFR of 30 to 59 mL/min/1.73 m2 (0.50 to 0.98 mL/s); and (4) severe CRI, GFR less than 30 mL/min/1.73 m2 (<0.50 mL/s). The primary outcome is death. RESULTS: Advanced and moderate CRI independently predicted death (hazard ratio, 1.06; 95% confidence interval [CI], 1.01 to 1.12; and hazard ratio, 1.23; 95% CI, 1.18 to 1.29). Severe anemia (hemoglobin level < 9.0 g/dL [<90 g/L]) also was an independent risk factor for death (hazard ratio, 1.38; 95% CI, 1.18 to 1.61). Use of beta-blockers (hazard ratio, 0.91; 95% CI, 0.86 to 0.97), acetylsalicylic acid (hazard ratio, 0.90; 95% CI, 0.84 to 0.97), lipid-lowering therapy (hazard ratio, 0.84; 95% CI, 0.78 to 0.89), and medical thrombolysis (hazard ratio, 0.89; 95% CI, 0.81 to 0.97) were associated with reduced risk for death. Medical interventions with beta-blockers, acetylsalicylic acid, lipid-lowering therapy, and thrombolysis and surgical intervention were significantly less likely to be used in patients with CRI. CONCLUSION: Despite universal access to health care, Canadian patients with CRI are more likely to die after a cardiac event and less likely to receive important interventions.