MicroRNA-133 Controls Brown Adipose Determination in Skeletal Muscle Satellite Cells by Targeting Prdm16

SummaryBrown adipose tissue (BAT) is an energy-dispensing thermogenic tissue that plays an important role in balancing energy metabolism. Lineage-tracing experiments indicate that brown adipocytes are derived from myogenic progenitors during embryonic development. However, adult skeletal muscle stem cells (satellite cells) have long been considered uniformly determined toward the myogenic lineage. Here, we report that adult satellite cells give rise to brown adipocytes and that microRNA-133 regulates the choice between myogenic and brown adipose determination by targeting the 3′UTR of Prdm16. Antagonism of microRNA-133 during muscle regeneration increases uncoupled respiration, glucose uptake, and thermogenesis in local treated muscle and augments whole-body energy expenditure, improves glucose tolerance, and impedes the development of diet-induced obesity. Finally, we demonstrate that miR-133 levels are downregulated in mice exposed to cold, resulting in de novo generation of satellite cell-derived brown adipocytes. Therefore, microRNA-133 represents an important therapeutic target for the treatment of obesity

Undernutrition during pregnancy in mice leads to dysfunctional cardiac muscle respiration in adult offspring

Summary Statement We show that in utero undernutrition is associated with impaired cardiac muscle energetics and increased plasma short-chain acylcarnitines in adult mice. Findings suggest that in utero undernutrition is associated with maladaptive programming processes that have negative effects on the heart. Synopsis Intrauterine growth restriction is associated with an increased risk of developing obesity, insulin resistance, and cardiovascular disease. However its effect on energetics in heart remains unknown. In this study, we examined respiration in cardiac muscle and liver from adult mice that were undernourished in utero. We report that in utero undernutrition is associated with impaired cardiac muscle energetics, including decreased fatty acid oxidative capacity, decreased maximum oxidative phosphorylation rate, and decreased proton leak respiration. No differences in oxidative characteristics were detected in liver. We also measured plasma acylcarnitine levels and found that short-chain acylcarnitines are increased with in utero undernutrition. Results reveal the negative impact of suboptimal maternal nutrition on adult offspring cardiac energy metabolism, which may have lifelong implications for cardiovascular function and disease risk

Scientific overview: CSCI – CITAC Annual General Meeting and Young Investigator’s Forum 2012

In 2012, the Annual General Meeting of the Clinical Investigator Trainee Association of Canada – Association des cliniciens-chercheurs en formation du Canada (CITAC – ACCFC) and the Canadian Society of Clinician Investigators (CSCI) was held 19-21 September in Ottawa. Several globally-renowned scientists, including 2012 Friesen International Prize recipient, Dr. Marc Tessier-Lavigne, the CSCI/Royal College Henry Friesen Award recipient, Dr. Morley Hollenberg, and the recipient of the Joe Doupe Young Investigator Award, Dr. Phillip Awadalla, presented on a range of topics on research in basic and translational science in medicine. This year’s CITAC Symposium featured presentations by Dr. Alain Beaudet, Dr. Michael Strong and Dr. Vivek Goel on the Role of Physician Scientists in Public Health and Policy, which was followed by a lively discussion on the role of basic science and clinical research in patient-oriented policy development. This scientific overview highlights the research presented by trainees at both the oral plenary and poster presentation sessions. As at previous meetings, research questions investigated by this year’s trainees span multiple medical disciplines; from basic science to clinical research to medical education. Below is a summary of the presentations showcased at the Young Investigator’s Forum

Scientific overview: CSCI-CITAC Annual General Meeting and Young Investigator’s Forum 2013

The 2013 joint Canadian Society of Clinician Investigators (CSCI)–Clinical Investigator Trainee Association of Canada/Association des cliniciens-chercheurs en formation du Canada (CITAC/ACCFC) annual general meeting(AGM) was held in Ottawa, September 2013. The symposium focused on “Applications of the ‘omics’ to Clinical Practice”, with presentations from Drs. William T. Gibson (University of British Columbia), Julie Ho (University of Manitoba) and David Hwang (University of Toronto), discussing topics of genome, proteome and the microbiome, respectively. Other highlights from the 2013 AGM include presentations by Dr. Salim Yusuf (McMaster University, 2013 CSCI-RCPSC Henry Friesen Award winner), Dr. Gary Lewis (University of Toronto, 2013 CSCI Distinguished Scientist Award winner) and Dr. Michael Taylor (University of Toronto, 2013 Joe Doupe Award winner). The CSCI/CITAC/Friends of CIHR Joint Symposium consisted of presentations from Drs. John Bell (University of Ottawa), Dan Drucker (University of Toronto) and Heather J. Dean (University of Manitoba). Finally, the meeting ended with the presentation “The Power of an Idea to Bring Ideas to Power” by Dr. Harvey V. Fineberg (President, U.S. Institute of Medicine), the winner of the 2013 Henry Friesen International Prize. Also presented at the conference was research by clinician investigator (CI) trainees from across Canada; ie., those enrolled in MD/MSc, MD/PhD or Clinician Investigator Program(CIP) programs. Canadian trainees’ research extended beyond the pillar of biomedical research, covering the spectrum between basic and clinical research, with a focus on the causes of significant morbidity and mortality for Canadians, including cancers, infectious diseases and other maladies. It is this research that we have summarized in this review

miRNA-132 orchestrates chromatin remodeling and translational control of the circadian clock

Mammalian circadian rhythms are synchronized to the external time by daily resetting of the suprachiasmatic nucleus (SCN) in response to light. As the master circadian pacemaker, the SCN coordinates the timing of diverse cellular oscillators in multiple tissues. Aberrant regulation of clock timing is linked to numerous human conditions, including cancer, cardiovascular disease, obesity, various neurological disorders and the hereditary disorder familial advanced sleep phase syndrome. Additionally, mechanisms that underlie clock resetting factor into the sleep and physiological disturbances experienced by night-shift workers and travelers with jet lag. The Ca2+/cAMP response element-binding protein-regulated microRNA, miR-132, is induced by light within the SCN and attenuates its capacity to reset, or entrain, the clock. However, the specific targets that are regulated by miR-132 and underlie its effects on clock entrainment remained elusive until now. Here, we show that genes involved in chromatin remodeling (Mecp2, Ep300, Jarid1a) and translational control (Btg2, Paip2a) are direct targets of miR-132 in the mouse SCN. Coordinated regulation of these targets underlies miR-132-dependent modulation of Period gene expression and clock entrainment: the mPer1 and mPer2 promoters are bound to and transcriptionally activated by MeCP2, whereas PAIP2A and BTG2 suppress the translation of the PERIOD proteins by enhancing mRNA decay. We propose that miR-132 is selectively enriched for chromatin- and translation-associated target genes and is an orchestrator of chromatin remodeling and protein translation within the SCN clock, thereby fine-tuning clock entrainment. These findings will further our understanding of mechanisms governing clock entrainment and its involvement in human diseases