BBB seminar: Arild Rustan
Metabolic studies in human skeletal muscle cells - Are cultured human myotubes far from home?
Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo
My presentation will focus on the way that human myotubes can be used as a tool to study energy metabolism in skeletal muscles. Special attention will be placed on changes in muscle energy metabolism between cells established from various donors, after different treatments of the myotubes, and how these processes can be measured using efficient fuel handling systems.
Satellite cells can be isolated from skeletal muscle biopsies, activated to proliferating myoblasts and differentiated into multinuclear myotubes in culture. These cell cultures represent an essential model system for intact human skeletal muscle and can be modulated ex vivo. The advantages of this system include: (1) the most relevant genetic background for the investigation of human disease (as opposed to rodent cell cultures), (2) the extracellular environment can be precisely controlled and (3) the cells are not immortalized, thereby offering the possibility of studying innate characteristics of the donor.
Measurement of cellular processes such as the uptake and oxidation of energy-rich substrates is important in cell biology. Often, phenotypes of metabolic abnormalities may transmit into in vitro systems with whole cells or enzymes isolated from the affected individual. Comparison between markers of disease in vivo and defects/changes in cellular metabolism in vitro has the potential to be a fruitful strategy for studies of metabolic abnormalities. The exploration of this field of research has to a large extent been slowed by time consuming and cumbersome methods for studying nutrient handling. We have developed and established two principles for the detection of substrate accumulation and oxidation that may help to overcome some of these obstacles. First, scintillation proximity assays (SPAs) designed to detect radioligand accumulation in adherent cell layers have been commercially available for more than a decade (e.g. Cytostar SPA and Scintiplate), but there are few published studies of nutrient metabolism. We have used SPAs to measure the accumulation and turnover of radiolabeled fatty acids and glucose in human cells grown on 96-well SPA plates monitored non-invasively in real time. Second, numerous protocols designed for the measurement of cellular metabolism use 14C-labeled substrates with simultaneous or subsequent capture of the 14CO2 produced. The substrate oxidation assay is a novel variant of previously described experimental approaches and uses standard 96-well tissue culture and filter plates. The accessibility and high throughput of the in vitro techniques discussed in this seminar should make them attractive tools for studies of cellular energy metabolism.
Aas V, Bakke SS, Feng YZ, Kase ET, Jensen J, Bajpeyi S, Thoresen GH, Rustan AC, Are cultured human myotubes far from home? Cell Tissue Res. 2013, 354:671-82
Wensaas AJ, Rustan AC, Lövstedt K, Kull B, Wikström S, Drevon CA, Hallén S, Cell-based multiwell assays for the detection of substrate accumulation and oxidation. J. Lipid Res. 2007, 48:961-7
Chairperson: Karl Johan Tronstad, Department of Biomedicine