August Krogh / CWS Seminar – University of Copenhagen

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August Krogh / CWS Seminar

Calcium signals mediate excitation-metabolism coupling in skeletal muscle

v/ Professor Enrique Jaimovich, Universidad de Chile, Chile

Abstract

In skeletal muscle fibers, a large fraction of mitochondria resides in close proximity to myofibrils where ATP production is essential for contraction. Sub-sarcolemmal mitochondria have a different distribution and contain different components of the metabolic protein complexes.

We studied mitochondrial Ca2+ transients following membrane depolarization by potassium (or electrical stimulation) of single skeletal muscle fibers, and their relation with metabolic output and membrane potential changes in mitochondria. Surface depolarization of adult fibers increased both cytoplasmic and mitochondrial Ca2+ levels which required functional IP3R and RyR1 channels. Inhibition of either one of these channels decreased basal O2 consumption rate.

Depolarization-induced Ca2+ signals were accompanied by a reduction in mitochondria membrane potential in sub-sarcolemmal mitochondria; Ca2+ signals propagated towards intermyofibrillar mitochondria, where mitochondrial membrane potential increased. These results suggest a Ca2+-dependent propagation of mitochondria membrane potential from the surface towards the center of the fiber.

Suggested readings

Casas M, Buvinic S and Jaimovich E (2014) ATP signaling in skeletal muscle: from fiber plasticity to regulation of metabolismExercise and Sport Sciences Reviews 42:110-116.
 
Arias-Calderón M, Almarza G, Díaz-Vegas A, Contreras-Ferrat A , Valladares D, Casas M, Toledo H, Jaimovich E and Buvinic S (2016) Characterization of a multiprotein complex involved in excitation-transcription coupling of skeletal muscle. Skeletal Muscle 6:15
 
Osorio-Fuentealba C, Contreras-Ferrat AE, Altamirano F, Espinosa A, Li Q,  Niu W, Lavandero S, Klip A,  Jaimovich E (2013) Electrical Stimuli Release ATP to Increase GLUT4 Translocation and Glucose Uptake via PI3Kγ-Akt-AS160 in Skeletal Muscle Cells. Diabetes, 62:1519-1526
 
Contreras-Ferrat A, Llanos P, Vásquez C, Espinosa A, Osorio-Fuentealba C, Arias-Calderon M, Lavandero S, Klip A, Hidalgo C, Jaimovich E. (2014) Insulin elicits a ROS-activated and an IP3-dependent Ca2+ release; both impinge on GLUT4 translocation J Cell Sci. 127:1911-1923.

Research profile

Enrique Jaimovich leads the Muscle Cell Physiology Laboratory at the Faculty of Medicine, Universidad de Chile. This laboratory hosts around 20 people, including Assistant Professors Mariana Casas and Paola Llanos, post-doctoral trainees, PhD students, MS students and technical staff. Their subject is skeletal muscle plasticity in health and disease and they have contributed a molecular mechanism that explains the effect of muscle electrical activity in the regulation of gene expression in the muscle cell. This mechanism appears to be altered in several animal models that are presently being studied in the laboratory; namely muscular dystrophy, obesity with insulin resistance, normal aging and cancer cachexia.

Time

12 June 2017

14:30-15:30: Seminar and discussion
15:30-16:30: Post seminar servings and socializing

Venue

Auditorium 1, August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen

Registration

Participation is free, but please register here.

For PhD students

PhD students participating in August Krogh seminars receive 0,2 ECTS per seminar

Contact

Jonas Møller Kristensen, jmkristensen@nexs.ku.dk, phone +45 3533 4776

Upcoming seminars

Link to other upcoming seminars.