APStracts 3:0380C, 1996.

Mitochondrial biogenesis during cellular differentiation . Moyes, C. D., O. A. Mathieu-Costello, N. Tsuchiya, C. Filburn, and R. G. Hansford. Department of Biology, Queen's University, Kingston, Ontario, K7L 3N6, Canada, Department of Medicine, University of California, San Diego, La Jolla, CA, 92093-0623, USA, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD, 21224, USA

APStracts 3:0380C, 1996.

Mitochondrial biogenesis was studied during differentiation of two immortalized cell lines (C2C12, 3T3) using enzyme measurements, northern blots and quantitative ultrastructure. Citrate synthase, isocitrate dehydrogenase and 3-hydroxyacylCoA dehydrogenase (nuclear encoded; mitochondrial matrix location) showed linear, 4- to 6-fold increases in enzymatic activity in C2C12 cells, but increased exponentially in 3T3 cells. Cytochrome oxidase and NADH dehydrogenase (nuclear and mitochondrial encoded; cristae location) increased to a lesser extent and with a pattern dissimilar to the first group. Northern blots and activity of succinate dehydrogenase (cristae location but entirely nuclear encoded) suggested the groupings were based upon location of the genes rather than the mature enzyme. However, quantitive electron microscopy and comparisons with adult tissue suggested that mitochondrial ultrastructure can influence the change in cristae enzymes. Cristae surface area per unit mitochondrial volume and per unit cell volume increased much less than did cristae enzymes. Available space on the inner membrane may become limiting and account for some aspects of the pattern of change in electron transport enzymes during differentiation.

Received 27 June 1996; accepted in final form 13 November 1996.
APS Manuscript Number C366-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996