tailieunhanh - Báo cáo khoa học: Parvalbumin deficiency in fast-twitch muscles leads to increased ‘slow-twitch type’ mitochondria, but does not affect the expression of fiber specific proteins

Parvalbumin (PV), a small cytosolic protein belonging to the family of EF-hand calcium-binding proteins, is highly expressed in mammalian fast-twitch muscle fibers. By acting as a ‘slow-onset’ Ca 2+ buffer, PV does not affect the rapid contraction phase, but significantly contributes to increase the rate of relaxation, as demonstrated in PV–⁄– mice. | iFEBS Journal Parvalbumin deficiency in fast-twitch muscles leads to increased slow-twitch type mitochondria but does not affect the expression of fiber specific proteins Peter Racay Patrick Gregory and Beat Schwaller Department of Medicine Division of Histology and GeneralEmbryology University of Fribourg Switzerland Keywords calcium binding E-F hand fast twitch muscle mitochondria organelle biogenesis Correspondence B. Schwaller Division of Histology Department of Medicine University of Fribourg CH-1700 Fribourg Switzerland Fax 41 26 3009732 Tel 41 26 3008508 E-mail Present address Comenius University Jessenius Faculty of Medicine Institute of Biochemistry Mala Hora 4 SK-03601 Martin Slovakia Received 20 July 2005 revised 21 October 2005 accepted 2 November 2005 doi Parvalbumin PV a small cytosolic protein belonging to the family of EF-hand calcium-binding proteins is highly expressed in mammalian fast-twitch muscle fibers. By acting as a slow-onset Ca2 buffer PV does not affect the rapid contraction phase but significantly contributes to increase the rate of relaxation as demonstrated in PV- - mice. Unexpectedly PV- - fast-twitch muscles were considerably more resistant to fatigue than the wild-type fast-twitch muscles. This effect was attributed mainly to the increased fractional volume of mitochondria in PV- - fast-twitch muscle extensor digitorum longus similar to levels observed in the slow-twitch muscle soleus. Quantitative analysis of selected mitochondrial proteins mitochondrial DNA-encoded cytochrome oxidase c subunit I and nuclear DNA-encoded cytochrome oxidase c subunit Vb and Fl-ATPase subunit b revealed the PV- - tibialis anterior mitochondria composition to be almost identical to that in wild-type soleus but not in wild-type fasttwitch muscles. Northern and western blot analyses of the same proteins in different muscle types and in liver are indicative of a complex regulation probably also at