The ryanodine receptor (Ryr, Ca2+ release channel) plays a central role in muscle contraction. It is mainly localized where the sarcoplasmic reticulum (SR) forms junctions with T-tubular and surface membranes (T-SR junction). It is responsible for release of Ca2+ from SR that triggers contraction. Release channels are suggested to be activated by two different mechanisms: mechanical interaction with dihydropyridine receptor (DHPr, voltage sensor) and calcium-induced calcium release (CICR). Skeletal muscle contains different Ryr isoforms that might contribute to the diversity of excitation-contraction coupling (ECC) mechanisms. My preliminary data disclosed two distinctive types of local Ca2+ signaling: Ca2+ sparks and release in small events. The goal of this proposal is to investigate the role of different release channel isoforms in Ca2+ release. I propose to take advantage of the fact that relative amounts of two major skeletal muscle Ryr isoforms (Ryrl and Ryr3) vary widely between muscle types and during muscle development in order to test three major hypotheses: 1. Ca2+ release in small events is directly controlled by voltage and provides a precursor Ca2+ that activates Ca2+ sparks. 2. Ca2+ sparks are produced by opening of multiple Ryr Ca2+ release channels. 3. Ryr3rs are the channels required to produce sparks in skeletal muscle and are activated by CICR. For this we will explore local calcium signaling in a variety of mature and developing mammalian, amphibian and fish skeletal muscle fibers with different Ryr isoforms composition and/or different numbers of Ryrs per T-SR junction. In parallel, we will monitor tissue expression of different Ryr isoforms by immunoblotting and/or immunostaining. Some muscle illnesses are increasingly been understood in terms of defects of molecules participating in ECC. Proposed studies will greatly advanced our knowledge of their functioning, which in turn could improve our understanding of their role in decease.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-MDCN-4 (01))
Program Officer
Lymn, Richard W
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Medicine & Dentistry of NJ
Schools of Medicine
United States
Zip Code
Shkryl, Vyacheslav M; Shirokova, Natalia (2006) Transfer and tunneling of Ca2+ from sarcoplasmic reticulum to mitochondria in skeletal muscle. J Biol Chem 281:1547-54
Isaeva, Elena V; Shkryl, Vyacheslav M; Shirokova, Natalia (2005) Mitochondrial redox state and Ca2+ sparks in permeabilized mammalian skeletal muscle. J Physiol 565:855-72
Isaeva, Elena V; Shirokova, Natalia (2003) Metabolic regulation of Ca2+ release in permeabilized mammalian skeletal muscle fibres. J Physiol 547:453-62
Brum, G; Gonzalez, A; Rengifo, J et al. (2000) Fast imaging in two dimensions resolves extensive sources of Ca2+ sparks in frog skeletal muscle. J Physiol 528:419-33
Shirokova, N; Shirokov, R; Rossi, D et al. (1999) Spatially segregated control of Ca2+ release in developing skeletal muscle of mice. J Physiol 521 Pt 2:483-95