Regulation of
Myosin Expression in Developing and Regenerating Extrafusal and Intrafusal Muscle Fibers with
Special Emphasis on the Role of Thyroid Hormones
T.
SOUKUP, I. JIRMANOVÁ
Institute of Physiology, Academy of
Sciences of the Czech Republic, Prague, Czech
Republic
Received
January 24, 2000
Accepted April 14, 2000
Summary
Expression
of the muscle phenotype is the result of
interaction between intrinsic and extrinsic
factors, the latter including innervation,
mechanical influences and hormonal signals. This minireview summarizes some of the current
knowledge regarding the regulation of myosin
heavy chain (MHC) isoform transitions during
muscle development and regeneration. It describes
the role of genetic factors, neural and
mechanical influences and it focuses on the
contribution of thyroid hormones to the
differentiation of muscle fiber phenotypes as
shown by the regulation of the expression of MHC
isoforms and development of myofibrillar ATPase
activity. Finally, it shortly summarizes results
regarding the differentiation of MHC isoforms in
regenerated muscle fibers of the graft after heterochronous isotransplantation in rats with
different thyroid status.
Key words
Myosin
heavy chains · Myofibrillar
proteins · Muscle cell
lineages · Muscle
innervation · Thyroid hormones ·
Muscle fiber types · Muscle spindles
Reprint
requests
Dr. T. Soukup, Institute of Physiology, Czech
Academy of Sciences, Vídeòská 1083, CZ-142 20
Prague, Czech Republic, Fax: +420 2 475 2488,
E-mail: tmsoukup@biomed.cas.cz
|