The neural regulation of gene expression in the muscle cell
TL;DR: The observation that a qualitatively different myosin appears in cross-reinnervated muscle indicates that a new species of protein has been synthesized, and it is suggested that the nerve influences gene expression in the muscle cell.
About: This article is published in Experimental Neurology.The article was published on 1970-05-01. It has received 88 citations till now. The article focuses on the topics: Myosin & Myosin light-chain kinase.
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1,464 citations
TL;DR: In this paper, the authors summarized the present knowledge about the mechanisms involved in the control of the phenotypic expression of mammalian muscle fibers and discussed how the activity imposed on the muscle fibers by the motoneuron finally induces in the muscle cells the expression of those genes that define its particular phenotype.
Abstract: In this review, the present knowledge about the mechanisms involved in the control of the phenotypic expression of mammalian muscle fibers is summarized. There is a discussion as to how the activity imposed on the muscle fibers by the motoneuron finally induces in the muscle cells the expression of those genes that define its particular phenotype. The functional and molecular heterogeneity of skeletal muscle is thus defined by the existence of motor units with varied function, while the homogeneity of muscle fibers belonging to the same motor unit is yet another indication of the importance of activity in the control of gene expression of the mammalian muscle fiber.
728 citations
TL;DR: A simple transition scheme has emerged from the multitude of data collected on fiber type conversions under a variety of conditions, and it is now clear that fiber type transitions do not proceed in immediate jumps from one extreme to the other, but occur in a graded and orderly sequential manner.
Abstract: Mammalian skeletal muscle is an extremely heterogeneous tissue, composed of a large variety of fiber types. These fibers, however, are not fixed units but represent highly versatile entities capable of responding to altered functional demands and a variety of signals by changing their phenotypic profiles. This adaptive responsiveness is the basis of fiber type transitions. The fiber population of a given muscle is in a dynamic state, constantly adjusting to the current conditions. The full range of adaptive ability spans fast to slow characteristics. However, it is now clear that fiber type transitions do not proceed in immediate jumps from one extreme to the other, but occur in a graded and orderly sequential manner. At the molecular level, the best examples of these stepwise transitions are myofibrillar protein isoform exchanges. For the myosin heavy chain, this entails a sequence going from the fastest (MHCIIb) to the slowest (MHCI) isoform, and vice-versa. Depending on the basal protein isoform profile and hence the position within the fast-slow spectrum, the adaptive ranges of different fibers vary. A simple transition scheme has emerged from the multitude of data collected on fiber type conversions under a variety of conditions.
651 citations
TL;DR: The characteristics of isometric twitch and tetanic contractions have been determined for normal, self‐innervated and cross‐innovated extensor digitorum longus (EDL) and soleus (SOL) muscles of the rat at 35° C and biochemical analyses of properties of myosin and actomyosin were used.
Abstract: 1. The characteristics of isometric twitch and tetanic contractions have been determined for normal (N-EDL, N-SOL), self-innervated (S-EDL, S-SOL) and cross-innervated (X-EDL, X-SOL) extensor digitorum longus (EDL) and soleus (SOL) muscles of the rat at 35° C. The muscles were then used for biochemical analyses of properties of myosin and actomyosin.
2. The ATPase activities of myosin and actomyosin of X-EDL decreased to the level of those of N-SOL or S-SOL, and the ATPase activities of X-SOL approached those of N-EDL or S-EDL. Of the various ATPase activities, the actin- and Mg2+-activated ATPase activity of myosin and the Mg2+-activated ATPase activity of actomyosin showed the highest degree of correlation with the intrinsic speed of shortening of the muscles.
3. Myosin of normal, self-innervated, and cross-innervated muscles combined with F-actin superprecipitated at rates which were proportional to the speed of muscle contraction.
4. The pH profile curve and the ATP-induced dinitrophenylation reaction revealed that the structure of myosin of X-EDL was altered to that of N-SOL or S-SOL, and the structure of myosin of X-SOL was modified to that of N-EDL or S-EDL.
5. No differences were found in the yield of myosin of normal, self-innervated, and cross-innervated extensor digitorum longus and soleus muscles.
299 citations
TL;DR: Early changes in the enzyme activity pattern of energy metabolism indicated a conversion of the fibres including their mitochondrial population, which is probably responsible for the early changes in contractile properties which occur before the transformation of the myosin.
Abstract: Fast-twitch tibialis anterior and extensor digitorum longus rabbit muscles were subjected to long-term intermittent (8 h daily) or continuous (24 h daily) indirect stimulation with a frequency pattern resembling that of a slow motoneuron. Increases in time to peak of isometric twitch contraction were observed without parallel changes in the pattern of myosin light chains or alterations in the distribution of slow and fast fibres as discernible by the histochemical ATPase reaction. However, changes in the fibre population and in the myosin light chain pattern were observed after intermittent stimulation periods exceeding 40 days or continuous stimulation periods longer than 20 days. Under these conditions even higher increases were found in contraction time. In one animal a complete change in fibre population was observed. In this case myosin light chains of the slow (LCS1, LCS2) and of the fast type (LCf1) were obviously synthetized simultaneously within the same fibre. Early changes in the enzyme activity pattern of energy metabolism indicated a conversion of the fibres including their mitochondrial population. These changes and the earlier reported changes in the sarcoplasmic reticulum are probably responsible for the early changes in contractile properties which occur before the transformation of the myosin.
254 citations
References
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TL;DR: An analytic investigation into the influence of nerve on muscle has been accomplished by dividing and cross-uniting nerves to fast and slow muscles, so that motoneurones formerly innervating the fast muscle come to innervate the slow muscle by virtue of the regenerative outgrowth of their fibres.
Abstract: In the preceding paper (Buller, Eccles & Eccles, 1960) evidence was presented which suggested that the differentiation of slow muscles of the cat hind limb to a large extent failed to occur after certain operative procedures on the spinal cord. This finding indicates that in some way the central nervous system controls muscle differentiation. A more analytic investigation into this postulated influence of nerve on muscle has been accomplished by dividing and cross-uniting nerves to fast and slow muscles, so that motoneurones formerly innervating the fast muscle come to innervate the slow muscle by virtue of the regenerative outgrowth of their fibres, and vice versa for the motoneurones of the slow muscle. The effect of this crossed innervation on the speed of muscle contraction has been tested at varying times after the cross-union. These investigations have also been carried out on animals subjected to the operative procedures on the spinal cord, as previously described (Buller et al. 1960). Cross-union experiments allow in addition an investigation into the possible effects in the reverse direction, i.e. of speed of muscle contraction on the conduction velocity of the axons and the after-hyperpolarization of the motoneurones which innervate it. A preliminary account of part of this investigation has already been published (Bulier, Eccles & Eccles, 1958).
1,052 citations
TL;DR: It is suggested that there are at least two qualitatively distinct actomyosin ATPases, and the nerve regulates the type of enzyme found in the muscle fiber, and preliminary observations indicate that under the influence of a foreign nerve, some acid-stabile fibers are converted to alkali- stabbed ones.
648 citations
577 citations
TL;DR: The present study was undertaken to determine whether physiological changes in cross-innervated muscles are accompanied by corresponding changes in preferential energy metabolism, and preliminary observations have been presented.
Abstract: MAMMALIAN skeletal muscles have been shown histochemically to consist of fibers with different enzymatic characteristics within the same muscle, indicating differences in energy metabolism. 1-3 Muscles with fast speeds of contraction are composed predominantly of fibers with high activities of enzymes of anaerobic glycolysis, while slow muscles consist almost entirely of fibers with high activities of enzymes of oxidative and lipid metabolism. 2,3 These enzymatic differences disappear following denervation, suggesting that the preferential energy metabolism of muscle fibers is determined by the nerve supply. 4,5 After sectioning and cross-uniting nerve to "fast" and "slow" muscles, the speeds of contraction of the muscles become reversed. 6,7 The present study was undertaken to determine whether these physiological changes in cross-innervated muscles are accompanied by corresponding changes in preferential energy metabolism. Preliminary observations have been presented. 8 Material and Methods Surgical section and cross union or reunion of the nerves to soleus
179 citations
TL;DR: Myosin obtained from red skeletal muscle of rabbit has a lower adenosine triphosphatase activity than myosin from white skeletal muscle, suggesting a change in the availability of sulfhydryl groups.
144 citations