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M Y Fiszman

Publications and source records attributed to M Y Fiszman.

At least 55 records · Page 3Linked to original sources
PubMed1985

The myosin alkali light chains of mouse ventricular and slow skeletal muscle are indistinguishable and are encoded by the same gene.

We have isolated a cDNA recombinant plasmid (pA29) identified as encoding part of the ventricular muscle myosin light chain MLC1v. This cDNA contains a 300-base pair fragment which under conditions of moderate stringency shows specific hybridization to MLC1v mRNA with no detectable cross-hybridization with the mRNAs encoding the fast skeletal muscle isoforms MLC1F and MLC3F, or the atrial muscle isoform MLC1A. Under these conditions hybridization is seen with an abundant mRNA present in slow skeletal muscle (soleus) which is indistinguishable from ventricular MLC1V mRNA on the basis of size and of thermal stability of hybrids formed with plasmid pA29. The mouse MLC1V and MLC1S proteins are found to co-migrate on two-dimensional gels. We therefore conclude that these isoforms are the same and are encoded by the same mRNA. Analysis of mouse DNA has identified a single region of the genome which hybridizes to this same fragment of pA29. This region has been isolated in a recombinant phage and has been shown to contain a single gene showing homology with MLC1V mRNA by R-loop analysis. We therefore conclude that MLC1V and MLC1S are encoded by a single gene. The pattern of segregation of a restriction fragment length polymorphism identified for this gene between Mus musculus and Mus spretus has been followed in an F1 backcross between these two mouse species. The results show the MLC1V/MLC1S gene to be closely linked to a marker at the distal end of mouse chromosome 9.

Animals↗
PubMed1985

The same myosin alkali light chain gene is expressed in adult cardiac atria and in fetal skeletal muscle.

We have isolated from a cDNA library constructed using mouse cardiac mRNA sequences, a clone (pC6) homologous to part of the mRNA encoding the myosin alkali light chain MLC1A from adult mouse atria. This sequence also hybridizes to mRNA encoding the fetal light chain form MLC1emb expressed in both fused myotubes in culture and in 18 day fetal skeletal muscle. These mRNA sequences are indistinguishable from the MLC1A messenger both on the basis of size and of their thermal stability of hybridization. In vitro translation of mRNA selected by hybridization with pC6 results in a protein that comigrates with the fetal MLC1emb isoform, and two-dimensional gel electrophoresis of adult atrial and fetal skeletal muscle proteins shows MLC1A and MLC1emb to be indistinguishable in the mouse. Southern blot hybridization of clone pC6 to mouse genomic DNA and the analysis of restriction fragment length polymorphisms between different mouse species demonstrates the presence of a single hybridizing locus in the mouse genome. These data provide strong evidence that the atrial MLC1A and fetal skeletal MLC1emb isoform are encoded by the same gene and by the same mRNA and are thus identical proteins.

Animals↗
PubMed1984

Changes in ganglioside metabolism during in vitro differentiation of quail embryo myoblasts.

The metabolism of gangliosides was studied during the in vitro differentiation of both normal quail myoblasts and myoblasts which have been transformed by a temperature-sensitive mutant of Rous sarcoma virus (RSV). These transformed cells can be maintained undifferentiated if incubated at 35 degrees C, but they will differentiate when shifted to 41 degrees C. (D. Montarras and M. Y. Fiszman (1983) J. Biol. Chem. 258, 3882-3888). The analysis of [14C]Glucosamine-labeled gangliosides by two-dimensional thin-layer chromatography reveals variations in the metabolism of the gangliosides during the process of differentiation. During the formation of myotubes, it was observed that the accumulation of GD1a is reduced, while the accumulation of GD3 is increased. Therefore, this results in the variation of the ratio GD3/GD1a which increases from 1.8 to 25 in the case of clones of transformed myoblasts, and from 0.5 to 1.7 in the case of uninfected myoblasts. These variations which have been observed seem to be specific of the myogenic differentiation since they cannot be reproduced when differentiation is inhibited by BUdR treatment or when fibroblasts reach confluency and are blocked in the G1 phase of cell cycle. Furthermore, the transformed myoblasts in vitro are shown to be a good model system since their gangliosides composition is very similar to that of muscle cells in vivo.

Animals↗
PubMed1983

Classification of tropomyosin components into an alpha-like or a beta-like family by partial peptide mapping.

Tropomyosins can be classified as belonging to an alpha-like or a beta-like family depending on the absence or presence, respectively in their protease-V8 digestion pattern of two peptides with an apparent molecular mass of 21 kDa. Chicken cardiac tropomyosin and the 43 kDa component from gizzard tropomyosin are accordingly classified as alpha-like tropomyosins, while the 33 kDa gizzard tropomyosin component is a beta-like tropomyosin. The 21 kDa peptides have an overall charge which is more positive than that of the intact tropomyosin or any other tropomyosin peptide and probably contain the -NH2 half of the molecule.

Animals↗
PubMed1983

Molecular and cell isoforms during development.

Development proceeds by way of a discrete yet overlapping series of biosynthetic and restructuring events that result in the continued molding of tissues and organs into highly restricted and specialized states required for adult function. Individual molecules and cells are replaced by molecular and cellular variants, called isoforms; these arise and function during embryonic development or later life. Isoforms, whether molecular or cellular, have been identified by their structural differences, which allow separation and characterization of each variant. These isoforms play a central and controlling role in the continued and dynamic remodeling that takes place during development. Descriptions of the individual phases of the orderly replacement of one isoform for another provides an experimental context in which the process of development can be better understood.

Actins↗
PubMed1983

A new muscle phenotype is expressed by subcultured quail myoblasts isolated from future fast and slow muscles.

Differentiation of quail myoblasts, isolated from thigh pectoralis and anterior latissimus dorsi muscle, was analyzed in primary cultures and in cultures obtained following repeated subculturing. Our study shows that quail myoblasts can survive many generations without losing their ability to form myotubes. However, during these subcultures the cells progressively express a new phenotype. This phenotype is characterized by a mixture of myosin light chains such that LC1F, LC2F, and LC2S are present in roughly equimolar amounts, each accounting for 25 to 30% of the total light chain synthesis while LC1S accounts for the remaining 10 to 15%, and by a mixture of fast and slow alpha tropomyosin in which alpha S accounts for 10 to 15% of the alpha subunits synthesis. Clonal analysis indicates that all cells in the population express this phenotype which is also characteristic of subcultures obtained from both future fast and slow muscles. Relationships between this phenotype and muscle development are discussed.

Animals↗
PubMed1982

Changes in tropomyosin during development of chick embryonic skeletal muscles in vivo and during differentiation of chick muscle cells in vitro.

We have studied the changes in tropomyosin subunits and their pattern of phosphorylation during embryonic development and also during in vitro differentiation of cultured muscle cells. We have found that in 10-day-old embryos tropomyosin consists of 75% beta subunit and 25% alpha subunit. However, only 60% of the beta subunit is phosphorylated while the alpha subunit is almost exclusively present in its phosphorylated form. During subsequent development, the amount of alpha-tropomyosin increases so that by hatching it represents 50% of the total subunits. During the same time, the amount of phosphorylated variants for both the alpha and the beta subunits decreases so that after hatching they represent less than 20% of each subunit. In cultures of differentiating myoblasts, the alpha subunit is synthesized before the beta subunit, and within each subunit, the unphosphorylated variants are the first to be synthesized. The reason for this discrepancy is not known at the present time.

Animals↗
PubMed1982

Phosphorylations of the subcellular matrix in cells transformed by Rous' sarcoma virus.

The transforming protein of Rous' sarcoma virus (RSV) is a phosphoprotein of Mr 60 000 (pp60src) which displays protein kinase activity specific for tyrosine residues; pp60src is associated with the plasma membrane and is recovered in the detergent-insoluble material which represents the subcellular matrix of the cell. After phosphorylation of this material of RSV-transformed cells with [gamma-32P]ATP, five phosphoproteins have been detected which are not seen in normal cells. These proteins (Mr = 135 000, 125 000, 75 000, 70 000, 60 000) contain phosphotyrosine. Their phosphorylation is strongly inhibited by anti-pp60src antibodies. In cells transformed by a temperature-sensitive mutant of RSV, these phosphoproteins, present at the permissive temperature, are no longer detected at the non-permissive temperature. It is concluded that these phosphorylations are mediated by pp60src protein kinase activity. This supports a possible role of the phosphorylation of cytoskeletal proteins in the transformation process.

Avian Sarcoma Viruses↗
PubMed1981

Characterization of the tropomyosin present in various chick embryo muscle types and in muscle cells differentiated in vitro.

Tropomyosin, present in various types of chick embryo muscle, has been characterized by two-dimensional gel electrophoresis. In skeletal muscle, it was found that both the alpha and beta subunits exist as two variants, alpha 1, alpha 2 and beta 1, beta 2. The most acidic variants (alpha 2 and beta 2) could be demonstrated to be phosphorylated and, based upon the facts that 1) after phosphatase treatment alpha 2 and beta 2 co-migrate with alpha 1 and beta 1 and 2) in vitro translation of skeletal muscle mRNA produces only alpha 1 and beta 1, we suggest that alpha 2 and beta 2 merely represent the phosphorylated forms of alpha 1 and beta 1. A similar situation is found in differentiated muscle cultures in vitro. In cardiac muscle or in cardiocytes, in culture, the only subunit of tropomyosin which is present (the alpha subunit) is also phosphorylated. However, in smooth muscle, none of the tropomyosin subunits is phosphorylated. The use of various modifications in the second dimension of two-dimensional gel electrophoresis has allowed us to separate completely the alpha subunits of slow and fast muscle tropomyosin and to show that: 1) the cardiac alpha subunit is distinct from either the slow alpha or the fast alpha subunit and 2) in vitro differentiated cells synthesize a tropomyosin which, by co-migration under various conditions, is identical with fast muscle tropomyosin.

Animals↗
PubMed1978

Morphological and biochemical differentiation in RSV transformed chick embryo myoblasts.

Chick embryo myoblasts have been transformed with a temperature sensitive mutant of Rous Sarcoma virus (RSV ts68). At permissive temperature (36 degrees C) it is shown that transformed myoblasts have lost their ability to form myotubes as well as to express the biochemical markers of myogenic differentiation. Upon a shift to the non-permissive temperature (41 degrees C), the normal program of differentiation is restored; myotubes are formed which express muscle specific proteins.

Acetylcholine↗
PubMed1976

Appearance of acetylcholine receptors in cultured myoblasts prior to fusion.

The development of the acetylcholine receptors in chick embryo myoblasts from 11-day old embryos was studied in vitro. Using the purified alpha-bungarotoxin labeled with radioactive iodide, a high concentration of acetylcholine receptors was found in the prefusing myoblasts; most of these receptors were located in the interior of the myoblasts. However, upon the completion of myoblasts fusion, the majority of the acetylcholine receptors appeared on the external cell surface of the myotubes.

Acetylcholine↗