Embryology of Two Murine Muscle Diseases: Muscular Dystrophy and Muscular Dysgenesis ?

Platzer, Ann C.

doi:10.1111/j.1749-6632.1979.tb56514.x

Cited by 7 publications

(5 citation statements)

References 35 publications

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“…Swollen sareoplasmie reticulum has previously been described in dystrophic muscles (2,11). In accordance with our observations, Platzer (12) found that the longitudinal tubules and terminal cisternae are dilated in dystrophic musele in contrast to the transverse system, whieh remains unaffected. Considering the function of the sareoplasmie reticulum in muscular contraction, PLATZER (12) suggested that a morphologically abnormal sareoplasmie reticulum may indicate a disability to store, release, or take up calcium with possible effects on normal muscular contraction.…”

Section: Discussionsupporting

confidence: 92%

Electron microscopic and histochemical studies on dystrophic masseter muscle

Mikkelsen

Kirkeby

1985

European J Oral Sciences

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Section: Discussionsupporting

confidence: 92%

Electron microscopic and histochemical studies on dystrophic masseter muscle

Mikkelsen

Kirkeby

1985

European J Oral Sciences

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“…suggested that triad formation can occur without the skeletal muscle D H P R % subunit. However, the majority of studies on dysgenic muscle reported that junctions with regularly spaced feet are missing (Platzer, 1979;Platzer and Gluecksohn-Waelsch, 1972;Banker, 1977). Our initial observations on primary dysgenic cultures added two important pieces of evidence to support the notion that D H P R -R y R interactions are not involved in triad formation: first, double immunofluorescence experiments showing RyR clusters without the corresponding D H P R % subunit demonstrated that residual, low-level expression of the skeletal % subunit could not account for the formation of a small number of normal junctions; secondly, functional analysis failed to detect any depolarization-induced Ca 2÷ release events, which would be expected if the observed RyR clusters actually resembled complete junctions.…”

Section: Triad Formationmentioning

confidence: 99%

Formation of triads without the dihydropyridine receptor alpha subunits in cell lines from dysgenic skeletal muscle.

Powell

Petherbridge

Flucher

1996

The Journal of Cell Biology

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Abstract. Muscular dysgenesis (mdg/mdg), a mutation of the skeletal muscle dihydropyridine receptor (DHPR) ot 1 subunit, has served as a model to study the functions of the DHPR in excitation-contraction coupling and its role in triad formation. We have investigated the question of whether the lack of the DHPR in dysgenic skeletal muscle results in a failure of triad formation, using cell lines (GLT and NLT) derived from dysgenic (mdg/mdg) and normal (+/+) muscle, respectively. The lines were generated by transfection of myoblasts with a plasmid encoding a Large T antigen. Both cell lines express muscle-specific proteins and begin organization of sarcomeres as demonstrated by immunocytochemistry. Similar to primary cultures, dysgenic (GLT) myoblasts show a higher incidence of cell fusion than their normal counterparts (NLT). NLT myotubes develop spontaneous contractile activity, and fluorescent Ca 2÷ recordings show Ca 2÷ release in response to depolarization. In contrast, GLTs show neither spontaneous nor depolarization-induced Ca 2+ transients, but do release Ca 2÷ from the sarcoplasmic reticulum (SR) in response to caffeine. Despite normal transverse tubule (T-tubule) formation, GLT myotubes lack the % subunit of the skeletal muscle DHPR, and the 0~2 subunit is mistargeted. Nevertheless, the ryanodine receptor (RyR) frequently develops its normal, clustered organization in the absence of both DHPR a subunits in the T-tubules.

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“…Second, the mdg and cn mutations both lead to a skeletal muscle dysfunction, and there are a number of similarities between the resulting phenotypes (Wick and Allenspach, 1978;Powell, 1990). These similarities can be appreciated from a comparison of the descriptions of the morphology of mdg/mdg muscle by Pai (1965a,b) and Platzer (1979) with those of cnicn muscle by Kieny et al (1983Kieny et al ( , 1988a. Third, exposure to pharmacological agents which prevent neuronal activation of skeletal muscle results in marked alterations in the latter tissue (Murray and Drachman, 1969;Drachman et al, 1976).…”

Section: The Absence Of Aryr Protein and Its Function As A Sr Calciummentioning

confidence: 99%

Failure to make normal α ryanodine receptor is an early event associated with the Crooked Neck Dwarf (cn) mutation in chicken

Airey

Baring

Beck

et al. 1993

Developmental Dynamics

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We have investigated the molecular basis of the Crooked Neck Dwarf (cn) mutation in embryonic chickens. Using biochemical and pharmacological techniques we are unable to detect normal α ryanodine receptor (RyR) protein in intact cn/cn skeletal muscle. Extremely low levels of αRyR immunoreactivity can be observed in mutant muscles, but the distribution of this staining differs from that in normal muscle and colocalizes with the rough endoplasmic reticulum immunoglobulin binding protein, BiP. This suggests the existence of an abnormal αRyR protein in mutant muscle. In day E12 cn/cn muscle the levels of RyR mRNA are reduced by ∼80%, while the levels of other muscle proteins, including the α1 subunit of the dihydropyridine receptor, the SRCa2+‐ATPase, calsequestrin, and glyceraldehyde‐3‐phosphate dehydrogenase, and their associated mRNAs are essentially normal in cn/cn muscle. There is also a failure to express αRyR in cn/cn cerebellar Purkinje neurons. Expression of the βRyR, a second RyR isoform, is not initiated in normal skeletal muscle until day E18. In cn/cn skeletal muscle significant muscle degeneration has occurred by this time and the βRyR is found at low levels in only a subset of fibers suggesting the reduced levels of this isoform are a secondary consequence of the mutation. The cardiac RyR isoform is found in cn/cn cardiac muscle, which contracts in a vigorous manner. In summary, a failure to make normal αRyR receptor appears to be an event closely associated with the cn mutation and one which may be largely responsible for development of the cn/cn phenotype in embryonic skeletal muscle. © 1993 Wiley‐Liss, Inc.

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Embryology of Two Murine Muscle Diseases: Muscular Dystrophy and Muscular Dysgenesis ?

Cited by 7 publications

References 35 publications

Electron microscopic and histochemical studies on dystrophic masseter muscle

Electron microscopic and histochemical studies on dystrophic masseter muscle

Formation of triads without the dihydropyridine receptor alpha subunits in cell lines from dysgenic skeletal muscle.

Failure to make normal α ryanodine receptor is an early event associated with the Crooked Neck Dwarf (cn) mutation in chicken

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