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Extensive motor neuron survival in the absence of secondary skeletal muscle fiber formation
Author(s) -
Brennan T.J.,
Olson E.N.,
Klein W.H.,
Winslow J.W.
Publication year - 1996
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19960701)45:1<57::aid-jnr5>3.0.co;2-g
Subject(s) - motor neuron , skeletal muscle , neuroscience , fiber , physical medicine and rehabilitation , biology , microbiology and biotechnology , medicine , chemistry , anatomy , spinal cord , organic chemistry
Mice with a null mutation in the myogenic basic helix‐loop‐helix regulatory gene myogenin have severe developmental muscle defects resulting in loss of secondary muscle fibers and perinatal death. In this study, we used the myogenin mutant mouse as a model to study the effects of the loss of secondary muscle fibers and the contribution of primary muscle fibers on the survival of motor neurons during programmed cell death. We demonstrate that in the absence of secondary skeletal muscle fibers there is complete survival of facial motor nucleus motor neurons and approximately 60% survival of spinal lumbar motor neurons in the myogenin mutant mouse. The surviving spinal motor neurons maintain axonal projections into the hindlimb and display aspects of synaptic contact into the remaining rudimentary fibers. These findings suggest that primary muscle fibers, representing approximately 10% of normal muscle mass, contribute significantly to the control of motor neuron cell survival in mammals. © 1996 Wiley‐Liss, Inc.