Inducing effect of skeletal muscle extracts on the appearance of calbindin-immunoreactive dorsal root ganglion cells in culture.
Calbindin D-28k is a calcium-binding protein which is not expressed by dorsal root ganglion cells cultured from 6-day-old (E6) chick embryos. When soluble muscle extracts from embryos at E11, E18 or chickens 2 weeks after hatching were added immediately after seeding, dorsal root ganglia cells grown at E6 displayed neuronal subpopulations expressing calbindin immunoreactivity with time; the effect of muscle extract on the percentage of calbindin-immunoreactive dorsal root ganglia cells followed a dose-response curve. When muscle extract was added to cultures after a 3 day delay, the percentage of calbindin-expressing neurons was unchanged. The effect produced by muscle extract and, to a lesser degree, skin extract on the appearance of calbindin-positive neurons was not reproduced by brain or liver extracts while all four exerted a trophic action on cultured neurons. Hence it is assumed that muscle extract contains a factor which produces an inductive effect on the initiation of calbindin-expression by uncommitted subpopulations of sensory neurons rather than a trophic influence on the selective survival of covertly committed neuronal subpopulations. The fact that muscle extract promoted calbindin expression by dorsal root ganglia cells in neuron-enriched as well as in mixed dorsal root ganglion cell cultures indicates that the factor would act directly on sensory neurons rather than indirectly through mediation of non-neuronal cells. Since the active muscular factor was non-dialysable, heat-inactivated, trypsin-sensitive and retained by molecular filters with a cut-off of 30 K, this factor is probably a protein.
Institut d'Histologie et d'Embryologie, Faculté de Médecine, Université de Lausanne, Switzerland.
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I
Barakat
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Droz
D000818:Animals; D064026:Calbindins; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D005727:Ganglia, Spinal / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D007150:Immunohistochemistry; D009132:Muscles / Q000032:analysis*; D009474:Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*; D014020:Tissue Extracts / Q000494:pharmacology*
D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D014020:Tissue Extracts