Effects of neurotrophin-3 gene mutation in the expression of neurocalcin.
Neurocalcin (NC) is a neuron-specific "EF-hand" calcium-binding protein present in a non-fully characterized subpopulation of dorsal root ganglion (DRG) neurons, some kinds of mechanoreceptors and proprioceptors, and in motor end-plates. In the present study we have characterized NC expression in spinal sensory and motor neurons, and their endings in newborn mouse. Because the neurotrophic factor neurotrophin-3 (NT-3) appears to plays a major role in the development and maturation of sensory and motor neuronal populations, we have studied NC immunoreactivity in newborn NT-3 null mutant. In NT-3 deficient animals the overall number of NC-immunoreactive DRG neurons was reduced by as much as 70% including all large neurons, but subpopulations of NC expressing small and intermediate-sized neurons survived. As expected no muscle spindles were found in NT-3 mutant mice while they were present and normally innervated by NC-positive nerve fibers in wild-type animals. On the other hand, NC immunoreactivity was dramatically decreased in motoneurons of the spinal cord, ventral root nerves and motor end-plates in the absence of NT-3. The present results demonstrate that NC-containing DRG neurons include all proprioceptive, and a subset of mechanoreceptive and proprioceptive. Furthermore, they strongly suggest that NT-3 is involved in the maturation of motor end-plates.
Germanà
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A
Department of Morphology, Biochemistry, Physiology and Animal Production, Section of Morphology, University of Messina, Messina, Italy. anavet@unime.it
del Valle
M E
ME
Laurà
R
R
Ciriaco
E
E
Vega
J A
JA
Germanà
G
G
D000818:Animals; D000831:Animals, Newborn; D000870:Anterior Horn Cells / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics*; D048429:Cell Size; D015536:Down-Regulation / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D008465:Mechanoreceptors / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics*; D051596:Neurocalcin; D009469:Neuromuscular Junction / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*; D020933:Neurotrophin 3 / Q000235:genetics*; D017729:Presynaptic Terminals / Q000378:metabolism / Q000648:ultrastructure; D044169:Receptors, Calcium-Sensing / Q000235:genetics*; D011984:Sensory Receptor Cells / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
D009419:Nerve Tissue Proteins; D051596:Neurocalcin; D020933:Neurotrophin 3; D044169:Receptors, Calcium-Sensing; C496689:Vsnl1 protein, mouse