Analysis of neurotrophin-3 expression using the lacZ reporter gene suggests its local mode of neurotrophic activity.
We replaced the mouse neurotrophin-3 gene with the Escherichia coli-derived lacZ gene by means of homologous recombination. The mice with this mutation were useful models for studying the distribution of neurotrophin-3 expression in vivo, because visualization by 5-bromo-4-chloro-3-indoyl-beta-D-galactopyranoside (X-Gal) staining was simple and rapid compared with in situ hybridization or immunohistochemistry. Whole-mount staining of mutant embryos at embryonic day 10 revealed that lacZ, a reporter for the neurotrophin-3 gene, was expressed in the mesencephalon, mandibular arch and somites. In the embryos at days 13-17, lacZ was markedly expressed in the peripheral target tissues of sensory and sympathetic neurons. We also found that spinal motor neurons and sensory neurons in trigeminal and dorsal root ganglia express lacZ. Some of these X-Gal staining regions overlapped with the sites expressing trkC, a high-affinity receptor for neurotrophin-3. The distribution of X-Gal staining in heterozygotes and homozygotes was similar to that of neurotrophin-3 messenger RNA detected by in situ hybridization. However, there was less lacZ expression in the dorsal root ganglia of homozygotes than neurotrophin-3 expression in wild-type mice. These results suggest that the neurotrophin-3 produced in the dorsal root ganglia also plays a role in the survival of some of the neurotrophin-3-positive neurons and that the local mode of neurotrophic activity is widely distributed.
Tojo
H
H
Discovery Research Laboratories II, Takeda Chemical Industries Ltd, Ibaraki, Japan.
Takami
K
K
Kaisho
Y
Y
Nakata
M
M
Abe
T
T
Shiho
O
O
Igarashi
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry / Q000235:genetics / Q000502:physiology; D005260:Female; D005697:Galactosides; D005727:Ganglia, Spinal / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D007211:Indoles; D007763:Lac Operon / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008818:Mice, Neurologic Mutants; D008969:Molecular Sequence Data; D009414:Nerve Growth Factors / Q000096:biosynthesis* / Q000502:physiology; D020933:Neurotrophin 3; D010525:Peripheral Nerves / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D001616:beta-Galactosidase / Q000235:genetics
D005697:Galactosides; D007211:Indoles; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; D001616:beta-Galactosidase; C044888:5-bromo-4-chloro-3-indolyl beta-galactoside