Distribution of a murine protein tyrosine phosphatase BL-beta-galactosidase fusion protein suggests a role in neurite outgrowth.
We have generated a gene trap insertion into the protein tyrosine phosphatase-BL (PTP-BL) locus, which produces a fusion of the N-terminal half of PTP-BL with beta-galactosidase. During development, beta-galactosidase activity was seen in all epithelial cells: strong staining was observed in the stomach and kidney epithelium, the ependymal layer of the central nervous system, and the surface ectoderm. Particularly prominent beta-galactosidase activity was seen in the peripheral nervous system, which correlated with neurite outgrowth. In epithelial cells, staining was seen in the apical portion of the cells. In nerves, beta-galactosidase activity was associated with growth cones as well as with Schwann cells. This suggests that the amino-terminal portion of PTP-BL contains sequences sufficient to target the fusion protein to specific subcellular compartments. In situ hybridization with a PTP-BL probe demonstrated that all tissues in which beta-galactosidase activity was seen were genuine sites of expression of the PTP-BL gene, although differences in the stability of the PTP-BL protein and the PTP-BL-beta-galactosidase fusion protein may exist. The distribution of beta-galactosidase activity in the peripheral nervous system, together with the structure of the wild-type protein, suggests that this phosphatase may have a role in regulation of the cytoskeleton during the development of the peripheral nervous system.
Thomas
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Department of Molecular Cell Biology, Max Planck Institute of Biophysical Chemistry, Göttingen, Germany. tthomas@gwdg.de
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D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D005314:Embryonic and Fetal Development / Q000235:genetics; D004847:Epithelial Cells / Q000201:enzymology; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006579:Heterozygote; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016254:Mutagenesis, Insertional; D016501:Neurites / Q000201:enzymology* / Q000648:ultrastructure; D010525:Peripheral Nerves / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D017027:Protein Tyrosine Phosphatases; D001616:beta-Galactosidase