title: Expression of DEP-1, a receptor-like protein-tyrosine-phosphatase, is enhanced with increasing cell density.
abstract: cDNA encoding a receptor-like protein-tyrosine-phosphatase (PTP) termed DEP-1 was isolated from a HeLa cell library. The cDNA predicts an enzyme consisting of an extracellular segment containing eight fibronectin type III repeats, a single transmembrane segment, and a single intracellular PTP domain. Following expression of DEP-1 cDNA in COS cells a glycoprotein of 180 kDa was detected and PTP activity was demonstrated in immunocomplexes with a C-terminal peptide antiserum. Endogenous DEP-1 was detected in WI-38 human embryonic lung fibroblasts by immunoblotting and immunocomplex PTP assays. Immunoblot analysis of DEP-1 expression in WI-38 cells revealed dramatically increased levels and activity of the PTP in dense cultures relative to sparse cultures. Also, DEP-1 activity, detected in PTP assays of immunocomplexes, was increased in dense cell cultures. In contrast, the expression levels of PTP-1B did not change with cell density. This enhancement of DEP-1 expression with increasing cell density was also observed in another fibroblast cell line, AG1518. The increase in DEP-1 occurs gradually with increasing cell contact and is initiated before saturation cell density is reached. These observations suggest that DEP-1 may contribute to the mechanism of contact inhibition of cell growth.
authors.affiliation: Cold Spring Harbor Laboratory, NY 11724-2208.
authors.forename: A
authors.initials: A
authors.lastname: Ostman
authors.forename: Q
authors.initials: Q
authors.lastname: Yang
authors.forename: N K
authors.initials: NK
authors.lastname: Tonks
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D002460:Cell Line; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D017931:DNA Primers; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D007668:Kidney; D008168:Lung; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis* / Q000302:isolation & purification; D054631:Receptor-Like Protein Tyrosine Phosphatases, Class 3; D017386:Sequence Homology, Amino Acid; D014162:Transfection
chemical_list: D017931:DNA Primers; C486288:PTPRJ protein, human; D017027:Protein Tyrosine Phosphatases; D054631:Receptor-Like Protein Tyrosine Phosphatases, Class 3