title: Expression of PRL-1 nuclear PTPase is associated with proliferation in liver but with differentiation in intestine.
abstract: Mechanisms controlling the tyrosine phosphorylation of cellular proteins are important in the regulation of cellular processes including growth and differentiation. It has become clear that a number of protein tyrosine phosphatases (PTPases) that dephosphorylate tyrosyl residues may play a role in the growth response, both in growth-promoting and growth-inhibiting capacities. We identified PRL-1, a unique nuclear PTPase that is an immediate-early gene in liver regeneration and is positively associated with growth, including fetal and neoplastic hepatic growth and anchorage-independent growth after overexpression in fibroblasts. In this study, we show that PRL-1 nuclear protein levels in regenerating liver parallel those of its mRNA, although the peak occurs later, just before the onset of DNA synthesis. We further show that PRL-1 is significantly expressed in intestinal epithelia and that, in contrast to the expression pattern of PRL-1 in liver, its expression is associated with cellular differentiation in intestine. Specifically, PRL-1 is expressed in villus but not crypt enterocytes and in confluent differentiated but not undifferentiated proliferating Caco-2 colon carcinoma cells. The expression of PRL-1 in intestine shows inverse correlation with proliferating cell nuclear antigen expression, a marker for S-phase cells. These results suggest that PRL-1 may play different roles in these two digestive tissues. Such a dichotomy of roles has previously been described for some protein tyrosine kinases and might be due to the availability of alternate substrates in different tissues.
authors: Department of Genetics, Children's Hospital, University of Pennsylvania School of Medicine, Philadelphia 19104-6145, USA.
authors: R H
authors: RH
authors: Diamond
authors: C
authors: C
authors: Peters
authors: S P
authors: SP
authors: Jung
authors: L E
authors: LE
authors: Greenbaum
authors: B A
authors: BA
authors: Haber
authors: D G
authors: DG
authors: Silberg
authors: P G
authors: PG
authors: Traber
authors: R
authors: R
authors: Taub
mesh_terms: D016475:3T3 Cells; D000328:Adult; D000818:Animals; D018938:Caco-2 Cells / Q000378:metabolism; D018797:Cell Cycle Proteins; D002454:Cell Differentiation; D002455:Cell Division; D002467:Cell Nucleus / Q000201:enzymology; D005333:Fetus / Q000378:metabolism; D006498:Hepatectomy / Q000379:methods; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000166:cytology* / Q000196:embryology; D008099:Liver / Q000166:cytology* / Q000378:metabolism*; D008115:Liver Regeneration; D008565:Membrane Proteins; D051379:Mice; D008871:Microvilli / Q000378:metabolism; D009363:Neoplasm Proteins; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; C490198:PTP4A1 protein, human; D017027:Protein Tyrosine Phosphatases; C087359:Ptp4a1 protein, mouse