Gene Expressions of Protein Tyrosine Phosphatases in Regenerating Rat Liver and Rat Ascites Hepatoma Cells

Abstract

mRNA levels for ten protein tyrosine phosphatases (PTPs), PTP‐S, PTPH1, PTP‐1, GLEPP1, LRP, PTP1D, PTPG1, PTPγ, PTPδ, and LAR, were determined during regeneration of rat liver, and mRNA levels for 5 PTPs, PTP‐S, PTP‐1, PTPγ, PTPδ, and LRP, were determined in three lines of rat ascites hepatoma cells. In regenerating rat liver, the expression patterns of PTP genes after partial hepatectomy could be classified into four groups. In group 1 (PTP‐S and PTPH1), the mRNA levels increased rapidly, reached a maximum 7 h after partial hepatectomy, remained at a plateau for 1–2 days and then decreased gradually. In group 2 (PTP‐1, GLEPP1, and LRP), the mRNA levels showed two peaks on days 1 and 5, and then decreased gradually. In group 3 (PTP1D and PTPG1), the mRNA levels increased rapidly, reached a maximum at 7 h, remained high for several days, and then did not decrease but rather increased after day 7. In group 4 (PTPγ, PTPδ, and LAR), the mRNA levels remained constant for the first 5 days and increased over the control levels after day 7. In rat ascites hepatomas, gene expression of non‐receptor‐like PTPs (PTP‐S and PTP‐1) showed various neoplastic alterations, whereas mRNAs of receptor‐like PTPs (PTPγ, PTPdL, and LRP) were lost or drastically decreased.

Downregulation of stomach cancer-associated protein tyrosine phosphatase-1 (SAP-1) in advanced human hepatocellular carcinoma

“…As in other cell types, the tyrosine phosphorylation of cellular proteins is indispensable for the growth and differentiation of hepatocytes (Palmer et al, 1999). In addition, the expression of several PTPs is upregulated during regeneration of the liver after partial hepatectomy in mice and rats (Higashitsuji et al, 1995;Kitamura et al, 1995;Saito et al, 1996). These observations thus implicate tyrosine phosphorylation events and, hence, PTPs in hepatocellular function under both physiological and pathological conditions.…”

“…These observations thus implicate tyrosine phosphorylation events and, hence, PTPs in hepatocellular function under both physiological and pathological conditions. Dysfunction of PTPs may thus contribute to the development of HCC, although few studies to date have implicated specific PTPs in the pathogenesis of this disease (Ikuta et al, 1994;Kitamura et al, 1995).…”

Analysis of gene expression in carbon tetrachloride-treated rat livers using a novel bioarray technology

“…Some examples include the Ptpro gene, which is a member of the protein tyrosine phosphatases, 79 and has a strong homology to GLEPP1, 80 which has been shown to increase at the time of liver injury. 81 The Cd44 gene family consists of widely distributed cell surface glycoproteins involved in inflammatory responses. 82 The principal carbohydrate ligand of Cd44, hyluronic acid, has been shown to be a useful marker for liver injury induced by CCl 4 in rats.…”

Development of an Assay Method for Activities of Serine/Threonine Protein Phosphatase Type 2B (Calcineurin) in Crude Extracts

“…The primers were designed based on the rat I-1 (26), as follows: I-1S, 5Ј-GAATTCCGTATGGAGCCCGACAACAGT-3Ј, and I-1AS, 5Ј-GCGGCCGCTTCAACTTCTGTCAGACCAA-3Ј. The total RNA from rat brain was prepared by acid guanidinium thiocyanate/phenol/chloroform extraction (27) and cDNA was synthesized as described by reverse transcriptase with oligo(dT) (28). The cDNA was amplified by PCR using I-1S and I-1AS as primers; then the PCR product was digested with EcoRI and NotI and ligated to the EcoRI and NotI fragment of pGEX-5X-1.…”