Subcellular localization of a protein-tyrosine phosphatase: evidence for association with chromatin

Abstract

A non-transmembrane protein-tyrosine phosphatase, PTP-S, has been shown to bind to DNA in vitro through its C-terminal noncatalytic domain. The cellular PTP-S gene product was identified as 42-44 kDa polypeptides in the rat fibroblast cell lines Rat2 and F111, by immunoblotting using polyclonal and monoclonal antibodies. Indirect immunofluorescence-staining experiments showed that PTP-S was predominantly associated with the nuclear compartment in interphase cells, although some fluorescence was present in cytoplasm. This protein appeared to be uniformly distributed throughout the cell during mitosis. Subcellular fractionation followed by immunoblotting supports the immunofluorescence data showing that PTP-S was present in the nucleus as well as cytoplasm. PTP-S could be released from the isolated nuclei by moderate salt concentration (400 mM NaCl) or mild treatment with DNAase I, suggesting that at least part of this protein present in the nucleus was associated with chromatin. PTP-S extracted from nuclei of Rat2 cells binds to DNA, as determined by DNA affinity chromatography. The nuclear location of this phosphatase, and its association with chromatin, provide support to our previous suggestion that the DNA-binding property of this phosphatase may be physiologically relevant.

Association of Lyn Tyrosine Kinase with the Nuclear Matrix and Cell‐Cycle‐Dependent Changes in Matrix‐Associated Tyrosine Kinase Activity

“…5 c) while relatively weak staining is seen in the nuclear matrix preparations (Fig. 5 D) indicating that majority of PTP-S is extracted along with chromatin as suggested previously [22]. The subnuclear localization was also confirmed by staining whole cells with anti-Lyn serum and observing different optical sections using a confocal microscope.…”

“…Previously, we have found that PTP-S, a non-transmembrane PTP, is associated with chromatin and, to a lesser extent, with the nuclear matrix [22]. Nuclear matrix preparations from HeLa and Rat 2 cells showed PTP activity using '2P-labelled poly(Glu80, Tyr20) as substrate ( Fig.…”

“…100-200 pg protein from various cell fractions was electrophoresed on SDSIPAGE and immunoblotting performed as reported previously [22], except that washing after the first antibody incubation was performed for IS min with three changes. Monoclonal anti-phosphotyrosine and polyclonal anti-Lyn serum were obtained from Santa Cruz and used at a dilution of 1 : 500.…”

“…It is present in the nucleus largely in association with chromatin [22]. A small fraction of this protein is also associated with the nuclear matrix.…”

Loss of the exon encoding the juxtamembrane domain is essential for the oncogenic activation of TPR-MET

“…Previous data provided evidence that a tyrosine phosphatase activity associates with the activated Met receptor (Villa-Moruzzi et al, 1993). More recently, we described the interaction of Met with PTP-S (Villa-Moruzzi et al, 1998) a soluble phosphatase located in the cytoplasm and in the nucleus of a variety of cells (Radha et al, 1994). PTP-S interacts with the juxtamembrane domain of the Met and has been implicated in regulation of cell proliferation (Kamatkar et al, 1996).…”