Protein tyrosine phosphatase activity in human endometrium

2001 ◽  
Vol 13 (3) ◽  
pp. 175 ◽  
Author(s):  
Seppo Partanen
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Phosphatase Activity ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Kinases ◽  
Tyrosine Phosphatase ◽  
Intrauterine Device ◽  
Human Endometrium ◽  
Protein Tyrosine ◽  
Glandular Cells

Protein tyrosine phosphatase (PTP) activity was demonstrated in human endometrium by a histochemical method using phosphotyrosine as substrate. For comparative purposes, non-specific acid phosphatase (AcP) activity was also examined. Protein tyrosine phosphatase activity was very low in proliferative and atrophic endometrium, but its activity was increased 9-fold in glandular epithelium during the secretory phase, and 48-fold in predecidual endometrium, induced by a progestagen-releasing intrauterine device, compared with the proliferative endometrium. Thus, PTP activity appeared to be progesterone-induced. Endometrial PTP appeared to be cellular rather than secretory in origin; its activity was inhibited by vanadate, and its histochemical properties were different from those of lysosomal AcP, but similar to those of prostatic-type AcP. Endometrial PTP may functionally counteract the effects of protein tyrosine kinases (PTKs) associated with growth factor receptors and cellular oncoproteins. Cyclic endometrial proliferation and differentiation are thought to be regulated by the autocrine and paracrine pathways by growth factors such as epidermal growth factor, insulin-like growth factor I and platelet-derived growth factors, and their receptors. However, cessation of proliferation could not be explained by the amounts of these growth factors present or their receptors, in that no constant changes at the interface of the late proliferative and early secretory phases were found. Down-regulation of stimulatory-signalling pathways of PTKs by endometrial PTP induced by progesterone may explain the decrease observed in proliferative activity of glandular cells in cyclic endometrium.

scholarly journals Regulation of membrane-associated tyrosine phosphatases in UMR 106.06 osteoblast-like cells

1995 ◽  
Vol 305 (2) ◽  
pp. 485-490 ◽  
Author(s):  
M C Southey ◽  
D M Findlay ◽  
B E Kemp
Keyword(s):  
Growth Factor ◽  
Molecular Mass ◽  
Phosphatase Activity ◽  
Cell Density ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Phosphatase ◽  
Protein Tyrosine Phosphatases ◽  
Apparent Molecular Mass ◽  
Tyrosine Phosphatases ◽  
Protein Tyrosine

Protein tyrosine phosphatases play an important role in cell metabolism. Three distinct protein tyrosine phosphatase activities have been identified in an osteoblast-like cell line, UMR 106.06. These activities comprised two membrane-associated phosphatases and one cytosolic phosphatase of apparent molecular mass > 153 kDa, 80 kDa and 40 kDa respectively, estimated by gel filtration. On the basis of differences in apparent molecular mass, proteolytic-digestion profiles, substrate specificities and responses to a range of extracellular influences and inhibitor molecules, the two membrane-associated tyrosine phosphatases are distinct proteins. Tyrosine phosphatase activity in UMR 106.06 cells was sensitive to cell density. Cells at confluence contained membrane protein tyrosine phosphatase with specific activity 9-fold higher than cells at medium or low cell density. This elevation in membrane tyrosine phosphatase activity was due specifically to an increase in the high-molecular-mass enzyme. This phosphatase was also responsive to extracellular matrix components. This activity was elevated in cells grown on a collagen type-I matrix independently of cell density. Membrane and cytosolic protein tyrosine phosphatases were differentially regulated by a variety of agents including phorbol 12-myristate 13-acetate, parathyroid hormone, epidermal growth factor, okadaic acid and transforming growth factor beta. These observations suggest that regulatory influences control tyrosine phosphorylation in UMR 106.06 cells including cell-cell contact, cell-matrix contact and signal transduction involving tyrosine and serine/threonine phosphorylation events.

Protein Tyrosine Kinase-Dependent Modulation of Isoflurane Effects on Cardiac Sarcolemmal KATPChannel

2002 ◽  
Vol 97 (5) ◽  
pp. 1198-1208 ◽  
Author(s):  
Anna Stadnicka ◽  
Wai-Meng Kwok ◽  
David C. Warltier ◽  
Zeljko J Bosnjak
Keyword(s):  
Growth Factor ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Kinases ◽  
Protein Tyrosine Kinase ◽  
Single Channel ◽  
Tyrosine Phosphatase ◽  
Volatile Anesthetics ◽  
Open Probability ◽  
Whole Cell ◽  
Protein Tyrosine

Background Cardiac adenosine triphosphate-sensitive potassium (K(ATP)) channels and protein tyrosine kinases (PTKs) are mediators of ischemic preconditioning, but the interaction of both and a role in myocardial protection afforded by volatile anesthetics have not been defined. Methods Whole cell and single channel patch clamp techniques were used to investigate the effects of isoflurane and the PTK inhibitor genistein on the cardiac sarcolemmal K(ATP) channel in acutely dissociated guinea pig ventricular myocytes. Results At 0.5 mm internal ATP, genistein (50 microm) elicited whole cell K(ATP) current (22.5 +/- 7.9 pA/pF). Genistein effects were concentration-dependent, with an EC50 of 32.3 +/- 1.4 microm. Another PTK inhibitor, tyrphostin B42, had a similar effect. The inactive analog of genistein, daidzein (50 microm), did not elicit K(ATP) current. Isoflurane (0.5 mm) increased genistein (35 microm)-activated whole cell K(ATP) current from 14.5 +/- 3.1 to 32.5 +/- 6.6 pA/pF. Stimulation of receptor PTKs with epidermal growth factor, nerve growth factor, or insulin attenuated genistein and isoflurane effects, and the protein tyrosine phosphatase inhibitor orthovanadate (1 mm) prevented their actions on K(ATP) current. In excised inside-out membrane patches, and at fixed 0.2 mm internal ATP, genistein (50 microm) increased channel open probability from 0.053 +/- 0.016 to 0.183 +/- 0.039, but isoflurane failed to further increase open probability (0.162 +/- 0.051) of genistein-activated channels. However, applied in the presence of genistein and protein tyrosine phosphatase 1B (1 microg/ml), isoflurane significantly increased open probability to 0.473 +/- 0.114. Conclusions These results suggest that the PTK-protein tyrosine phosphatase signaling pathway may be one of the regulators of cardiac sarcolemmal K(ATP) channel and may play a role in modulating its responsiveness to isoflurane. Relative importance of this modulation for cardioprotection by volatile anesthetics remains to be established.

scholarly journals Regulation of Phosphoinositide Levels in the Retina by Protein Tyrosine Phosphatase 1B and Growth Factor Receptor-Bound Protein 14

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 602
Author(s):  
Raju V. S. Rajala ◽  
Austin McCauley ◽  
Rahul Rajala ◽  
Kenneth Teel ◽  
Ammaji Rajala
Keyword(s):  
Growth Factor ◽  
Protein Tyrosine Phosphatase ◽  
Tyrosine Kinases ◽  
Knockout Mouse ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Mouse Retina ◽  
Protein Tyrosine Phosphatase 1B ◽  
Protein Tyrosine ◽  
Growth Factor Receptor Bound

Protein tyrosine kinases and protein phosphatases play a critical role in cellular regulation. The length of a cellular response depends on the interplay between activating protein kinases and deactivating protein phosphatases. Protein tyrosine phosphatase 1B (PTP1B) and growth factor receptor-bound protein 14 (Grb14) are negative regulators of receptor tyrosine kinases. However, in the retina, we have previously shown that PTP1B inactivates insulin receptor signaling, whereas phosphorylated Grb14 inhibits PTP1B activity. In silico docking of phosphorylated Grb14 and PTP1B indicate critical residues in PTP1B that may mediate the interaction. Phosphoinositides (PIPs) are acidic lipids and minor constituents in the cell that play an important role in cellular processes. Their levels are regulated by growth factor signaling. Using phosphoinositide binding protein probes, we observed increased levels of PI(3)P, PI(4)P, PI(3,4)P2, PI(4,5)P2, and PI(3,4,5)P3 in PTP1B knockout mouse retina and decreased levels of these PIPs in Grb14 knockout mouse retina. These observations suggest that the interplay between PTP1B and Grb14 can regulate PIP metabolism.

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