Expression of Human Protein Tyrosine Phosphatase Epsilon in Leucocytes: a Potential ERK Pathway‐Regulating Phosphatase

• Published in: Scandinavian journal of immunology 2002-08, Vol.56 (2), p.195-203
• Main Authors: WABAKKEN, T., HAUGE, H., FINNE, E. F., WIEDLOCHA, A., AASHEIM, H.‐C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Cell Line; Female; Gene Expression - drug effects; HL-60 Cells; Humans; Jurkat Cells; Leukocytes - drug effects; Leukocytes - enzymology; Male; Mice; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases - metabolism; Molecular Sequence Data; Protein Tyrosine Phosphatases - genetics; Rats; Receptor-Like Protein Tyrosine Phosphatases, Class 4; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Tetradecanoylphorbol Acetate - pharmacology; Tissue Distribution
• ISSN: 0300-9475; 1365-3083
• DOI: 10.1046/j.1365-3083.2002.01126.x

The expression of protein tyrosine phosphatase epsilon (PTPε) was studied in human tissues and blood cells. High mRNA expression was observed in peripheral blood leucocytes, particularly in monocytes and granulocytes which revealed at least four distinct transcripts. In lymphocytes, PTPε expression was induced after 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) or antigen‐receptor stimulation, indicating that PTPε plays a role in the events taking place after antigen engagement. Previously, PTPε has been shown to be involved in regulating voltage‐gated potassium channel activity, insulin‐receptor signalling and Janus kinase‐signal transducers and activators of transcription (STAT) signalling. Transfection of cells with different PTPε constructs and activator protein‐1 reporter gene indicates that the catalytic activity of PTPε is involved in the regulation of the mitogen‐activated protein kinase cascade. In particular, the extracellular signal‐regulated kinases (ERK1/2) were shown to be inhibited in both phosphorylation status and enzymatic activity after overexpression of PTPε. Thus, PTPε emerges as a phosphatase with a potential to regulate the ERK1/2 pathway either directly or indirectly through its catalytic activity.