Regulation of signaling at regions of cell-cell contact by endoplasmic reticulum-bound protein-tyrosine phosphatase 1B.
Protein-tyrosine phosphatase 1B (PTP1B) is a ubiquitously expressed PTP that is anchored to the endoplasmic reticulum (ER). PTP1B dephosphorylates activated receptor tyrosine kinases after endocytosis, as they transit past the ER. However, PTP1B also can access some plasma membrane (PM)-bound substrates at points of cell-cell contact. To explore how PTP1B interacts with such substrates, we utilized quantitative cellular imaging approaches and mathematical modeling of protein mobility. We find that the ER network comes in close proximity to the PM at apparently specialized regions of cell-cell contact, enabling PTP1B to engage substrate(s) at these sites. Studies using PTP1B mutants show that the ER anchor plays an important role in restricting its interactions with PM substrates mainly to regions of cell-cell contact. In addition, treatment with PTP1B inhibitor leads to increased tyrosine phosphorylation of EphA2, a PTP1B substrate, specifically at regions of cell-cell contact. Collectively, our results identify PM-proximal sub-regions of the ER as important sites of cellular signaling regulation by PTP1B.
Beth Israel Deaconess Medical Center, Harvard University, Boston, Massachusetts, United States of America. fghaj@ucdavis.edu
Fawaz G
FG
Haj
Ola
O
Sabet
Ali
A
Kinkhabwala
Sabine
S
Wimmer-Kleikamp
Vassilis
V
Roukos
Hong-Mei
HM
Han
Markus
M
Grabenbauer
Martin
M
Bierbaum
Claude
C
Antony
Benjamin G
BG
Neel
Philippe I
PI
Bastiaens
D000818:Animals; D019556:COS Cells; D002450:Cell Communication; D002460:Cell Line; D002522:Chlorocebus aethiops; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism* / Q000648:ultrastructure; D008954:Models, Biological; D009154:Mutation; D017434:Protein Structure, Tertiary; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1