Protein tyrosine phosphatase 1B negatively regulates macrophage development through CSF-1 signaling.
Protein tyrosine phosphatase 1B (PTP-1B) is a ubiquitously expressed cytosolic phosphatase with the ability to dephosphorylate JAK2 and TYK2, and thereby down-regulate cytokine receptor signaling. Furthermore, PTP-1B levels are up-regulated in certain chronic myelogenous leukemia patients, which points to a potential role for PTP-1B in myeloid development. The results presented here show that the absence of PTP-1B affects murine myelopoiesis by modifying the ratio of monocytes to granulocytes in vivo. This bias toward monocytic development is at least in part due to a decreased threshold of response to CSF-1, because the PTP-1B -/- bone marrow presents no abnormalities at the granulocyte-monocyte progenitor level but produces significantly more monocytic colonies in the presence of CSF-1. This phenomenon is not due to an increase in receptor levels but rather to enhanced phosphorylation of the activation loop tyrosine. PTP-1B -/- cells display increased inflammatory activity in vitro and in vivo through the constitutive up-regulation of activation markers as well as increased sensitivity to endotoxin. Collectively, our data indicate that PTP-1B is an important modulator of myeloid differentiation and macrophage activation in vivo and provide a demonstration of a physiological role for PTP-1B in immune regulation.
Division of Experimental Medicine, McGill University, Montreal, QC, Canada H3G 1Y6.
Krista M
KM
Heinonen
Nadia
N
Dubé
Annie
A
Bourdeau
Wayne S
WS
Lapp
Michel L
ML
Tremblay
D000818:Animals; D006098:Granulocytes / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000235:genetics; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008817:Mice, Mutant Strains; D009000:Monocytes / Q000276:immunology; D010766:Phosphorylation; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D015398:Signal Transduction
D008070:Lipopolysaccharides; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; C516609:Ptpn1 protein, mouse