title: TC-PTP-deficient bone marrow stromal cells fail to support normal B lymphopoiesis due to abnormal secretion of interferon-{gamma}.
abstract: The T-cell protein tyrosine phosphatase (TC-PTP) is a negative regulator of the Jak/Stat cytokine signaling pathway. Our study shows that the absence of TC-PTP leads to an early bone marrow B-cell deficiency characterized by hindered transition from the pre-B cell to immature B-cell stage. This phenotype is intrinsic to the B cells but most importantly due to bone marrow stroma abnormalities. We found that bone marrow stromal cells from TC-PTP(-/-) mice have the unique property of secreting 232-890 pg/mL IFN-gamma. These high levels of IFN-gamma result in 2-fold reduction in mitotic index on IL-7 stimulation of TC-PTP(-/-) pre-B cells and lower responsiveness of IL-7 receptor downstream Jak/Stat signaling molecules. Moreover, we noted constitutive phosphorylation of Stat1 in those pre-B cells and demonstrated that this was due to soluble IFN-gamma secreted by TC-PTP(-/-) bone marrow stromal cells. Interestingly, culturing murine early pre-B leukemic cells within a TC-PTP-deficient bone marrow stroma environment leads to a 40% increase in apoptosis in these malignant cells. Our results unraveled a new role for TC-PTP in normal B lymphopoiesis and suggest that modulation of bone marrow microenvironment is a potential therapeutic approach for selected B-cell leukemia.
authors.affiliation: McGill Cancer Centre, McGill University, Montreal, QC, Canada.
authors.forename: Annie
authors.initials: A
authors.lastname: Bourdeau
authors.forename: Nadia
authors.initials: N
authors.lastname: Dubé
authors.forename: Krista M
authors.initials: KM
authors.lastname: Heinonen
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Théberge
authors.forename: Karen M
authors.initials: KM
authors.lastname: Doody
authors.forename: Michel L
authors.initials: ML
authors.lastname: Tremblay
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D001854:Bone Marrow Cells / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D006706:Homeostasis / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism*; D015851:Interleukin-7 / Q000494:pharmacology; D038041:Lymphopoiesis / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D017154:Stromal Cells / Q000378:metabolism*
chemical_list: D015851:Interleukin-7; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D007371:Interferon-gamma; D011494:Protein Kinases; D054578:Protein Tyrosine Phosphatase, Non-Receptor Type 2; D017027:Protein Tyrosine Phosphatases; C516653:Ptpn2 protein, mouse