Jon McMahel
Indiana University
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Publication
Featured researches published by Jon McMahel.
Journal of Biological Chemistry | 1997
Yuan Xiao Zhu; Hui Bin Sun; Monica Lik-Shing Tsang; Jon McMahel; Susan Grigsby; Tinggui Yin; Yu-Chung Yang
Interleukin-9 receptor (IL-9R) complex consists of a ligand-specific α chain and IL-2R γ chain. In this study, two regions in the cytoplasmic domain of human IL-9Rα were found to be important for IL-9-mediated cell growth. A membrane-proximal region that contains the BOX1 consensus sequence is required for IL-9-induced cell proliferation and tyrosine phosphorylation of Janus kinases (JAKs). Deletion of this region or internal deletion of the BOX1 motif abrogated IL-9-induced cell proliferation and signal transduction. However, substitution of the Pro-X-Pro in the BOX1 motif with Ala-X-Ala failed to abolish IL-9-induced cell proliferation but decreased IL-9-mediated tyrosine phosphorylation of JAK kinases, insulin receptor substrate-2, and signal transducer and activator of transcription 3 (STAT3) and expression of c-mycand junB. Another important region is downstream of the BOX1 motif and contains a STAT3 binding motif YLPQ. Deletion of this region significantly impaired IL-9-induced cell growth, activation of JAK kinases, insulin receptor substrate-2, and STAT3 and expression of early response genes. A point mutation changing YLPQ into YLPA greatly reduced IL-9-induced activation of STAT3 and expression of c-myc but did not affect cell proliferation. These results suggest that cooperation or cross-talk of signaling molecules associated with different domains of IL-9Rα other than STAT3 is essential for IL-9-mediated cell growth.
British Journal of Haematology | 1998
Christie M. Traycoff; Bartley Halstead; Susan Rice; Jon McMahel; Edward F. Srour; Kenneth Cornetta
To investigate the mechanisms behind the leukaemic expansion of chronic myelogenous leukaemia (CML), we examined the cell cycle status and activation kinetics of purified subpopulations of CD34+ cells from normal and CML bone marrow (BM). Propidium iodide staining was used to assess cell cycle status of fresh cells or those stimulated with cytokines. Although the cell cycle status of fresh low‐density cells from CML and normal BM was similar, a larger percentage of CML CD34+ cells were cycling than those from normal BM. The HLA‐DR− compartment of CML CD34+ cells, a fraction enriched for normal, non‐leukaemic progenitors, contained a higher percentage of quiescent cells than the CD34+ HLA‐DR+ fraction. When the activation of CD34+ cells was examined in response to SCF or IL‐3 alone, or SCF+IL‐3+IL‐6, CML CD34+ cells exited G0/G1 more rapidly than normal CD34+ cells. Interestingly, although normal BM CD34+ cells failed to cycle in response to IL‐6 alone, or in the absence of exogenous cytokines, 30% of CML cells cycled under these conditions. No differences in the degree of apoptosis were documented among CML and normal CD34+ cells in these cultures. These data suggest that enhanced cell cycle activation of CML CD34+ cells, by either autocrine stimuli or via enhanced sensitivity to exogenous stimuli, may be partially responsible for the pronounced cellular expansion characteristic of CML.
Blood | 1997
André Gothot; Robert Pyatt; Jon McMahel; Susan Rice; Edward F. Srour
Blood | 1997
Amy C. Ladd; Robert Pyatt; André Gothot; Susan Rice; Jon McMahel; Christie M. Traycoff; Edward F. Srour
Experimental Hematology | 1998
Traycoff Cm; Attilio Orazi; Amy C. Ladd; Susan Rice; Jon McMahel; Edward F. Srour
Experimental Hematology | 1998
André Gothot; Robert Pyatt; Jon McMahel; Susan Rice; Edward F. Srour
Blood | 1998
Ponnazhagan Veena; Christie M. Traycoff; David A. Williams; Jon McMahel; Susan Rice; Ken Cornetta; Edward F. Srour
Archive | 2013
André Gothot; Robert Pyatt; Jon McMahel; Susan Rice; Edward F. Srour
Archive | 2011
André Gothot; Robert Pyatt; Jon McMahel; Susan Rice; Edward F. Srour
Archive | 2011
Amy C. Ladd; Robert Pyatt; André Gothot; Susan Rice; Jon McMahel; Christie M. Traycoff; F Edward