Roger Briesewitz | PubMed Health

PubMed2003

A bifunctional molecule that displays context-dependent cellular activity.

The cell-permeable dihydrofolate reductase inhibitor methotrexate was covalently linked to a ligand for the protein FKBP to create a bifunctional molecule called MTXSLF. The covalent tether between the two ligands was designed to be prohibitively short, so that unfavorable protein-protein interactions between DHFR and FKBP preclude formation of a trimeric complex. In vitro and in vivo experiments demonstrate that MTXSLF is an effective inhibitor of human DHFR, but that efficacy is decreased in the presence of human FKBP due to the high concentration of FKBP and its tight affinity for MTXSLF. MTXSLF also inhibits Plasmodium falciparum DHFR in vitro, but a low concentration of the weaker binding Plasmodium FKBP has no effect on the inhibitory potency of MTXSLF in vivo. These studies illustrate a potentially general strategy for modulating the biological activity of synthetic molecules that depends on the ligand-binding properties of a nontarget protein.

Amino Acid Sequence↗

PubMed2003

Discovery of a fusion kinase in EOL-1 cells and idiopathic hypereosinophilic syndrome.

Idiopathic hypereosinophilic syndrome (HES) is a myeloproliferative disease of unknown etiology. Recently, it has been reported that imatinib mesylate (Gleevec), an inhibitor of Bcr-Abl kinase useful in the treatment of chronic myeloid leukemia, is also effective in treating HES; however, the molecular target of imatinib in HES is unknown. This report identifies a genetic rearrangement in the eosinophilic cell line EOL-1 that results in the expression of a fusion protein comprising an N-terminal region encoded by a gene of unknown function with the GenBank accession number NM_030917 and a C-terminal region derived from the intracellular domain of the platelet-derived growth factor receptor alpha (PDGFRalpha). The fusion gene was also detected in blood cells from two patients with HES. We propose naming NM_030917 Rhe for Rearranged in hypereosinophilia. Rhe-PDGFRalpha fusions result from an apparent interstitial deletion that links Rhe to exon 12 of PDGFRalpha on chromosome 4q12. The fusion kinase Rhe-PDGFRalpha is constitutively phosphorylated and supports IL-3-independent growth when expressed in BaF3 cells. Proliferation and viability of EOL-1 and BaF3 cells expressing Rhe-PDGFRalpha are ablated by the PDGFRalpha inhibitors imatinib, vatalanib, and THRX-165724.

Adult↗