RESUMO
Expression of miR-143 and miR-145 is reduced in hematopoietic stem/progenitor cells (HSPCs) of myelodysplastic syndrome patients with a deletion in the long arm of chromosome 5. Here we show that mice lacking miR-143/145 have impaired HSPC activity with depletion of functional hematopoietic stem cells (HSCs), but activation of progenitor cells (HPCs). We identify components of the transforming growth factor ß (TGFß) pathway as key targets of miR-143/145. Enforced expression of the TGFß adaptor protein and miR-145 target, Disabled-2 (DAB2), recapitulates the HSC defect seen in miR-143/145-/- mice. Despite reduced HSC activity, older miR-143/145-/- and DAB2-expressing mice show elevated leukocyte counts associated with increased HPC activity. A subset of mice develop a serially transplantable myeloid malignancy, associated with expansion of HPC. Thus, miR-143/145 play a cell context-dependent role in HSPC function through regulation of TGFß/DAB2 activation, and loss of these miRNAs creates a preleukemic state.
Assuntos
Células-Tronco Hematopoéticas/metabolismo , MicroRNAs/metabolismo , Síndromes Mielodisplásicas/genética , Transdução de Sinais/genética , Fator de Crescimento Transformador beta/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Proteínas Reguladoras de Apoptose , Medula Óssea/patologia , Transplante de Medula Óssea , Linhagem Celular Tumoral , Modelos Animais de Doenças , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética , Síndromes Mielodisplásicas/patologia , Quimeras de TransplanteRESUMO
UDP-galactopyranose mutase (UGM) is a flavo-enzyme involved in the bacterial cell wall biosynthesis. UGM catalyzes the reversible isomerization of UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). UDP-Galf is the activated precursor of galactofuranose (Galf) residues that are essential components of the cell wall of certain pathogenic bacteria such as Klebsiella pneumoniae and Mycobacterium tuberculosis. Neither UGM nor Galf residues are found in humans, making Galf biosynthesis a potential drug target for developing antibacterial agents. We report the identification of novel inhibitors of UGM by in silico docking of the LeadQuest compound database against UGM from Escherichia coli. The 13 most promising inhibitors were then evaluated against K. pneumonia and M. tuberculosis UGMs by enzyme inhibition studies. Two inhibitors were identified with IC50 values of â¼1â µM and subsequently these compounds were docked into the recently solved X-ray structure of Deinococcus radiodurans UGM. The structure-activity relationships of the initial 13 compounds evaluated as inhibitors are discussed.