Anti-MAP3K5 monoclonal antibody, clone 3F5

Aim: In this study we explored the association between genetic variations in MAP3K5 and PDE7B genes, residing on chromosome 6q23, and disease severity in beta-hemoglobinopathy patients, as well as the association between these variants with response to hydroxyurea (HU) treatment. Furthermore, we examined MAP3K5 expression in the context of high fetal hemoglobin (HbF) and upon HU treatment in erythroid progenitor cells from healthy and KLF1 haploinsufficient individuals. Materials & methods: For this purpose, we genotyped beta-thalassemia intermedia and major patients and healthy controls, as well as a cohort of compound heterozygous sickle cell disease/beta-thalassemia patients receiving HU as HbF augmentation treatment. Furthermore, we examined MAP3K5 expression in the context of high HbF and upon HU treatment in erythroid progenitor cells from healthy and KLF1 haploinsufficient individuals. Results: A short tandem repeat in the MAP3K5 promoter and two intronic MAP3K5 gene variants, as well as a PDE7B variant, are associated with low HbF levels and a severe disease phenotype. Moreover, MAP3K5 mRNA expression levels are altered in the context of high HbF and are affected by the presence of HU. Lastly, the above-mentioned MAP3K5 variants are associated with HU treatment efficacy. Conclusion: Our data suggest that these MAP3K5 variants are indicative of b-thalassemia disease severity and response to HU treatment.

Apoptosis signal-regulating kinase 1 (ASK1, also known as MAP3K5), a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family, regulates diverse physiological processes. The activity of ASK1 is triggered by various stress stimuli and is involved in the pathogenesis of cancer, neurodegeneration, inflammation, and diabetes. ASK1 forms a high molecular mass complex whose activity is, under non-stress conditions, suppressed through interaction with thioredoxin and the scaffolding protein 14-3-3. The 14-3-3 protein binds to the phosphorylated Ser-966 motif downstream of the ASK1 kinase domain. The role of 14-3-3 in the inhibition of ASK1 has yet to be elucidated. In this study we performed structural analysis of the complex between the ASK1 kinase domain phosphorylated at Ser-966 (pASK1-CD) and the 14-3-3 protein. Small angle x-ray scattering (SAXS) measurements and chemical cross-linking revealed that the pASK1-CD14-3-3 complex is dynamic and conformationally heterogeneous. In addition, structural analysis coupled with the results of phosphorus NMR and time-resolved tryptophan fluorescence measurements suggest that 14-3-3 interacts with the kinase domain of ASK1 in close proximity to its active site, thus indicating this interaction might block its accessibility and/or affect its conformation.