Ble knockout Skin conditional knockout T cell-specific knockout Endothelial cell-specific knockout Endothelial cell-specific inducible knockout

Ble knockout Skin conditional knockout T cell-specific knockout Endothelial cell-specific knockout Endothelial cell-specific inducible knockout Phenotypeacid residues in the N-terminal kinase domain have been implicated in the regulation of MAP4K4 activity including lysine 54 (K54), aspartate 153 (D153, corresponding site of NIK D152), threonine 181 (T181), threonine 187 (T187) and threonine 191 (T191) [9, 12, 13]. Result of in vitro kinase assay using MAP4K4 mutant protein as enzyme and myelin basic protein (MBP) as substrate showed that mutation of T187 to E slightly increased the catalytic activity of MAP4K4 [9], suggesting that this is a potential phosphorylation site. Regarding T181, there is no in vitro kinase assay result available showing that T181A (replacing threonine to alanine) mutation abolishes MAP4K4 kinase activity, whereas T181D or T181E mutation increases or restores MAP4K4 activity. However, this mutant (T181E) was used in a recent study as a phosphor-mimetic mutant [12]. Mutation of T191 to glutamate (E) or K54 to arginine (R), completely abrogated the kinase activity of MAP4K4, indicating that these two residues are required for MAP4K4 kinase activity. If T191 is a phosphorylation site, the result suggests that phosphorylation of T191 has a negative impact on MAP4K4 kinase activity. Phosphorylation of T181 and T187 or T191 has not been verified in vivo. The biochemical and biological consequences PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28914615 of these phosphorylations Thonzonium (bromide) chemical information remain to be determined. Identifying upstream kinases responsible for the phosphorylation will help to understand how MAP4K4 is regulated in biological contests. Taking the global phosphoproteomics approach and by comparing the corresponding SILAC (Stable Isotope Labeling by Amino acids in Cell) ratios of EGF (epidermal growth factor) stimulation and erlotinib (EGFR inhibitor) treatment in lung adenocarcinoma cells, a prior study identified two serine sites S648 and S708 in the middle domain of MAP4K4 as EGFR (epidermal growth factor receptor) signaling-dependent phosphorylation sites [22]. Serine 648 is conserved among the five MAP4K4 isoforms mentioned above [7, 9], but serine 708 is missing in the corresponding position of the above isoforms, suggesting that there could be an unidentified isoform of MAP4K4 or it was simply due to incorrect matches [23]. Although phosphorylation of these sites need to be further verified by mutation strategy and the biochemicalRef. [11] [19] [13] [16] [12] [18]Embryonic lethality Reduced plasma glucose levels and enhanced insulin sensitivity Aberrant wound repair and epidermal cell migration defects Systemic inflammation and type 2 diabetes Embryonic lethality Protected from vascular inflammation and atherosclerosisGao et al. Cell Biosci (2016) 6:Page 3 ofHuman MAP4K4/ HGKT187 K54 T181 T191 S648 SKDF25 Mouse MAP4K4/ NIK D152 RCNHKDD20 D306 (574-616)CNH(1288 aa)KDKinase DomainProline-rich motifCNHCitron homology DomainFig. 1 Schematic diagram of MAP4K4 structure. Both human and mouse MAP4K4 are composed of an N-terminal kinase domain and a C-terminal citron-homology domain. Mouse MAP4K4 contains proline-rich motifs. Sites involved in regulation of kinase activity and potential phosphorylation sites are indicatedand biological consequences of these phosphorylations remain to be determined, the observation that in vivo phosphorylation of these sites are regulated by EGFR signaling strongly support that the intermediate regions of MAP4K4 may also play an importan.