Epitope Mapping of Antidiacylglycerol Kinase α Monoclonal Antibody DaMab-2

Epitope mapping of an anti-diacylglycerol kinase delta monoclonal antibody DdMab-1

Diacylglycerol kinase δ (DGKδ) is a type II DGK, which catalyzes diacylglycerol phosphorylation to produce phosphatidic acid. DGKδ is expressed in several types of tissues and organs including the stomach, testis, bone marrow, and lymph node. Here, we established an anti-human DGKδ (hDGKδ) mAb, DdMab-1 (mouse IgG_2a, kappa), which is useful for Western blot analysis. We also introduced deletion or point mutations to hDGKδ, and performed western blotting to determine the binding epitope of DdMab-1. DdMab-1 reacted with the dN670 mutant, but not with the dN680 mutant, indicating that the N-terminus of the DdMab-1 epitope is mainly located between amino acids 670 and 680 of the protein. Further analysis using point mutants demonstrated that R675A, R678A, K679A, and K682A mutants were not detected, and V680A was only weakly detected by DdMab-1, indicating that Arg675, Arg678, Lys679, Val680 and Lys682 are important for binding of DdMab-1 to hDGKδ.

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DGKδ catalyzes diacylglycerol phosphorylation to produce phosphatidic acid.

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We established a novel anti-hDGKδ mAb, DdMab-1.

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DdMab-1 is useful for Western blot analysis.

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R675, R678, K679, V680, and K682 are important for binding of DdMab-1 to hDGKδ.

Epitope Mapping of the Anti-Diacylglycerol Kinase Monoclonal Antibody DhMab-4 for Immunohistochemical Analysis

Diacylglycerol kinase (DGK) plays a pivotal role in intracellular signaling pathways in mammals. Activated G protein-coupled receptor activates phospholipase C (PLC) through heterotrimeric G protein, following which PLC hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP₂) into diacylglycerol (DG) and inositol 1,4,5-trisphosphate (IP₃). DGK catalyzes DG phosphorylation to produce phosphatidic acid. DG and phosphatidic acid function as second messengers and their intracellular concentrations are regulated by DGK; therefore, DGK plays an important role in regulating many biological processes. There are ten DGK isozymes, of which DGKη is classified as a type II DGK. Reports have shown that DGKη is associated with several diseases; for example, it is highly expressed in the hippocampus and cerebellum and is a key element in bipolar disorder. Although a DGKη-specific monoclonal antibody (mAb) is necessary to reveal the association between the expression of DGKη and diseases, an anti-DGKη mAb for immunohistochemistry has not yet been established. In this study, we established a specific anti-human DGKη (hDGKη) mAb, DhMab-4 (mouse IgG_2b, kappa). DhMab-4 strongly stained Purkinje cells of human cerebellum in immunohistochemistry analysis. For epitope mapping of DhMab-4, we produced deletion or point mutants of hDGKη and performed western blotting to determine the binding epitope of DhMab-4. DhMab-4 reacted with dN745 mutant but not with dN750 mutant, indicating that the N-terminus of the DhMab-4 epitope is located between amino acids 745 and 750. More detailed analysis using point mutants demonstrated that five mutants, that is, D747A, P748A, F749A, G750A, and T752A, were not detected by DhMab-4. These results indicate that Asp747, Pro748, Phe749, Gly750, and Thr752 are important for DhMab-4 binding to hDGKη.

Epitope Mapping of Anti-Diacylglycerol Kinase ζ Monoclonal Antibody for the Detection of T Cells by Immunohistochemical Analyses

The diacylglycerol kinases (DGKs) are a family of proteins that catalyze the phosphorylation of the cell membrane lipid diacylglycerol (DG), a cellular component that is important in lipid biochemistry and signal transduction, into phosphatidic acid. DG-mediated signal transduction downstream of the T cell receptor has previously been reported to be terminated in most cases by one of 10 DGK isoforms, DGKζ. In this study, we performed immunohistochemical analysis using a rabbit anti-DGKζ monoclonal antibody (mAb) (clone EPR22040-80) against tissues from the tonsils of a patient with oropharyngeal squamous cell carcinoma. We demonstrated that many DGKζ-expressing T cells are localized in the tonsils. We further characterized the binding epitope using an enzyme-linked immunosorbent assay and found that Pro790, Gln791, Gly792, and Leu795 residues of DGKζ are important for facilitating anti-DGKζ mAb binding to DGKζ. This anti-DGKζ mAb could be valuable in immunohistochemical analyses in determining the distribution of DGKζ-expressing T cells in pathophysiological tissues.

Establishment and Epitope Mapping of Anti-Diacylglycerol Kinase α Monoclonal Antibody DaMab-8 for Immunohistochemical Analyses

Diacylglycerol kinase (DGK) converts diacylglycerol (DG) into phosphatidic acid (PA). DGKα, 1 of the 10 DGK isozymes, is involved in T cell function. In the present study, we describe a specific monoclonal antibody DaMab-8 (mouse IgG₁, kappa) against DGKα, which is extremely useful for performing immunohistochemical analysis for T cells in oropharyngeal squamous cell carcinomas. Furthermore, we characterized the binding epitope of DaMab-8 using Western blotting and found that the sites Asn610, Leu611, Trp612, Gly613, Asp614, His619, Tyr623, and Gly624 of DGKα are important for facilitating the DaMab-8 binding to the DGKα protein. Thus, DaMab-8 could be advantageous for immunohistochemical analyses toward clarifying the distribution of DGKα-expressing T cells in every pathophysiological tissue.