Alternative Splicing Generates a Diacylglycerol Kinase α Transcript That Acts as a Dominant-Negative Modulator of Superoxide Production in Localized Aggressive Periodontitis

Background: Diacylglycerol (DAG), levels of which are tightly regulated by diacylglycerol kinases (DGKs), is a lipid mediator linked to key biologic functions. Members of the DGK family undergo alternative splicing, generating the protein diversity necessary to control different intracellular DAG pools. DGKa function is altered in polymorphonuclear neutrophils (PMNs) of patients with localized aggressive periodontitis (LAgP), suggesting a genetic basis. Here, the authors assess DGKa spliced transcripts in human LAgP neutrophils. Methods: In an expression library of a patient with LAgP, PMNs were screened for different DGKa transcripts. Realtime polymerase chain reaction and in vitro expression assays were performed to assess the fate of different transcripts on protein translocation and superoxide production in human leukemia cells (HL-60) and COS-7 cells. Results: A DGKa transcript that lacks exon 10 (DGK alpha Delta 10) and generates a premature stop codon and a truncated protein was identified as being upregulated in LAgP neutrophils. In vitro assays revealed that DGKaD10 translocation occurred even in the absence of important regulatory motifs. Transfection of HL-60 neutrophil-like cells with the DGKaD10 spliced variant induced an increase in the stimulated production of superoxide anion replicating the phenotype of LAgP PMNs. Conclusion: DGKaD10 can act as a dominant-negative transcript that can modulate superoxide production and provides an example of genetic regulation of the inflammatory response that may be relevant to human inflammatory diseases such as LAgP.