The expression of diacylglycerol kinase isoforms α and ζ correlates with the progression of experimental autoimmune encephalomyelitis in rats

Multiple sclerosis (MS) is characterized by neuroinflammation and neurodegeneration, whose precise processes are not fully understood. Diacylglycerol kinase (DGK) isozymes of alpha, beta, gamma and zeta expressed abundantly in the brain and/or the immune system, may be regulatory targets for MS. In this study, we analyzed the four DGK isozymes along the induction, peak and recovery phases in an experimental autoimmune encephalomyelitis (EAE) rat model of MS. The expression of these DGK isozymes and the diacylglycerol (DAG) pathway in the EAE rat brainstems were analyzed by qRT-PCR, immunohistochemistry, immunofluorescence double staining, western blotting and ELISA. Our results showed that the mRNA content of the four DGK isozymes decreased significantly, and their immunoreactivity in myelin sheathes (DGK alpha, beta) and neurons (DGK gamma, zeta) became weaker at the beginning of the induction phase. With the progressive increase in clinical signs, DGK alpha, DGK gamma and DGK zeta mRNA increased and DGK beta mRNA decreased, and microglia were involved in the formation of perivascular cuffing. In the peak phase, both DGK alpha and DGK zeta were expressed in neurons and inflammatory cells, and DGK zeta was also positive in microglia. During the recovery phase, the mRNA content and immunoreactivity of these DGK isozymes generally reached normal levels. Moreover, our results revealed that changes in DAG accumulation and PKC delta phosphorylation were almost the same as those of DGK alpha and DGK zeta mRNA. In summary, the four DGK isozymes are involved in the EAE process. The predominant and broad presence of DGK alpha and DGK zeta suggests that they may regulate the pathological process by attenuating DAG/PKC delta pathway signaling during EAE evolution.

Automated summary

The study revealed that the four DGK isozymes play important roles in the process of experimental autoimmune encephalomyelitis (EAE). DGKα and DGKζ may regulate the pathological process by attenuating DAG/PKC delta pathway signaling during EAE evolution.