Asymmetric Arginine Dimethylation Of SKN-1 By PRMT-1 Affects Oxidative Stress Defense And Aging In C.elegans

Aging is necessary stage for every organism.There are a lot of diseases associated with the aging in human,such as blood hypertension,atherosclerosis and Alzheimer's disease.At present,there are several main theories for aging,such as free radical theory,theory of telomere shortening,and energy restriction.It is very attractive to study the relationship between aging and the resistance to oxidative stress.So,discovering a new gene and mechanism of regulating oxidative stress defense and aging is very important for studying the regulation of aging.C.elegans is a good model for aging study,because it has a strong ability to reproduce,short reproductive cycle,convenient genetic operations,and a large number of mutants and so on,which can avoid the long study cycle and complex operation in mammals.SKN-1 is a very important transcription factor that can regulate both oxidative stress defense and aging.SKN-1 and its mammalian homologs Nrf/CNC have obvious differences in their DNA binding domain,but their functions are conservative.In a certain condition,the intestinal SKN-1 can accumulate within the nucleus to activate its target gene expression about detoxification,which improves the oxidative resistance and anti-aging ability in C.elegans.It has been indicated that the regulation of oxidative stress defense and aging by SKN-1 is closely related to its phosphorylation modification.For example,the phosphorylation of SKN-1 by GSK-3 can inhibits the localization of SKN-1 in the intestine.But it is still unclear if any other posttranslational modification of SKN-1 occurs.Arginine methylation is a very important posttranslational modification.The C.elegans arginine methyltransferase 1(prmt-1)has highly conservative sequence and function to mammalian prmt-1.The evidences showed that the abilities of oxidative resistance and anti-aging in C.elegans were decreased obviously in prmt-1 mutant.There are a certain number of arginines in SKN-1 protein.Moreover,both protein SKN-1 and PRMT-1 are highly express in C.elegans intestine.So it is interesting to get to know whether the arginines of SKN-1 can be methylated by PRMT-1,which can regulate the oxidative resistance and aging in C.elegans.In order to know the answers of this question,we first used IP and GST-pulldown methods and found that SKN-1 can interact with PRMT-1,and the arginine of SKN-1 can be methylated in vivo.Then,Arg484 and Arg516 were identified to be asymmetricaly dimethylated by PRMT-1 by methylation assay and mass spectrometry.Moreover,our results showed that PRMT-1 influenced the accumulation of SKN-1 in the intestines,and affected the target gene expressions of SKN-1 by Real-time PCR and confocal microscope.All of the results suggest that SKN-1 can be asymmetrically dimethylated by PRMT-1,and this modification affects the function of SKN-1 in the oxidative resistance and anti-aging in C.elegans.These results in our study will built the base for studying the crosstalk of posttranslational modifications between phosphorylation and arginine methylation of SKN-1,which are involed in regulating oxidative resistance and aging in C.elegans.And it also provide the clue to know deeply the functions of Nrf-2and Nrf/CNC in mammals.