Study On The Role Of Dlk2 In Skeletal Muscle Development And Function

Dlk1 as a transmembrane protein has been shown to play a key role in skeletal muscle development and adipogenesis;the role of Dlk2,which is highly similar to Dlk1,in skeletal muscle development remains to be clarified.Previously our laboratory carried out some work on the relationship between Dlk2 and skeletal muscle development.Manipulating Dlk2 in C2C12 cells showed that Dlk2 acfected ability of differentiation in the middle and late stages,and dynamic gene-expression analysis of the differentiation indicated that Dlk2 plays an important role in maintaining the differentiation potential of myoblasts.In order to further explore the relationship between Dlk2 and skeletal muscle development,we first established a C2C12 cell line with complete knockout of Dlk2 by CRISPR-Cas9 technique,and found that the ability of myogenic differentiation was significantly decreased compared with the control group.We established the Dlk2-/-zebrafish using CRISPR-Cas9 technique,and found that the survival rate and appearance of Dlk2-/-zebrafish were not abnormal,but the swimming activity in water,especially the maximum acceleration,decreased significantly compared with the wild type,suggesting knockout of Dlk2 might have an effect on the muscle explosiveness of zebrafish.However,immunofluorescence with Rhodamine labeled phalloidin failed to detect any significant difference in length or morphology of the muscle filaments of Dlk2-/-zebrafish larva;and neither the expression level of the Myogenic factors of Dlk2-/-zebrafish including MyoD,MyoG and Myomaker,as tested by qPCR and in situ hybridization.Interestinly,MCK was significantly down-regulated during development,which may contribute importantly in the decreased activity of Dlk2-/-zebrafish larva.Finally,we found that Heyl of Notch pathway in Dlk2-/-zebrafish was also down-regulated compared with wild type,especially in the neural tube.This suggests that Dlk2 may act simultaneously on the development of skeletal muscle and nervous system of zebrafish through Notch signaling pathway.In summary,combined with some preliminary work in our laboratory,we found that Dlk2 can regulate the development and function of skeletal muscle,and provides a new clue for studying the relationship of functional development between skeletal muscle and nervous system.