许氏平鲉Myomaker通过调控成肌细胞融合促进肌肉肥大生长的调控机制OACSTPCD

To explore the regulatory role of myomaker during muscle growth in teleosts,Sebastes schlegelii,an important marine economic fish species in northern China was used in this study,which displays indeterminate muscle growth,and demonstrated that myomaker gene plays an important role in its muscle growth.The full length of the myomaker gene of S.schlegelii is 5 386 bp,with coding se-quence of 870 bp,encoding a protein of 289 amino acids.Whole-mount in situ hybridization of S.schlegelii embryos revealed that myomaker expression was initiated at the somite stage and showed in-tense expression exclusively in the developing somites.However,in the pre-hatching and larval stages the signal was mainly concentrated in the head and anterior part of trunk.After overexpression of myo-maker by feeding larval S.schlegelii with plasmid for 30 days,the expression of myomaker was signifi-cantly elevated.myomaker could promote hypertrophy growth of muscle based on the evidence that the overexpression group contained significantly fewer number of small-scale fibers(500～1 000 μm2)and more of large-scale fibers(＞1 000 μm2)than those in the control group.The ratio of large-scale fibers(＞5 000 μm2)in the overexpression group is still larger than that in the control group after 90 days cul-ture post the termination of overexpression treatment.In addition,S.schlegelii myomaker could drive the fusion of C2C12 myoblasts.It is speculated that myomaker drives hypertrophy growth of muscle in S.schlegelii by promoting myoblast fusion.This study highlights the important role of myomaker in regulating muscle growth in nonmodel species and provides a foundation to our understanding of the mechanisms involved in the indeterminate growth in large scale teleost fish.