Cytoskeleton Actin Affects Osteogenic Differentiation By Regulating Mitochondrial Dynamics

Background:Mitochondrial are widely existed in various eukaryotes because of its special structures and functions,which is one of the main energy production features of cells.Many kinds of enzymes have been located in mitochondrial,which is the major site for energy conversion and energy generation.The special functionality of mitochondria is closely related to changes in its structure.Among them,the basis for achieving its function is mitochondrial fusion and fission,also known as mitochondrial dynamics.Under normal circumstances,mitochondrial fusion and fission occur simultaneously and maintain a state of dynamic equilibrium,so that the morphology,structure and function of mitochondria in the cell can be maintained in a stable condition.However,it is noteworthy that there is an interaction between mitochondria and the cytoskeleton,which can adjust the dynamic balance of mitochondrial fusion and fission.The cytoskeleton is an indispensable protein scaffold for the mitochondrial network.And also,it is an important spatial structure for achieving mitochondrial dynamics.In the past decade,great progress has been made in the field of mitochondrial dynamics.whatever the observation of phenomena or the study of precise structures and mechanisms,all of them have been made remarkable breakthroughs,especially the interaction mode between mitochondria and cytoskeleton which people pay more attention to.More and more studies have proved that mitochondria have undergone dramatic and dynamic changes in morphology,number,distribution and respiratory capacity during cell differentiation and dedifferentiation.However,the study of mitochondria in stem cell differentiation is still incomplete,and further research is urgently needed.Based on previous research,our research group found that the amount of actin expression and the spatial structure of human adipose-derived stem cells have undergone drastic changes during osteogenic differentiation,and thus regulate lipid production and bone loss.Considering about the mitochondrial outer membrane regulates lipid production and also has a direct effect on actin,we speculate that mitochondrial dynamics is the key factor in regulating this phenomenon,and the research will be concerned on this.Objective:This study focused on observing changes in actin and its mitochondrial dynamics during osteogenic differentiation of human fibroblasts.The purpose of our experiment is to provid relevant biologically information for studying mitochondria and osteogenic differentiation mechanisms.Methods:At the first stage,detect the changes of actin and mitochondrial dynamics between the osteogenic differentiation of human fibroblasts.At the second stage,Cytochalasin D and Jasplkinolide were added to the growth medium and osteogenic differentiation medium respectively,then the changes of cell ability and mitochondrial dynamics by Immunofluorescence and western blot,in the treatment of 1d,4d and 7d.Finally,cell performance and mitochondrial were detected and compare when Cyto D or JAS was added into the medium of osteoblastic differentiation.Result:Cyto D can induce the effect of osteogenic induction media,but JAS increase the effect of it.JAS increase the effect of mitochondrial dynamics significantly than Cyto D.actin polymerization increase the osteogenic differentiation;actin polymerization and depolymerization affect the colocalization ratio between mitochondrial and actin in osteogenic differentiation.Conclusion actin polymerization increase the osteogenic differentiation;actin polymerization and depolymerization affect the colocalization ratio between mitochondrial and actin in osteogenic differentiation.Our exploration on the effect of osteogenic differentiation by Cyto D and JAS and the changes about mitochondrial dynamics which can provide important biological information for studying the mitochondrial and differentiation mechanism.