Establishment Of Animal Model Of Chronic Kidney Disease Muscle Atrophy And Drawing Of Transcriptome Mapping

Chronic Kidney Disease（CKD）is not a disease but a collection of kidney diseases.At present,chronic kidney disease is defined as a decrease in renal function and the glomerular filtration rate（GFR）is less than 60 m L/Min per 1.73 m2or markers with renal damage over 3 months or both.Diabetes and hypertension are the main causes of CKD in all high-income,middle-income countries and many low-income countries^[1].The incidence,prevalence,and mortality of chronic kidney disease vary among different countries,different races and different societies.The causes of chronic kidney disease are complex.We try to explore the complex mechanism of chronic kidney disease from the perspective of epigenetics^[2].Various complications follow during the progression of chronic kidney disease.In addition to the most common cardiovascular diseases,including hypertension,vascular calcification,and anemia due to decreased kidney erythropoietin;reduced red blood cell production and iron deficiency;Vitamin D,calcium and phosphate metabolism disorders caused by mineral bone disease（CKD-MBD）and chronic kidney disease muscle atrophy^[3-5].The persistent muscle protein catabolism in chronic kidney disease results in a large amount of muscle loss.Even small but persistent imbalances in protein synthesis and catabolism can cause large amounts of protein loss.In patients,loss of cellular proteins increases the incidence and mortality of muscle wasting.However,there is no reliable way to prevent chronic kidney disease-induced muscle atrophy^[6].Catabolic pathways leading to protein consumption include activation of the ubiquitin-proteasome system（UPS）,caspase-3,lysosomes,and myostatin（negative regulators of skeletal muscle growth）^[7].Complications associated with chronic kidney disease can activate these pathways,such as metabolic acidosis,defective insulin signaling,inflammation,elevated levels of angiotensin II,abnormal appetite regulation,and impaired micro RNA responses.Inflammation stimulates cell signaling pathways to produce myostatin,which accelerates catabolism mediated by the ubiquitin-proteasome system.Blocking this pathway can prevent muscle protein loss.Inhibition of myostatin may lead to new treatments for chronic kidney disease and its complications^[8].In order to further study the mechanism of the development of muscle atrophy in chronic kidney disease,with a view to finding suitable targets for further prevention and treatment,we established a mouse model of chronic kidney disease,with C57BL/6 mice as the background,and passed 5/6^th surgical method of nephrectomy was completed on both sides within two weeks and after the adjustment of the high and low protein diet in the later period,the mouse model of chronic kidney disease muscle atrophy was successfully established,which laid a solid foundation for our subsequent experiments.Next,we collected a large number of tibia anterior muscle samples from mice in the sham operation group and corresponding mice in the operation group.They were frozen in liquid nitrogen and stored at-80°C,followed by experiments such as immunofluorescence staining,RNA and protein extraction.Transcriptomic analysis（RNA-Seq and Ch IP-Seq）of RNA extracted from mouse muscles was later used to find key regulatory targets that may affect the process of muscle atrophy.This study starts with the establishment of animal models,and gradually finds targets that have undergone significant changes in epigenetics through bioinformatics analysis,which is later verified by in vivo and in vitro related experiments.This will help us to better understand the mechanism of the development and development of chronic kidney disease muscle atrophy,and to find suitable targets to provide ideas for subsequent targeted drug treatment.