Objective To construct a conditional knockout mice model of cysteine-rich angiogenesis inducer 61(Cyr61,also known as Ccn1)gene in myocardium and skeletal muscle regulated by CRE recombinant enzyme.Methods C57BL/6 mice were used to create CKmm-Cre+/-Cyr61flox/flox mice by using CRISPR/Cas9 technology.The successful construction of conditional knockout mice was confirmed by identifying the Cyr61flox/flox,3'LoxP and Cre enzyme sequences in mice.The knockout efficiency of Cyr61 was confirmed by Western blot.The skeletal mus-cle function of Cyr61 knockout mice was evaluated and following related indicators in the myocardium and skeletal muscle were detected by Western blot:Aging(p53,p21),inflammatory response(TNF-α,IL-18,IL-1β),fibrosis(vimentin,TGF-β,α-SMA,COL1).Results The mice were successfully bred and identified.In comparison with the control group,Cyr61 protein level showed a significant decrease in both myocardium and skeletal muscle in the experimental group(P＜0.01).Compared with the control group,the experimental group mice showed increased skeletal muscle grip strength(P＜0.05),enhanced maximum single contraction force(P＜0.01),and increased average cross-sectional area of the anterior tibialis muscle(P＜0.05).The expression level of p21,TNF-α,IL-18,IL-1β,TGF-β,and COL1 proteins in the myocardium and skeletal muscle of the experimental group was all lower than those of the control group(P＜0.05).Conclusions Myocardial and skeletal muscle-specific Cyr61 gene condi-tional knockout mice were successfully constructed based on Cre-LoxP technology and heritable trait could be passed stably.

Alpha-ketoglutarate (AKG) is a key molecule in the Krebs cycle determining the overall rate of the citric acid cycle of the organism. It is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. AKG as a precursor of glutamate and glutamine is a central metabolic fuel for cells of the gastrointestinal tract as well. AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in the skeletal muscles and can be used in clinical applications. In addition to these health benefits, a recent study has shown that AKG can extend the lifespan of adult Caenorhabditis elegans by inhibiting ATP synthase and TOR. AKG not only extends lifespan, but also delays age-related disease. In this review, we will summarize the advances in AKG research field, in the content of its physiological functions and applications.
Adenosine Triphosphate ; Adult ; Bone and Bones ; Caenorhabditis elegans ; Citric Acid Cycle ; Gastrointestinal Tract ; Glutamic Acid ; Glutamine ; Humans ; Insurance Benefits ; Metabolism ; Muscle, Skeletal ; Muscles ; Nitrogen ; Proteolysis