The role of 5′-adenosine monophosphate-activated protein kinase(AMPK)in skeletal muscle atrophy

As a key coordinator of metabolism,AMP-activated protein kinase(AMPK)is vitally involved in skeletal muscle maintenance.AMPK exerts its cellular effects through its function as a serine/threonine protein kinase by regulating many downstream targets and plays important roles in the development and growth of skeletal muscle.AMPK is activated by phosphorylation and exerts its function as a kinase in many processes,including synthesis and degradation of proteins,mitochondrial biogenesis,glucose uptake,and fatty acid and cholesterol metabolism.Skeletal muscle atrophy is a result of various diseases or disorders and is characterized by a decrease in muscle mass.The pathogenesis and therapeutic strategies of skeletal muscle atrophy are still under investigation.In this review,we discuss the role of AMPK in skeletal muscle metabolism and atrophy.We also discuss targeting AMPK for skeletal muscle treatment,including exercise,AMPK activators including 5-amino-4-imidazolecarboxamide ribonucleoside and metformin,and low-level lasers.These studies show the important roles of AMPK in regulating muscle metabolism and function;thus,the treatment of skeletal muscle atrophy needs to take into account the roles of AMPK.

MACF1 deficiency suppresses tooth mineralization through IGF1 mediated crosstalk between odontoblasts and ameloblasts

Tooth mineralization is a ubiquitous and tightly regulated process involving complicated interactions between dental epithelium and mesenchyme.Key molecules in tooth mineralization remain poorly identified.Microtubule actin cross-linking factor 1(MACF1)is a spectraplakin protein that plays pivotal roles in the brain,muscle,lung,and bone developmental process.^(1-3) To study the specific functions of MACF1 in bone formation,we established Macf1 conditional knockout mice using the Cre-LoxP system driven by Osxterix promoter(Osx-Cre;Macf1^(f/f)).^(2) Not surprisingly,Osx-Cre;Macf1^(f/f) mice displayed the phenotypes of delayed ossification and decreased bone mass.Moreover,the OsxCre;Macf1^(f/f) mice unexpectedly showed a white and opaque appearance of incisors,contrary to the normal yellowbrown and transparent incisors.Since Osxterix is expressed in dental mesenchyme during tooth development,the abnormal tooth appearance might imply a new function of MACF1 in odontoblasts,or even ameloblasts.Therefore,the present study aimed to investigate the role of MACF1 during tooth development.

An integrated genome-wide analysis identifies HUR/ELAVL1 as a positive regulator of osteogenesis through enhancing theβ-catenin signaling activity

Osteoporosis is a prevalent multifactorial bone disease with a strong genetic contribution.The heritability of traits that contribute to osteoporosis(bone mass,bone mineral density(BMD),bone size,bone loss and fractures)ranges from 50 to 85%,suggesting that a comprehensive understanding of the genetic basis may help identify new therapeutic targets.1 However,the genetic characteristics remain obscure,and the existing drug targets are associated with various challenges.Numerous studies have demonstrated that high-throughput sequencing data analysis is fruitful for identifying novel targets of human diseases.2 We therefore integrated GWAS and transcriptome analyses through Multi-marker Analysis of GenoMic Annotation(MAGMA)and weighted gene co-expression network analysis3(WGCNA)to identify new network modules and potential therapeutic genes for osteoporosis.As an illustration,the flow chart presenting the process of the present study was shown in Figure S1.