Low intensity near-infrared light promotes bone regeneration via circadian clock protein cryptochrome 1

Bone regeneration remains a great clinical challenge. Low intensity near-infrared(NIR) light showed strong potential to promote tissue regeneration, offering a promising strategy for bone defect regeneration. However, the effect and underlying mechanism of NIR on bone regeneration remain unclear. We demonstrated that bone regeneration in the rat skull defect model was significantly accelerated with low-intensity NIR stimulation. In vitro studies showed that NIR stimulation could promote the osteoblast differentiation in bone mesenchymal stem cells(BMSCs) and MC3T3-E1 cells, which was associated with increased ubiquitination of the core circadian clock protein Cryptochrome 1(CRY1) in the nucleus. We found that the reduction of CRY1 induced by NIR light activated the bone morphogenetic protein(BMP) signaling pathways, promoting SMAD1/5/9 phosphorylation and increasing the expression levels of Runx2 and Osterix. NIR light treatment may act through sodium voltage-gated channel Scn4a, which may be a potential responder of NIR light to accelerate bone regeneration. Together, these findings suggest that low-intensity NIR light may promote in situ bone regeneration in a CRY1-dependent manner, providing a novel, efficient and non-invasive strategy to promote bone regeneration for clinical bone defects.

生物信息学资源助力蛋白质磷酸化的系统层次理解

Protein phosphorylation,catalyzed by protein kinases(PKs),is one of the most prevalent post-translational modifications(PTMs)in eukaryotes.Phosphorylation occurring at different positions in a protein sequence can possess distinct functional impacts,and sitespecific phosphorylation may drastically alter a protein’s conformation,activity,and trafficking.Traditionally,biologists usually focused on studying regulatory mechanisms of phosphorylation in a limited number of proteins,mainly due to a lack of highthroughput technology.During the past two decades,advances in liquid chromatography coupled with tandem mass spectrometry(LC-MS/MC)have boomed a revolutionary technology named phosphoproteomics,which can simultaneously quantify thousands of phosphorylation sites(p-sites),and provide a great opportunity for a systems-level understanding of phosphorylation.Besides LCMS/MC,other approaches such as immunohistochemistry(IHC)and immune-detection by sequencing(ID-seq)have also emerged.

Phosphorylation Promotes the Accumulation of PERIOD Protein Foci

Circadian clock drives the 24-h rhythm in our behavior and physiology.The molecular clock consists of a series of transcriptional/translational feedback loops operated by a number of clock genes.A very recent study reported that the clock protein PERIOD(PER)is organized into discrete foci at the nuclear envelope in fly circadian neurons,which is believed to be important for controlling the subcellular localization of clock genes.Loss of inner nuclear membrane protein lamin B receptor(LBR)leads to disruption of these foci,but how they are regulated is yet unknown.Here,we found that PER foci are likely phase-separated condensates,the formation of which is mediated by intrinsically disordered region in PER.Phosphorylation promotes the accumulation of these foci.Protein phosphatase 2A,which is known to dephosphorylate PER,hampers the accumulation of the foci.On the other hand,the circadian kinase DOUBLETIME(DBT)which phosphorylates PER enhances the accumulation of the foci.LBR likely facilitates PER foci accumulation by destabilizing the catalytic subunit of protein phosphatase 2A,MICROTUBULE STAR(MTS).In conclusion,here,we demonstrate a key role for phosphorylation in promoting the accumulation of PER foci,while LBR modulates this process by impinging on the circadian phosphatase MTS.

Functional characterization of novel NPRL3 mutations identified in three families with focal epilepsy

Focal epilepsy accounts for 60% of all forms of epilepsy, but the pathogenic mechanism is not well understood. In this study,three novel mutations in NPRL3(nitrogen permease regulator-like 3), c.937_945del, c.1514dup C and 6,706-bp genomic DNA(g DNA) deletion, were identified in three families with focal epilepsy by linkage analysis, whole exome sequencing(WES) and Sanger sequencing. NPRL3 protein is a component of the GATOR1 complex, a major inhibitor of m TOR signaling. These mutations led to truncation of the NPRL3 protein and hampered the binding between NPRL3 and DEPDC5, which is another component of the GATOR1 complex. Consequently, the mutant proteins enhanced m TOR signaling in cultured cells, possibly due to impaired inhibition of m TORC1 by GATOR1. Knockdown of nprl3 in Drosophila resulted in epilepsy-like behavior and abnormal synaptic development. Taken together, these findings expand the genotypic spectrum of NPRL3-associated focal epilepsy and provide further insight into how NPRL3 mutations lead to epilepsy.

Nuclear Envelope Protein MAN1 Regulates the Drosophila Circadian Clock via Period

Almost all organisms exhibit ~24-h rhythms, or circadian rhythms, in a plentitude of biological processes.These rhythms are driven by endogenous molecular clocks consisting of a series of transcriptional and translational feedback loops. Previously, we have shown that the inner nuclear membrane protein MAN1 regulates this clock and thus the locomotor rhythm in flies, but the mechanism remains unclear. Here, we further confirmed the previous findings and found that knocking down MAN1 in the pacemaker neurons of adult flies is sufficient to lengthen the period of the locomotor rhythm. Molecular analysis revealed that knocking down MAN1 led to reduced m RNA and protein levels of the core clock gene period(per),likely by reducing its transcription. Over-expressing per rescued the long period phenotype caused by MAN1 deficiency whereas per mutation had an epistatic effect on MAN1, indicating that MAN1 sets the pace of the clock by targeting per.

Tau Accumulation and Defective Autophagy:A Common Pathological Mechanism Underlying Repeat-Expansion-Induced Neurodegenerative Diseases?

Repetitive DNA tracts(microsatellites)occur thousands of times throughout the human genome,and their expansion is known to cause many diseases.Expansion of CAG repeats encoding poly glutamine(polyQ)tracts is a pathological cause of nine neurodegenerative diseases:spinal and bulbar muscular atrophy,Huntington’s disease,dentatorubropallidoluysian atrophy,and six autosomal dominant forms of spinocerebellar ataxia(SCA1,2,3,6,7,and 17)[1].

Chronotypes and affective disorders:A clock for mood?

Affective disorders are often accompanied by circadian rhythm disruption and the major symptoms of mental illness occur in a rhythmic manner.Chronotype,also known as circadian preference for rest or activity,is believed to exert a substantial influence on mental health.Here,we review the connection between chronotypes and affective disorders,and discuss the potential underlying mechanisms between these two phenomena.

The molecular mechanism of natural short sleep:A path towards understanding why we need to sleep

Sleep constitutes a third of human life and it is increasingly recognized as important for health.Over the past several decades,numerous genes have been identified to be involved in sleep regulation in animal models,but most of these genes when disturbed impair not only sleep but also health and physiological functions.Human natural short sleepers are individuals with lifelong short sleep and no obvious adverse outcomes associated with the lack of sleep.These traits appear to be heritable,and thus characterization of the genetic basis of natural short sleep provides an opportunity to study not only the genetic mechanism of human sleep but also the relationship between sleep and physiological function.This review focuses on the current understanding of mutations associated with the natural short sleep trait and the mechanisms by which they contribute to this trait.

A New Link Between Insulin Signaling and Fragile X Syndrome

Fragile X syndrome （FXS） is the most common cause of inherited intellectual disability and the most common known genetic cause of autism or autism spectrum disorders. FXS is caused by silencing or mutation of the fragile X mental retardation gene （FMR1）, a known RNA-binding protein that acts as a negative regulator of translation [1, 2]. FXS patients demonstrate a myriad of symptoms that can vary widely between individuals, including impaired cognition, physical abnormalities, sleep problems, hyperarousal to sensory stimuli, increased anxiety, obsessive compulsive disorder-like behavior, attention-deficit hyperactive disorder symptoms, self-injurious behavior, aggression, and increased risk of seizures [3]. The molecular mechanisms underlying FXS are not clear, and currently there is no ideal treatment.