Furin is a pro-protein convertase that moves between the trans-Golgi network and cell surface in the secretory pathway.We have previously reported that cerebral overexpres-sion of furin promotes cognitive functions in mice.Here,by generating the brain-specific furin conditional knockout(ckO)mice,we investigated the role of furin in brain development.We found that furin deficiency caused early death and growth retardation.Magnetic resonance im-aging showed severe hydrocephalus.In the brain of furin cko mice,impaired ciliogenesis and the derangement of microtubule structures appeared along with the down-regulated expres-sion of RAB28,a ciliary vesicle protein.In line with the widespread neuronal loss,ependymal cell layers were damaged.Further proteomics analysis revealed that cell adhesion molecules including astrocyte-enriched ITGB8 and BCAR1 were altered in furin cKO mice;and astrocyte overgrowth was accompanied by the reduced expression of sox9,indicating a disrupted differ-entiation into ependymal cells.Together,whereas alteration of RAB28 expression correlated with the role of vesicle trafficking in ciliogenesis,dysfunctional astrocytes might be involved in ependymal damage contributing to hydrocephalus in furin ckO mice.The structural and mo-lecular alterations provided a clue for further studying the potential mechanisms of furin.
RNA interfering therapy has emerged as a promising therapeutic modality to treat cancer.The specific and efficient delivery of RNA into a tumor is crucial for achieving effective cancer gene therapy but remains a huge challenge.Herein,we report a novel furin-responsive small interfering RNA(siRNA)delivery vehicle with multiple functions for colorectal tumor treatment.A peptide-based siRNA delivery vehicle RVRR-P18-Gd,consisting of furin enzyme-specific peptide substrate Arg-Val-Arg-Arg(RVRR)with positive charge for siRNA binding,a Gd(III)chelated 1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴-tetraacetic acid(DOTA)(DOTA-Gd)for magnetic resonance imaging,and purpurin 18 as photosensitizer for photodynamic therapy(PDT),was rationally designed and synthesized.Taking advantage of the cationic amphiphilic feature,RVRR-P18-Gd molecules spontaneously self-assembled with negatively charged Hif-1αsiRNA into stable nanoparticles via attractive electrostatic interaction,which effectively prevented siRNA degradation by nucleases,prolonged the circulation half-life,and enhanced tumor accumulation.Moreover,the specific release of Hif-1αsiRNA mediated by endogenous furin significantly downregulated Hif-1αexpression in colorectal cancer cells,resulting in enhanced therapeutic susceptibility,and with the PDT effect,effectively suppressed HCT116 tumor growth in living mice.This work highlights a powerful and universal approach to precisely deliver siRNA to targeted tumors for efficient synergistic therapy.
The current pandemic of COVID-19 caused by a novel coronavirus,severe acute respiratory syndrome coronavirus-2(SARS-CoV-2),threatens human health around the world.Of particular concern is that bats are recognized as one of the most potential natural hosts of SARS-CoV-2;however,coronavirus ecology in bats is still nascent.Here,we performed a degenerate primer screening and next-generation sequencing analysis of 112 bats,collected from Hainan Province,China.Three coronaviruses,namely bat betacoronavirus(Bat CoV)CD35,Bat CoV CD36 and bat alpha-coronavirus CD30 were identified.Bat CoV CD35 genome had 99.5%identity with Bat CoV CD36,both sharing the highest nucleotide identity with Bat Hp-betacoronavirus Zhejiang2013(71.4%),followed by SARS-CoV-2(54.0%).Phylogenetic analysis indicated that Bat CoV CD35 formed a distinct clade,and together with Bat Hp-betacoronavirus Zhejiang2013,was basal to the lineage of SARS-CoV-1 and SARS-CoV-2.Notably,Bat CoV CD35 harbored a canonical furin-like S1/S2 cleavage site that resembles the corresponding sites of SARS-CoV-2.The furin cleavage sites between CD35 and CD36 are identical.In addition,the receptor-binding domain of Bat CoV CD35 showed a highly similar structure to that of SARS-CoV-1 and SARS-CoV-2,especially in one binding loop.In conclusion,this study deepens our understanding of the diversity of coronaviruses and provides clues about the natural origin of the furin cleavage site of SARS-CoV-2.
