RNA interference has been widely used for gene therapy of various infectious diseases and malignant tumors. However, its poor stability in serum has limited further clinic application. Here, we found that stability of siRNA in serum enhanced obviously when 3′-terminus of sense strand （siRNA-pS） was conjugated with peptide, while same conjugation at 3′-terminus of antisense strand brought no such effects. And it was also found that only the peptide residue in siRNA-pS could be cut off by RNase A. All these results indicated that nucleases in serum prefer to invade siRNA duplex through the 3′-end of sense strand.
Ficolins are serum complement lectins,with a structure similar to mannose-binding lectin （MBL） and lung surfactant protein （SP）-A and SP-D.Ficolins activate the lectin complement system and play important roles in host innate immunity.Ficolins are members of the collectin family of proteins,which act as pattern recognition receptors （PRRs）.They are soluble oligomeric defense proteins with lectin-like activity,and are able to recognize pathogen-associated molecular patterns （PAMPs）,which are carbohydrate molecules on the surface of pathogens,and of apoptotic,necrotic,and malignant cells.Upon binding to their specific PAMPs,ficolins may trigger activation of the immune system either （1） by initiating activation of complement via the lectin pathway,（2） by a primitive type of opsonophagocytosis,or （3） by stimulating secretion of the inflammatory cytokines interferon （IFN）-γ,interleukin （IL）-17,IL-6,and tumor necrosis factor （TNF）-α,and production of nitric oxide （NO）by macrophages,thus limiting the infection and concurrently orchestrating the subsequent adaptive immune response.Recently,a number of reports have shown that dysfunction or abnormal expression of ficolins may play crucial roles in viral and bacterial diseases and in inflammation.This review summarizes the reports on the roles of ficolins in the infectious diseases,and provides insight into ficolins as novel innate immune therapeutic options to treat these diseases.
Certain carbohydrate antigens of malignantly trans- formed cells have been identified as markers for the onset of can- cer and have become targets for the development of anticancer vaccine therapies. For tumor antigens, many carbohydrate antigens belong to T-independent （TI） antigens. Carbohydrate conjugated to protein carriers can switch TI antigen to a T-dependent （TD） anti- gen. Attempts to add an innate immune response element （such as Toll-like receptor ligand） to carbohydrate TI-antigens have also been studied. Glycosylation inhibitors or small interfering RNA have also been used for antitumor and/or antiviral agents. This review aims at describing the vast spectrum of tumor carbohydrate antigens and strategies to develop cancer vaccines and drugs.
LIU MinPAN QinLUO FenglingMEYERS CraigZHANG Xiao-Lian
In this paper,a series of peptide-siRNA conjugates with phosphodiester unit as the linker targeting to Cdc2 gene were synthesized by solid phase stepwise strategy.The conjugation of peptides at either 3’-terminus of siCdc2 bring no change to the classical A-form of RNA duplex,but slightly compromise the thermodynamic stability.Peptide conjugation at the 3’-terminus of sense strand could improve the serum stability obviously,however,the opposite peptide conjugation at the 3’-terminus of antisense strand shows no such influence.According to the results of artificial silencing activity assay system,peptide conjugation at 3’-terminus of antisense strand slightly weakens the silencing activity of siCdc2.But sense strand peptide conjugation exhibits similar silencing activity as native siCdc2,meanwhile,it could mitigate the unwanted off-target effect of sense strand targeting to its own mRNA.
WANG XiaoFengHUANG YeLIU YangCHEN YueJIN HongWeiZHENG YiDU QuanYANG ZhenJunZHANG LiHe
In this study,a series of 5′-phosphorylated siRNAs with D-/L-isonucleotide(isoNA)or locked nucleic acid(LNA)incorporated at the 5′-terminus were synthesized.It was found that after incorporating either isoNA or LNA at the 5′-terminus of the antisense strand or sense strand,the silencing activity of modified strands has been inhibited,which cannot be recovered by phosphorylation at the 5′-terminus;however,the silencing activity of unmodified strand to its own target was increased.This work indicates that the isoNA and LNA modification at 5′-terminus can interfere with the strand selection during the RISC assembling process,and the disturbance of the 5′-phosporylation should not be the only viable mechanism.
Investigation intracellular trafficking of siRNAs following their delivery to cells is of great interest to elucidate dynamics of siRNA in cytoplasm. In this study, we present a novel confocal laser scanning microscopy （CLSM） method to evaluate a novel delivery system of 3＇-peptide-siRNA therapeutic, which was named 3＇-pAs-siRNA/CLD. This method could not only calculate the content of the intracellular 3＇-peptide-siRNA, but also quantify its co-localization with cellular substructure. We observed that 3＇-pAs-siRNA/CLD, which provided the better antitumor capability, also had a better cell uptake, endosome escape and a longer retention time in A375. This novel strategy was proved to be efficient, quantified and visualized, thus making the dynamics research of siRNA in cytoplasm clear and simplified.
Yiping DiaoJing SunMengyi YangBo XuLihe ZhangZhenjun Yang
