Characterization of endogenous nucleic acids that bind to NgAgo in Natronobacterium gregoryi sp2 cells

As nucleic acid-guided endonucleases,some prokaryotic Argonautes have been used as programmable nucleases.Natronobacterium gregoryi Argonaute(NgAgo)has also been proposed for gene editing,but this remains very controversial.Until now,the endogenous nucleic acids that bind to NgAgo in Natronobacterium gregoryi sp2(N.gregoryi sp2)have not been characterized.We expressed the conserved PIWI domain of NgAgo and used it to induce anti-PIWI antibody.We also cultured the N.gregoryi sp2 strain and performed immunoprecipitation,chromatin immunoprecipitation(ChIP),and RNA immunoprecipitation(RIP)assays.The nucleic acids that endogenously bound NgAgo in N.gregoryi sp2 cells were sequenced and analyzed.The results showed that NgAgo endogenously bound RNA rather than DNA.NgAgo-associated RNAs were mainly transcripts of genes that encoded tRNA,transcriptional regulators,RNA polymerases,and RNA-binding proteins.NgAgo mainly binds to the transcripts inside genes or in their upstream sequences.Interestingly,the top enriched motif of peaks was the same as that of miR-1289,suggesting that NgAgo may regulate gene expression post-transcriptionally.GO enrichment analysis showed that the peak-associated genes were enriched in transmembrane transport processes.These results revealed that NgAgo binds RNA and may function in post-transcriptional regulation in vivo.

A novel peptide specifically binding to VEGF receptor suppresses angiogenesis in vitro and in vivo

Vascular endothelial growth factor(VEGF),one of the most important angiogenic factors,plays an essential role in both physiological and pathological angiogenesis through binding to VEGF receptors(VEGFRs).Here we report a novel peptide designated HRHTKQRHTALH(peptide HRH),which was isolated from the Ph.D.-12 phage display library using VEGFR-Fc fusion protein as the bait.This peptide was found to dose-dependently inhibit the proliferation of human umbilical vein endothelial cells stimulated by VEGF.The anti-angiogenesis effect of the HRH peptide was further confirmed in vivo using the chick chorioallantoic membrane assay,which was also dose-dependent.Besides,peptide HRH was proved to inhibit corneal neovascularization in an alkali-burnt rat corneal model and a suture-induced rat corneal model.Taken together,these findings suggest that the HRH peptide can inhibit angiogenesis both in vitro and in vivo.Consequently,the HRHTKQRHTALH peptide might be a promising lead peptide for the development of potential angiogenic inhibitors.