沙門氏菌誘導之微核醣核酸376a透過抑制細胞週期進而促進沙門氏菌之增生

Abstract

許多病原菌透過干擾素主的細胞週期延緩細胞的分裂和上皮組織的更新，使得菌株在上皮細胞的附著時間延長，進而增加感染成功的機會。此外，病原菌也會透過干擾素主的微核醣核酸表現量以抵抗宿主的防禦機制。研究已知鼠傷寒血清型腸道沙門氏菌會促進宿主細胞週期G1/S的轉變，同時也會使宿主細胞停留在G2/M 週期，細胞週期的干擾能促進沙門氏菌在宿主細胞內的複製。本篇研究發現沙門氏菌感染人類結直腸腺癌細胞 HT-29後8小時，透過誘導微核醣核酸376a的表現量增加，造成宿主細胞停留在G2/M 週期。如果抑制HT-29細胞的微核醣核酸376a表現量，則細胞感染後 16 和 24 小時細胞內的沙門氏菌數量有顯著減少。我們分析微核醣核酸376a 下游的基因發現ANGEL2 和 PPP1R10參與細胞週期的調控，且實驗證實微核醣核酸376a 直接抑制這兩個基因的表現。細胞受沙門氏菌感染時，抑制微核醣核酸376a的表現量能減少G2/M週期延遲的細胞數，但此時同時抑制ANGEL2 或 PPP1R10 可以回復G2/M週期延遲的細胞數。這些結果發現沙門氏菌感染會誘導微核醣核酸376a的表現，藉由微核醣核酸376a抑制其目標基因造成宿主細胞的G2/M 細胞週期延遲。

Many bacterial pathogens can interfere with the cell cycle of infected cells to promotes their colonization. Bacterial pathogens also can interfere with the expression of microRNA(miRNA) in order to overcome host defenses. Salmonella enterica serovar Typhimurium promote G1/S transition and induce G2/M arrest to increase intracellular bacterial replication. We find that intracellular Salmonella induces the G2/M phase arrest of epithelial cells after 8 hours post-infection (h.p.i.), and it is dependent on the Salmonella-induced miR-376a. Inhibition of miR-376a in HT-29 cells results in decrease in intracellular replication of Salmonella at 16 and 24 h.p.i. Analysis of miR-376a targets reveals that the expression of two genes, ANGEL2 and PPP1R10, is inhibited by miR-376a. Inhibition of miR-376a reduces Salmonella-induced G2/M phase arrest, and silencing of ANGEL2 or PPP1R10 can reverse the inhibitory effect of the miR-376a antagomiR on G2/M phase arrest. Collectively, these findings suggest that upregulation of miR-376a upon Salmonella infection induces G2/M phase arrest by miR-376a targets inhibition.