AUTHOR=Wan Weiqiang , Zhang Shan , Zhao Mingliang , OuYang Xuan , Yu Yonghui , Xiong Xiaolu , Zhao Ning , Jiao Jun 

TITLE=Lysosomal trafficking regulator restricts intracellular growth of Coxiella burnetii by inhibiting the expansion of Coxiella-containing vacuole and upregulating nos2 expression

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1336600

DOI=10.3389/fcimb.2023.1336600

ISSN=2235-2988

ABSTRACT=<p><italic>Coxiella burnetii</italic> is an obligate intracellular bacterium that causes Q fever, a zoonotic disease typically manifests as a severe flu-illness. After invading into the host cells, <italic>C. burnetii</italic> delivers effectors to regulate the vesicle trafficking and fusion events to form a large and mature <italic>Coxiella</italic>-containing vacuole (CCV), providing sufficient space and nutrition for its intracellular growth and proliferation. Lysosomal trafficking regulator (LYST) is a member of the Beige and Chediak-Higashi syndrome (BEACH) family, which regulates the transport of vesicles to lysosomes and regulates TLR signaling pathway, but the effect of LYST on <italic>C. burnetii</italic> infection is unclear. In this study, a series of experiments has been conducted to investigate the influence of LYST on intracellular growth of <italic>C. burnetii</italic>. Our results showed that <italic>lyst</italic> transcription was up-regulated in the host cells after <italic>C. burnetii</italic> infection, but there is no significant change in <italic>lyst</italic> expression level after infection with the Dot/Icm type IV secretion system (T4SS) mutant strain, while CCVs expansion and significantly increasing load of <italic>C. burnetii</italic> appeared in the host cells with a silenced <italic>lyst</italic> gene, suggesting LYST inhibits the intracellular proliferation of <italic>C. burnetii</italic> by reducing CCVs size. Then, the size of CCVs and the load of <italic>C. burnetii</italic> in the HeLa cells pretreated with E-64d were significantly decreased. In addition, the level of iNOS was decreased significantly in LYST knockout THP-1 cells, which was conducive to the intracellular replication of <italic>C. burnetii</italic>. This data is consistent with the phenotype of L-NMMA-treated THP-1 cells infected with <italic>C. burnetii</italic>. Our results revealed that the upregulation of <italic>lyst</italic> transcription after infection is due to effector secretion of <italic>C. burnetii</italic> and LYST inhibit the intracellular replication of <italic>C. burnetii</italic> by reducing the size of CCVs and inducing <italic>nos2</italic> expression.</p>