The Metalloprotease, Mpr1, Engages AnnexinA2 to Promote the Transcytosis of Fungal Cells across the Blood-Brain Barrier

Frontiers in Cellular and Infection Microbiology

Na Pombejra, Sarisa¹  Gelli, Angie¹  Salemi, Michelle²  Phinney, Brett S.² 

[1] Department of Pharmacology, School of Medicine, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, United States;Proteomics Core Facility, Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, United States

关键词: Metalloprotease;    Blood-Brain Barrier;    Annexin A2;    Cryptococcus neoformans;    Saccharomyces cerevisiae;    Proteomics;    Transcytosis;    Cytoskeleton;    brain endothelial microvascular cells;   

DOI  :  10.3389/fcimb.2017.00296

学科分类：生物科学（综合）

来源: Frontiers

【 摘 要 】

Eukaryotic pathogens display multiple mechanisms for breaching the blood-brain barrier (BBB) and invading the central nervous system (CNS). Of the fungal spp., that cause disease in mammals, only some cross brain microvascular endothelial cells which constitute the BBB, and invade the brain. Cryptococcus neoformans, the leading cause of fungal meningoencephalitis, crosses the BBB directly by transcytosis or by co-opting monocytes. We previously determined that Mpr1, a secreted fungal metalloprotease, facilitates association of fungal cells to brain microvascular endothelial cells and we confirmed that the sole expression of CnMPR1 endowed S. cerevisiae with an ability to cross the BBB. Here, the gain of function conferred onto S. cerevisiae by CnMPR1 (i.e. Sc strain) was used to identify targets of Mpr1 that might reside on the surface of the BBB. Following biotin-labeling of BBB surface proteins, Sc-associated proteins were identified by LC-MS/MS. Of the 62 proteins identified several were cytoskeleton-endocytosis-associated including AnnexinA2 (AnxA2). Using an in vitro model of the human BBB where AnxA2 activity was blocked, we found that the lack of AnxA2 activity prevented the movement of S. cerevisiae across the BBB (i.e. transcytosis of Sc strain) but unexpectedly, TEM analysis revealed that AnxA2 was not required for the association or the internalization of Sc. Additionally, the co-localization of AnxA2 and Sc suggest that successful crossing of the BBB is dependent on an AxnA2-Mpr1-mediated interaction. Collectively the data suggest that AnxA2 plays a central role in fungal transcytosis in human brain microvascular endothelial cells. The movement and exocytosis of Sc is dependent on membrane trafficking events that involve AnxA2 but these events appear to be independent from the actions of AnxA2 at the host cell surface. We propose that Mpr1 activity promotes cytoskeleton remodeling in brain microvascular endothelial cells and thereby engages AnxA2 in order to facilitate fungal transcytosis of the BBB.

【 授权许可】

CC BY