Lipid raft/caveolae signaling is required for Cryptococcus neoformans invasion into human brain microvascular endothelial cells

Journal of Biomedical Science

Ambrose Jong¹  Gregory M Shackleford¹  Chun-Hua Wu¹  Sheng-He Huang³  Min Long² 

[1] Divisions Hematology-Oncology, The Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA;Department of Microbiology, Southern Medical University, Guangzhou, China;Division of Infectious Diseases, The Saban Research Institute, Children's Hospital Los Angeles, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90027, USA

关键词: lipid raft;    brain microvascular endothelial cells;    CD44;    caveolin-1;    Cryptococcus neoformans;   

Others  :  825652
DOI  :  10.1186/1423-0127-19-19

 received in 2011-10-24, accepted in 2012-02-08,  发布年份 2012

【 摘 要 】

Background

Cryptococcus neoformans has a predilection for central nervous system infection. C. neoformans traversal of the blood brain barrier, composed of human brain microvascular endothelial cells (HBMEC), is the crucial step in brain infection. However, the molecular mechanism of the interaction between Cryptococcus neoformans and HBMEC, relevant to its brain invasion, is still largely unknown.

Methods

In this report, we explored several cellular and molecular events involving the membrane lipid rafts and caveolin-1 (Cav1) of HBMEC during C. neoformans infection. Immunofluorescence microscopy was used to examine the roles of Cav1. The knockdown of Cav1 by the siRNA treatment was performed. Phosphorylation of Cav1 relevant to its invasion functions was investigated.

Results

We found that the host receptor CD44 colocalized with Cav1 on the plasma membrane, and knockdown of Cav1 significantly reduced the fungal ability to invade HBMEC. Although the CD44 molecules were still present, HBMEC membrane organization was distorted by Cav1 knockdown. Concomitantly, knockdown of Cav1 significantly reduced the fungal crossing of the HBMEC monolayer in vitro. Upon C. neoformans engagement, host Cav1 was phosphorylated in a CD44-dependent manner. This phosphorylation was diminished by filipin, a disrupter of lipid raft structure. Furthermore, the phosphorylated Cav1 at the lipid raft migrated inward to the perinuclear localization. Interestingly, the phospho-Cav1 formed a thread-like structure and colocalized with actin filaments but not with the microtubule network.

Conclusion

These data support that C. neoformans internalization into HBMEC is a lipid raft/caveolae-dependent endocytic process where the actin cytoskeleton is involved, and the Cav1 plays an essential role in C. neoformans traversal of the blood-brain barrier.

【 授权许可】

   
2012 Long et al; licensee BioMed Central Ltd.

【 图 表 】

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