Interactions between fungal hyaluronic acid and host CD44 promote internalization by recruiting host autophagy proteins to forming phagosomes.

Phagocytosis and autophagy play critical roles in immune defense. The human fungal pathogen Cryptococcus neoformans (Cn) subverts host autophagy-initiation complex (AIC)-related proteins, to promote its phagocytosis and intracellular parasitism of host cells. The mechanisms by which the pathogen engages host AIC-related proteins remain obscure. Here, we show that the recruitment of host AIC proteins to forming phagosomes is dependent upon the activity of CD44, a host cell surface receptor that engages fungal hyaluronic acid (HA). This interaction elevates intracellular Ca2+ concentrations and activates CaMKKβ and its downstream target AMPKα, which results in activation of ULK1 and the recruitment of AIC components. Moreover, we demonstrate that HA-coated beads efficiently recruit AIC components to phagosomes and CD44 interacts with AIC components. Taken together, these findings show that fungal HA plays a critical role in directing the internalization and productive intracellular membrane trafficking of a fungal pathogen of global importance. © 2021 The Authors.

Citation

Shengli Ding, Jing Yang, Xuehuan Feng, Aseem Pandey, Rola Barhoumi, Dongmei Zhang, Samantha L Bell, Yue Liu, Luciana Fachini da Costa, Allison Rice-Ficht, Robert O Watson, Kristin L Patrick, Qing-Ming Qin, Thomas A Ficht, Paul de Figueiredo. Interactions between fungal hyaluronic acid and host CD44 promote internalization by recruiting host autophagy proteins to forming phagosomes. iScience. 2021 Mar 19;24(3):102192

PMID: 33718841

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