# CDC42 supports HBV entry by NTCP translocation to the plasma membrane and macropinocytosis

## TL;DR

This study shows that the protein CDC42 helps the hepatitis B virus enter liver cells by moving a key receptor to the cell surface and using a specific cell uptake process.

## Contribution

The study reveals CDC42's role in HBV entry via NTCP translocation and macropinocytosis, which were previously unrecognized mechanisms.

## Key findings

- CDC42 promotes NTCP translocation to the plasma membrane via Rab11-dependent recycling endosomes.
- Macropinocytosis, not clathrin-mediated endocytosis, is the CDC42-dependent pathway for HBV internalization.
- HBV entry depends equally on macropinocytosis and clathrin-mediated pathways, but only macropinocytosis requires CDC42.

## Abstract

CDC42 is a member of Rho GTPase family that regulates various biological processes and its activity can be hijacked by invading pathogens. Here, we discovered that the level of active CDC42 in hepatocytes positively correlates with the entry capacity of hepatitis B virus (HBV). Mechanistically, CDC42 activation effectively promotes the transport of the viral receptor sodium taurocholate co-transporting polypeptide (NTCP) to the plasma membrane via Rab11 dependent recycling endosomal pathway. NTCP interacts with Rab11 and activation of CDC42 signaling reinforces the interaction between NTCP and Rab11. We further show that clathrin mediated endocytosis (CME), the known HBV entry pathway, is independent of CDC42 activity. Intriguingly, we reveal that CDC42 dependent macropinocytosis is a route for HBV entry, which is equally essential for viral infection as CME. Together, our findings uncover new mechanisms for HBV entry that involve unrecognized functions of CDC42 and suggest that Rho GTPase signaling might represent a potential target for antiviral therapy.

CDC42 regulates HBV entry through two mechanisms. It promotes the recruitment of NTCP receptor to the cell surface and enhances the macropinocytosis mediated internalization of NTCP bound virions, thereby facilitating HBV infection.

CDC42 promotes NTCP translocation to the plasma membrane through Rab11 related recycling endosomes.Macropinocytosis is an important pathway for HBV internalization.Macropinocytosis mediated, but not clathrin mediated, HBV internalization depends on CDC42.

CDC42 promotes NTCP translocation to the plasma membrane through Rab11 related recycling endosomes.

Macropinocytosis is an important pathway for HBV internalization.

Macropinocytosis mediated, but not clathrin mediated, HBV internalization depends on CDC42.

CDC42 regulates HBV entry through two mechanisms. It promotes the recruitment of NTCP receptor to the cell surface and enhances the macropinocytosis mediated internalization of NTCP bound virions, thereby facilitating HBV infection.