The Host Protein Aquaporin-9 is Required for Efficient Plasmodium falciparum Sporozoite Entry into Human Hepatocytes

Front Cell Infect Microbiol. 2021 Jun 29;11:704662. doi: 10.3389/fcimb.2021.704662. eCollection 2021.

Abstract

Hepatocyte invasion by Plasmodium sporozoites represents a promising target for innovative antimalarial therapy, but the molecular events mediating this process are still largely uncharacterized. We previously showed that Plasmodium falciparum sporozoite entry into hepatocytes strictly requires CD81. However, CD81-overexpressing human hepatoma cells remain refractory to P. falciparum infection, suggesting the existence of additional host factors necessary for sporozoite entry. Here, through differential transcriptomic analysis of human hepatocytes and hepatoma HepG2-CD81 cells, the transmembrane protein Aquaporin-9 (AQP9) was found to be among the most downregulated genes in hepatoma cells. RNA silencing showed that sporozoite invasion of hepatocytes requires AQP9 expression. AQP9 overexpression in hepatocytes increased their permissiveness to P. falciparum. Moreover, chemical disruption with the AQP9 inhibitor phloretin markedly inhibited hepatocyte infection. Our findings identify AQP9 as a novel host factor required for P. falciparum sporozoite hepatocyte-entry and indicate that AQP9 could be a potential therapeutic target.

Keywords: Aquaporin-9; CD81; Plasmodium falciparum; hepatocytes; liver stage; sporozoites.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aquaporins*
  • Hepatocytes / metabolism
  • Humans
  • Plasmodium falciparum
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism
  • Sporozoites* / metabolism
  • Tetraspanin 28 / metabolism

Substances

  • AQP9 protein, human
  • Aquaporins
  • Protozoan Proteins
  • Tetraspanin 28