Fig. 3: Influenza virus uses mGluR2 as an endocytic receptor for its CME.
From: Influenza virus uses mGluR2 as an endocytic receptor to enter cells
a, Knockdown of CLTC significantly prevented mGluR2 internalization in H1N1-virus-internalized A549 cells. Cell nucleus, blue; mGluR2, green. b, Direct interaction of mGluR2 and HA shown using a pull-down assay with the agarose beads coupled with anti-Flag antibodies. c, Co-localization of mGluR2 and HA confirmed using a STED super-resolution microscopy assay. Cell nucleus, blue; mGluR2, red; and viral HA, green. d, mGluR2 molecules detected on the cell membrane where influenza virus attached, on the membrane of different stages of CCPs of influenza virus and on the membrane of matured CCVs of influenza virus by means of immunoelectron microscopy in mGluR2-overexpressing A549 cells. Green arrow, mGluR2; red arrow, influenza virus. Scale bar, 100 nm. e,g, mGluR2–GST (e) or mGluR2–ma (g) did not affect the viability of A549 cells. f,h, mGluR2–GST (f) or mGluR2–ma (h) treatment significantly reduced H1N1 virus replication but did not reduce adenovirus type 5 replication in A549 cells. i, Internalization of transferrin was affected by chlorpromazine (a CME inhibitor) but not by mGluR2-GST or mGluR2-ma. The microscopy-based assay shown in a and i was performed under unpermeabilized conditions and that shown in c was performed under permeabilized conditions. The solid line represents median and dashed lines represent quartiles of the data in the violin graphs of a and i. The images in a–d and i are representative of three independent experiments. Error bar in panels e–h indicates the standard deviation. The data shown in a and c–i are means ± s.d. (n = 3 biologically independent experiments). Statistical analysis was performed using the unpaired, two-tailed Student’s t-test. NS, not significant. *P < 0.05; ***P < 0.001; ****P < 0.0001. Exact P values are available in Source Data.
