Fig. 6: Dephosphorylation of LC3 promotes LFA1-mediated lymphocyte adhesion.

a Effect of LC3b phosphorylation at T50 on lymphocyte adhesion to ICAM1-coated dishes under PMA stimulation. LC3b with mutation of T50 to Ala (LC3b-T50A, dephosphorylated form, n = 49) or to Glu (LC3b-T50E, constitutively phosphorylated form, n = 60) or without mutation (LC3b-WT, n = 45) was introduced into LC3b-knockout BAF/LFA1 cells (LC3b-KO). WT: parental cells before LC3b deletion, n = 48; (-): LC3b-KO without CLIP-LC3b expression, n = 47. b Effect of LC3b phosphorylation on LFA1 levels at the contact surface of the cells shown in (a). WT: n = 40; (-): n = 44; LC3b-WT: n = 40; LC3b-T50A: n = 45; LC3b-T50E: n = 68. c Effect of ciliobrevin D (cilD), a dynein inhibitor, on lymphocyte adhesiveness. Vehicle: n = 38; cilD: n = 40. d Effect of cilD on the contact surface level of LFA1. Vehicle: n = 30; cilD: n = 31. e Effects of Rose Bengal Lactone (RBL), a kinesin inhibitor, on lymphocyte adhesiveness. Vehicle: n = 43; RBL: n = 48. f Effect of RBL on LFA1 levels at the contact surface. Vehicle: n = 36; RBL: n = 36. g A model of LC3-mediated LFA1 transport to enhance lymphocyte adhesion. Outside-in signaling activates AMPK and induces the formation of intracellular clusters to facilitate lymphocyte adhesion. Activated LFA1 forms intracellular clusters, which are partly derived from surface LFA1, with Rab7 and LC3b. Direct interaction of LC3b with RAPL inhibits LC3b phosphorylation at T50 promoted by Rap1 activation via outside-in signaling, leading to FYCO1- and kinesin-dependent transport of LFA1⁺LC3⁺ clusters to the cell contact surface and promoting the accumulation of LFA1 at the surface to increase lymphocyte adhesion. Statistical analyses were performed using unpaired nonparametric two-sided Student’s t tests (c–f), or one-way ANOVA with Dunnett correction (a, b) for multiple comparisons. Source data are provided as a Source Data file.