1. TCR signaling induces nuclear actin polymerization.
TCR signaling induces nuclear actin polymerization. (A) Top: Jurkat NCLA cells were placed on TCR-stimulatory coverslips and subjected to live-cell microscopy. Shown are still images at the indicated time after contact with the stimulatory surface (see also movie S1). Bottom: Single-cell analysis of actin dynamics over 10 min after activation. Individual cells were imaged as in (A), and the periods in which polymerized F-actin was detected in the nucleus (green) or at the PM (red) are indicated. p.a., post activation. (B) Primary human CD4+ T cell expressing nuc.lifeact interacting with SEB-pulsed Raji B cells. Top: Representative still images of live-cell movies. Inset: Boxed contact region (cont.) in high contrast (see also movie S2). Bottom: Single-cell analysis of actin dynamics over 50 min after contact with the Raji B cell. (C to E) Nuclear actin polymerization in Jurkat NLA cells in response to surface-bound (C, top, and D) or soluble (C, bottom, and E) stimuli. Shown are representative images (see also movie S3) and relative occurrence of nuclear F-actin filaments (mean and SD from three experiments in which at least 30 cells were analyzed per condition each). Statistical significance relative to the αCD3/28 (D) or PMA/Iono (E) control was assessed by one-sample t test. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ DMSO, dimethyl sulfoxide. Visualization of nuclear F-actin with nuclear lifeact.GFP after (+) or without (−) stimulation with PMA/Iono in primary human CD4+ T cells (F). Visualization of endogenous nuclear actin filaments with Alexa Fluor 488 Phalloidin in A3.01 T cells without stimulation (−) or after stimulation (+) with PMA/Iono (G). Scale bars, 5 μm. Arrowheads indicate examples of nuclear F-actin filaments.
N. Tsopoulidis et al. Sci. Immunol. 2019;4:eaav1987
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