ER-to-Golgi transport and SEC23-dependent COPII vesicles regulate T cell alloimmunity
Stephanie Kim, … , David Ginsburg, Pavan Reddy
Stephanie Kim, … , David Ginsburg, Pavan Reddy
Published January 19, 2021
Citation Information: J Clin Invest. 2021;131(2):e136574. https://doi.org/10.1172/JCI136574.
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ER-to-Golgi transport and SEC23-dependent COPII vesicles regulate T cell alloimmunity

Abstract

T cell–mediated responses are dependent on their secretion of key effector molecules. However, the critical molecular determinants of the secretion of these proteins are largely undefined. Here, we demonstrate that T cell activation increases trafficking via the ER-to-Golgi pathway. To study the functional role of this pathway, we generated mice with a T cell–specific deletion in SEC23B, a core subunit of coat protein complex II (COPII). We found that SEC23B critically regulated the T cell secretome following activation. SEC23B-deficient T cells exhibited a proliferative defect and reduced effector functions in vitro, as well as in experimental models of allogeneic and xenogeneic hematopoietic cell transplantation in vivo. However, T cells derived from 3 patients with congenital dyserythropoietic anemia II (CDAII), which results from Sec23b mutation, did not exhibit a similar phenotype. Mechanistic studies demonstrated that unlike murine KO T cells, T cells from patients with CDAII harbor increased levels of the closely related paralog, SEC23A. In vivo rescue of murine KO by expression of Sec23a from the Sec23b genomic locus restored T cell functions. Together, our data demonstrate a critical role for the COPII pathway, with evidence for functional overlap in vivo between SEC23 paralogs in the regulation of T cell immunity in both mice and humans.

Authors

Stephanie Kim, Rami Khoriaty, Lu Li, Madison McClune, Theodosia A. Kalfa, Julia Wu, Daniel Peltier, Hideaki Fujiwara, Yaping Sun, Katherine Oravecz-Wilson, Richard A. King, David Ginsburg, Pavan Reddy

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Figure 4

SEC23B-dependent COPII regulates naive T cell functions in vitro and in vivo.

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SEC23B-dependent COPII regulates naive T cell functions in vitro and in ...
(A) Overlay of histograms based on flow cytometry plots indicating expression of intracellular T-bet, GATA3, and RORγt in WT and SEC23B-deficient naive CD4+ T cells that were cultured in media containing Th1-, Th2-, and Th17-polarizing cytokines, respectively (n = 3). (B) Proliferative capacity of WT and SEC23B-deficient T cells as measured by CFSE dilutions in vitro (n = 6/group). Partial rescue of proliferation upon addition of exogenous murine IL-2 in T cells stimulated with αCD3 and αCD28 for 3 days (n = 6/group). (C) Cell death as measured by Annexin V and 7AAD staining (n = 3/group) in SEC23B-deficient T cells compared with WT following stimulation by αCD3 and αCD28 for 3 days. (D) In vivo proliferative capacity of SEC23B-deficient T cells compared with WT as measured by CFSE dilutions following their transfer into allogeneic BALB/c recipient mice (n = 3/group). (E) 51Cr release assay using WT or SEC23B-deficient T cells primed with allogeneic splenic cells and used as effector cells against either syngeneic C57BL/6J or allogeneic BALB/c BMDC target cells (n = 3/group). (A, C and D) Statistical significance was determined by 2-tailed unpaired Student’s t test; ***P < 0.001. (B) Statistical significance was determined by 1-way ANOVA and post hoc Tukey’s test; **P < 0.01, ***P < 0.001. (F and G) Survival and GVHD scores of mice that received syngeneic T cell–depleted bone marrow, and T cells from either syngeneic donors, allogeneic WT C57BL/6J donors, or allogeneic Sec23bfl/– Cd4Cre C57BL/6J donors. Allogeneic recipients were BALB/c (n = 12/group) (F) or C3H.SW (n =6/group) (G) strain. Significance was determined by 1-way ANOVA and post hoc Tukey’s test for GVHD score and Mantel-Cox log rank test for survival; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.