Rho Kinase Promotes Alloimmune Responses by Regulating the Proliferation and Structure of T Cells

Abstract

Coordinated rearrangements of the actin-myosin cytoskeleton facilitate early and late events in T cell activation and signal transduction. As many important features of cell shape rearrangement involve small GTP-binding proteins, we examined the contribution of Rho kinase to the functions of mature T cells. Inhibitors of the Rho kinase pathway all had similar actions to inhibit the proliferation of primary lymphocyte cultures. Likewise, transfection of the human Jurkat T cell line with a dominant negative, kinase-defective mutant of Rho kinase diminished Jurkat cell proliferation. Furthermore, inhibition of Rho kinase substantially attenuated the program of cytokine gene expression that characterizes T cell activation, blocked actomyosin polymerization, and prevented aggregation of the TCR/CD3 complex colocalized with lipid rafts. These actions are relevant to immune responses in vivo, as treatment with a Rho kinase inhibitor considerably prolonged the survival of fully allogeneic heart transplants in mice and diminished intragraft expression of cytokine mRNAs. Thus, Rho GTPases acting through Rho kinase play a unique role in T cell activation during cellular immune responses by promoting structural rearrangements that are critical for T cell signaling.

Azathioprine Suppresses Ezrin-Radixin-Moesin-Dependent T Cell-APC Conjugation through Inhibition of Vav Guanosine Exchange Activity on Rac Proteins

“…Rac, Ras, Cdc42, Rap, and RhoA activation assays Levels of Rac1-, Rac2-, Cdc42-, RhoA-, Rap-, and Ras-bound GTP were determined by established immunoblot techniques (Upstate Biotechnology) (15,25). In brief, T cells were stimulated for indicated periods of time in the presence or absence of azathioprine, 6-MP, or 6-TG.…”

A Novel E3 Ubiquitin Ligase Substrate Screen Identifies Rho Guanine Dissociation Inhibitor as a Substrate of Gene Related to Anergy in Lymphocytes

“…The Rho GTPase family members have been shown to play a pivotal role in regulating changes in actin cytoskeleton, which in turn affects many aspects of cellular function (12,24,25). Previous studies have shown that specific inactivation of RhoA kinase activity in T cells resulted in defective TCR/CD3 complex polarization (21,22). Similarly, anergic T cells stimulated with anti-CD3-coated beads displayed impaired actin cup formation at the T cell/ bead interface, due to defects in actin cytoskeleton reorganization (26).…”

“…with the specific Rho kinase pharmacological inhibitor Y-27632, resulted in inhibition of IL-2 production in T cells (21,22).…”

ROCK Inhibition – A New Therapeutic Avenue in Kidney Protection

“…These data are consistent with the importance of immunological factors in chronic graft injury. The Rho/ROCK pathway is potentially crucial in mediating immunological as well as nonimmunological injury in chronic graft loss as it is involved in adhesion, migration, proliferation, and cytokine release (Amano et al 1997;Chihara et al 1997;Tharaux et al 2003). The activation of T-cells is involved in alloimmune responses.…”

“…The activation of T-cells is involved in alloimmune responses. Here the Rho/ROCK pathway plays a pivotal role in T-cell activation during cellular immune responses by promoting structural rearrangements that are critical for T-cell signaling (Tharaux et al 2003). Besides, a role for Rho/ROCK in HLA class I signaling pathways that have been implicated in the process of chronic rejection has been shown.…”