ABSTRACT
Rab GTPases control membrane traffic and receptor-mediated endocytosis. Within this context, Rab5a plays an important role in the spatial regulation of intracellular transport and signal transduction processes. Here, we report a previously uncharacterized role for Rab5a in the regulation of T-cell motility. We show that Rab5a physically associates with protein kinase Cϵ (PKCϵ) in migrating T-cells. After stimulation of T-cells through the integrin LFA-1 or the chemokine receptor CXCR4, Rab5a is phosphorylated on an N-terminal Thr-7 site by PKCϵ. Both Rab5a and PKCϵ dynamically interact at the centrosomal region of migrating cells, and PKCϵ-mediated phosphorylation on Thr-7 regulates Rab5a trafficking to the cell leading edge. Furthermore, we demonstrate that Rab5a Thr-7 phosphorylation is functionally necessary for Rac1 activation, actin rearrangement, and T-cell motility. We present a novel mechanism by which a PKCϵ-Rab5a-Rac1 axis regulates cytoskeleton remodeling and T-cell migration, both of which are central for the adaptive immune response.
Subject(s)
Adaptive Immunity/physiology , Cell Movement/physiology , Protein Kinase C-epsilon/metabolism , T-Lymphocytes/metabolism , rab5 GTP-Binding Proteins/metabolism , Cell Line , Cytoskeleton/genetics , Cytoskeleton/metabolism , Female , Humans , Lymphocyte Function-Associated Antigen-1/genetics , Lymphocyte Function-Associated Antigen-1/metabolism , Male , Phosphorylation/physiology , Protein Kinase C-epsilon/genetics , Receptors, CXCR4/genetics , Receptors, CXCR4/metabolism , T-Lymphocytes/cytology , rab5 GTP-Binding Proteins/geneticsABSTRACT
In vivo gene replacement is one of the most compelling concepts in modern medicine. Adeno-associated virus (AAV) vectors are currently among the most frequently used viral vectors for gene therapy and they have shown therapeutic efficacy in a range of animal models. The lack of pathogenicity of the virus, low immunogenicity, its stability, and many available serotypes have increased AAV's potential as a delivery vehicle for gene therapy applications. There are some limitations to the use of rAAV in gene therapy. The first is their size. Due to the small size of the vector, the ability to conduct a therapeutic gene expression cassette is limited. Another limitation is the common occurrence of neutralizing antibodies in human populations. This review will focus on the biology of AAV, its use as a vector for gene therapy and mechanisms of AAV/host cell interaction.
