TY - JOUR
T1 - Direct interaction between protein kinase Cθ (PKCθ) and 14-3-3τ in T cells
T2 - 14-3-3 Overexpression results in inhibition of PKCθ translocation and function
AU - Meller, Nahum
AU - Liu, Yun Cai
AU - Collins, Tassie L.
AU - Bonnefoy-Bérard, Nathalie
AU - Baier, Gottfried
AU - Isakov, Noah
AU - Altman, Amnon
PY - 1996/1/1
Y1 - 1996/1/1
N2 - Recent studies have documented direct interactions between 14-3-3 proteins and several oncogene and proto-oncogene products involved in signal transduction pathways. Studies on the effects of 14-3-3 proteins on protein kinase C (PKC) activity in vitro have reported conflicting results, and previous attempts to demonstrate a direct association between PKC and 14-3-3 were unsuccessful. Here, we examined potential physical and functional interactions between PKC0, a Ca2+-independent PKC enzyme which is expressed selectively in T lymphocytes, and the 14-3-3τ isoform in vitro and in intact T cells. PKCθ and 14-3-3τ coimmunoprecipitated from Jurkat T cells, and recombinant 14-3-3τ interacted directly with purified PKCθ in vitro. Transient overexpression of 14-3-3τ suppressed stimulation of the interleukin 2 (IL-2) promoter mediated by contransfected wild-type or constitutively active PKCτ, as well as by endogenous PKC in ionomycin- and/or phorbol ester-stimulated cells. This did not represent a general inhibition of activation events, since PKC-independent (but Ca2+-dependent activation of an IL-4 promoter element was not inhibited by 14-3-3τ under similar conditions. Overexpression of wild-type 14-3-3τ also inhibited phorbol ester-induced PKCτ translocation from the cytosol to the membrane in Jurkat cells, while a membrane-targeted form of 14-3-3τ caused increased localization of PKCτ in the particulate fraction in unstimulated cells. Membrane-targeted 14-3-3τ was more effective than wild-type 14-3-3τ in suppressing PKCθ-dependent IL-2 promoter activity, suggesting that 14-3-3τ inhibits the function of PKCθ not only by preventing its translocation to the membrane by also by associating with it. The interaction between 14-3-3 and PKCθ may represent an important general mechanism for regulating PKC- dependent signals and, more specifically, PKCθ-mediated functions during T- cell activation.
AB - Recent studies have documented direct interactions between 14-3-3 proteins and several oncogene and proto-oncogene products involved in signal transduction pathways. Studies on the effects of 14-3-3 proteins on protein kinase C (PKC) activity in vitro have reported conflicting results, and previous attempts to demonstrate a direct association between PKC and 14-3-3 were unsuccessful. Here, we examined potential physical and functional interactions between PKC0, a Ca2+-independent PKC enzyme which is expressed selectively in T lymphocytes, and the 14-3-3τ isoform in vitro and in intact T cells. PKCθ and 14-3-3τ coimmunoprecipitated from Jurkat T cells, and recombinant 14-3-3τ interacted directly with purified PKCθ in vitro. Transient overexpression of 14-3-3τ suppressed stimulation of the interleukin 2 (IL-2) promoter mediated by contransfected wild-type or constitutively active PKCτ, as well as by endogenous PKC in ionomycin- and/or phorbol ester-stimulated cells. This did not represent a general inhibition of activation events, since PKC-independent (but Ca2+-dependent activation of an IL-4 promoter element was not inhibited by 14-3-3τ under similar conditions. Overexpression of wild-type 14-3-3τ also inhibited phorbol ester-induced PKCτ translocation from the cytosol to the membrane in Jurkat cells, while a membrane-targeted form of 14-3-3τ caused increased localization of PKCτ in the particulate fraction in unstimulated cells. Membrane-targeted 14-3-3τ was more effective than wild-type 14-3-3τ in suppressing PKCθ-dependent IL-2 promoter activity, suggesting that 14-3-3τ inhibits the function of PKCθ not only by preventing its translocation to the membrane by also by associating with it. The interaction between 14-3-3 and PKCθ may represent an important general mechanism for regulating PKC- dependent signals and, more specifically, PKCθ-mediated functions during T- cell activation.
UR - http://www.scopus.com/inward/record.url?scp=0029789477&partnerID=8YFLogxK
U2 - 10.1128/mcb.16.10.5782
DO - 10.1128/mcb.16.10.5782
M3 - Article
AN - SCOPUS:0029789477
SN - 0270-7306
VL - 16
SP - 5782
EP - 5791
JO - Molecular and Cellular Biology
JF - Molecular and Cellular Biology
IS - 10
ER -