TY - JOUR

T1 - Protein kinase C (PKC) alpha and PKC theta are the major PKC isotypes involved in TCR down-regulation

AU - von Essen, Marina

AU - Nielsen, Martin W

AU - Bonefeld, Charlotte M

AU - Boding, Lasse

AU - Larsen, Jeppe M

AU - Leitges, Michael

AU - Baier, Gottfried

AU - Odum, Niels

AU - Geisler, Carsten

N1 - Keywords: Amino Acid Motifs; Animals; Antigens, CD3; Cell Line, Tumor; Cells, Cultured; Down-Regulation; Humans; Hybridomas; Isoenzymes; Jurkat Cells; Leucine; Mice; Mice, Knockout; Protein Kinase C; Protein Kinase C-alpha; RNA, Small Interfering; Receptors, Antigen, T-Cell; Signal Transduction; T-Lymphocyte Subsets

PY - 2006

Y1 - 2006

N2 - It is well known that protein kinase C (PKC) plays an important role in regulation of TCR cell surface expression levels. However, eight different PKC isotypes are present in T cells, and to date the particular isotype(s) involved in TCR down-regulation remains to be identified. The aim of this study was to identify the PKC isotype(s) involved in TCR down-regulation and to elucidate the mechanism by which they induce TCR down-regulation. To accomplish this, we studied TCR down-regulation in the human T cell line Jurkat, in primary human T cells, or in the mouse T cell line DO11.10 in which we either overexpressed constitutive active or dominant-negative forms of various PKC isotypes. In addition, we studied TCR down-regulation in PKC knockout mice and by using small interfering RNA-mediated knockdown of specific PKC isotypes. We found that PKCalpha and PKCtheta were the only PKC isotypes able to induce significant TCR down-regulation. Both isotypes mediated TCR down-regulation via the TCR recycling pathway that strictly depends on Ser(126) and the di-leucine-based receptor-sorting motif of the CD3gamma chain. Finally, we found that PKCtheta was mainly implicated in down-regulation of directly engaged TCR, whereas PKCalpha was involved in down-regulation of nonengaged TCR.

AB - It is well known that protein kinase C (PKC) plays an important role in regulation of TCR cell surface expression levels. However, eight different PKC isotypes are present in T cells, and to date the particular isotype(s) involved in TCR down-regulation remains to be identified. The aim of this study was to identify the PKC isotype(s) involved in TCR down-regulation and to elucidate the mechanism by which they induce TCR down-regulation. To accomplish this, we studied TCR down-regulation in the human T cell line Jurkat, in primary human T cells, or in the mouse T cell line DO11.10 in which we either overexpressed constitutive active or dominant-negative forms of various PKC isotypes. In addition, we studied TCR down-regulation in PKC knockout mice and by using small interfering RNA-mediated knockdown of specific PKC isotypes. We found that PKCalpha and PKCtheta were the only PKC isotypes able to induce significant TCR down-regulation. Both isotypes mediated TCR down-regulation via the TCR recycling pathway that strictly depends on Ser(126) and the di-leucine-based receptor-sorting motif of the CD3gamma chain. Finally, we found that PKCtheta was mainly implicated in down-regulation of directly engaged TCR, whereas PKCalpha was involved in down-regulation of nonengaged TCR.

M3 - Journal article

C2 - 16751397

VL - 176

SP - 7502

EP - 7510

JO - Journal of Immunology

JF - Journal of Immunology

SN - 0022-1767

IS - 12

ER -