T cell activation by concanavalin A in the presence of cyclosporin A: immunosuppressor withdrawal induces NFATp translocation and interleukin‐2 gene transcription

Abstract

Cyclosporin A (CSA), an immunosuppressive agent used in organ transplantation and to treat some autoimmune diseases, blocks the Ca2+-dependent steps involved in T cell receptor triggering leading to interleukin (IL)-2 production. Considering that the early steps of T cell activation are insensitive to CSA, we asked whether the initial activation achieved in presence of this immunosuppressor could affect the capacity of the T cell to respond to a mitogenic restimulation. We found that T cells activated by concanavalin A (ConA) for 48 h in the presence of CSA retain the capacity to proliferate in response to ConA once the immunosuppressor is removed. These cells are able to transcribe anew the IL-2 gene, without the requirement of new protein synthesis, and to up-regulate the alpha chain of the IL-2 receptor. Furthermore, we present the first direct evidence that the nuclear factor AP-1 is present in the nucleus of the T cells primed for 48 h in presence of CSA and that withdrawal of the immunosuppressor leads to the translocation of NFATp from the cytoplasm to the nucleus.

Calcineurin modulates the catabolic and anabolic activity of chondrocytes and participates in the progression of experimental osteoarthritis

“…The precise molecular mechanism of TGF␤ induction in chondrocytes is unclear. CSA can up-regulate several transcription regulators (32,33), while potently inhibiting the activity of NF-AT. For example, CSA exposure prolongs the presence of activator protein 1 in the nucleus (32).…”

“…For example, CSA exposure prolongs the presence of activator protein 1 in the nucleus (32). In renal tubular epithelial cells, the induction of TGF␤1 by CSA may occur through a cascade of signals involving protein kinase C␤ (PKC␤) activation, leading to ERK activation and resulting in increased levels of transcription of the TGF␤1 gene (33). Therefore, it is possible that CSAinduced activation of PKC or MAP kinase pathways might lead to the up-regulation of TGF␤ in chondrocytes.…”

Characterization of a Gene Encoding Two Isoforms of a Mitochondrial Protein Up-regulated by Cyclosporin A in Activated T Cells

“…T Cell Activation-T cells were purified as previously described (10). Briefly, spleen cells (4 ϫ 10 8 /ml) were incubated with 75 g of wheat germ agglutinin for 10 min and loaded on top of a tube containing 8 ml of balanced salt solution containing 50% fetal calf serum.…”

“…However, other biochemical pathways such as the Ras/Raf pathway responsible for AP-1 formation are not affected by CSA (8,9). Finally, the stability of AP-1, a factor expressed transiently during activation, is increased in T cells activated in the presence of CSA (10).…”

Embryonic Thymic Epithelium Naturally Devoid of APCs Is Acutely Rejected in the Absence of Indirect Recognition

“…RNA preparation and RT-PCR were performed as previously described (28). The following primers (50 pmol/reaction) were used: ␤-actin: 3Ј-CAC GAT TTC CCT CTC AGC, 5Ј-GCA CCA CAC CTT CTA CAA; IL2: 3Ј-TGC TGA CTC ATC ATC GA, 5Ј-AGG ATG GAG AAT TAC AG; IFN-␥: 3Ј-CGA CTC CTT TTC CGC TTC CTG AG, 5Ј-TGA ACG CTA CAC ACT GCA TCT TGG; IL4: 3Ј-CAT GGT GGC TCA GTA CTA, 5Ј-GTC TCT CGT CAC TGA CGG C; IL-10: 3Ј-CTG TCT AGG TCC TGG AGT CCA GCA GAC TCA A, 5Ј-TCA AAC AAA GGA CCA GCT GGA CAA CAT ACT G; TNF-␣: 3Ј-CGC ACG TGG AAC TGG CAG AAG, 5Ј-GGT ACA ACC CAT CGG CTG GCA; TGF-␤: 3Ј-AGG AGC GCA CAA TCA TGT TG, 5Ј-CGG CAG CTG TAC ATT GAC TT.…”