| 1. |
- Hallermalm, K, et al.
(författare)
-
Tumor necrosis factor-alpha induces coordinated changes in major histocompatibility class I presentation pathway, resulting in increased stability of class I complexes at the cell surface
- 2001
-
Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 98:4, s. 1108-1115
-
Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that similar to interferon γ (IFN-γ), tumor necrosis factor-α (TNF-α) induces coordinated changes at different steps of the major histocompatibility complex (MHC) class I processing and presentation pathway in nonprofessional antigen-presenting cells (APCs). TNF-α up-regulates the expression of 3 catalytic immunoproteasome subunits—LMP2, LMP7, and MECL-1—the immunomodulatory proteasome activator PA28α, the TAP1/TAP2 heterodimer, and the total pool of MHC class I heavy chain. It was also found that in TNF-α–treated cells, MHC class I molecules reconstitute more rapidly and have an increased average half-life at the cell surface. Biochemical changes induced by TNF-α in the MHC class I pathway were translated into increased sensitivity of TNF-α–treated targets to lysis by CD8+ cytotoxic T cells, demonstrating improved presentation of at least certain endogenously processed MHC class I–restricted peptide epitopes. Significantly, it was demonstrated that the effects of TNF-α observed in this experimental system were not mediated through the induction of IFN-γ. It appears to be likely that TNF-α–mediated effects on MHC class I processing and presentation do not involve any intermediate messengers. Collectively, these data demonstrate the existence of yet another biologic activity exerted by TNF-α, namely its capacity to act as a coordinated multi-step modulator of the MHC class I pathway of antigen processing and presentation. These results suggest that TNF-α may be useful when a concerted up-regulation of the MHC class I presentation machinery is required but cannot be achieved by IFN-γ.
|
|
| 2. |
- Hunt, L, et al.
(författare)
-
Gene-specific expression and calcium activation of Arabidopsis thaliana phospholipase C isoforms
- 2004
-
Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 162:3, s. 643-654
-
Tidskriftsartikel (refereegranskat)abstract
- PI-PLCs synthesise the calcium releasing second messenger IP3. We investigated the expression patterns of the Arabidopsis PI-PLC gene family and measured in vitro activity of encoded enzymes. Gene specific RT-PCR and promoter-GUS fusions were used to analyse AtPLC gene expression patterns. The five available AtPLC cDNAs were expressed as fusion proteins in Escherichia coli. All members of the AtPLC gene family were expressed in multiple organs of the plant. AtPLC1, and AtPLC5 expression was localized to the vascular cells of roots and leaves with AtPLC5::GUS also detected in the guard cells. AtPLC4::GUS was detected in pollen and cells of the stigma surface. In seedlings, AtPLC2 and AtPLC3 were constitutively expressed, while AtPLCs 1, 4 and 5 were induced by abiotic stresses. AtPLC1-5 were all shown to have phospholipase C activity in the presence of calcium ions. AtPLCs showed limited tissue specific expression and expression of at least three genes was increased by abiotic stress. The differing calcium sensitivities of recombinant AtPLC protein activities may provide a mechanism for generating calcium signatures.
|
|
