Apr 15, 1997

Functional redundancy of the Nur77 and Nor-1 orphan steroid receptors in T-cell apoptosis

The EMBO Journal
L E ChengA Winoto


The transcription factor Nur77 (NGFI-B), a member of the steroid nuclear receptor superfamily, is induced to a high level during T-cell receptor (TCR)-mediated apoptosis. A transgenic dominant-negative Nur77 protein can inhibit the apoptotic process accompanying negative selection in thymocytes, while constitutive expression of Nur77 leads to massive cell death. Nur77-deficient mice, however, have no phenotype, suggesting the possible existence of a protein with redundant function to Nur77. To explore this possibility, we have characterized the role of two Nur77 family members, Nurr1 and Nor-1, in TCR-induced apoptosis. We found that Nor-1 and Nurr1 can transactivate through the same DNA element as Nur77, and that their transactivation activities can be blocked by a Nur77 dominant-negative protein. In thymocytes, Nor-1 protein is induced to a very high level upon TCR stimulation and has similar kinetics to Nur77. In contrast, Nurr1 is undetectable in stimulated thymocytes. Furthermore, constitutive expression of Nor-1 in thymocytes leads to massive apoptosis and up-regulation of CD25, suggesting a functional redundancy between Nur77 and Nor-1 gene products. As in the case of our Nur77-FL mice, FasL is not detectable in the thym...Continue Reading

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Mentioned in this Paper

Apoptosis, Intrinsic Pathway
Leukocyte Differentiation Antigens, Human
T Cell Apoptotic Process
Interleukin 2 Receptor, Alpha
Trans-Activation, Genetic
Thyroid Hormone Receptor

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Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis