Retinoid-related orphan receptor α (RORα) (NR1F1) is a member of the nuclear receptor superfamily whose biological functions are largely unknown. Since staggerer mice, which carry a deletion in the RORα gene, suffer from immune abnormalities, we generated an adenovirus encoding RORα1 to investigate its potential role in control of the inflammatory response. We demonstrated that RORα is expressed in human primary smooth-muscle cells and that ectopic expression of RORα1 inhibits TNFα-induced IL-6, IL-8 and COX-2 expression in these cells. RORα1 negatively interferes with the NF-κB signalling pathway by reducing p65 translocation as demonstrated by western blotting, immunostaining and electrophoretic mobility shift assays. This action of RORα1 on NF-κB is associated with the induction of IκBα, the major inhibitory protein of the NF-κB signalling pathway, whose expression was found to be transcriptionally upregulated by RORα1 via a ROR response element in the IκBα promoter. Taken together, these data identify RORα1 as a potential target in the treatment of chronic inflammatory diseases, including atherosclerosis and rheumatoid arthritis.

Retinoid-related orphan receptor ␣ (ROR␣) is a member of the nuclear receptor superfamily. To study its physiological role we generated null-mutant mice by targeted insertion of a lacZ reporter gene encoding the enzyme ␤-galactosidase. In heterozygous ROR␣ ؉/؊ mice we found ␤-galactosidase activity, indicative of ROR␣ protein expression, confined to the central nervous system, skin and testis. In the central nervous system, the ROR␣ gene is expressed in cerebellar Purkinje cells, the thalamus, the suprachiasmatic nuclei, and retinal ganglion cells. In skin, ROR␣ is strongly expressed in the hair follicle, the epidermis, and the sebaceous gland. Finally, the peritubular cells of the testis and the epithelial cells of the epididymis also strongly express ROR␣. Recently, it was reported that the ataxic mouse mutant staggerer (sg͞sg) is caused by a deletion in the ROR␣ gene. The analysis of the cerebellar and the behavioral phenotype of homozygous ROR␣ ؊/؊ mice proves identity to sg͞sg mice. Although the absence of ROR␣ causes dramatic developmental effects in the cerebellum, it has no apparent morphological effect on thalamus, hypothalamus, and retina. Similarly, testis and skin of ROR␣ ؊/؊ mice display a normal phenotype. However, the pelage hair of both sg͞sg and ROR␣ ؊/؊ is significantly less dense and when shaved shows reluctance to regrow.Nuclear receptors form a structurally related superfamily of ligand-activated transcription factors (1). They are involved in several aspects of vertebrate physiology, such as development and homeostasis. Important examples are the steroid hormone receptors that regulate, in a ligand-dependent manner, specific sets of responding genes. The retinoid-related orphan nuclear receptor (ROR) ␣ (2, 3), ROR␤ (4), and ROR␥ (5) constitute a subfamily of nuclear receptors that bind to DNA both as monomers and dimers. Distribution of ROR␣ mRNA suggests that this receptor is widely expressed and functions in several organs including brain, heart, liver, lung, and testis; highest levels were found in peripheral blood leukocytes and skin (M.B.-A., unpublished data). ROR␣ exists in four splicing isoforms: ROR␣1-4. They display different N-terminal domains causing different DNA binding site preferences (3), and they display differential expression profiles: in the thalamus there is only ROR␣1 mRNA; ROR␣4 (ϭRZR␣) (2) transcripts are predominant in leukocytes and skin; ROR␣2 and ROR␣3 transcripts are exclusively detected in testis; and in the remaining tissues including the cerebellum there is a mixture of ROR␣1 and ROR␣4 transcripts (M.B.-A., unpublished results). In the central nervous system (CNS) ROR␣ mRNA localizes to the cerebellar Purkinje cells (PCs), various thalamic nuclei, and, during development, to other brain areas (6, 7). To study the physiological role of this orphan receptor we generated ROR␣ null-mutant mice by gene targeting. In the course of this work the genetic basis of the staggerer (sg) mutation in mouse was identified by positional cloning as a deletion in the R...

Hypoxia-ischaemia in the developing brain results in brain injury with prominent features of apoptosis. In the present study, a third generation dipeptidyl broad-spectrum caspase inhibitor, quinoline-Val-Asp(Ome)-CH2-O-phenoxy (Q-VDOPh), was tested in a model of unilateral focal ischaemia with reperfusion in 7-day-old rats. Q-VD-OPh (1 mg/kg, i.p.) reduced cell death, resulting in significant neuroprotection at 48 h of recovery (infarct volume of 12.6 ± 2.8 vs. 24.3 ± 2.2%, p ¼ 0.006). The neuroprotective effects observed at 48 h post-ischaemia hold up at 21 days of survival time and attenuate neurological dysfunction. Analysis by gender revealed that females were strongly protected (6.7 ± 3.3%, p ¼ 0.006), in contrast to males in which there was no significant effect, when Q-VD-OPh was given after clip removal on the left common carotid artery. Immunoblot analysis demonstrated that Q-VD-OPh inhibits caspase 3 cleavage into its p17 active form and caspase 1 up-regulation and cleavage in vivo. Following ischaemia in P7 rats, males and females displayed different time course and pattern of cytochrome c release and active p17 caspase 3 during the first 24 h of recovery. In contrast, no significant difference was observed for caspase 1 expression between genders. These results indicate that ischaemia activates caspases shortly after reperfusion and that the sex of the animal may strongly influences apoptotic pathways in the pathogenesis of neonatal brain injury. The specificity, effectiveness, and reduced toxicity of Q-VD-OPh may determine the potential use of peptide-derived irreversible caspase inhibitors as promising therapeutics.