Impaired renal function and increased plasma levels of oxypurinol and granulysin correlated with the poor prognosis of allopurinol-SCAR. Allopurinol prescription is suggested to be avoided in subjects with renal insufficiency and HLA-B*58:01 carriers. An early intervention to increase the clearance of plasma oxypurinol may improve the prognosis of allopurinol-SCAR.

Viral proteases are essential for pathogenesis and virulence of severe acute respiratory syndrome coronavirus (SARS-CoV). Little information is available on SARS-CoV papain-like protease 2 (PLP2), and development of inhibitors against PLP2 is attractive for antiviral therapy. Here, we report the characterization of SARS-CoV PLP2 (from residues 1414 to 1858) purified from baculovirus-infected insect cells. We demonstrate that SARS-CoV PLP2 by itself differentially cleaves between the amino acids Gly180 and Ala181, Gly818 and Ala819, and Gly2740 and Lys2741 of the viral polypeptide pp1a, as determined by reversed-phase high-performance liquid chromatography analysis coupled with mass spectrometry. This protease is especially selective for the P1, P4, and P6 sites of the substrate. The study demonstrates, for the first time among coronaviral PLPs, that the reaction mechanism of SARS-CoV PLP2 is characteristic of papain and compatible with the involvement of the catalytic dyad (Cys)-S(-)/(His)-Im(+)H ion pair. With a fluorogenic inhibitor-screening platform, we show that zinc ion and its conjugates potently inhibit the enzymatic activity of SARS-CoV PLP2. In addition, we provided evidence for evolutionary reclassification of SARS-CoV. The results provide important insights into the biochemical properties of the coronaviral PLP family and a promising therapeutic way to fight SARS-CoV.

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Huntington's Disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The resultant mutant Htt protein (mHtt) forms aggregates in the brain and several peripheral tissues (e.g., the liver), and causes devastating widespread pathology. Since aggregates of mHtt have been found in the liver, defects in liver function might contribute to peripheral abnormalities in HD mice. We previously reported that two crucial transcription factors PPARγ (peroxisome proliferator-activated receptor-γ) and C/EBPα (CCAAT/enhancer-binding protein α) are potential therapeutic targets of HD. We herein demonstrate that the transcript level of PPARγ was markedly downregulated in the livers of a transgenic mouse model of HD (R6/2). Treatment of R6/2 mice with an agonist of PPARγ (thiazolidinedione, TZD) normalized the reduced PPARγ transcript. By reducing Htt aggregates and thereby ameliorating the recruitment of PPARγ into Htt aggregates, TZD treatment also elevated the availability of the PPARγ level and subsequently normalized the expression of its downstream genes [including PGC-1α (PPAR coactivator-1α) and several mitochondrial genes] and C/EBPα in the liver. The aforementioned protective effects appeared to be exerted by a direct activation of the PPARγ agonist (rosiglitazone) because rosiglitazone reduced mHtt aggregates and rescued energy deficiency in a hepatoma cell line (HepG2). These findings show that the impairment of PPARγ contributes to the liver dysfunction observed in HD. Treatment with PPARγ agents (TZD and rosiglitazone) enhanced the function of PPARγ, and might lead to therapeutic benefits.