The Saccharomyces cerevisiae transcription factor Aft1 is activated in iron-deficient cells to induce the expression of iron regulon genes, which coordinate the increase of iron uptake and remodel cellular metabolism to survive low-iron conditions. In addition, Aft1 has been implicated in numerous cellular processes including cell-cycle progression and chromosome stability; however, it is unclear if all cellular effects of Aft1 are mediated through iron homeostasis. To further investigate the cellular processes affected by Aft1, we identified .70 deletion mutants that are sensitive to perturbations in AFT1 levels using genome-wide synthetic lethal and synthetic dosage lethal screens. Our genetic network reveals that Aft1 affects a diverse range of cellular processes, including the RIM101 pH pathway, cell-wall stability, DNA damage, protein transport, chromosome stability, and mitochondrial function. Surprisingly, only a subset of mutants identified are sensitive to extracellular iron fluctuations or display genetic interactions with mutants of iron regulon genes AFT2 or FET3. We demonstrate that Aft1 works in parallel with the RIM101 pH pathway and the role of Aft1 in DNA damage repair is mediated by iron. In contrast, through both directed studies and microarray transcriptional profiling, we show that the role of Aft1 in chromosome maintenance and benomyl resistance is independent of its iron regulatory role, potentially through a nontranscriptional mechanism.
Objectives In severe rapidly progressive SSc, autologous haematopoietic stem cell transplantation (AHSCT) allows significant improvements in overall and event-free survival. We undertook this study to identify, appraise and synthesize the evidence on health-related quality of life (HRQoL) before and after AHSCT for SSc. Methods We performed a systematic review of the literature, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, in PubMed and ScienceDirect from database inception to 1 February 2019. All articles with original HRQoL data were selected. Results The search identified 1080 articles, of which 8 were selected: 3 unblinded randomized controlled trials [American Scleroderma Stem Cell versus Immune Suppression Trial (ASSIST), Autologous Stem Cell Transplantation International Scleroderma, Scleroderma: Cyclophosphamide or Transplantation), 3 uncontrolled phase I or II trials and 2 cohort studies. HRQoL data from 289 SSc patients treated with AHSCT and 125 treated with intravenous CYC as a comparator with median 1.25–4.5 years follow-up were included. HRQoL was evaluated with the HAQ Disability Index (HAQ-DI; 275 patients), the 36-item Short Form Health Survey (SF-36; 249 patients) and the European Quality of Life 5-Dimensions questionnaire (EQ-5D; 138 patients). The quality of the studies was moderate to low. AHSCT was associated with significant improvement in the HAQ-DI (P = 0.02–<0.001), SF-36 Physical Component Summary score (P = 0.02–<0.0001) and EQ-5D index-based utility score (P < 0.001). The SF-36 Mental Component Summary score improved in the ASSIST (n = 19) and one small retrospective cohort (n = 30 patients, P = 0.005) but did not improve significantly in 2 randomized controlled trials (n = 200 patients, P = 0.1–0.91). Conclusion AHSCT in severe SSc patients is associated with significant and durable improvement in physical HRQoL.
In gout, hyperuricemia promotes urate crystal deposition, which stimulates the NLRP3 inflammasome and interleukin-1β (IL-1β)-mediated arthritis. Incident gout without background hyperuricemia is rarely reported. To identify hyperuricemia-independent mechanisms driving gout incidence and progression, we characterized erosive urate crystalline inflammatory arthritis in a young female patient with normouricemia diagnosed as having sufficient and weighted classification criteria for gout according to the American College of Rheumatology (ACR)/EULAR gout classification criteria (the proband).Methods. We conducted whole-genome sequencing, quantitative proteomics, whole-blood RNA-sequencing analysis using serum samples from the proband. We used a mouse model of IL-1β-induced knee synovitis to characterize proband candidate genes, biomarkers, and pathogenic mechanisms of gout.Results. Lubricin level was attenuated in human proband serum and associated with elevated acute-phase reactants and inflammatory whole-blood transcripts and transcriptional pathways. The proband had predicted damaging gene variants of NLRP3 and of inter-α trypsin inhibitor heavy chain 3, an inhibitor of lubricin-degrading cathepsin G. Changes in the proband's serum protein interactome network supported enhanced lubricin degradation, with cathepsin G activity increased relative to its inhibitors, SERPINB6 and thrombospondin 1. Activation of Toll-like receptor 2 (TLR-2) suppressed levels of lubricin mRNA and lubricin release in cultured human synovial fibroblasts (P < 0.01). Lubricin blunted urate crystal precipitation and IL-1β induction of xanthine oxidase and urate in cultured macrophages (P < 0.001). In lubricin-deficient mice, injection of IL-1β in knees increased xanthine oxidase-positive synovial resident M1 macrophages (P < 0.05).Conclusion. Our findings linked normouricemic erosive gout to attenuated lubricin, with impaired control of cathepsin G activity, compounded by deleterious NLRP3 variants. Lubricin suppressed monosodium urate crystallization and blunted IL-1β-induced increases in xanthine oxidase and urate in macrophages. The collective activities of articular lubricin that could limit incident and erosive gouty arthritis independently of hyperuricemia are subject to disruption by inflammation, activated cathepsin G, and synovial fibroblast TLR-2 signaling.
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