The vacuolar membrane ATPase (V-ATPase) is a protein complex that utilizes ATP hydrolysis to drive protons from the cytosol into the vacuolar lumen, acidifying the vacuole and modulating several key cellular response systems in Saccharomyces cerevisiae. To study the contribution of V-ATPase to the biology and virulence attributes of the opportunistic fungal pathogen Candida albicans, we created a conditional mutant in which VMA3 was placed under the control of a tetracycline-regulated promoter (tetR-VMA3 strain). Repression of VMA3 in the tetR-VMA3 strain prevents V-ATPase assembly at the vacuolar membrane and reduces concanamycin A-sensitive ATPase-specific activity and proton transport by more than 90%. Loss of C. albicans VATPase activity alkalinizes the vacuolar lumen and has pleiotropic effects, including pH-dependent growth, calcium sensitivity, and cold sensitivity. Candida albicans is a major opportunistic human fungal pathogen and is responsible for 6.8% of hospital-acquired infections in the United States (1). Despite the availability of several classes of antifungal drugs, attributable mortality, cost of care, and length of stay due to invasive candidiasis remain unacceptably high (2, 3). In addition, resistance to currently available antifungal drugs is emerging (see reference 4 for a review). Therefore, development of new antifungal drug targets remains a critical need. A diverse set of factors contributing to C. albicans virulence have been identified, including the secretion of aspartyl proteases and lipases, filamentation, and biofilm formation (5-8). Understanding the biology and regulation of these processes and pathways may illuminate new candidates for antifungal therapy.The vacuole is a dynamic acidic organelle found in yeast and plants that is analogous to the mammalian lysosome. It functions in an array of cellular homeostasis processes and thereby plays an important role in stress response, adaptation to novel environments, and cell differentiation (9-13). Furthermore, in C. albicans, intact vacuolar function is important for filamentation and virulence (12)(13)(14)(15). Vacuolar function depends on the maintenance of acidic pH by the vacuolar H-ATPase (V-ATPase), an enzyme complex that functions in organelle acidification across eukaryotes (16,17). The V-ATPase utilizes hydrolysis of ATP to transport protons from the cytosol into a variety of organelles. V-ATPase-mediated acidification and membrane energization are necessary for important vacuolar functions, including calcium and metal homeostasis (18), cargo sorting and membrane trafficking in endocytic and secretory pathways (19), and drug resistance (20). In Saccharomyces cerevisiae, the V-ATPase is expressed at the vacuolar membrane and the membrane of prevacuolar compartments and the Golgi compartment.The V-ATPase complex consists of the V 1 and V o subcomplexes (16). The V 1 subcomplex is composed of peripherally associated subunits that form the sites of ATP binding and hydrolysis on the cytosolic side of the membrane. The V o su...

Background: V-ATPase regulates pH, and Candida albicans virulence is pH-dependent. Results: Deletion of V-ATPase V o a subunit Vph1p, but not Stv1p, alkalinizes vacuoles; several virulence-related traits remain unaffected. Conclusion: Vacuolar acidification is not essential for in vitro filamentation, biofilm formation, and macrophage killing in C. albicans. Significance: Stv1p in non-vacuolar organelles may play important roles in C. albicans infectivity, particularly if Vph1p is not functional.

SUMMARY Pathological hyperphosphorylation and aggregation of tau (pTau) and neuroinflammation, driven by interleukin-1β (IL-1β), are the major hallmarks of tauopathies. Here, we show that pTau primes and activates IL-1β. First, RNA-sequence analysis suggests paired-helical filaments (PHFs) from human tauopathy brain primes nuclear factor κB (NF-κB), chemokine, and IL-1β signaling clusters in human primary microglia. Treating microglia with pTau-containing neuronal media, exosomes, or PHFs causes IL-1β activation, which is NLRP3, ASC, and caspase-1 dependent. Suppression of pTau or ASC reduces tau pathology and inflammasome activation in rTg4510 and hTau mice, respectively. Although the deletion of MyD88 prevents both IL-1β expression and activation in the hTau mouse model of tauopathy, ASC deficiency in myeloid cells reduces pTau-induced IL-1β activation and improves cognitive function in hTau mice. Finally, pTau burden co-exists with elevated IL-1β and ASC in autopsy brains of human tauopathies. Together, our results suggest pTau activates IL-1β via MyD88- and NLRP3-ASC-dependent pathways in myeloid cells, including microglia.

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With increased research funding for Alzheimer’s disease (AD) and related disorders across the globe, large amounts of data are being generated. Several studies employed machine learning methods to understand the ever-growing omics data to enhance early diagnosis, map complex disease networks, or uncover potential drug targets. We describe results based on a Target Central Resource Database protein knowledge graph and evidence paths transformed into vectors by metapath matching. We extracted features between specific genes and diseases, then trained and optimized our model using XGBoost, termed MPxgb(AD). To determine our MPxgb(AD) prediction performance, we examined the top twenty predicted genes through an experimental screening pipeline. Our analysis identified potential AD risk genes: FRRS1, CTRAM, SCGB3A1, FAM92B/CIBAR2, and TMEFF2. FRRS1 and FAM92B are considered dark genes, while CTRAM, SCGB3A1, and TMEFF2 are connected to TREM2-TYROBP, IL-1β-TNFα, and MTOR-APP AD-risk nodes, suggesting relevance to the pathogenesis of AD.