The AAA ATPase Vps4 Plays Important Roles in Candida albicans Hyphal Formation and is Inhibited by DBeQ

Computational prediction of Homo sapiens-Candida albicans protein-protein interactions reveal key virulence factors using dual RNA-Seq data analysis

A prevalent pathobiont, Candida albicans, accounts for approximately 70% of fungal infections worldwide owing to its virulence traits that culminate in devastating fatalities within healthcare facilities. Protein-protein interactions (PPIs) between Homo sapiens and C. albicans play a pivotal role in infection and disease progression. Additionally, scarcity of information on H. sapiens-C. albicans protein-protein interactions makes it difficult to understand the molecular mechanisms underlying infection and host immune responses. Investigating these PPIs can provide crucial insights into host-pathogen relationships and facilitate the development of novel therapeutic interventions. To address this challenge, we utilized computational techniques based on homology and domain to project 56,515 human-fungal pathogen protein-protein interactions (HF-PPIs) involving 6830 human and 486 C. albicans proteins. We have identified 16 key virulence factors of C. albicans, including SOD1, ERG10, GFA1, and VPS4, as potential therapeutic targets. As evidenced by dual RNA-Seq data acquired at various stages of infection such as 15, 30, 60, 120, and 240 min, these fungal genes interact with down-regulated human immunomodulatory genes specifically, ADRM1, DAXX, RYBP, SGTA, and SRGN. In addition to their intrinsically disordered regions, these human genes are particularly susceptible to fungal manipulation. Through the identification of experimentally validated virulence factors and their interaction partners, this investigation constructs HF-PPI between H. sapiens and C. albicans. Our knowledge of human-fungal pathogen protein-protein interactions will be improved by integrating computational and experimental data in order to facilitate the development of efficient fungal infection prevention and treatment protocols.

DBeQ derivative targets vacuolar protein sorting 4 functions in cancer cells and suppresses tumor growth in mice

Vacuolar protein sorting 4 (VPS4) is an AAA-ATPase that catalyzes the endosomal sorting complex required for transport-III disassembly, mediating various cellular membrane-remodeling processes including endolysosomal membrane repair and autophagosome closure. Humans have 2 VPS4 paralogs, VPS4A and VPS4B, and the loss of either paralog has been identified in a significant proportion of cancers, rendering them dependent on the remaining paralog for survival. In this study, we explored VPS4 inhibition as an anticancer strategy by investigating the mechanisms of VPS4 inhibition-induced cell death and developing small-molecule compounds that target VPS4 functions. We found that genetic inhibition of VPS4 triggered both caspase-8 (CASP8)-dependent apoptosis and caspase-independent cell death in osteosarcoma cells. We synthesized approximately 100 derivatives of the VPS4 and related AAA-ATPase valosin-containing protein inhibitor DBeQ and screened for their inhibitory effects on VPS4 ATPase activity using the EnzChek phosphate assay and a high-content assay monitoring GFP-CHMP4B puncta formation. In cells, the lead compound 4-107 caused endolysosomal damage, disrupted subsequent membrane repair, inhibited autophagy, and led to the accumulation of the endosomal sorting complex required for transport on membranes. These effects were accompanied by the stabilization of CASP8 on autophagosomal membranes, leading to the induction of CASP8-mediated apoptosis. Notably, the CASP8-mediated cell death induced by 4-107 was further enhanced by the loss of either VPS4 paralog. Moreover, 4-107 exhibited antitumor activity in a syngeneic mouse model of neuroblastoma. Our findings provide an important step for targeting VPS4 in cancer and developing VPS4 inhibitors as a cancer treatment strategy. SIGNIFICANCE STATEMENT: VPS4A and VPS4B, paralogs of the AAA-ATPase VPS4, are critical for cancer cell survival. This study reports that 4-107, a DBeQ derivative, inhibits VPS4 ATPase activity, induces CASP8-mediated apoptosis, and suppresses tumor growth in mice. This study supports the further development of VPS4A/B inhibitors as a promising anticancer treatment strategy.

Nanoplastics and bisphenol A exposure alone or in combination induce hepatopancreatic damage and disturbances in carbohydrate metabolism in the Portunus trituberculatus

Bisphenol A (BPA) is a widely found endocrine-disrupting chemical (EDC). Nanoplastics (NPs) represent a novel environmental pollutant, and the combined toxicity of these pollutants on the hepatopancreas of marine arthropods is understudied. To investigate the potential risks associated with co-exposure to BPA and NPs on the hepatopancreas, Portunus trituberculatus was treated with 100 μg/L BPA, 104 particles/L NPs, and a combination of 100 μg/L BPA + 104 particles/L NPs for 21 days, respectively. Histological observation demonstrated that co-exposure severely damaged both hepatopancreas tissue and mitochondrial structure. Transcriptome analysis revealed that 1498 transcripts were differentially expressed under different exposure conditions, and these transcripts are involved in biological processes such as cellular processes and carbohydrate metabolism. BPA and NPs co-exposure modulate pyruvic acid (PA) levels by increasing the activity of pyruvate kinase (PK), leading to changes in glycogen and glucose (GLU) content within tissues, thus affecting glycolysis. The dysregulation of the CHI3L1, ACSS2 and ACYP2 genes induced by BPA and NPs co-exposure may collectively regulate the process of carbohydrate metabolism. Notably, the downregulation of the VPS4 gene and the upregulation of the GBA1, Pin1 and CCND2 gene may affect the cell cycle, potentially impacting cell proliferation after BPA and NPs co-exposure. These data indicate that co-exposure to BPA and NPs is more significantly cytotoxic and leads to changes in carbohydrate metabolism, cell proliferation, and histological damage in the hepatopancreas of P. trituberculatus. This knowledge emphasizes the need for proactive measures to mitigate the adverse effects of these environmental pollutants on human and ecological health while also providing valuable insights into the relevant molecular mechanisms.

Valosin-Containing Protein (VCP)/p97 Oligomerization

Valosin-containing protein (VCP), also known as p97, is an evolutionarily conserved AAA+ ATPase essential for cellular homeostasis. Cooperating with different sets of cofactors, VCP is involved in multiple cellular processes through either the ubiquitin-proteasome system (UPS) or the autophagy/lysosomal route. Pathogenic mutations frequently found at the interface between the NTD domain and D1 ATPase domain have been shown to cause malfunction of VCP, leading to degenerative disorders including the inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD), amyotrophic lateral sclerosis (ALS), and cancers. Therefore, VCP has been considered as a potential therapeutic target for neurodegeneration and cancer. Most of previous studies found VCP predominantly exists and functions as a hexamer, which unfolds and extracts ubiquitinated substrates from protein complexes for degradation. However, recent studies have characterized a new VCP dodecameric state and revealed a controlling mechanism of VCP oligomeric states mediated by the D2 domain nucleotide occupancy. Here, we summarize our recent knowledge on VCP oligomerization, regulation, and potential implications of VCP in cellular function and pathogenic progression.

Synthetic Lethal Interaction between the ESCRT Paralog Enzymes VPS4A and VPS4B in Cancers Harboring Loss of Chromosome 18q or 16q

Few therapies target the loss of tumor suppressor genes in cancer. We examine CRISPR-SpCas9 and RNA-interference loss-of-function screens to identify new therapeutic targets associated with genomic loss of tumor suppressor genes. The endosomal sorting complexes required for transport (ESCRT) ATPases VPS4A and VPS4B score as strong synthetic lethal dependencies. VPS4A is essential in cancers harboring loss of VPS4B adjacent to SMAD4 on chromosome 18q and VPS4B is required in tumors with co-deletion of VPS4A and CDH1 (E-cadherin) on chromosome 16q. We demonstrate that more than 30% of cancers selectively require VPS4A or VPS4B. VPS4A suppression in VPS4B-deficient cells selectively leads to ESCRT-III filament accumulation, cytokinesis defects, nuclear deformation, G2/M arrest, apoptosis, and potent tumor regression. CRISPR-SpCas9 screening and integrative genomic analysis reveal other ESCRT members, regulators of abscission, and interferon signaling as modifiers of VPS4A dependency. We describe a compendium of synthetic lethal vulnerabilities and nominate VPS4A and VPS4B as high-priority therapeutic targets for cancers with 18q or 16q loss.

Neggers, Paolella, and colleagues identify the ATPases VPS4A and VPS4B as selective vulnerabilities and potential therapeutic targets in cancers harboring loss of chromosome 18q or 16q. In VPS4B-deficient cancers, VPS4A suppression leads to ESCRT-III dysfunction, nuclear deformation, and abscission defects. Moreover, ESCRT proteins and interferons can modulate dependency on VPS4A.

The ESCRT System Plays an Important Role in the Germination in Candida albicans by Regulating the Expression of Hyphal-Specific Genes and the Localization of Polarity-Related Proteins

Candida albicans is an important opportunistic fungal pathogen, and its pathogenicity is closely related to its ability to form hyphae. ESCRT system was initially discovered as a membrane-budding machinery involved in the formation of multivesicular bodies. More recently, the role of ESCRT is vastly expanded. Early reports showed that the ESCRT system is involved in inducing hyphae under neutral-alkaline environment via the Rim101 pathway. We previously found that in the environment that contains serum, one ESCRT protein, Vps4, is essential for polarity maintenance during hyphal formation, as its deletion causes the formation of multiple hyphae. In this study, we found that Vps4 is also essential for the proper localization of Cdc42 and Cdc3, which may be related to its role in polarity maintenance. We also discovered that deletions of the ESCRT proteins significantly delay germination and cause downregulation of hyphal-specific genes, most prominent of which is HGC1. Since Hgc1 is essential for many aspects of hyphal growth, its downregulation could explain our observed phenotypes. Our further studies show that ESCRT proteins are involved in the dynamics of Ras1. Deletions of VPS4 or SNF7 significantly decrease the recovery rate of GFP-Ras1 in the fluorescence recovery after photobleaching experiment. The decreased Ras1 dynamics may disrupt the signaling pathway and lead to downregulation of hyphal-specific genes. Therefore, in this study we discovered a novel and Rim101 independent mechanism used by the ESCRT system to regulate hyphal induction and polarity maintenance, which could provide insights on the pathogenicity mechanism of Candia albicans.

Synthetic lethality between VPS4A and VPS4B triggers an inflammatory response in colorectal cancer

Somatic copy number alterations play a critical role in oncogenesis. Loss of chromosomal regions containing tumor suppressors can lead to collateral deletion of passenger genes. This can be exploited therapeutically if synthetic lethal partners of such passenger genes are known and represent druggable targets. Here, we report that VPS4B gene, encoding an ATPase involved in ESCRT‐dependent membrane remodeling, is such a passenger gene frequently deleted in many cancer types, notably in colorectal cancer (CRC). We observed downregulation of VPS4B mRNA and protein levels from CRC patient samples. We identified VPS4A paralog as a synthetic lethal interactor for VPS4B in vitro and in mouse xenografts. Depleting both proteins profoundly altered the cellular transcriptome and induced cell death accompanied by the release of immunomodulatory molecules that mediate inflammatory and anti‐tumor responses. Our results identify a pair of novel druggable targets for personalized oncology and provide a rationale to develop VPS4 inhibitors for precision therapy of VPS4B‐deficient cancers.

The Curious Case of "Case Report" of Infections Caused by Human and Animal Fungal Pathogens: An Educational Tool, an Online Archive, or a Format in Need of Retooling

Case reports describe the unusual occurrence and complications of diseases, diagnostic challenges, and notable therapeutic successes. Some journals have discontinued the case reports, while new case report journals have appeared in recent years. During the eightieth anniversary of Mycopathologia, it is fitting to examine the relevance of the case report since the journal continues to traverse the boundaries of basic and clinical sciences. A random sample of recent case reports and other articles were selected from Mycopathologia. Springer Nature individual article download statistics, and Google Scholar and Scopus citations numbers were compared to assess the reader access and bibliometric impact of case reports. Our analysis indicated that the case report format continues to be a vital element of publication in a cross-disciplinary journal such as Mycopathologia. Medical and veterinary case reports covering fungal pathogens are widely read as evident from their download numbers. The download numbers have a positive correlation with the completeness of the report, the topics and geographic origin of reports have a neutral influence, and the recency leads to lower downloads. There is no discernible trend between the download numbers and the citations of case reports as measured by Google Scholar and Scopus. A specially designed checklist for Mycopathologia case reports and new format MycopathologiaIMAGES are being introduced to improve the quality and relevance of case reports further.