scholarly journals RbdB, a Rhomboid Protease Critical for SREBP Activation and Virulence in Aspergillus fumigatus

mSphere ◽  
2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Sourabh Dhingra ◽  
Caitlin H. Kowalski ◽  
Arsa Thammahong ◽  
Sarah R. Beattie ◽  
Katherine M. Bultman ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Aspergillus Fumigatus ◽  
Molecular Mechanisms ◽  
Treatment Options ◽  
Invasive Pulmonary Aspergillosis ◽  
Pathogenic Fungi ◽  
Siderophore Production ◽  
Rhomboid Protease ◽  
Hypoxic Conditions ◽  
Life Threatening

ABSTRACT Aspergillus fumigatus causes life-threatening infections, and treatment options remain limited. Thus, there is an urgent need to find new therapeutic targets to treat this deadly disease. Previously, we have shown that SREBP transcription factors and their regulatory components are critical for the pathobiology of A. fumigatus. Here we identify a role for RbdB, a rhomboid protease, as an essential component of SREBP activity. Our results indicate that mutants lacking rbdB have growth defects under hypoxic conditions, are hypersusceptible to voriconazole, lack extracellular siderophore production, and fail to cause disease in a murine model of invasive pulmonary aspergillosis. This study increases our understanding of the molecular mechanisms involved in SREBP activation in pathogenic fungi and provides a novel therapeutic target for future development. SREBP transcription factors play a critical role in fungal virulence; however, the mechanisms of sterol regulatory element binding protein (SREBP) activation in pathogenic fungi remains ill-defined. Screening of the Neurospora crassa whole-genome deletion collection for genes involved in hypoxia responses identified a gene for an uncharacterized rhomboid protease homolog, rbdB, required for growth under hypoxic conditions. Loss of rbdB in Aspergillus fumigatus also inhibited growth under hypoxic conditions. In addition, the A. fumigatus ΔrbdB strain also displayed phenotypes consistent with defective SREBP activity, including increased azole drug susceptibility, reduced siderophore production, and full loss of virulence. Expression of the basic helix-loop-helix (bHLH) DNA binding domain of the SREBP SrbA in ΔrbdB restored all of the phenotypes linking RdbB activity with SrbA function. Furthermore, the N-terminal domain of SrbA containing the bHLH DNA binding region was absent from ΔrbdB under inducing conditions, suggesting that RbdB regulates the protein levels of this important transcription factor. As SrbA controls clinically relevant aspects of fungal pathobiology in A. fumigatus, understanding the mechanisms of SrbA activation provides opportunities to target this pathway for therapeutic development. IMPORTANCE Aspergillus fumigatus causes life-threatening infections, and treatment options remain limited. Thus, there is an urgent need to find new therapeutic targets to treat this deadly disease. Previously, we have shown that SREBP transcription factors and their regulatory components are critical for the pathobiology of A. fumigatus. Here we identify a role for RbdB, a rhomboid protease, as an essential component of SREBP activity. Our results indicate that mutants lacking rbdB have growth defects under hypoxic conditions, are hypersusceptible to voriconazole, lack extracellular siderophore production, and fail to cause disease in a murine model of invasive pulmonary aspergillosis. This study increases our understanding of the molecular mechanisms involved in SREBP activation in pathogenic fungi and provides a novel therapeutic target for future development.

scholarly journals Vascular Dysfunction in Preeclampsia

Cells ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 3055
Author(s):  
Megan A. Opichka ◽  
Matthew W. Rappelt ◽  
David D. Gutterman ◽  
Justin L. Grobe ◽  
Jennifer J. McIntosh
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Vascular Dysfunction ◽  
Treatment Options ◽  
Cardiovascular Disorder ◽  
Endothelial Damage ◽  
Spiral Artery ◽  
Mitochondrial Stress ◽  
Inflammatory State ◽  
Life Threatening

Preeclampsia is a life-threatening pregnancy-associated cardiovascular disorder characterized by hypertension and proteinuria at 20 weeks of gestation. Though its exact underlying cause is not precisely defined and likely heterogenous, a plethora of research indicates that in some women with preeclampsia, both maternal and placental vascular dysfunction plays a role in the pathogenesis and can persist into the postpartum period. Potential abnormalities include impaired placentation, incomplete spiral artery remodeling, and endothelial damage, which are further propagated by immune factors, mitochondrial stress, and an imbalance of pro- and antiangiogenic substances. While the field has progressed, current gaps in knowledge include detailed initial molecular mechanisms and effective treatment options. Newfound evidence indicates that vasopressin is an early mediator and biomarker of the disorder, and promising future therapeutic avenues include mitigating mitochondrial dysfunction, excess oxidative stress, and the resulting inflammatory state. In this review, we provide a detailed overview of vascular defects present during preeclampsia and connect well-established notions to newer discoveries at the molecular, cellular, and whole-organism levels.

scholarly journals Chromatin profiling reveals genome stability heterogeneity in clinical isolates of the human pathogen Aspergillus fumigatus

2021 ◽  
Author(s):  
Ana Cristina Colabardini ◽  
Fang Wang ◽  
Zhengqiang Miao ◽  
Lakhansing Pardeshi ◽  
Clara Valero ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Genome Stability ◽  
Genome Instability ◽  
Invasive Pulmonary Aspergillosis ◽  
Biosynthetic Gene Cluster ◽  
Clinical Isolates ◽  
Immunosuppressed Patients ◽  
Life Threatening ◽  
Metabolites Production ◽  
Chromatin Profiling

Invasive Pulmonary aspergillosis is a life-threatening infection in immunosuppressed patients caused by the filamentous fungus Aspergillus fumigatus. Chromatin structure regulation is important for genome stability maintenance and has the potential to lead to genome rearrangements driving differences in virulence and pathogenesis of different A. fumigatus isolates. Here, we compared the chromatin activities of the most investigated clinical isolates Af293 and CEA17 and uncovered striking differences in the number, locations and expression of transposable elements. We found evidence for higher genome instability in Af293 as compared to CEA17 and identified a spontaneous Af293 variant that exhibits gross chromosomal alterations including the loss of a 320 kb long segment in chromosome VIII and the amplification of a biosynthetic gene cluster. As a consequence of these re-arrangements, the variant shows increased secondary metabolites production, growth and virulence. Our work emphasizes genome stability heterogeneity as an evolutionary driver of A. fumigatus fitness and virulence.

scholarly journals Heterogeneity in the transcriptional response of the human pathogen Aspergillus fumigatus to the antifungal agent caspofungin

Genetics ◽  
2021 ◽  
Author(s):  
Ana Cristina Colabardini ◽  
Fang Wang ◽  
Zhiqiang Dong ◽  
Lakhansing Pardeshi ◽  
Marina Campos Rocha ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Antifungal Agent ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Invasive Pulmonary Aspergillosis ◽  
Transcriptional Response ◽  
Cell Wall Remodeling

Abstract Aspergillus fumigatus is the main causative agent of invasive pulmonary aspergillosis (IPA), a severe disease that affects immunosuppressed patients worldwide. The fungistatic drug caspofungin is the second line of therapy against IPA but has increasingly been used against clinical strains that are resistant to azoles, the first line antifungal therapy. In high concentrations, caspofungin induces a tolerance phenotype with partial reestablishment of fungal growth called caspofungin paradoxical effect (CPE), resulting from a change in the composition of the cell wall. An increasing number of studies has shown that different isolates of A. fumigatus exhibit phenotypic heterogeneity, including heterogeneity in their CPE response. To gain insights into the underlying molecular mechanisms of CPE response heterogeneity, we analyzed the transcriptomes of two A. fumigatus reference strains, Af293 and CEA17, exposed to low and high caspofungin concentrations. We found that there is a core transcriptional response that involves genes related to cell wall remodeling processes, mitochondrial function, transmembrane transport, and amino acid and ergosterol metabolism, and a variable response related to secondary metabolite (SM) biosynthesis and iron homeostasis. Specifically, we show here that the overexpression of a SM pathway that works as an iron chelator extinguishes the CPE in both backgrounds, whereas iron depletion is detrimental for the CPE in Af293 but not in CEA17. We next investigated the function of the transcription factor CrzA, whose deletion was previously shown to result in heterogeneity in the CPE response of the Af293 and CEA17 strains. We found that CrzA constitutively binds to and modulates the expression of several genes related to processes involved in caspofungin tolerance, and that crzA deletion differentially impacts the SM production and growth of Af293 and CEA17. As opposed to the ΔcrzACEA17 mutant, the ΔcrzA Af293 mutant fails to activate cell wall remodeling genes upon caspofungin exposure, which most likely severely affects its macrostructure and extinguishes its CPE. This work describes how heterogeneity in the response to an antifungal agent between A. fumigatus strains stems from heterogeneity in the function of a transcription factor and its downstream target genes.

scholarly journals Molecular and Clinical Aspects of Chronic Manifestations in Chagas Disease: A State-of-the-Art Review

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1493
Author(s):  
Germán J. Medina-Rincón ◽  
Sebastián Gallo-Bernal ◽  
Paula A. Jiménez ◽  
Lissa Cruz-Saavedra ◽  
Juan David Ramírez ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Molecular Mechanisms ◽  
Treatment Options ◽  
Diagnosis And Treatment ◽  
Clinical Aspects ◽  
Chronic Complications ◽  
Life Threatening ◽  
Host Parasite ◽  
Prompt Diagnosis ◽  
Disease Present

Chronic manifestations of Chagas disease present as disabling and life-threatening conditions affecting mainly the cardiovascular and gastrointestinal systems. Although meaningful research has outlined the different molecular mechanisms underlying Trypanosoma cruzi’s infection and the host-parasite interactions that follow, prompt diagnosis and treatment remain a challenge, particularly in developing countries and also in those where the disease is considered non-endemic. This review intends to present an up-to-date review of the parasite’s life cycle, genetic diversity, virulence factors, and infective mechanisms, as well as the epidemiology, clinical presentation, diagnosis, and treatment options of the main chronic complications of Chagas disease.

scholarly journals Heterogeneity in the transcriptional response of the human pathogen Aspergillus fumigatus to the antifungal agent caspofungin

2021 ◽  
Author(s):  
Ana Cristina Colabardini ◽  
Fang Wang ◽  
Zhiqiang Dong ◽  
Lakhansing Pardeshi ◽  
Marina C Rocha ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Antifungal Agent ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Invasive Pulmonary Aspergillosis ◽  
Transcriptional Response ◽  
Cell Wall Remodeling

Aspergillus fumigatus is the main causative agent of invasive pulmonary aspergillosis (IPA), a severe disease that affects immunosuppressed patients worldwide. The fungistatic drug caspofungin is the second line therapy against IPA but has increasingly been used against clinical strains that are resistant to azoles, the first line antifungal therapy. In high concentrations, caspofungin induces a tolerance phenotype with partial reestablishment of fungal growth called caspofungin paradoxical effect (CPE), resulting from a change in the composition of the cell wall. An increasing number of studies has shown that different isolates of A. fumigatus exhibit phenotypic heterogeneity, including heterogeneity in their CPE response. To gain insights into the underlying molecular mechanisms of CPE response heterogeneity, we analyzed the transcriptomes of two A. fumigatus reference strains, Af293 and CEA17, exposed to low and high caspofungin concentrations. We found that there is a core transcriptional response that involves genes related to cell wall remodeling processes, mitochondrial function, transmembrane transport, and amino acid and ergosterol metabolism, and a variable response related to secondary metabolite (SM) biosynthesis and iron homeostasis. Specifically, we show here that the overexpression of a SM pathway that works as an iron chelator extinguishes the CPE in both backgrounds, whereas iron depletion is detrimental for the CPE in Af293 but not in CEA17. We next investigated the function of the transcription factor CrzA, whose deletion was previously shown to result in heterogeneity in the CPE response of the Af293 and CEA17 strains. We found that CrzA constitutively binds to and modulates the expression of several genes related to processes involved in caspofungin tolerance, and that crzA deletion differentially impacts the SM production and growth of Af293 and CEA17. As opposed to the ? crzA CEA17 mutant, the ? crzA Af293 mutant fails to activate cell wall remodeling genes upon caspofungin exposure, which most likely severely affects its macrostructure and extinguishes its CPE. This work describes how heterogeneity in the response to an antifungal agent between A. fumigatus strains stems from heterogeneity in the function of a transcription factor and its downstream target genes.

scholarly journals Gene Therapy Approaches to Biological Pacemakers

2018 ◽  
Vol 5 (4) ◽  
pp. 50 ◽  
Author(s):  
Melad Farraha ◽  
Saurabh Kumar ◽  
James Chong ◽  
Hee Cho ◽  
Eddy Kizana
Keyword(s):  
Gene Therapy ◽  
Molecular Mechanisms ◽  
Treatment Options ◽  
Transduction Efficiency ◽  
Therapy Targets ◽  
Gene Therapy Vectors ◽  
Life Threatening ◽  
Transfer Vectors ◽  
Pacemaker Dysfunction ◽  
Therapy Strategies

Bradycardia arising from pacemaker dysfunction can be debilitating and life threatening. Electronic pacemakers serve as effective treatment options for pacemaker dysfunction. They however present their own limitations and complications. This has motivated research into discovering more effective and innovative ways to treat pacemaker dysfunction. Gene therapy is being explored for its potential to treat various cardiac conditions including cardiac arrhythmias. Gene transfer vectors with increasing transduction efficiency and biosafety have been developed and trialed for cardiovascular disease treatment. With an improved understanding of the molecular mechanisms driving pacemaker development, several gene therapy targets have been identified to generate the phenotypic changes required to correct pacemaker dysfunction. This review will discuss the gene therapy vectors in use today along with methods for their delivery. Furthermore, it will evaluate several gene therapy strategies attempting to restore biological pacing, having the potential to emerge as viable therapies for pacemaker dysfunction.

An Overview of Dementias

2012 ◽  
Vol 21 (3) ◽  
pp. 75-84
Author(s):  
Venkata Vijaya K. Dalai ◽  
Jason E. Childress ◽  
Paul E Schulz
Keyword(s):  
Clinical Presentation ◽  
Treatment Options ◽  
Current Treatment ◽  
Great Variability ◽  
Health Concern ◽  
Public Health Concern ◽  
Life Threatening ◽  
The Common ◽  
Neurodegenerative Dementias ◽  
Made In

Dementia is a major public health concern that afflicts an estimated 24.3 million people worldwide. Great strides are being made in order to better diagnose, prevent, and treat these disorders. Dementia is associated with multiple complications, some of which can be life-threatening, such as dysphagia. There is great variability between dementias in terms of when dysphagia and other swallowing disorders occur. In order to prepare the reader for the other articles in this publication discussing swallowing issues in depth, the authors of this article will provide a brief overview of the prevalence, risk factors, pathogenesis, clinical presentation, diagnosis, current treatment options, and implications for eating for the common forms of neurodegenerative dementias.

scholarly journals Impairing flow-mediated endothelial remodeling reduces extravasation of tumor cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gautier Follain ◽  
Naël Osmani ◽  
Valentin Gensbittel ◽  
Nandini Asokan ◽  
Annabel Larnicol ◽  
...  
Keyword(s):  
Blood Flow ◽  
Tumor Cells ◽  
Molecular Mechanisms ◽  
Metastatic Progression ◽  
Metastatic Dissemination ◽  
Secondary Tumors ◽  
Flow Profiles ◽  
Endothelial Response ◽  
Life Threatening

AbstractTumor progression and metastatic dissemination are driven by cell-intrinsic and biomechanical cues that favor the growth of life-threatening secondary tumors. We recently identified pro-metastatic vascular regions with blood flow profiles that are permissive for the arrest of circulating tumor cells. We have further established that such flow profiles also control endothelial remodeling, which favors extravasation of arrested CTCs. Yet, how shear forces control endothelial remodeling is unknown. In the present work, we aimed at dissecting the cellular and molecular mechanisms driving blood flow-dependent endothelial remodeling. Transcriptomic analysis of endothelial cells revealed that blood flow enhanced VEGFR signaling, among others. Using a combination of in vitro microfluidics and intravital imaging in zebrafish embryos, we now demonstrate that the early flow-driven endothelial response can be prevented upon specific inhibition of VEGFR tyrosine kinase and subsequent signaling. Inhibitory targeting of VEGFRs reduced endothelial remodeling and subsequent metastatic extravasation. These results confirm the importance of VEGFR-dependent endothelial remodeling as a driving force of CTC extravasation and metastatic dissemination. Furthermore, the present work suggests that therapies targeting endothelial remodeling might be a relevant clinical strategy in order to impede metastatic progression.

scholarly journals Neuroinflammation and the Kynurenine Pathway in CNS Disease: Molecular Mechanisms and Therapeutic Implications

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1548
Author(s):  
Mustafa N. Mithaiwala ◽  
Danielle Santana-Coelho ◽  
Grace A. Porter ◽  
Jason C. O’Connor
Keyword(s):  
Molecular Mechanisms ◽  
Treatment Options ◽  
Treatment Strategies ◽  
Kynurenine Pathway ◽  
Economic Problem ◽  
Cns Disease ◽  
Therapeutic Implications ◽  
Efficacious Treatment ◽  
The Central Nervous System ◽  
Significant Health

Diseases of the central nervous system (CNS) remain a significant health, social and economic problem around the globe. The development of therapeutic strategies for CNS conditions has suffered due to a poor understanding of the underlying pathologies that manifest them. Understanding common etiological origins at the cellular and molecular level is essential to enhance the development of efficacious and targeted treatment options. Over the years, neuroinflammation has been posited as a common link between multiple neurological, neurodegenerative and neuropsychiatric disorders. Processes that precipitate neuroinflammatory conditions including genetics, infections, physical injury and psychosocial factors, like stress and trauma, closely link dysregulation in kynurenine pathway (KP) of tryptophan metabolism as a possible pathophysiological factor that ‘fuel the fire’ in CNS diseases. In this study, we aim to review emerging evidence that provide mechanistic insights between different CNS disorders, neuroinflammation and the KP. We provide a thorough overview of the different branches of the KP pertinent to CNS disease pathology that have therapeutic implications for the development of selected and efficacious treatment strategies.

Sign in / Sign up

Export Citation Format

Share Document