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MBio Oct 2023Inflammasomes are essential for host defense against intracellular bacterial pathogens like , as they activate caspases, which promote cytokine release and cell death to...
Inflammasomes are essential for host defense against intracellular bacterial pathogens like , as they activate caspases, which promote cytokine release and cell death to control infection. In mice, interferon (IFN) signaling promotes inflammasome responses against bacteria by inducing a family of IFN-inducible GTPases known as guanylate-binding proteins (GBPs). Within murine macrophages, IFN promotes the rupture of the -containing vacuole (LCV), while GBPs are dispensable for this process. Instead, GBPs facilitate the lysis of cytosol-exposed . In contrast, the functions of IFN and GBPs in human inflammasome responses to are poorly understood. We show that IFN-γ enhances inflammasome responses to in human macrophages. Human GBP1 is required for these IFN-γ-driven inflammasome responses. Furthermore, GBP1 co-localizes with and/or LCVs in a type IV secretion system (T4SS)-dependent manner and promotes damage to the LCV, which leads to increased exposure of the bacteria to the host cell cytosol. Thus, our findings reveal species- and pathogen-specific differences in how GBPs function to promote inflammasome responses.
Topics: Humans; Animals; Mice; Inflammasomes; Legionella; Vacuoles; Carrier Proteins; Signal Transduction; Legionella pneumophila; GTP-Binding Proteins
PubMed: 37737612
DOI: 10.1128/mbio.01707-23 -
ELife Sep 2023The transcriptional regulator SsrB acts as a switch between virulent and biofilm lifestyles of non-typhoidal serovar Typhimurium. During infection, phosphorylated SsrB...
The transcriptional regulator SsrB acts as a switch between virulent and biofilm lifestyles of non-typhoidal serovar Typhimurium. During infection, phosphorylated SsrB activates genes on Pathogenicity Island-2 (SPI-2) essential for survival and replication within the macrophage. Low pH inside the vacuole is a key inducer of expression and SsrB activation. Previous studies demonstrated an increase in SsrB protein levels and DNA-binding affinity at low pH; the molecular basis was unknown (Liew et al., 2019). This study elucidates its underlying mechanism and in vivo significance. Employing single-molecule and transcriptional assays, we report that the SsrB DNA-binding domain alone (SsrBc) is insufficient to induce acid pH-sensitivity. Instead, His12, a conserved residue in the receiver domain confers pH sensitivity to SsrB allosterically. Acid-dependent DNA binding was highly cooperative, suggesting a new configuration of SsrB oligomers at SPI-2-dependent promoters. His12 also plays a role in SsrB phosphorylation; substituting His12 reduced phosphorylation at neutral pH and abolished pH-dependent differences. Failure to flip the switch in SsrB renders avirulent and represents a potential means of controlling virulence.
Topics: Virulence; Salmonella typhimurium; Biofilms; Biological Assay; DNA
PubMed: 37706506
DOI: 10.7554/eLife.85690 -
Frontiers in Microbiology 2023Q fever is a zoonotic disease caused by , an obligatory intracellular bacterial pathogen. Like other intracellular pathogens, is able to survive and reproduce within... (Review)
Review
Q fever is a zoonotic disease caused by , an obligatory intracellular bacterial pathogen. Like other intracellular pathogens, is able to survive and reproduce within host cells by manipulating host cellular processes. In particular, the relationship between infection and host autophagy, a cellular process involved in degradation and recycling, is of great interest due to its intricate nature. Studies have shown that autophagy can recognize and target intracellular pathogens such as and for degradation, limiting their replication and promoting bacterial clearance. However, can actively manipulate the autophagic pathway to create an intracellular niche, known as the -containing vacuole (CCV), where it can multiply and evade host immune responses. promotes the fusion of CCVs with lysosomes through mechanisms involving virulence factors such as Cig57 and CvpF. This review summarizes the latest findings on the dynamic interaction between host autophagy and infection, highlighting the complex strategies employed by both the bacterium and the host. A better understanding of these mechanisms could provide important insights into the development of novel therapeutic interventions and vaccine strategies against infections.
PubMed: 37808314
DOI: 10.3389/fmicb.2023.1281303 -
Nature Communications Sep 2023Members of the NETWORKED (NET) family are involved in actin-membrane interactions. Here we show that two members of the NET family, NET4A and NET4B, are essential for...
Members of the NETWORKED (NET) family are involved in actin-membrane interactions. Here we show that two members of the NET family, NET4A and NET4B, are essential for normal guard cell actin reorganization, which is a process critical for stomatal closure in plant immunity. NET4 proteins interact with F-actin and with members of the Rab7 GTPase RABG3 family through two distinct domains, allowing for simultaneous localization to actin filaments and the tonoplast. NET4 proteins interact with GTP-bound, active RABG3 members, suggesting their function being downstream effectors. We also show that RABG3b is critical for stomatal closure induced by microbial patterns. Taken together, we conclude that the actin cytoskeletal remodelling during stomatal closure involves a molecular link between actin filaments and the tonoplast, which is mediated by the NET4-RABG3b interaction. We propose that stomatal closure to microbial patterns involves the coordinated action of immune-triggered osmotic changes and actin cytoskeletal remodelling likely driving compact vacuolar morphologies.
Topics: Actins; Vacuoles; Actin Cytoskeleton; Cell Physiological Phenomena; Osmosis
PubMed: 37730720
DOI: 10.1038/s41467-023-41337-z -
Cancer Innovation Aug 2023Doxorubicin is a widely used cytotoxic chemotherapy agent for treating different malignancies. However, its use is associated with dose-dependent cardiotoxicity, causing...
BACKGROUND
Doxorubicin is a widely used cytotoxic chemotherapy agent for treating different malignancies. However, its use is associated with dose-dependent cardiotoxicity, causing irreversible myocardial damage and significantly reducing the patient's quality of life and survival. In this study, an animal model of doxorubicin-induced cardiomyopathy was used to investigate the pathogenesis of doxorubicin-induced myocardial injury. This study also investigated a possible treatment strategy for alleviating myocardial injury through resveratrol therapy in vitro.
METHODS
Adult male C57BL/6J mice were randomly divided into a control group and a doxorubicin group. Body weight, echocardiography, surface electrocardiogram, and myocardial histomorphology were measured. The mechanisms of doxorubicin cardiotoxicity in H9c2 cell lines were explored by comparing three groups (phosphate-buffered saline, doxorubicin, and doxorubicin with resveratrol).
RESULTS
Compared to the control group, the doxorubicin group showed a lower body weight and higher systolic arterial pressure, associated with reduced left ventricular ejection fraction and left ventricular fractional shortening, prolonged PR interval, and QT interval. These abnormalities were associated with vacuolation and increased disorder in the mitochondria of cardiomyocytes, increased protein expression levels of α-smooth muscle actin and caspase 3, and reduced protein expression levels of Mitofusin2 (MFN2) and Sirtuin1 (SIRT1). Compared to the doxorubicin group, doxorubicin + resveratrol treatment reduced caspase 3 and manganese superoxide dismutase, and increased MFN2 and SIRT1 expression levels.
CONCLUSION
Doxorubicin toxicity leads to abnormal mitochondrial morphology and dysfunction in cardiomyocytes and induces apoptosis by interfering with mitochondrial fusion. Resveratrol ameliorates doxorubicin-induced cardiotoxicity by activating SIRT1/MFN2 to improve mitochondria function.
PubMed: 38089747
DOI: 10.1002/cai2.64 -
Advanced Science (Weinheim,... Aug 2023Demyelinating disorders are among the most common and debilitating diseases in neurology. Canavan disease (CD) is a lethal demyelinating disease caused by mutation of...
Demyelinating disorders are among the most common and debilitating diseases in neurology. Canavan disease (CD) is a lethal demyelinating disease caused by mutation of the aspartoacylase (ASPA) gene, which leads to the accumulation of its substrate N-acetyl-l-aspartate (NAA), and consequently demyelination and vacuolation in the brain. In this study, hypoimmunogenic human induced pluripotent stem cell (iPSC)-derived oligodendrocyte progenitor cells (OPC) are developed from a healthy donor as an "off-the-shelf" cell therapy. Hypoimmunogenic iPSCs are generated through CRISPR/Cas9 editing of the human leukocyte antigen (HLA) molecules in healthy donor-derived iPSCs and differentiated into OPCs. The OPCs are engrafted into the brains of CD (nur7) mice and exhibit widespread distribution in the brain. The engrafted OPCs mature into oligodendrocytes that express the endogenous wildtype ASPA gene. Consequently, the transplanted mice exhibit elevated human ASPA expression and enzymatic activity and reduced NAA level in the brain. The transplanted OPCs are able to rescue major pathological features of CD, including defective myelination, extensive vacuolation, and motor function deficits. Moreover, the hypoimmunogenic OPCs exhibit low immunogenicity both in vitro and in vivo. The hypoimmunogenic OPCs can be used as "off-the-shelf" universal donor cells to treat various CD patients and many other demyelinating disorders, especially autoimmune demyelinating diseases, such as multiple sclerosis.
Topics: Humans; Mice; Animals; Myelin Sheath; Induced Pluripotent Stem Cells; Oligodendrocyte Precursor Cells; Oligodendroglia; Multiple Sclerosis; Canavan Disease
PubMed: 37271923
DOI: 10.1002/advs.202206910 -
The EMBO Journal Jul 2023The facultative intracellular pathogen Brucella abortus interacts with several organelles of the host cell to reach its replicative niche inside the endoplasmic...
The facultative intracellular pathogen Brucella abortus interacts with several organelles of the host cell to reach its replicative niche inside the endoplasmic reticulum. However, little is known about the interplay between the intracellular bacteria and the host cell mitochondria. Here, we showed that B. abortus triggers substantive mitochondrial network fragmentation, accompanied by mitophagy and the formation of mitochondrial Brucella-containing vacuoles during the late steps of cellular infection. Brucella-induced expression of the mitophagy receptor BNIP3L is essential for these events and relies on the iron-dependent stabilisation of the hypoxia-inducible factor 1α. Functionally, BNIP3L-mediated mitophagy appears to be advantageous for bacterial exit from the host cell as BNIP3L depletion drastically reduces the number of reinfection events. Altogether, these findings highlight the intricate link between Brucella trafficking and the mitochondria during host cell infection.
Topics: Brucella abortus; Mitophagy; Vacuoles; Endoplasmic Reticulum; Mitochondria
PubMed: 37232029
DOI: 10.15252/embj.2022112817 -
PLoS Pathogens Aug 2023Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms...
Toscana virus is a major cause of arboviral disease in humans in the Mediterranean basin during summer. However, early virus-host cell interactions and entry mechanisms remain poorly characterized. Investigating iPSC-derived human neurons and cell lines, we found that virus binding to the cell surface was specific, and 50% of bound virions were endocytosed within 10 min. Virions entered Rab5a+ early endosomes and, subsequently, Rab7a+ and LAMP-1+ late endosomal compartments. Penetration required intact late endosomes and occurred within 30 min following internalization. Virus entry relied on vacuolar acidification, with an optimal pH for viral membrane fusion at pH 5.5. The pH threshold increased to 5.8 with longer pre-exposure of virions to the slightly acidic pH in early endosomes. Strikingly, the particles remained infectious after entering late endosomes with a pH below the fusion threshold. Overall, our study establishes Toscana virus as a late-penetrating virus and reveals an atypical use of vacuolar acidity by this virus to enter host cells.
Topics: Humans; Sandfly fever Naples virus; Endocytosis; Endosomes; Vacuoles; Virus Internalization; Hydrogen-Ion Concentration
PubMed: 37578957
DOI: 10.1371/journal.ppat.1011562 -
Frontiers in Plant Science 2023Phosphorus (P) deficiency hinders cotton ( L.) growth and development, seriously affecting lint yield and fiber quality. However, it is still unclear how P fertilizer...
INTRODUCTION
Phosphorus (P) deficiency hinders cotton ( L.) growth and development, seriously affecting lint yield and fiber quality. However, it is still unclear how P fertilizer affects fiber length.
METHODS
Therefore, a two-year (2019-2020) pool-culture experiment was conducted using the split-plot design, with two cotton cultivars (CCRI-79; low-P tolerant and SCRC-28; low-P sensitive) as the main plot. Three soil available phosphorus (AP) contents (P: 3 ± 0.5, P: 6 ± 0.5, and P (control) with 15 ± 0.5 mg kg) were applied to the plots, as the subplot, to investigate the impact of soil AP content on cotton fiber elongation and length.
RESULTS
Low soil AP (P and P) decreased the contents of the osmotically active solutes in the cotton fibers, including potassium ions (K), malate, soluble sugar, and sucrose, by 2.2-10.2%, 14.4-47.3%, 8.7-24.5%, and 10.1-23.4%, respectively, inhibiting the vacuoles from facilitating fiber elongation through osmoregulation. Moreover, soil AP deficiency also reduced the activities of enzymes participated in fiber elongation (plasma membrane H-ATPase (PM-H-ATPase), vacuole membrane H-ATPase (V-H-ATPase), vacuole membrane H-translocating inorganic pyrophosphatase (V-H-PPase), and phosphoenolpyruvate carboxylase (PEPC)). The PM-H-ATPase, V-H-ATPase, V-H-PPase, and PEPC were reduced by 8.4-33.0%, 7.0-33.8%, 14.1-38.4%, and 16.9-40.2%, respectively, inhibiting the transmembrane transport of the osmotically active solutes and acidified conditions for fiber cell wall, thus limiting the fiber elongation. Similarly, soil AP deficiency reduced the fiber length by 0.6-3.0 mm, mainly due to the 3.8-16.3% reduction of the maximum velocity of fiber elongation (V). Additionally, the upper fruiting branch positions (FB) had higher V and longer fiber lengths under low soil AP.
DISCUSSION
Cotton fibers with higher malate content and V-H-ATPase and V-H-PPase activities yielded longer fibers. And the malate and soluble sugar contents and V-H-ATPase and PEPC activities in the SCRC-28's fiber were more sensitive to soil AP deficiency in contrast to those of CCRI-79, possibly explaining the SCRC-28 fiber length sensitivity to low soil AP.
PubMed: 37662180
DOI: 10.3389/fpls.2023.1254103 -
Molecular Therapy : the Journal of the... May 2024Sialidosis (mucolipidosis I) is a glycoprotein storage disease, clinically characterized by a spectrum of systemic and neurological phenotypes. The primary cause of the...
Sialidosis (mucolipidosis I) is a glycoprotein storage disease, clinically characterized by a spectrum of systemic and neurological phenotypes. The primary cause of the disease is deficiency of the lysosomal sialidase NEU1, resulting in accumulation of sialylated glycoproteins/oligosaccharides in tissues and body fluids. Neu1 mice recapitulate the severe, early-onset forms of the disease, affecting visceral organs, muscles, and the nervous system, with widespread lysosomal vacuolization evident in most cell types. Sialidosis is considered an orphan disorder with no therapy currently available. Here, we assessed the therapeutic potential of AAV-mediated gene therapy for the treatment of sialidosis. Neu1 mice were co-injected with two scAAV2/8 vectors, expressing human NEU1 and its chaperone PPCA. Treated mice were phenotypically indistinguishable from their WT controls. NEU1 activity was restored to different extent in most tissues, including the brain, heart, muscle, and visceral organs. This resulted in diminished/absent lysosomal vacuolization in multiple cell types and reversal of sialyl-oligosacchariduria. Lastly, normalization of lysosomal exocytosis in the cerebrospinal fluids and serum of treated mice, coupled to diminished neuroinflammation, were measures of therapeutic efficacy. These findings point to AAV-mediated gene therapy as a suitable treatment for sialidosis and possibly other diseases, associated with low NEU1 expression.
PubMed: 38796704
DOI: 10.1016/j.ymthe.2024.05.029