Multiple sclerosis: the NLRP3 inflammasome, gasdermin D, and therapeutics.

Multiple sclerosis (MS) stands as a chronic inflammatory disease characterized by its neurodegenerative impacts on the central nervous system. The complexity of MS and the significant challenges it poses to patients have made the exploration of effective treatments a crucial area of research. Among the various mechanisms under investigation, the role of inflammation in MS progression is of particular interest. Inflammatory responses within the body are regulated by various cellular mechanisms, one of which involves the nucleotide-binding oligomerization domain (NOD)-, leucine-rich repeat (LRR)-, and pyrin domains (PYD)-containing protein 3 (NLRP3). NLRP3 acts as a sensor within cells, playing a pivotal role in controlling the inflammatory response. Its activation is a critical step leading to the assembly of the NLRP3 inflammasome complex, a process that has profound implications for inflammatory diseases like MS. The NLRP3 inflammasome's activation is intricately linked to the subsequent activation of caspase 1 and gasdermin D (GsdmD), signaling pathways that are central to the inflammatory process. GsdmD, a prominent member of the Gasdermin protein family, is particularly noteworthy for its role in pyroptotic cell death, a form of programmed cell death that is distinct from apoptosis and is characterized by its inflammatory nature. This pathway's activation contributes significantly to the pathology of MS by exacerbating inflammatory responses within the nervous system. Given the detrimental effects of unregulated inflammation in MS, therapeutics targeting these inflammatory processes offer a promising avenue for alleviating the symptoms experienced by patients. This review delves into the intricacies of the pyroptotic pathways, highlighting how the formation of the NLRP3 inflammasome induces such pathways and the potential intervention points for therapeutic agents. By inhibiting key steps within these pathways, it is possible to mitigate the inflammatory response, thereby offering relief to those suffering from MS. Understanding these mechanisms not only sheds light on the pathophysiology of MS but also paves the way for the development of novel therapeutic strategies aimed at controlling the disease's progression through the modulation of the body's inflammatory response.

Nanotechnology-based delivery systems to overcome drug resistance in cancer.

Cancer nanomedicine is defined as the application of nanotechnology and nanomaterials for the formulation of cancer therapeutics that can overcome the impediments and restrictions of traditional chemotherapeutics. Multidrug resistance (MDR) in cancer cells can be defined as a decrease or abrogation in the efficacy of anticancer drugs that have different molecular structures and mechanisms of action and is one of the primary causes of therapeutic failure. There have been successes in the development of cancer nanomedicine to overcome MDR; however, relatively few of these formulations have been approved by the United States Food and Drug Administration for the treatment of cancer. This is primarily due to the paucity of knowledge about nanotechnology and the fundamental biology of cancer cells. Here, we discuss the advances, types of nanomedicines, and the challenges regarding the translation of in vitro to in vivo results and their relevance to effective therapies.

The OsCPK17-OsPUB12-OsRLCK176 module regulates immune homeostasis in rice.

Plant immunity is fine-tuned to balance growth and defense. However, little is yet known about molecular mechanisms underlying immune homeostasis in rice (Oryza sativa). In this study, we reveal that a rice calcium-dependent protein kinase (CDPK), OsCPK17, interacts with and stabilizes the receptor-like cytoplasmic kinase (RLCK) OsRLCK176, a close homolog of Arabidopsis thaliana BOTRYTIS-INDUCED KINASE 1 (AtBIK1). Oxidative burst and pathogenesis-related gene expression triggered by pathogen-associated molecular patterns are significantly attenuated in the oscpk17 mutant. The oscpk17 mutant and OsCPK17-silenced lines are more susceptible to bacterial diseases than the wild-type plants, indicating that OsCPK17 positively regulates rice immunity. Furthermore, the plant U-box (PUB) protein OsPUB12 ubiquitinates and degrades OsRLCK176. OsCPK17 phosphorylates OsRLCK176 at Ser83, which prevents the ubiquitination of OsRLCK176 by OsPUB12 and thereby enhances the stability and immune function of OsRLCK176. The phenotypes of the ospub12 mutant in defense responses and disease resistance show that OsPUB12 negatively regulates rice immunity. Therefore, OsCPK17 and OsPUB12 reciprocally maintain OsRLCK176 homeostasis and function as positive and negative immune regulators, respectively. This study uncovers positive cross talk between CDPK- and RLCK-mediated immune signaling in plants and reveals that OsCPK17, OsPUB12, and OsRLCK176 maintain rice immune homeostasis.

The evaluation of online Modified Objective Structured Examination (MOSE) as postgraduate admissions re-examination: A report from Fujian Medical University, China.

OBJECTIVES: This paper aims to explore the successful implementation of online postgraduate admissions re-examination in China, specifically focusing on the Modified Objective Structured Examination (MOSE). It introduced the specific practice of the online postgraduate admissions re-examination in China and investigated the perceptions of applicants, postgraduate supervisors and admissions staffs about the online MOSE re-examination. METHODS: Surveys were administrated 3 years after the implementation of online MOSE postgraduate admissions re-examination in China. Separate surveys were conducted with applicants, postgraduate supervisors, and admissions staff members to gather their opinions and suggestions regarding the online MOSE re-examination. RESULTS: A total of 65 applicants, 43 postgraduate supervisors and seven admissions staff members completed the surveys. Over 80% of the applicants agreed that the online MOSE comprehensively evaluated their medical humanities, communication, medical knowledge, and overall competence. Furthermore, 89.30% of postgraduate supervisors believed that the students recruited through online MOSE were either "not significantly different," "better," or "much better" compared to those recruited through on-site re-examination. Admissions staff members also expressed a favorable view of online MOSE re-examination. CONCLUSION: The online MOSE re-examination is an effective, convenient, and affirmative evaluation method for postgraduate admissions re-examination.

Gasdermin D kills bacteria.

The recognition of pathogen- or damage- associated molecular patterns (PAMPs/DAMPs) signals a series of coordinated responses as part of innate immunity or host cell defense during infection. The inflammasome is an assemblage of multiprotein complexes in the cytosol that activate inflammatory caspases and release pro-inflammatory mediators. This review examines the two-edged sword activity of gasdermin D (GSDMD). Since its discovery in 2015, GSDMD has played a crucial role in the programmed necrotic type of cell death called pyroptosis. Pyroptosis is an important response in host self-protection against danger signals and infection. Although excessive pyroptosis has a deleterious effect on the host, it proves to have a game-changing therapeutic application against pathogenic invasion when controlled. Here, we explore the mechanism utilized by GSDMD, the best studied member of the gasdermin protein family, in host immune defense against many bacteria. While the protein contributes to the clearance of some bacteria, we also discussed results from previous studies and research, that its presence might hinder effective immunity against other pathogens, thus aiding pathogenic invasion and spread.

Study of peripheral blood inflammatory factor levels and their clinical value in patients with lupus nephritis.

OBJECTIVE: To explore the effect of traditional Chinese and western medicine on the levels of inflammatory cytokines in the peripheral blood of patients with lupus nephritis (LN). METHODS: A total of 80 patients with LN admitted to the hospital from August 2016 to August 2017 were retrospectively analyzed. They were equally separated into an experimental group and a control group by the different types of medications. The control group was treated with western medicine, and the experimental group was treated with the combination of traditional Chinese and western medicines. The therapeutic effects were compared. RESULTS: The levels of IL-6, IL-18 and TNF-α in the experimental group after treatment were (5.47±1.66) pg/ml, (31.66±3.87) pg/ml, and (9.28±3.06) pg/ml, respectively, which were significantly lower than (13.71±3.86) pg/ml, (68.47±4.26) pg/ml, and (22.17±6.54) pg/ml before treatment. The difference was statistically significant (t1 = 12.403, t2 = 40.450, t3 = 11.291, all P<0.001). In the control group after treatment, the levels of IL-6, IL-18 and TNF-α were (12.68±1.32) pg/ml, (68.22±3.42) pg/ml, and (19.78±5.57) pg/ml, respectively. The difference in control and experimental groups was statistically significant (t1 = 21.501, t2 = 44.771, t3 = 10.449, P<0.001). The total effective rate was 95.00% (38/40) in the experimental group and 80.00% (32/40) in control group, (X2 = 4.114, P<0.001). There SLEDAI scores of the experimental group were much lower than control after 8 and 12 weeks of treatment (t1 = 8.186, t2 = 20.776, P<0.001). Moreover, the liver and kidney Yin deficiency symptoms in both groups were significantly improved after treatment (P<0.01). CONCLUSION: The combined treatment of traditional Chinese and western medicine can successfully prevent the secretion of serum IL-6, IL-18 and TNF-α, control the development of disease, boost the therapeutic outcome, and alleviate the immune injury of the body.

Integrating Single-Cell Transcriptome and Network Analysis to Characterize the Therapeutic Response of Chronic Myeloid Leukemia.

Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by a unique BCR-ABL fusion gene. Tyrosine kinase inhibitors (TKIs) were developed to target the BCR-ABL oncoprotein, inhibiting its abnormal kinase activity. TKI treatments have significantly improved CML patient outcomes. However, the patients can develop drug resistance and relapse after therapy discontinues largely due to intratumor heterogeneity. It is critical to understand the differences in therapeutic responses among subpopulations of cells. Single-cell RNA sequencing measures the transcriptome of individual cells, allowing us to differentiate and analyze individual cell populations. Here, we integrated a single-cell RNA sequencing profile of CML stem cells and network analysis to decipher the mechanisms of distinct TKI responses. Compared to normal hematopoietic stem cells, a set of genes that were concordantly differentially expressed in various types of stem cells of CML patients was revealed. Further transcription regulatory network analysis found that most of these genes were directly controlled by one or more transcript factors and the genes have more regulators in the cells of the patients who responded to the treatment. The molecular markers including a known drug-resistance gene and novel gene signatures for treatment response were also identified. Moreover, we combined protein-protein interaction network construction with a cancer drug database and uncovered the drugs that target the marker genes directly or indirectly via the protein interactions. The gene signatures and their interacted proteins identified by this work can be used for treatment response prediction and lead to new strategies for drug resistance monitoring and prevention. Our single-cell-based findings offered novel insights into the mechanisms underlying the therapeutic response of CML.

Renal tubular epithelial cell necroptosis promotes tubulointerstitial fibrosis in patients with chronic kidney disease.

Renal fibrosis, a common pathological manifestation of virtually all types of chronic kidney disease (CKD), ultimately predisposes patients to end-stage renal disease. However, there is no effective therapy for renal fibrosis. Our earlier studies proved that RIP3-mediated necroptosis might be an important mode of renal tubular cell death in rats with chronic renal injury. Under transmission electron microscopy (TEM), we found morphological changes in the necrosis of human renal tissue, and the percentage of necrotic cells increased significantly in patients with stages 2 and 3a CKD. Immunofluorescence analyses showed that the percentages of TUNEL+ /RIP3+ double-positive and TUNEL+ /MLKL+ double-positive tubular epithelial cells in renal tubules of patients with stages 2 and 3a CKD were significantly increased compared to those in control patients without renal disease. Immunohistochemistry analyses of renal biopsy specimens from patients with CKD revealed RIP3, MLKL, and p-MLKL upregulation in patients with stages 2 and 3a CKD, suggesting that necroptosis of renal tubular epithelial cells in CKD patients occurs, and the peak of necroptosis was in stages 2 and 3a CKD. We showed that profibrotic factor proteins (TGF-ß1, Smad2 and Smad3) and fibroblast activation markers (α-SMA and Vimentin) were specifically upregulated in stage 2 and 3a CKD patients. In addition, Pearson correlation analysis showed that the percentage of necroptotic renal tubular epithelial cells was positively correlated with TGF-ß1 and collagen-I. We also showed that RIP1/3 or MLKL inhibitors decreased the expression of RIP3, MLKL, TGF-ß1, and Smad3 in HK-2 cells treated with TNF-α. FGF-2, α-SMA, Vimentin and FN were overexpressed in the hRIFs cultured with the supernatant of necroptotic HK-2 cells, whereas necroptosis blockers (Nec-1s, GSK'872 and NSA) and TGF-ß1/Smad3 pathway antagonists (LY364947 and SIS3) reduced FGF-2, α-SMA, Vimentin and FN levels. Collectively, necroptosis of renal tubular epithelial cells in CKD patients occurs, and the peak of necroptosis was in stages 2 and 3a CKD. Renal tubular epithelial cell necroptosis mediates renal tubulointerstitial fibrosis in patients with chronic kidney disease, which is related to the TGF-ß1/Smad3 signaling pathway.

Ustilaginoidea virens Nuclear Effector SCRE4 Suppresses Rice Immunity via Inhibiting Expression of a Positive Immune Regulator OsARF17.

Rice false smut caused by the biotrophic fungal pathogen Ustilaginoidea virens has become one of the most important diseases in rice. The large effector repertory in U. virens plays a crucial role in virulence. However, current knowledge of molecular mechanisms how U. virens effectors target rice immune signaling to promote infection is very limited. In this study, we identified and characterized an essential virulence effector, SCRE4 (Secreted Cysteine-Rich Effector 4), in U. virens. SCRE4 was confirmed as a secreted nuclear effector through yeast secretion, translocation assays and protein subcellular localization, as well as up-regulation during infection. The SCRE4 gene deletion attenuated the virulence of U. virens to rice. Consistently, ectopic expression of SCRE4 in rice inhibited chitin-triggered immunity and enhanced susceptibility to false smut, substantiating that SCRE4 is an essential virulence factor. Furthermore, SCRE4 transcriptionally suppressed the expression of OsARF17, an auxin response factor in rice, which positively regulates rice immune responses and resistance against U. virens. Additionally, the immunosuppressive capacity of SCRE4 depended on its nuclear localization. Therefore, we uncovered a virulence strategy in U. virens that transcriptionally suppresses the expression of the immune positive modulator OsARF17 through nucleus-localized effector SCRE4 to facilitate infection.

SnRK1A-mediated phosphorylation of a cytosolic ATPase positively regulates rice innate immunity and is inhibited by Ustilaginoidea virens effector SCRE1.

Rice false smut caused by Ustilaginoidea virens is becoming one of the most recalcitrant rice diseases worldwide. However, the molecular mechanisms underlying rice immunity against U. virens remain unknown. Using genetic, biochemical and disease resistance assays, we demonstrated that the xb24 knockout lines generated in non-Xa21 rice background exhibit an enhanced susceptibility to the fungal pathogens U. virens and Magnaporthe oryzae. Consistently, flg22- and chitin-induced oxidative burst and expression of pathogenesis-related genes in the xb24 knockout lines were greatly attenuated. As a central mediator of energy signaling, SnRK1A interacts with and phosphorylates XB24 at Thr83 residue to promote ATPase activity. SnRK1A is activated by pathogen-associated molecular patterns and positively regulates plant immune responses and disease resistance. Furthermore, the virulence effector SCRE1 in U. virens targets host ATPase XB24. The interaction inhibits ATPase activity of XB24 by blocking ATP binding to XB24. Meanwhile, SCRE1 outcompetes SnRK1A for XB24 binding, and thereby suppresses SnRK1A-mediated phosphorylation and ATPase activity of XB24. Our results indicate that the conserved SnRK1A-XB24 module in multiple crop plants positively contributes to plant immunity and uncover an unidentified molecular strategy to promote infection in U. virens and a novel host target in fungal pathogenesis.

Role of EXO1 nuclease activity in genome maintenance, the immune response and tumor suppression in Exo1D173A mice.

DNA damage response pathways rely extensively on nuclease activity to process DNA intermediates. Exonuclease 1 (EXO1) is a pleiotropic evolutionary conserved DNA exonuclease involved in various DNA repair pathways, replication, antibody diversification, and meiosis. But, whether EXO1 facilitates these DNA metabolic processes through its enzymatic or scaffolding functions remains unclear. Here, we dissect the contribution of EXO1 enzymatic versus scaffolding activity by comparing Exo1DA/DA mice expressing a proven nuclease-dead mutant form of EXO1 to entirely EXO1-deficient Exo1-/- and EXO1 wild type Exo1+/+ mice. We show that Exo1DA/DA and Exo1-/- mice are compromised in canonical DNA repair processing, suggesting that the EXO1 enzymatic role is important for error-free DNA mismatch and double-strand break repair pathways. However, in non-canonical repair pathways, EXO1 appears to have a more nuanced function. Next-generation sequencing of heavy chain V region in B cells showed the mutation spectra of Exo1DA/DA mice to be intermediate between Exo1+/+ and Exo1-/- mice, suggesting that both catalytic and scaffolding roles of EXO1 are important for somatic hypermutation. Similarly, while overall class switch recombination in Exo1DA/DA and Exo1-/- mice was comparably defective, switch junction analysis suggests that EXO1 might fulfill an additional scaffolding function downstream of class switching. In contrast to Exo1-/- mice that are infertile, meiosis progressed normally in Exo1DA/DA and Exo1+/+ cohorts, indicating that a structural but not the nuclease function of EXO1 is critical for meiosis. However, both Exo1DA/DA and Exo1-/- mice displayed similar mortality and cancer predisposition profiles. Taken together, these data demonstrate that EXO1 has both scaffolding and enzymatic functions in distinct DNA repair processes and suggest a more composite and intricate role for EXO1 in DNA metabolic processes and disease.

The Effect of TLR9, MyD88, and NF-κB p65 in Systemic Lupus Erythematosus.

Purpose: This study was conducted to characterize the expression level of peripheral blood toll-like receptors 9 (TLR9), nuclear factor kappa-B protein 65 (NF-κB p65), and myeloid differentiation factor88 (MyD88) of active systemic lupus erythematosus (SLE) and analyse their clinical significance. Methods: The prospective cohort study enrolled 30 active SLE patients (SG1 group), 30 stable SLE patients (SG2 group), and 20 healthy individuals (RG group) in the First Affiliated Hospital of Hainan Medical University between January 2018 and June 2020. All SLE patients were treated with methylprednisolone tablets. Quantitative polymerase chain reaction (qPCR) was used to determine the levels of TLR9, MyD88, and NF-κB p65 in the peripheral blood mononuclear cell (PBMC). ELISA was adopted for the determination of serum interleukin (IL-6) and tumor necrosis factor-α (TNF-α). Results: Patients in SG1 showed the highest mRNA levels of TLR9, MyD88, and NF-κB p65, followed by SG2, and then RG. SG1 had the highest serum levels of IL-6 and TNF-α, followed by SG2 and RG. The level of TLR9 was positively correlated with the SLE disease activity index (SLEDAI) and negatively correlated with complement component 3 (C3) and complement component 4 (C4). MyD88 and NF-κB p65 were positively correlated with SLEDAI. Conclusion: Compared with a healthy status, SLE induces an increase in TLR9, MyD88, NF-κB p65, IL-6, and TNF-α levels, and the activation of the TLR9-MyD88-NF-κB p65 signal path was associated with the pathogenesis of SLE.

Clinical Efficacy of Gandakang Tablets plus Methylprednisolone in Patients with Systemic Lupus Erythematosus.

Objective: To evaluate the clinical efficacy of Gandakang tablets plus methylprednisolone in patients with systemic lupus erythematosus (SLE). Methods: From February 2015 to February 2019, 60 eligible patients with SLE were recruited and assigned via the random number table method at a ratio of 1 : 1 to receive either methylprednisolone (control group) or Gandakang tablets plus methylprednisolone (observation group). The primary endpoint was clinical efficacy, and the secondary endpoints included Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score, immunoglobulin (Ig), inflammatory factor levels, and adverse events. Results: Gandakang tablets plus methylprednisolone were associated with a significantly higher treatment efficacy versus methylprednisolone alone (P < 0.05). Gandakang tablets plus methylprednisolone resulted in significantly lower SLEDAI scores and lower levels of IgG, IgM, IgA, tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), and interleukin-6 (IL-6) versus single medication of methylprednisolone (P < 0.05). The two groups showed a similar incidence of adverse events (P > 0.05). Patients given Gandakang tablets plus methylprednisolone had higher mental health, emotional role, physical role, social functioning, and bodily pain scores versus those receiving the monotherapy of methylprednisolone (P < 0.05). Conclusion: Gandakang tablets plus methylprednisolone is effective in the treatment of SLE by enhancing the patients' immunity, mitigating the inflammatory response, eliminating negative emotions, and improving their quality of life.

Ustilaginoidea virens secretes a family of phosphatases that stabilize the negative immune regulator OsMPK6 and suppress plant immunity.

Rice false smut caused by Ustilaginoidea virens is emerging as a devastating disease of rice (Oryza sativa) worldwide; however, the molecular mechanisms underlying U. virens virulence and pathogenicity remain largely unknown. Here we demonstrate that the small cysteine-rich secreted protein SCRE6 in U. virens is translocated into host cells during infection as a virulence factor. Knockout of SCRE6 leads to attenuated U. virens virulence to rice. SCRE6 and its homologs in U. virens function as a novel family of mitogen-activated protein kinase phosphatases harboring no canonical phosphatase motif. SCRE6 interacts with and dephosphorylates the negative immune regulator OsMPK6 in rice, thus enhancing its stability and suppressing plant immunity. Ectopic expression of SCRE6 in transgenic rice promotes pathogen infection by suppressing the host immune responses. Our results reveal a previously unidentified fungal infection strategy in which the pathogen deploys a family of tyrosine phosphatases to stabilize a negative immune regulator in the host plant to facilitate its infection.

Pyroptosis and pyroptosis-inducing cancer drugs.

Pyroptosis, an inflammatory form of lytic cell death, is a type of cell death mediated by the gasdermin (GSDM) protein family. Upon recognizing exogenous or endogenous signals, cells undergo inflammasome assembly, GSDM cleavage, the release of proinflammatory cytokines and other cellular contents, eventually leading to inflammatory cell death. In this review, we discuss the roles of the GSDM family for anti-cancer functions and various antitumor drugs that could activate the pyroptosis pathways.

Clinical analysis of multi-target treatment for complex lupus nephritis.

OBJECTIVE: To observe the efficacy and safety of multi-target (tacrolimus + mycophenolate mofetil + prednisone) therapy for type III + V and IV + V type lupus nephritis. METHODS: A total of 56 patients with lupus nephritis were randomly divided into a treatment group receiving multi-target treatment and a control group receiving intravenous cyclophosphamide combined with prednisone treatment, with 28 patients in each group. Clinical indicators and adverse reactions were observed before and 4, 12, 24, 48 and 72 weeks after treatment. RESULTS: One patient withdrew from the treatment group and two patients from the control group due to adverse reactions within 72 weeks of treatment. Compared with those before treatment, urine protein quantification, ds-DNA antibody titer and systemic lupus erythematosus disease activity index (SLEDAI) scores were significantly decreased at 24 h after 72 weeks of treatment in both groups (P < 0.05). The total remission rate was 85.2% in the treatment group and 57.7% in the control group (P < 0.05) and dte total response rate was 59.3% and 30.8%, respectively (P < 0.05). CONCLUSION: Multiple target treatment of type III + V or IV + V type lupus nephritis has a higher total remission rate, a shorter treatment time, and a lower incidence of adverse reactions than cyclophosphamide and prednisone combined therapy.

Artificial Intelligence and Cancer Drug Development.

BACKGROUND: The development of cancer drugs is among the most focused "bench to bedside activities" to improve human health. Because of the amount of data publicly available to cancer research, drug development for cancers has significantly benefited from big data and Artificial Intelligence (AI). In the meantime, challenges, like curating the data of low quality, remain to be resolved. OBJECTIVES: This review focused on the recent advancements and challenges of AI in developing cancer drugs. METHODS: We discussed target validation, drug repositioning, de novo design, and compounds' synthetic strategies. RESULTS AND CONCLUSION: AI can be applied to all stages during drug development, and some excellent reviews detailing the applications of AI in specific stages are available.

The PdeK-PdeR two-component system promotes unipolar localization of FimX and pilus extension in Xanthomonas oryzae pv. oryzicola.

Bacterial type IV pili (T4P) contribute to virulence and can be rapidly extended and retracted to mediate twitching motility. T4P biogenesis, which is normally limited to the cell poles, is regulated by extracellular stimuli and internal signals such as cyclic di-GMP (c-di-GMP). The c-di-GMP­binding protein FimX interacts with the T4P assembly complex and, when intracellular c-di-GMP concentrations are low, assumes a unipolar localization and promotes T4P biogenesis. Here, we demonstrated that FimX formed a complex with the two-component system consisting of the histidine kinase PdeK and its downstream response regulator PdeR. This complex promoted T4P assembly in the phytopathogen Xanthomonas oryzae pv. oryzicola and virulence in rice. PdeK and the c-di-GMP phosphodiesterase activity of PdeR were required for the unipolar localization of FimX, leading to T4P extension. High amounts of c-di-GMP reduced the affinity of FimX for PdeR in vitro, consistent with FimX promoting T4P extension only under conditions of low c-di-GMP. We propose that low intracellular amounts of c-di-GMP created by PdeR facilitate the recruitment of FimX to the leading pole of motile cells. Our findings indicate that the PdeK-PdeR two-component system connects environmental cues to second messenger turnover, resulting in a change in the intracellular concentration of c-di-GMP that promotes T4P biogenesis and virulence.

Gasdermin D in pyroptosis.

Pyroptosis is the process of inflammatory cell death. The primary function of pyroptosis is to induce strong inflammatory responses that defend the host against microbe infection. Excessive pyroptosis, however, leads to several inflammatory diseases, including sepsis and autoimmune disorders. Pyroptosis can be canonical or noncanonical. Upon microbe infection, the canonical pathway responds to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), while the noncanonical pathway responds to intracellular lipopolysaccharides (LPS) of Gram-negative bacteria. The last step of pyroptosis requires the cleavage of gasdermin D (GsdmD) at D275 (numbering after human GSDMD) into N- and C-termini by caspase 1 in the canonical pathway and caspase 4/5/11 (caspase 4/5 in humans, caspase 11 in mice) in the noncanonical pathway. Upon cleavage, the N-terminus of GsdmD (GsdmD-N) forms a transmembrane pore that releases cytokines such as IL-1ß and IL-18 and disturbs the regulation of ions and water, eventually resulting in strong inflammation and cell death. Since GsdmD is the effector of pyroptosis, promising inhibitors of GsdmD have been developed for inflammatory diseases. This review will focus on the roles of GsdmD during pyroptosis and in diseases.

A bacterial kinase phosphorylates OSK1 to suppress stomatal immunity in rice.

The Xanthomonas outer protein C2 (XopC2) family of bacterial effectors is widely found in plant pathogens and Legionella species. However, the biochemical activity and host targets of these effectors remain enigmatic. Here we show that ectopic expression of XopC2 promotes jasmonate signaling and stomatal opening in transgenic rice plants, which are more susceptible to Xanthomonas oryzae pv. oryzicola infection. Guided by these phenotypes, we discover that XopC2 represents a family of atypical kinases that specifically phosphorylate OSK1, a universal adaptor protein of the Skp1-Cullin-F-box ubiquitin ligase complexes. Intriguingly, OSK1 phosphorylation at Ser53 by XopC2 exclusively increases the binding affinity of OSK1 to the jasmonate receptor OsCOI1b, and specifically enhances the ubiquitination and degradation of JAZ transcription repressors and plant disease susceptibility through inhibiting stomatal immunity. These results define XopC2 as a prototypic member of a family of pathogenic effector kinases and highlight a smart molecular mechanism to activate jasmonate signaling.