Indoxyl sulfate exacerbates alveolar bone loss in chronic kidney disease through ferroptosis.

OBJECTIVES: The purpose of this study was to determine whether indoxyl sulfate (IS) is involved in alveolar bone deterioration and to elucidate the mechanism underlying alveolar bone loss in chronic kidney disease (CKD) patients. MATERIALS AND METHODS: Mice were divided into the control group, CP group (ligature-induced periodontitis), CKD group (5/6 nephrectomy), and CKD + CP group. The concentration of IS in the gingival crevicular fluid (GCF) was determined by HPLC. The bone microarchitecture was evaluated by micro-CT. MC3T3-E1 cells were stimulated with IS, and changes in mitochondrial morphology and ferroptosis-related factors were detected. RT-PCR, western blotting, alkaline phosphatase activity assays, and alizarin red S staining were utilized to assess how IS affects osteogenic differentiation. RESULTS: Compared with that in the other groups, alveolar bone destruction in the CKD + CP group was more severe. IS accumulated in the GCF of mice with CKD. IS activated the aryl hydrocarbon receptor (AhR) in vitro, inhibited MC3T3-E1 cell osteogenic differentiation, caused changes in mitochondrial morphology, and activated the SLC7A11/GPX4 signaling pathway. An AhR inhibitor attenuated the aforementioned changes induced by IS. CONCLUSIONS: IS activated the AhR/SLC7A11/GPX4 signaling pathway, inhibited osteogenesis in MC3T3-E1 cells, and participated in alveolar bone resorption in CKD model mice through ferroptosis.

Identification of an LysR family transcriptional regulator that activates motility and flagellar gene expression in Vibrio parahaemolyticus.

Vibrio parahaemolyticus utilizes a polar flagellum for swimming in liquids and employs multiple lateral flagella to swarm on surfaces and in viscous environments. The VPA0961 protein is an LysR family transcriptional regulator that can regulate the swimming and swarming motility of V. parahaemolyticus, but the detailed regulatory mechanisms are not yet fully understood. Herein, we designated the protein as AcsS, which stands for activator of swimming and swarming motility. Our data provided evidence that deleting the acsS gene significantly reduced both swimming and swarming motility of V. parahaemolyticus. Furthermore, AcsS was found to activate the expression of both polar (flgA, flgM, flgB, and flgK) and lateral (motY, fliM, lafA, and fliD) flagellar genes. Overexpression of AcsS in Escherichia coli induced the expression of flgA, motY, and lafA, but did not affect the expression of flgB, flgK, flgM, fliM, and fliD. Interestingly, His-tagged AcsS did not bind to the upstream DNA regions of all the tested genes, suggesting indirect regulation. In conclusion, AcsS positively regulated the swimming and swarming motility of V. parahaemolyticus by activating the transcription of polar and lateral flagellar genes. This work enriched our understanding of the gene expression regulation within the dual flagellar systems of V. parahaemolyticus.

The effect of environmental calcium on gene expression, biofilm formation and virulence of Vibrio parahaemolyticus.

Calcium (Ca2+) can regulate the swarming motility and virulence of Vibrio parahaemolyticus BB22. However, the effects of Ca2+ on the physiology of V. parahaemolyticus RIMD2210633, whose genomic composition is quite different with that of BB22, have not been investigated. In this study, the results of phenotypic assays showed that the biofilm formation, c-di-GMP production, swimming motility, zebrafish survival rate, cytoxicity against HeLa cells, and adherence activity to HeLa cells of V. parahaemolyticus RIMD2210633 were significantly enhanced by Ca2+. However, Ca2+ had no effect on the growth, swarming motility, capsular polysaccharide (CPS) phase variation and hemolytic activity. The RNA sequencing (RNA-seq) assay disclosed 459 significantly differentially expressed genes (DEGs) in response to Ca2+, including biofilm formation-associated genes and those encode virulence factors and putative regulators. DEGs involved in polar flagellum and T3SS1 were upregulated, whereas majority of those involved in regulatory functions and c-di-GMP metabolism were downregulated. The work helps us understand how Ca2+ affects the behavior and gene expression of V. parahaemolyticus RIMD2210633.

3D Directional Assembly of Liquid Crystal Molecules.

The precise construction of hierarchically long-range ordered structures using molecules as fundamental building blocks can fully harness their anisotropy and potential. However, the 3D, high-precision, and single-step directional assembly of molecules is a long-pending challenge. Here, a 3D directional molecular assembly strategy via femtosecond laser direct writing (FsLDW) is proposed and the feasibility of this approach using liquid crystal (LC) molecules as an illustrative example is demonstrated. The physical mechanism for femtosecond (fs) laser-induced assembly of LC molecules is investigated, and precise 3D arbitrary assembly of LC molecules is achieved by defining the discretized laser scanning pathway. Additionally, an LC-based Fresnel zone plate array with polarization selection and colorization imaging functions is fabricated to further illustrate the potential of this method. This study not only introduces a 3D high-resolution alignment method for LC-based functional devices but also establishes a universal protocol for the precise 3D directional assembly of anisotropic molecules.

OTP970 Is Required for RNA Editing of Chloroplast ndhB Transcripts in Arabidopsis thaliana.

RNA editing is essential for compensating for defects or mutations in haploid organelle genomes and is regulated by numerous trans-factors. Pentatricopeptide repeat (PPR) proteins are the prime factors that are involved in RNA editing; however, many have not yet been identified. Here, we screened the plastid-targeted PLS-DYW subfamily of PPR proteins belonging to Arabidopsis thaliana and identified ORGANELLE TRANSCRIPT PROCESSING 970 (OTP970) as a key player in RNA editing in plastids. A loss-of-function otp970 mutant was impaired in RNA editing of ndhB transcripts at site 149 (ndhB-C149). RNA-immunoprecipitation analysis indicated that OTP970 was associated with the ndhB-C149 site. The complementation of the otp970 mutant with OTP970 lacking the DYW domain (OTP970∆DYW) failed to restore the RNA editing of ndhB-C149. ndhB gene encodes the B subunit of the NADH dehydrogenase-like (NDH) complex; however, neither NDH activity and stability nor NDH-PSI supercomplex formation were affected in otp970 mutant compared to the wild type, indicating that alteration in amino acid sequence is not necessary for NdhB function. Together, these results suggest that OTP970 is involved in the RNA editing of ndhB-C149 and that the DYW domain is essential for its function.