Coordination between two cis-elements of WRKY33, bound by the same transcription factor, confers humid adaption in Arabidopsis thaliana.

To cope with flooding-induced hypoxia, plants have evolved different strategies. Molecular strategies, such as the N-degron pathway and transcriptional regulation, are known to be crucial for Arabidopsis thaliana's hypoxia response. Our study uncovered a novel molecular strategy that involves a single transcription factor interacting with two identical cis-elements, one located in the promoter region and the other within the intron. This unique double-element adjustment mechanism has seldom been reported in previous studies. In humid areas, WRKY70 plays a crucial role in A. thaliana's adaptation to submergence-induced hypoxia by binding to identical cis-elements in both the promoter and intron regions of WRKY33. This dual binding enhances WRKY33 expression and the activation of hypoxia-related genes. Conversely, in arid regions lacking the promoter cis-element, WRKY70 only binds to the intron cis-element, resulting in limited WRKY33 expression during submergence stress. The presence of a critical promoter cis-element in humid accessions, but not in dry accessions, indicates a coordinated regulation enabling A. thaliana to adapt and thrive in humid habitats.

Genome evolution of the psammophyte Pugionium for desert adaptation and further speciation.

Deserts exert strong selection pressures on plants, but the underlying genomic drivers of ecological adaptation and subsequent speciation remain largely unknown. Here, we generated de novo genome assemblies and conducted population genomic analyses of the psammophytic genus Pugionium (Brassicaceae). Our results indicated that this bispecific genus had undergone an allopolyploid event, and the two parental genomes were derived from two ancestral lineages with different chromosome numbers and structures. The postpolyploid expansion of gene families related to abiotic stress responses and lignin biosynthesis facilitated environmental adaptations of the genus to desert habitats. Population genomic analyses of both species further revealed their recent divergence with continuous gene flow, and the most divergent regions were found to be centered on three highly structurally reshuffled chromosomes. Genes under selection in these regions, which were mainly located in one of the two subgenomes, contributed greatly to the interspecific divergence in microhabitat adaptation.

Exposure to short-chain chlorinated paraffins induces astrocyte activation via JAK2/STAT3 signaling pathway.

In the last few decades, short-chain chlorinated paraffins (SCCPs) have become the most heavily produced monomeric organohalogen compounds, and have been reported to induce multiple organ toxicity. However, the effects of SCCPs on the central nervous system are unknown. In the present study, we show that SCCP exposure induced astrocyte proliferation and increased the expression of two critical markers of astrocyte activation, glial fibrillary acidic protein and inducible nitric oxide synthase, in vivo and in vitro. SCCP exposure also increased inflammatory factory gene expression. Moreover, SCCP treatment triggered Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signalling, as shown by increased phosphorylation and STAT3 translocation to the nucleus. Both JAK2 and STAT3 inhibition effectively attenuated SCCP-induced astrocyte activation. Finally, JAK2 inhibition significantly rescued STAT3 phosphorylation and nuclear translocation. Taken together, JAK2/STAT3 pathway activation contributed to SCCP-induced astrocyte activation. These data will help elucidate the molecular mechanism underlying SCCP-induced neurotoxicity.

Gut Microbiota from Short-Chain Chlorinated Paraffin-Exposed Mice Promotes Astrocyte Activation by Disrupting the Intestinal Tight Junction via Zonulin Upregulation.

Short-chain chlorinated paraffins (SCCPs) are novel toxicants in food and are reported to possess neurotoxicity. Here, we investigated the mechanism of SCCP-induced astrocyte activation and neuroinflammation. SCCP gavage induced astrocyte activation and neuronal cell death with the changes of gut microbiome and metabolites. Antibiotic cocktail administration to deplete the gut microbiome ameliorated the astrocyte activation and inflammation induced by SCCPs. In fecal microbiota transplantation (FMT) assays, mice that received transplanted gut microbiome from SCCP-treated mice showed increased astrocyte activation and elevated inflammatory response. In addition, SCCP exposure promotes zonulin expression and tight junction injury, and antibiotic cocktail administration inhibited that in the intestinal tract. Increased zonulin and tight junction injury were also observed in SCCPs_FMT mice. The zonulin inhibition protected the tight junction in the intestinal tract from SCCP exposure and suppressed astrocyte activation. In summary, this study proposes a novel possibility for SCCP-induced astrocyte activation and neurotoxicity by the gut microbiome-mediated zonulin expression and tight junction.

[The Effect of Matrix Remodeling Associated 7 (MXRA7) Expression on the Biological Function of SHI-1 Cells].

OBJECTIVE: To express matrix remodeling associated 7 (MXRA7) in the human acute myeloid leukemia SHI-1 cell line and to assess the role of MXRA7 in the biological function of SHI-1 cells. METHODS: The full-length cDNA sequence of human MXRA7 was synthesized and subcloned into the lentivirus shuttle vector pRRL-Venus. SHI-1 cells were transfected with the lentivirus which was packaged with 293T cells. The YFP-positive cells were sorted by flow cytometry and the stable cell lines were obtained by expanded culture. The expression and distribution of MXRA7 in SHI-1 cells were verified by real-time qPCR, Western blot and laser confocal techniques. Cell proliferation and cell cycle were measured by flow cytometry, and apoptosis was determined by Annexin V and 7-AAD staining. The expression of apoptosis related proteins were detected by Western blot. RESULTS: The stable SHI-1 cell line overexpressing MXRA7 was established successfully. Laser confocal analysis confirmed that MXRA7 was expressed in the cytoplasm of SHI-1 cells. Compared with the control cell line, the overexpression of MXRA7 showed no effect on the cell proliferation and cell cycle, but reduced the percentage of apoptosis cells induced by methotrexate. Moreover, the expression of BCL-2 protein was increased by overexpression of MXRA7, which can inhibit cell apoptosis. CONCLUSION: The SHI-1 stable cell line overexpressing MXRA7 was established successfully, and MXRA7 could inhibit drug-induced apoptosis through increasing the expression of BCL-2 protein.

Allelic shift in cis-elements of the transcription factor RAP2.12 underlies adaptation associated with humidity in Arabidopsis thaliana.

Populations of widespread species are usually geographically distributed through contrasting stresses, but underlying genetic mechanisms controlling this adaptation remain largely unknown. Here, we show that in Arabidopsis thaliana, allelic changes in the cis-regulatory elements, WT box and W box, in the promoter of a key transcription factor associated with oxygen sensing, RELATED TO AP 2.12 (RAP2.12), are responsible for differentially regulating tolerance to drought and flooding. These two cis-elements are regulated by different transcription factors that downstream of RAP2.12 results in differential accumulation of hypoxia-responsive transcripts. The evolution from one cis-element haplotype to the other is associated with the colonization of humid environments from arid habitats. This gene thus promotes both drought and flooding adaptation via an adaptive mechanism that diversifies its regulation through noncoding alleles.

Flagellar Hook Protein FlgE Induces Microvascular Hyperpermeability via Ectopic ATP Synthase ß on Endothelial Surface.

We previously demonstrated the immunostimulatory efficacy of Pseudomonas aeruginosa flagellar hook protein FlgE on epithelial cells, presumably via ectopic ATP synthases or subunits ATP5B on cell membranes. Here, by using recombinant wild-type FlgE, mutant FlgE (FlgEM; bearing mutations on two postulated critical epitopes B and F), and a FlgE analog in pull-down assay, Western blotting, flow cytometry, and ELISA, actual bindings of FlgE proteins or epitope B/F peptides with ATP5B were all confirmed. Upon treatment with FlgE proteins, human umbilical vein endothelial cells (HUVECs) and SV40-immortalized murine vascular endothelial cells manifested decreased proliferation, migration, tube formation, and surface ATP production and increased apoptosis. FlgE proteins increased the permeability of HUVEC monolayers to soluble large molecules like dextran as well as to neutrophils. Immunofluorescence showed that FlgE induced clustering and conjugation of F-actin in HUVECs. In Balb/c-nude mice bearing transplanted solid tumors, FlgE proteins induced a microvascular hyperpermeability in pinna, lungs, tumor mass, and abdominal cavity. All effects observed in FlgE proteins were partially or completely impaired in FlgEM proteins or blocked by pretreatment with anti-ATP5B antibodies. Upon coculture of bacteria with HUVECs, FlgE was detectable in the membrane and cytosol of HUVECs. It was concluded that FlgE posed a pathogenic ligand of ectopic ATP5B that, upon FlgE-ATP5B coupling on endothelial cells, modulated properties and increased permeability of endothelial layers both in vitro and in vivo. The FlgE-ectopic ATP5B duo might contribute to the pathogenesis of disorders associated with bacterial infection or ectopic ATP5B-positive cells.

Antimony-induced astrocyte activation via mitogen-activated protein kinase activation-dependent CREB phosphorylation.

Recent studies suggest that the chemical element antimony (Sb) is neurotoxic; however, the molecular mechanisms behind Sb-related neuronal damage are currently unknown. In this study, we found that Sb exposure promoted astrocyte proliferation and increased the expression of inducible nitric oxide synthase (iNOS) and glial fibrillary acidic protein (GFAP), two key protein markers of reactive astrogliosis, at both the gene and protein level, suggesting that Sb induced astrocyte activation. Moreover, the p38 mitogen-activated protein kinase (p38 MAPK) and extracellular signal-related kinase (ERK) pathways were activated following Sb exposure. Inhibition of p38 MAPK reduced Sb-induced iNOS and GFAP upregulation, while inhibiting ERK reduced GFAP expression only, in Sb-exposed C6 cells. Sb treatment also induced the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), and the inhibition of CREB caused a reduction in Sb-induced GFAP and iNOS expression. Furthermore, inhibiting both p38 MAPK and ERK effectively alleviated CREB phosphorylation in Sb-exposed C6 cells. Taken together, our results suggest that p38 MAPK and ERK activation mediate Sb-induced astrocyte activation through CREB phosphorylation. These results help to clarify the molecular mechanisms underlying Sb-associated neurotoxicity.