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Award ID contains: 1952823

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  1. Abstract MAPK signaling modules play crucial roles in regulating numerous biological processes in all eukaryotic cells. How MAPK signaling specificity and strength are tightly controlled remains a major challenging question. InArabidopsisstomatal development, the MAPKK Kinase YODA (YDA) functions at the cell periphery to inhibit stomatal production by activating MAPK 3 and 6 (MPK3/6) that directly phosphorylate stomatal fate-determining transcription factors for degradation in the nucleus. Recently, we demonstrated that BSL1, one of the four BSL protein phosphatases, localizes to the cell cortex to activate YDA, elevating MPK3/6 activity to suppress stomatal formation. Here, we showed that at the plasma membrane, all four members of BSL proteins contribute to the YDA activation. However, in the nucleus, specific BSL members (BSL2, BSL3, and BSU1) directly deactivate MPK6 to counteract the linear MAPK pathway, thereby promoting stomatal formation. Thus, the pivotal MAPK signaling in stomatal fate determination is spatially modulated by a signaling dichotomy of the BSL protein phosphatases inArabidopsis, providing a prominent example of how MAPK activities are integrated and specified by signaling compartmentalization at the subcellular level. 
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  2. Abstract Cell polarity is a fundamental feature underlying cell morphogenesis and organismal development. In theArabidopsisstomatal lineage, the polarity protein BASL controls stomatal asymmetric cell division. However, the cellular machinery by which this intrinsic polarity site is established remains unknown. Here, we identify the PRAF/RLD proteins as BASL physical partners and mutating fourPRAFmembers leads to defects in BASL polarization. Members of PRAF proteins are polarized in stomatal lineage cells in a BASL-dependent manner. Developmental defects of theprafmutants phenocopy those of thegnommutants. GNOM is an activator of the conserved Arf GTPases and plays important roles in membrane trafficking. We further find PRAF physically interacts with GNOM in vitro and in vivo. Thus, we propose that the positive feedback of BASL and PRAF at the plasma membrane and the connected function of PRAF and GNOM in endosomal trafficking establish intrinsic cell polarity in theArabidopsisstomatal lineage. 
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  3. Summary In the leaf epidermis, stomatal pores allow gas exchange between plants and the environment. The production of stomatal guard cells requires the lineage cells to divide asymmetrically. In this Insight review, we describe an emerging picture of how intrinsic molecules drive stomatal asymmetric cell division in multidimensions, from transcriptional activities in the nucleus to the dynamic assembly of the polarity complex at the cell cortex. Given the significant roles of stomatal activity in plant responses to environmental changes, we incorporate recent advances in external cues feeding into the regulation of core molecular machinery required for stomatal development. The work we discuss here is mainly based on the dicot plantArabidopsis thalianawith summaries of recent progress in the monocots. 
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  4. Abstract A number of studies have examined the effects of 1,25‐dihydroxyvitamin D3(1,25(OH)2D3) on intestinal inflammation driven by immune cells, while little information is currently available about its impact on inflammation caused by intestinal epithelial cell (IEC) defects. Mice lacking IEC‐specificRab11aa recycling endosome small GTPase resulted in increased epithelial cell production of inflammatory cytokines, notably IL‐6 and early onset of enteritis. To determine whether vitamin D supplementation may benefit hosts with epithelial cell‐originated mucosal inflammation, we evaluated in vivo effects of injected 1,25(OH)2D3or dietary supplement of a high dose of vitamin D on the gut phenotypes of IEC‐specificRab11aknockout mice (Rab11aΔIEC). 1,25(OH)2D3administered at 25 ng, two doses per mouse, by intraperitoneal injection, reduced inflammatory cytokine production in knockout mice compared to vehicle‐injected mice. Remarkably, feeding mice with dietary vitamin D supplementation at 20,000 IU/kg spanning fetal and postnatal developmental stages led to improved bodyweights, reduced immune cell infiltration, and decreased inflammatory cytokines. We found that these vitamin D effects were accompanied by decreased NF‐κB (p65) in the knockout intestinal epithelia, reduced tissue‐resident macrophages, and partial restoration of epithelial morphology. Our study suggests that dietary vitamin D supplementation may prevent and limit intestinal inflammation in hosts with high susceptibility to chronic inflammation. 
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  5. Free, publicly-accessible full text available January 1, 2026