Cover image: Pictured is a megakaryocyte (cyan) with microtubules (magenta) in a 3D hydrogel. Ines Guinard et al. examined megakaryocytes, which mature in the confined microenvironment of the bone marrow and produce platelets in the bloodstream. The authors found that mechanical confinement activates the megakaryocytes’ Rho-GTPase signaling pathway, increasing intracellular tension and preventing platelet formation. According to the authors, the cytoskeletal structures that maintain intracellular tension disappear when megakaryocytes reach the bloodstream. See the article by Guinard et al. e2407829121. Image credit: Catherine Léon.
PLANT CELL:东京大学发现负调控植物抗病反应的新机制
植物通过细胞表面的pattern recognition receptors (PRRs) （如ELONGATION Factor-TU (EF-TU) RECEPTOR (EFR) and FLAGELLIN SENSING 2 (FLS2)）来识别致病菌。PRRs 属于leucine-rich repeat receptor kinase (LRR-RK) family并可以通过NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD)来产生活性氧。本研究借助coimmunoprecipitation analysis利用拟南芥的EFR, FLS2, and RBOHD 发现了一个 LRR-RK-QIAN SHOU KINASE 1 (QSK1),左为PRR-RBOHD complex-associated protein发挥作用. QSK1抑制FLS2 and EFR，从而作为 PRR-triggered immunity (PTI)负调控子发挥作用.
QSK1 受致病菌效应子HopF2Pto（a mono-ADP ribosyltransferase）,抑制FLS2 and EFR水平，从而抑制PTI. HopF2Pto在转录水平上抑制 PROSCOOP （encoding important stress-regulated phytocytokines ）以及它们的受体 MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2. HopF2Pto的丰度受到QSK1 正调控，从而致病。
小结：本研究借助蛋白互作分析发现了一个负调控植物抗病反应基因QSK1.
原文：The leucine-rich repeat receptor kinase QSK1 regulates PRR-RBOHD complexes targeted by the bacterial effector HopF2Pto
