WNT4

引言骨分泌蛋白，称为骨因子，调节骨代谢和全身稳态。然而，关于真正的骨因子和它们的细胞来源是什么以及它们是如何被调节的基本问题仍然不清楚。2024年4月3日，南方医科大学白晓春、邹志鹏及中国科学院深圳先进技术研究院陈棣共同通讯在Cell Metabolism在线发表题为“An integrated multi-omics analysis reveals osteokines involved in global regulation”的研究论文，该研究分析了骨骼和骨骼外组织、成骨细胞(OB)条件培养基、骨髓上清(BMS)和血清，以寻找基础骨因子和那些对衰老和机械加载/卸载有反应的骨因子。通过整合RNA-seq、scRNA-seq和蛋白质组学方法的数据，该研究确定了375个候选骨因子及其对衰老和机械动力学的响应变化。此外，分析了它们在骨中的细胞来源和它们促进的器官间通讯(骨-脑、肝和主动脉)。值得注意的是，衰老的OBs分泌脂肪酸结合蛋白，使衰老向血管平滑肌细胞(VSMCs)传播。综上所述，该研究确定了以前未知的候选骨因子，并在它们之间建立了一个动态的调控网络，从而为进一步研究它们的系统作用提供了宝贵的资源。骨因子是指由骨产生和释放的一组细胞因子或肽，它们随后发挥自分泌、旁分泌和/或内分泌作用。骨是一种高度动态和代谢活跃的组织，在整个生命过程中经历不断的重塑以保持其强健的结构和功能，这一重塑过程涉及破骨细胞骨吸收和成骨细胞骨形成的协调作用。骨细胞(包括OBs细胞、破骨细胞、骨细胞、软骨细胞和骨髓基质细胞[BMSCs])之间广泛的分子通讯是精确调节骨形成和吸收的基本机制。OBs分泌多种骨因子，包括巨噬细胞集落刺激因子(M-CSF)，RANKL/OPG、SEMA3A和WNT5a调节破骨细胞的发生。此外，OBs分泌WNT4以自分泌方式促进骨形成，并以旁分泌方式抑制破骨细胞形成和吸收。骨细胞产生SOST抑制OB分化并促进破骨细胞分化。另一方面，破骨细胞分泌诸如CT-1、S1P、EphrinB2和SEMA4D等骨因子这些骨因子作用于OBs和骨细胞，影响成骨。此外，转化生长因子-β (TGF-β)调节破骨细胞OB串扰，将OB祖细胞募集到骨吸收部位，并促进骨形成。模式图（Credit: Cell Metabolism）近几十年来，骨生物学的重大进展揭示了骨的内分泌功能。骨源性FGF23调节肾脏中磷酸盐稳态的发现首次确立了骨作为内分泌器官的地位骨钙素促进胰岛素分泌和胰腺β细胞增殖，增加男性生育所需的睾酮生物合成，并修复神经变性导致的认知缺陷。另一个有趣的发现是OBs衍生的脂钙素-2 (LCN2)通过下丘脑的黑素皮质素4受体抑制食物摄入并调节葡萄糖水平。还报道了一系列调节骨髓微环境和造血的骨因子，如OBs衍生的CXCL9和骨细胞衍生的白细胞介素(IL)-34。这些发现表明骨因子在骨代谢和全身稳态中起重要作用。然而，现有的研究是有限的，缺乏整合。目前，对于骨因子的基本特征，如存在什么骨因子，从哪类骨细胞分泌骨因子，以及它们如何受环境因素的调节等，还缺乏全面的认识。此外，多组学方法提供了对生物学和疾病更全面的理解，使新的诊断和治疗靶点得以确定。该研究使用大量和单细胞转录组学和蛋白质组学进行了综合分析，以确定可能有助于骨代谢和全身稳态的骨因子。还鉴定了基础骨因子、衰老相关骨因子、机械反应性骨因子和OBs分泌骨因子(OBKs)，定位了它们在骨中的细胞来源，并分析了这些骨因子在器官间的通讯。孟德尔随机化(MR)分析显示，低骨密度(BMD)可能是动脉粥样硬化性心血管疾病(ASCVD)的潜在因果危险因素。衰老OBs分泌脂肪酸结合蛋白3 (FABP3)，使衰老向血管平滑肌细胞(VSMCs)扩散。总的来说，该研究建立了一个影响骨重塑和全局稳态的骨因子动态网络，为深入研究提供了宝贵的资源。原文链接https://doi-org.libproxy1.nus.edu.sg/10.1016/j.cmet.2024.03.006责编|探索君排版|探索君文章来源|“iNature”End往期精选围观一文读透细胞死亡(Cell Death) | 24年Cell重磅综述（长文收藏版）热文Nature | 破除传统：为何我们需要重新思考肿瘤的命名方式热文Nature | 2024年值得关注的七项技术热文Nature | 自身免疫性疾病能被治愈吗？科学家们终于看到了希望热文CRISPR技术进化史 | 24年Cell综述

本文为转化医学网原创，转载请注明出处 作者：Sophia 导读： 心脏成纤维细胞 （CF） 是负责沉积和重塑胶原蛋白的原代细胞，与心力衰竭 （HF） 显着相关。TEAD1已被证明对心脏发育和体内平衡至关重要。然而，成纤维细胞内源性TEAD1在心脏重塑中的应用仍不完全清楚。 2024年2月19日，复旦大学附属中山医院心内科葛均波院士、孙爱军教授共同通讯在期刊《Signal Transduction and Targeted Therapy》发表题为“TEA domain transcription factor 1(TEAD1) induces cardiac fibroblasts cells remodeling through BRD4/Wnt4 pathway”的研究论文， 研究表明TEAD1 是通过 BRD4/Wnt4 信号通路与病理性心脏重塑相关的促纤维化 CFs 表型的重要调节因子。 https://www-nature-com.libproxy1.nus.edu.sg/articles/s41392-023-01732-w 研究背景 01 心力衰竭 （HF） 仍然是全球发病率和死亡率的主要因素，其发病率和患病率稳步上升。尽管在预防和治疗方面取得了进展，但心衰的结局往往不尽如人意。心脏重塑的过程涉及心脏结构和功能的复杂改变，包括生理适应和病理变化。生理重塑是指心脏对各种条件的正常适应性反应，例如定期运动、怀孕或儿童时期的生长。相反，病理性心脏重塑是指为应对各种疾病或病症（如高血压、心衰或心肌梗塞）而发生的适应不良变化。这一过程的特征是心肌细胞 （CM） 肥大、心脏成纤维细胞 （CF） 活化和细胞外基质 （ECM） 沉积，这是对各种心脏应激的反应。从这些病理过程中，CF 的表型变化会加剧细胞外基质 （ECM） 沉积和心脏纤维化，最终导致心脏组织的顺应性降低并最终发生晚期 HF。然而， 驱动 HF 中 CFs 分化和心脏重塑的关键因素以及细胞水平的分子机制仍不清楚。 囊性纤维化对于维持心脏的结构完整性至关重要，并参与各种生理和病理过程，包括心脏重塑。在病理条件下，各种来源的CF可以分化为肌成纤维细胞。几十年来，人们一直在争论肌成纤维细胞的起源。虽然现在普遍认为它们通过增殖起源于现有的成纤维细胞，但周等人还认识到，起源于心内膜的成纤维细胞作为肌成纤维细胞的一个亚群起着关键作用，对压力超负荷损伤后严重心脏纤维化的发展做出了重大贡献。肌成纤维细胞的关键特征，无论其来源如何，都会导致心脏组织的病理重塑以及胶原蛋白和其他 ECM 成分的过度沉积，最终导致心脏纤维化。因此， 揭示肌成纤维细胞活化的机制对于开发靶向疗法以预防或减轻心脏重塑和心功能不全至关重要。 研究进展 02 转录组学分析显示，在横主动脉收缩 （TAC） 和 Ang-II 输注后 4 周，小鼠心脏 TEAD1 表达持续上调。进一步的研究表明，CF是表达TEAD1水平升高的主要细胞类型，以响应压力过载。通过将TEAD1-floxed小鼠与CFs和肌成纤维细胞特异性Cre小鼠杂交来实现条件性TEAD1敲除。超声心动图和组织学分析表明，CF 和肌成纤维细胞特异性 TEAD1 缺乏症以及用 TEAD1 抑制剂 VT103 治疗可改善 TAC 诱导的心脏重塑。从机制上讲， RNA-seq 和 ChIP-seq 分析将 Wnt4 确定为一种新的 TEAD1 靶标。TEAD1 已被证明通过 Wnt 信号通路促进成纤维细胞向肌成纤维细胞的转化，并且基因 Wnt4 敲低抑制了具有 TEAD1 过表达的 CF 中的促转化表型。 此外，免疫共沉淀结合质谱、染色质免疫沉淀和荧光素酶测定表明 TEAD1 和 BET 蛋白 BRD4 之间存在相互作用，导致 Wnt4 启动子的结合和激活。这些发现表明，TEAD1可能为未来研究其心脏重塑和心衰的治疗潜力奠定基础。 研究结果 03 在这项研究中，我们将 TEAD1 鉴定为病理性心脏重塑的新型调节因子，并发现 TEAD1 表达在心脏重塑的人类患者以及由 TAC 或 Ang-II 刺激诱导的慢性压力超负荷小鼠中均上调。我们进一步证明，这种TEAD1上调对CFs是选择性的，而不是CMs。使用CFs或肌成纤维细胞-TEAD1敲除小鼠和TEAD1抑制剂，我们发现TEAD1缺乏改善了TAC和Ang-II诱导的心脏重塑和TAC诱导的心功能障碍。 TEAD1 与 BRD4 相互作用以激活启动子 Wnt4 的转录活性，从而通过 Wnt 信号通路促进成纤维细胞转化为肌成纤维细胞表型（图 7）。 综上所述，这项工作已将TEAD1确定为抑制成纤维细胞到肌成纤维细胞分化和预防心脏重塑和HF的发生和进展的潜在治疗靶点。 TEA 结构域转录因子 1（TEAD1） 通过 BRD4/Wnt4 通路诱导心肌成纤维细胞重塑。 TEAD1 通过 Wnt 信号通路促进 TAC 或 Ang-II 诱导的病理性心脏重塑过程中成纤维细胞向肌成纤维细胞的转变。TAC 或 Ang II 刺激诱导 TEAD1 表达，TEAD1 与 Wnt4 的启动子结合，通过与 BRD4 相互作用促进其表达。过表达的 Wnt4 增强了 β-连环蛋白的核易位，从而激活了经典的 Wnt 信号通路，促进成纤维细胞向肌成纤维细胞的转变。 参考资料： https://www-nature-com.libproxy1.nus.edu.sg/articles/s41392-023-01732-w 注：本文旨在介绍医学研究进展，不能作为治疗方案参考。如需获得健康指导，请至正规医院就诊。 热门·直播/活动 🕓 上海｜3月01日-02日 ▶第三届长三角单细胞组学技术应用论坛暨空间组学前沿论坛将在上海召开，诚邀您的参与！ 点击对应文字 查看详情

Researchers compared a pair of superficially similar motor neurons in fruit flies to examine how their differing use of the same genome produced distinctions in form and function. Figuring out how hundreds of different kinds of brain cells develop from their unique expression of thousands of genes promises to not only advance understanding of how the brain works in health, but also what goes wrong in disease. A new MIT study that precisely probes this "molecular logic" in two neuron types of the Drosophila fruit fly, shows that even similar cells push and pull many levers to develop distinct functions. In the study in Neuron, a team of neurobiologists at The Picower Institute for Learning and Memory found that the two closely related neuronal subtypes differed from each other in how they expressed more than 800 genes, or ~5% of the total genes encoded in the fly genome. By manipulating genes whose expression differed most prominently, the scientists were then able to show how they produced several of the observable differences between the cells. "There is a global effort in neuroscience to identify all the different types of neurons to define their unique properties and their gene expression pro " said study senior author Troy Littleton, Menicon Professor of Neuroscience in MIT's Departments of Biology and Brain and Cognitive Sciences. "That information can be used as a toolkit for studying how newly found disease genes map on to those particular neurons to indicate which ones might be most affected in specific brain disorders. "We wanted to use Drosophila as a way to see whether we can, in fact, determine how the transcriptome of two similar neurons is differentially used to understand which key genes specify their unique structural and functional properties." Under the microscope The two neuron types compared in the study both emerge from the fly's analog of a spinal cord to control muscles by releasing the neurotransmitter glutamate at connections called synapses. The neurons' main functional differences are that "phasic" neurons connect to many muscles and emit big, occasional bursts of glutamate while "tonic" neurons each connect to only one muscle and provide more of a constant drip of the chemical. This duality, which is also found in neurons of the human brain, provides a flexible range of control. Picower Institute postdoc Suresh Jetti led the effort in Littleton's lab to determine how these two neurons develop their differences. The team began with an unusually deep characterization of how the two cell types differ in form and function and then took a highly precise look at the gene expression pro or transcriptomes. On close examination, the tonic and phasic cells showed a variety of important differences. Phasic neurons make fewer synapses on an individual muscle than tonic ones do, but because they innervate so many more muscles, phasic neurons have to make about four times as many synapses in total. The tonic neurons have more inputs from other neurons thanks to more widely reaching dendrites (the branches that lead into the cell). On the output side of things, the phasic neurons produced much more powerful signals when stimulated and were more likely to send them than tonic neurons were. Analysis showed that the synaptic sites that prompt glutamate release, called active zones (AZs), took in more calcium ions in phasic neurons than tonic ones. A particularly new and intriguing finding was that the AZs in tonic and phasic neurons took on different shapes. Tonic AZs were round, like donuts, while phasic ones were more triangular or star-shaped. Littleton hypothesizes that this difference could allow for more calcium ions to crowd into the phasic active zones, perhaps explaining their greater bursts of glutamate release compared to tonic neurons. Expressing their differences To assess gene expression, Jetti employed a technique called "isoform patchseq" in which he identified the exact same tonic and phasic neurons in hundreds of flies and extracted RNA from their individual nuclei and cell bodies. The technique, while very hard work, provided the team with an unusually rich vein of transcriptomic information from precisely the cells of interest, Littleton said, including not only how gene expression differed between the two cell types, but also how gene splicing and RNA editing were different. In all, the expression of 822 genes was significantly different between the two neuron types. About 35 of the genes were known to help guide the growth of the axon branches that neurons extend to forge their connections with muscle -- a set of differences pertinent to why tonic neurons innervate only one muscle while phasic ones innervate many. Other differentially expressed genes related to the structure and function of synapses, while more than 20 others suggested differences in the neuromodulatory chemicals each neuron was sensitive to as inputs. The team found that transport proteins were more prominently expressed in phasic neurons, perhaps explaining how they keep up with the greater demand to forge more synapses across many muscles. The team also found that while tonic neurons express "sialylation" genes to attach sugars to proteins on their synaptic membrane, phasic ones expressed unique "ubiquitin" genes that break down proteins. After documenting which genes were most prominently different, the team set out to determine what they do by disrupting their function and seeing how that affected the cells. For instance, Jetti, Littleton and colleagues found that interfering with specific ubiquitination genes caused phasic neurons to overgrow synapses. Disrupting sialylation, meanwhile, caused synaptic undergrowth in tonic neurons. Tonic neurons also expressed 40 times more of a gene called Wnt4, and disrupting Wnt4 reduced synaptic growth in this population of neurons. The scientists had also found that phasic neurons express a calcium-ion buffering gene >30-fold more than tonic ones. When they mutated that gene to disrupt its function, they found that phasic neurons, which normally have lower baseline calcium levels, now display higher resting calcium similar to the tonic neurons. And in another experiment they showed they could distinctly disrupt each cell's AZ shapes by interfering with cytoskeletal genes that each neuron expressed especially highly. When the team reduced a gene that phasic neurons express a lot, their AZs became elongated, but tonic AZs were unaffected. When the team reduced a gene that phasic neurons highly express, their AZs became less round without affecting AZs in phasic cells. In all, the analysis enabled the team to begin constructing a model of the molecular differences that make the two cells differ, though Littleton said they still have more work to understand how the full repertoire of gene expression differences define the unique properties of the two neuronal subtypes. In addition to Littleton and Jetti, the paper's other authors are Andres Crane, Yulia Akbergenova, Nicole Aponte-Santiago, Karen Cunningham, and Charles Whittaker. The JPB Foundation, The Picower Institute for Learning and Memory, and the National Institutes of Health funded the research.