<p>In this issue of <i>Acta Physiologica</i>, Tatzl et al. [<span>1</span>] investigate the relevance of the <i>leucine-rich repeat transmembrane protein 4 like 1</i> (<i>lrrtm4l1</i>) gene, a zebrafish orthologue of the human <i>LRRTM4</i>, on behavioral, transcriptomic, and metabolomic readouts in mixed sex adult zebrafish (summarized in Figure 1). <i>LRRTM4</i> is one of four members of the <i>LRRTM</i> gene family, which code for synaptic cell adhesion molecules that promote excitatory synapse development, including synaptic insertion and stabilization of AMPA receptors. <i>LRRTM4</i> is associated with neurodevelopmental disorders, including autism spectrum disorder (ASD) and attempted suicide [<span>2</span>].</p><p>Using RNASeq, the authors identified 126 differentially expressed genes in the telencephalon of <i>lrrtm4l1</i> knockout (<i>lrrtm4l1</i><sup><i>−/−</i></sup>) fish. Among these, they highlight the upregulation of <i>rimkla</i> and <i>arhgap12</i>. The <i>rimkla</i> gene is linked to cognition and memory consolidation [<span>3</span>]. The mammalian orthologue of the <i>arhgap12b</i> gene (i.e., <i>ARHGAP12</i>) promotes endocytosis of postsynaptic AMPA receptors, opposing the effect of <i>LRRTM4</i> [<span>4</span>]. Notable downregulated genes include <i>tyrosine hydroxylase</i>, essential for catecholamine synthesis, and <i>plasmolipin</i>, encoding a major component of myelin sheaths; both genes have previously been linked to various disorders. Pathway analyses implicated semaphorin-plexin signaling, as well as fatty acid metabolism and degradation, as well as valine, leucine, and isoleucine degradation. Semaphorin-plexin signaling is involved in axon guidance and neuronal morphogenesis during neurodevelopment and might stabilize synaptic transmission both during development and adulthood [<span>5</span>].</p><p>Consistent with the differentially expressed genes, metabolomic changes in <i>lrrtm4l1</i><sup><i>−/−</i></sup> zebrafish revealed elevated levels of homovanillic acid, the end product of dopamine metabolism, and lower levels of adenosine. Additionally, <i>lrrtm4l1</i><sup><i>−/−</i></sup> zebrafish showed a trend toward higher serotonin and lower melatonin levels. Unbiased metabolite feature analysis revealed six significant features, including two upregulated features with fragmentation profiles similar to phospholipids and one downregulated feature that was similar to methyl vanillate.</p><p>To investigate the consequences of the observed transcriptomic and metabolic alterations, the authors performed several behavioral experiments in <i>lrrtm4l1</i><sup><i>−/−</i></sup> and wild-type zebrafish. In the open field test, <i>lrrtm4l1</i><sup><i>−/−</i></sup> fish displayed a lower total distance traveled and nominally increased immobile time. Additionally, their swimming movements appeared more erratic, and they displayed increased thigmotaxis, a potential indicator of increased anxiety-like behavior. The increased a
在这一期的《生理学报》中,Tatzl等人研究了富含亮氨酸的重复跨膜蛋白4 like 1 (lrrtm4l1)基因与人类LRRTM4的斑马鱼同源基因,与雌雄同体成年斑马鱼的行为、转录组学和代谢组学数据的相关性(总结见图1)。LRRTM4是LRRTM基因家族的四个成员之一,其编码突触细胞粘附分子,促进兴奋性突触的发育,包括突触插入和AMPA受体的稳定。LRRTM4与神经发育障碍有关,包括自闭症谱系障碍(ASD)和自杀未遂。使用RNASeq,作者在lrrtm4l1敲除(lrrtm4l1−/−)鱼的端脑中鉴定了126个差异表达基因。其中,他们强调了rimkla和arhgap12的上调。rimkla基因与认知和记忆巩固有关。arhgap12b基因的哺乳动物同源基因(即ARHGAP12)促进突触后AMPA受体的内吞作用,与LRRTM4[4]的作用相反。显著下调的基因包括酪氨酸羟化酶(儿茶酚胺合成所必需的)和浆磷脂(髓鞘的主要成分);这两种基因之前都与各种疾病有关。通路分析涉及信号通路,以及脂肪酸代谢和降解,以及缬氨酸,亮氨酸和异亮氨酸降解。信号通路参与神经发育过程中轴突的引导和神经元的形态发生,并可能在发育和成年期稳定突触传递。与差异表达基因一致的是,lrrtm4l1−/−斑马鱼的代谢组学变化表明,多巴胺代谢的最终产物同质香草酸水平升高,腺苷水平降低。此外,lrrtm4l1−/−斑马鱼表现出更高的血清素和更低的褪黑素水平的趋势。无偏代谢物特征分析揭示了6个显著特征,包括两个与磷脂相似的片段化上调特征和一个与香草酸甲酯相似的下调特征。为了研究观察到的转录组学和代谢改变的后果,作者在lrrtm4l1−/−和野生型斑马鱼中进行了几项行为实验。在野外测试中,lrrtm4l1−/−鱼显示出较低的总移动距离,名义上增加了静止时间。此外,他们的游泳动作似乎更不稳定,他们表现出更大的移动性,这是焦虑样行为增加的潜在指标。在新型的水箱潜水测试中,增加的底部居住进一步支持了焦虑的增加,以及进入浅色/深色水箱的浅色区(浅色区反映出更容易焦虑的隔间)的频率减少,尽管在浅色和黑暗隔间中花费的时间在基因型之间没有差异。为了测试社会(新奇)偏好,作者使用了走廊社会互动测试,他们发现两种基因型之间没有差异。值得注意的是,尽管lrrtm4l1 - / -鱼的整体社交能力完好无损,但在镜像测试中,lrrtm4l1 - / -鱼比野生型鱼表现出更少的攻击性行为。与攻击减少一致,作者可以在斑马鱼社会决策网络(SDMN)中涉及的远端脑区发现高水平的lrrtm4l1表达。SDMN被包括攻击性在内的社会遭遇激活,可能以性别特定的方式激活。总之,转录组学和代谢测量将lrrtm4l1与脂肪酸代谢和某些氨基酸的降解以及神经发育和突触传递联系起来。观察到的行为表型表明lrrtm4l1在常见精神表型中的作用。未来的研究测量其他大脑区域的神经递质和基因表达,可以揭示其他区域儿茶酚胺能系统的潜在改变,例如间脑,多巴胺能神经元突出,酪氨酸羟化酶被发现下调,同型香草酸水平升高。此外,正如作者所建议的那样,考虑到相关的精神表型,即ASD和图雷特综合征,在男性中比在女性中更常见,性别差异测试可能会为lrrtm4l1的工作机制提供进一步的见解。此外,LRRTM4在女性中显示出比男性更高的自杀企图相关性[b],并且攻击行为也可能在性别之间表现出差异[b]。在更广泛的背景下,本研究的发现进一步支持了兴奋性突触调节紊乱与lrrtm,特别是LRRTM4在精神疾病病理中的潜在关键作用的相关性。 事实上,兴奋性(谷氨酸能)信号对包括抑郁症、精神分裂症和包括ASD在内的神经发育障碍在内的几种精神疾病的病理生理起着至关重要的作用,并与这些疾病的治疗有关[7-9]。lrrtm通过与突触前伙伴、神经素和硫酸肝素蛋白聚糖结合,促进兴奋性突触的发育和可塑性。此外,它们有助于突触后AMPA受体的稳定和维持(见图1中的示意图)。一致地,缺乏LRRTM4已被证明可降低突触兴奋性和整体突触数量[10]。这可能解释了lrrtm与几种精神障碍的关联。此外,研究结果显示磷脂的上调和脂肪酸代谢的变化突出了脂质信号在精神疾病中的重要作用。据我们所知,这是第一个将lrrtm与脂质信号/代谢联系起来的研究。脂质、脂质信号传导和脂质代谢越来越被认为是脑内和细胞间信号传导的重要介质。在一系列精神障碍患者和临床前模型中发现了不同脂质种类和参与脂质代谢和信号传导的基因的变化。重要的是,脂质信号与炎症有关,而炎症本身又与精神疾病有关。事实上,炎症对心理健康的影响被认为是通过脂质代谢介导的,可能是通过损害兴奋性突触的信号传导和可塑性[7,11]。因此,LRRTM4可能是炎症和脂质信号传导对突触病理影响的重要介质。总之,这项研究为进一步探索LRRTM4作为神经精神干预的候选靶点提供了一个有说服力的论据,特别是在以改变攻击和焦虑为特征的疾病中,但也可能不止于此。Maja R. Adel:概念化,写作-原稿,写作-审查和编辑。弗洛里安·弗罗伊登伯格:概念化,写作-原稿,写作-审查和编辑,可视化。作者声明无利益冲突。
{"title":"Lack of Synaptic Adhesion Proteins Makes Zebrafish More Anxious and Less Aggressive","authors":"Maja R. Adel, Florian Freudenberg","doi":"10.1111/apha.70065","DOIUrl":"https://doi.org/10.1111/apha.70065","url":null,"abstract":"<p>In this issue of <i>Acta Physiologica</i>, Tatzl et al. [<span>1</span>] investigate the relevance of the <i>leucine-rich repeat transmembrane protein 4 like 1</i> (<i>lrrtm4l1</i>) gene, a zebrafish orthologue of the human <i>LRRTM4</i>, on behavioral, transcriptomic, and metabolomic readouts in mixed sex adult zebrafish (summarized in Figure 1). <i>LRRTM4</i> is one of four members of the <i>LRRTM</i> gene family, which code for synaptic cell adhesion molecules that promote excitatory synapse development, including synaptic insertion and stabilization of AMPA receptors. <i>LRRTM4</i> is associated with neurodevelopmental disorders, including autism spectrum disorder (ASD) and attempted suicide [<span>2</span>].</p><p>Using RNASeq, the authors identified 126 differentially expressed genes in the telencephalon of <i>lrrtm4l1</i> knockout (<i>lrrtm4l1</i><sup><i>−/−</i></sup>) fish. Among these, they highlight the upregulation of <i>rimkla</i> and <i>arhgap12</i>. The <i>rimkla</i> gene is linked to cognition and memory consolidation [<span>3</span>]. The mammalian orthologue of the <i>arhgap12b</i> gene (i.e., <i>ARHGAP12</i>) promotes endocytosis of postsynaptic AMPA receptors, opposing the effect of <i>LRRTM4</i> [<span>4</span>]. Notable downregulated genes include <i>tyrosine hydroxylase</i>, essential for catecholamine synthesis, and <i>plasmolipin</i>, encoding a major component of myelin sheaths; both genes have previously been linked to various disorders. Pathway analyses implicated semaphorin-plexin signaling, as well as fatty acid metabolism and degradation, as well as valine, leucine, and isoleucine degradation. Semaphorin-plexin signaling is involved in axon guidance and neuronal morphogenesis during neurodevelopment and might stabilize synaptic transmission both during development and adulthood [<span>5</span>].</p><p>Consistent with the differentially expressed genes, metabolomic changes in <i>lrrtm4l1</i><sup><i>−/−</i></sup> zebrafish revealed elevated levels of homovanillic acid, the end product of dopamine metabolism, and lower levels of adenosine. Additionally, <i>lrrtm4l1</i><sup><i>−/−</i></sup> zebrafish showed a trend toward higher serotonin and lower melatonin levels. Unbiased metabolite feature analysis revealed six significant features, including two upregulated features with fragmentation profiles similar to phospholipids and one downregulated feature that was similar to methyl vanillate.</p><p>To investigate the consequences of the observed transcriptomic and metabolic alterations, the authors performed several behavioral experiments in <i>lrrtm4l1</i><sup><i>−/−</i></sup> and wild-type zebrafish. In the open field test, <i>lrrtm4l1</i><sup><i>−/−</i></sup> fish displayed a lower total distance traveled and nominally increased immobile time. Additionally, their swimming movements appeared more erratic, and they displayed increased thigmotaxis, a potential indicator of increased anxiety-like behavior. The increased a","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"241 7","pages":""},"PeriodicalIF":5.6,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.70065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>Fluctuations of intracellular ionic concentrations are powerful signaling tools in living cells [<span>1</span>]. Among these ions, Ca<sup>2+</sup> plays a well-documented and ubiquitous role in the regulation of cellular events, ranging from development and growth to intercellular signaling and information processing, and, ultimately, Ca<sup>2+</sup> regulates cell survival or cell death. All these effects are mediated through the extended family of Ca<sup>2+</sup>-sensors.</p><p>A recent paper published by Alpar, Harkany, and their coworkers in Acta Physiologica [<span>2</span>] revealed a complex and developmentally regulated signaling network centered on dynamic changes of expression of the archetypal Ca<sup>2+</sup> sensor, secretagogin. They show that changes in secretagogin expression are affected by neuronal activity, and therefore establish a novel link between excitation and intracellular signaling processing. The study of Hanics et al. critically challenges the notion of secretagogin, used widely as a neuronal marker, as a static marker by demonstrating its dynamic expression in response to neuronal activity during mammalian brain development. Using a combination of human foetal brain mapping, genetically modified mice (Scgn-iCre::Ai9), single-cell RNA sequencing, and both in vitro and in vivo activity manipulation models, the authors provide compelling evidence that secretagogin expression is both developmentally regulated and sensitive to neuronal activity.</p><p>One of the main functions of Ca<sup>2+</sup> sensors in the information processing loops of the central nervous system is the regulation of vesicular neurotransmitter release. Fusion of the vesicle membrane with the plasma membrane, known as exocytosis, leads to the formation of a water-filled channel, the fusion pore, a conduit for molecules in the vesicle lumen to exit into the extracellular space. This evolutionary invention emerged in primordial eukaryotic cells [<span>3-5</span>] and mediates a myriad of processes, including the release of neurotransmitters, hormones, and other signaling molecules, all essential for maintaining cell-to-cell communication in multicellular organisms. The release of vesicle content may occur only if the fusion pore widens sufficiently. Over seven decades ago, Bernard Katz proposed that the fusion pore opens completely upon exocytosis. Therefore, since those days, the fusion mechanism has been intensively studied, mainly focusing on how the merger of the two membranes occurs. This led to the discovery of SNARE proteins, targets of proteolytic botulinum neurotoxins, and the concept that a rather complex array of events, including vesicle priming and docking at the active zone to fusion pore formation upon an increase in cytosolic Ca<sup>2+</sup>, mediates stimulus-secretion coupling to within milliseconds [<span>6</span>]. Secretagogin is linked to regulated exocytosis through an extended interactome which includes SNAP-23, DOC2α, ARFGAP2
{"title":"Secretagogin, Driven by Neuronal Activity, Transiently Regulates Exocytosis During Development","authors":"Robert Zorec, Alexei Verkhratsky","doi":"10.1111/apha.70066","DOIUrl":"https://doi.org/10.1111/apha.70066","url":null,"abstract":"<p>Fluctuations of intracellular ionic concentrations are powerful signaling tools in living cells [<span>1</span>]. Among these ions, Ca<sup>2+</sup> plays a well-documented and ubiquitous role in the regulation of cellular events, ranging from development and growth to intercellular signaling and information processing, and, ultimately, Ca<sup>2+</sup> regulates cell survival or cell death. All these effects are mediated through the extended family of Ca<sup>2+</sup>-sensors.</p><p>A recent paper published by Alpar, Harkany, and their coworkers in Acta Physiologica [<span>2</span>] revealed a complex and developmentally regulated signaling network centered on dynamic changes of expression of the archetypal Ca<sup>2+</sup> sensor, secretagogin. They show that changes in secretagogin expression are affected by neuronal activity, and therefore establish a novel link between excitation and intracellular signaling processing. The study of Hanics et al. critically challenges the notion of secretagogin, used widely as a neuronal marker, as a static marker by demonstrating its dynamic expression in response to neuronal activity during mammalian brain development. Using a combination of human foetal brain mapping, genetically modified mice (Scgn-iCre::Ai9), single-cell RNA sequencing, and both in vitro and in vivo activity manipulation models, the authors provide compelling evidence that secretagogin expression is both developmentally regulated and sensitive to neuronal activity.</p><p>One of the main functions of Ca<sup>2+</sup> sensors in the information processing loops of the central nervous system is the regulation of vesicular neurotransmitter release. Fusion of the vesicle membrane with the plasma membrane, known as exocytosis, leads to the formation of a water-filled channel, the fusion pore, a conduit for molecules in the vesicle lumen to exit into the extracellular space. This evolutionary invention emerged in primordial eukaryotic cells [<span>3-5</span>] and mediates a myriad of processes, including the release of neurotransmitters, hormones, and other signaling molecules, all essential for maintaining cell-to-cell communication in multicellular organisms. The release of vesicle content may occur only if the fusion pore widens sufficiently. Over seven decades ago, Bernard Katz proposed that the fusion pore opens completely upon exocytosis. Therefore, since those days, the fusion mechanism has been intensively studied, mainly focusing on how the merger of the two membranes occurs. This led to the discovery of SNARE proteins, targets of proteolytic botulinum neurotoxins, and the concept that a rather complex array of events, including vesicle priming and docking at the active zone to fusion pore formation upon an increase in cytosolic Ca<sup>2+</sup>, mediates stimulus-secretion coupling to within milliseconds [<span>6</span>]. Secretagogin is linked to regulated exocytosis through an extended interactome which includes SNAP-23, DOC2α, ARFGAP2","PeriodicalId":107,"journal":{"name":"Acta Physiologica","volume":"241 7","pages":""},"PeriodicalIF":5.6,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/apha.70066","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}