EEF1A1

随着医学技术的快速发展，多年来癌症的诊断和治疗取得了巨大的成就。然而，转移仍然发生在许多癌症患者中，并占癌症相关死亡的90%。 随着医学技术的快速发展，多年来癌症的诊断和治疗取得了巨大的成就。然而，转移仍然发生在许多癌症患者中，并占癌症相关死亡的90%。在过去的十年里，尽管由于早期诊断的快速发展，癌症患者的存活率得到了显著的提高，但在转移性癌症的治疗方面却取得了有限的成就。 目前，化疗和靶向治疗仍是转移性癌症患者的一线治疗方式。然而，耐药性和严重的毒副作用严重制约了治疗结果。因此，了解肿瘤转移的生物学过程，找出导致肿瘤转移的关键调控因子，对于制定有效的治疗策略至关重要。 图片来源：https://doi.org/10.1016/j.apsb.2022.12.004 近日，来自中山大学的研究者们在Acta Pharmaceutica Sinica B杂志上发表了题为“Nanoparticles (NPs)-mediated lncBCMA silencing to promote eEF1A1 ubiquitination and suppress breast cancer growth and metastasis”的文章，该研究揭示了纳米粒介导的lncBCMA沉默促进eEF1A1泛素化并抑制乳腺癌生长和转移。 长非编码RNA(LncRNAs)在肿瘤转移中起重要作用。探索转移相关的lncRNA，开发有效的体内靶向调控lncRNA功能的策略，对于转移性肿瘤的治疗至关重要，但这仍然是一个巨大的挑战。 在本研究中，研究者发现了一种新的功能性lncRNA(记为lncBCMA)，它可以通过拮抗真核细胞翻译延长因子1A1(EEF1A1)的泛素化来促进三阴性乳腺癌(TNBC)的生长和转移，从而稳定其表达。 基于这一调控机制，设计了一种可用于系统递送lncBCMA siRNA(SiBCMA)的内体pH响应型纳米颗粒(NP)平台。这种NPs介导的siBCMA可以有效地沉默lncBCMA的表达，促进eEF1A1的泛素化，从而显著抑制TNBC肿瘤的生长和转移。这些结果表明，lncBCMA可作为预测TNBC患者预后的潜在生物标志物，NPs介导的lncBCMA沉默可能是转移性TNBC治疗的一种有效策略。 NPS介导的LncBCMA沉默抑制PDX肿瘤模型中TNBC的生长和转移 图片来源：https://doi.org/10.1016/j.apsb.2022.12.004 综上所述，我们发现了一种新的具有功能的lncRNA(即lncBCMA)，它在调节TNBC肿瘤的生长和转移中发挥重要作用。分子机制研究表明，该lncRNA可以通过拮抗其泛素化来稳定eEF1A1的表达，从而促进TNBC细胞的增殖、迁移和侵袭。 利用胞体pH响应型纳米粒体内携带siBCMA，可以有效地抑制lncBCMA的表达，促进eEF1A1泛素化，从而显著抑制肿瘤的生长和转移。NncBCMA可用于预测TNBC患者的预后，NPs介导的lncBCMA沉默可能是治疗转移性TNBC的一种有前途的策略。（生物谷 Bioon.com） 参考文献 Ke Yang et al. Nanoparticles (NPs)-mediated lncBCMA silencing to promote eEF1A1 ubiquitination and suppress breast cancer growth and metastasis. Acta Pharm Sin B. 2023 Aug;13(8):3489-3502. doi: 10.1016/j.apsb.2022.12.004.

在一项新的研究中，来自美国圣犹达儿童研究医院的研究人员揭示人类核糖体解码信使RNA（mRNA）的速度比细菌核糖体慢10倍，但解码更准确。他们组合使用了领域领先的结构生物学方法来更好地了解核糖体的工作原理。他们精确地指出了人类中该过程变慢的地方，这将是开发新的癌症和感染治疗方法的有用信息。相关研究结果于2023年4月5日在线发表在Nature期刊上，论文标题为“mRNA decoding in human is kinetically and structurally distinct from bacteria”。核糖体是细胞内的分子机器，负责通过对mRNA进行解码来合成蛋白。通过对细菌和人类核糖体进行机理研究，人们可以了解它们的相似性和差异性，以开发药物和了解疾病。许多抗生素，即我们用来治疗细菌感染的药物，是通过靶向细菌核糖体来发挥作用的。在人类中，核糖体如何准确解码mRNA的变化与衰老和疾病有关，代表了一种潜在的治疗干预点。这使得这项新的研究对感染和癌症的治疗产生了影响。论文通讯作者、圣犹达儿童研究医院结构生物学系的Scott Blanchard博士说，“几十年来，细菌一直被研究得很好，但我们所做的那种研究，细致的机制研究，在人类核糖体上一直是缺失的。我们对人类核糖体非常感兴趣，因为它们是寻找癌症和病毒（SARS-CoV-2）感染新疗法所需要的靶标。”解析革命核糖体使用一种叫做氨基酰-tRNA（tRNA）的分子作为底物对mRNA进行解码。解码过程涉及几个不同的步骤。这些作者部署了单分子荧光共振能量转移（smFRET）和低温电镜（cryo-EM）等方法来研究人类核糖体解码机制。这种单分子成像为他们提供了关于事情发生速度的信息。在这种情况下，他们就可知道人类核糖体在这种解码过程中经历不同步骤的速度有多快。冷冻电镜为他们提供结构信息，可以让他们了解人类核糖体的外形或它在每个步骤中的构象（形状）是怎样的。通过结合这两种方法，他们获得了关于与细菌相比，这些过程在人类中发生的速度有多快的信息，以及关于他们观察到的任何差异的内在结构原因。论文共同第一作者、圣犹达儿童研究医院结构生物学系的Mikael Holm博士说，“我们想知道人类核糖体读取遗传密码的速度有多快，它找到与mRNA互补的tRNA的速度有多快。我们发现，人类核糖体的这一过程比细菌中的要慢10倍左右。不过，这种缓慢增加了准确性，因为已知人类核糖体在翻译遗传密码时比细菌核糖体更准确。”具体来说，这些作者发现虽然人类和细菌都对mRNA进行解码，但在这种解码过程中氨基酰-tRNA移动的反应途径在人类核糖体上是不同的，而且明显更慢。这些差异来自于人类核糖体和人类延伸因子eEF1A中的结构元件，它们共同负责为每个mRNA密码子忠实地整入正确的tRNA。核糖体和eEF1A中构象变化的不同性质和时间可能解释了人类核糖体如何实现更大的解码准确性。论文共同第一作者、圣犹达儿童研究医院结构生物学系的Kundhavai Natchiar博士说，“通过我们的低温电镜结构研究，我们能够将人类核糖体结构解析为原子分辨率，这揭示了前所未有的特征，如人类核糖体中存在的rRNA和蛋白修饰、离子和溶剂分子。这些特征精细地描述了药物分子与人类核糖体相互作用的分子基础，这对于基于人类核糖体的药物设计和发现是不可或缺的。”在作用时被捕获这些作者还准确地指出了人类核糖体中这种解码过程的哪一步放缓了。在核糖体选择正确的tRNA的过程中，有两个步骤：初始选择和校对选择。第二步，即校对选择，是核糖体第二次检查它是否选择了正确的分子。这一步在人类中比在细菌中慢了10倍。结构域封闭和初始三元复合物结合。图片来自Nature, 2023, doi:10.1038/s41586-023-05908-w。想一想体操运动员，当他们完成他们的动作时，在垫子上把自己扭曲成不同的形状。这类似于核糖体如何过渡到不同构象以达到不同的结果。这项新的研究表明人类核糖体所经历的很多构象在细菌核糖体中是不存在的，因此可能与校对选择过程的减慢有关。这些作者还发现几种药物靶向的是校对选择过程，而不是初始选择。因此，这些药物没有靶向人类和细菌之间相似的步骤，而是专注于最不同、最慢的步骤。论文共同第一作者、圣犹达儿童研究医院结构生物学系的Emily Rundlet博士说，“在结构生物学中，一种大分子机器的单一快照并不总是足以解释它的功能。通常情况下，回答你的生物学问题所需要的快照并不是这种分子的最稳定形式，相反地，是它的短命的难以捕捉的形式。将smFRET和低温电镜一起使用，为结构生物学带来了时间的维度，这使我们能够直观地看到人类解码的重要瞬时中间步骤，并在一种新的水平上理解不同的机制。”参考资料：Mikael Holm et al.mRNA decoding in human is kinetically and structurally distinct from bacteria. Nature, 2023, doi:10.1038/s41586-023-05908-w.

Scientists have found that human ribosomes decode mRNA slower than bacteria, with implications for drug development. Scientists at St. Jude Children's Research Hospital revealed that human ribosomes decode messenger RNA (mRNA) 10 times slower than bacterial ribosomes, but do so more accurately. The study, published today in Nature, used a combination of field-leading structural biology approaches to better understand how ribosomes work. The scientists pinpointed where the process slows down in humans, which will be useful information for developing new therapeutics for cancer and infections. Ribosomes are molecular machines within cells, responsible for synthesizing proteins by decoding mRNA. By conducting mechanistic studies on bacterial and human ribosomes, researchers can understand their similarities and differences to develop drugs and understand disease. Many antibiotics, the drugs we use to treat bacterial infections, work by targeting bacterial ribosomes. In humans, changes in how accurately ribosomes decode mRNA have been linked to aging and disease, representing a potential point of therapeutic intervention. This gives the work implications for the treatment of infections and cancer. "Bacteria have been very well studied for many decades, but the kind of studies that we do, careful mechanistic studies, have been missing on human ribosomes," said corresponding author Scott Blanchard, Ph.D., St. Jude Department of Structural Biology. "We're very interested in human ribosomes because those are what need to be targeted to find new treatments for cancer and viral infections such as COVID." Resolution revolution Ribosomes decode mRNA using a molecule called aminoacyl-transfer RNA (tRNA) as substrate. The decoding process involves several different steps. The researchers deployed methods such as single-molecule fluorescence resonance energy transfer (smFRET) and cryo-electron microscopy (cryo-EM) to examine the human ribosome decoding mechanisms. The single-molecule imaging gives the researchers information on how quickly things occur. So, in this case, how quickly human ribosomes go through the different steps during the decoding process. Cryo-EM gives the researchers structural information. So, how the human ribosome looks or what conformations (shapes) it is in at each step. By combining these two methods, the scientists get information on how quickly these processes occur in humans compared to bacteria as well as about the underlying structural causes for any differences they observe. "We wanted to know how quickly a human ribosome can read the genetic code, how quickly it finds the tRNA that's complementary to the mRNA," said co-first author Mikael Holm, Ph.D., St. Jude Department of Structural Biology. "We found that the process is about 10 times slower for human ribosomes than it is in bacteria. But this slow down adds accuracy, because human ribosomes are known to be more accurate at translating the code than bacterial ribosomes." Specifically, the researchers found that while humans and bacteria both decode mRNA, the reaction pathway of aminoacyl-tRNA movement during the decoding process is different on human ribosomes and is significantly slower. These differences arise from structural elements in the human ribosome and in the human elongation factor, eEF1A, that together are responsible for faithfully incorporating the right tRNA for each mRNA codon (piece of the sequence). The distinct nature and timing of conformational changes within the ribosome and eEF1A may explain how human ribosomes achieve greater decoding accuracy. "With our cryo-EM structural studies, we were able to resolve human ribosome structures to atomic resolution, which revealed unprecedented features such as rRNA and protein modifications, ions and solvent molecules present in the human ribosome," said co-first author Kundhavai Natchiar, Ph.D., St. Jude Department of Structural Biology. "These features finely characterize the molecular basis of interactions of the drug molecules with the human ribosome, which is indispensable for human ribosome-based drug design and discovery." Caught in the act The researchers also pinpointed exactly which step of the decoding process slowed down in human ribosomes. There are two steps in the process of the ribosome selecting the right tRNA: initial selection and proofreading selection. The second step, proofreading selection, is where the ribosome checks for a second time that it chose the right molecule. That is the step that is 10 times slower in humans than in bacteria. Think of a gymnast, contorting themselves into different shapes on the mat as they work through their routine. This is similar to how ribosomes transition into various conformations to achieve different results. The research showed that a lot of conformational gymnastics that human ribosomes undergo are not present in bacterial ribosomes and are thus likely tied to the slowdown of the proofreading selection process. The researchers also found that several drugs target the proofreading selection process, not initial selection. So, instead of hitting the step that is similar between humans and bacteria, these drugs focus on the most different, slowest step. "In structural biology, a single snapshot of a macromolecular machine is not always sufficient to explain how it functions," said co-first author Emily Rundlet, Ph.D., St. Jude Department of Structural Biology. "Often, the snapshot that's needed to answer your biological question is not the most stable form of the molecule, but instead it is short-lived and difficult to capture. Using smFRET and cryo-EM together brings the dimension of time to structural biology, which allows us to visualize important transient intermediate steps of human decoding and understand the different mechanisms on a new level."