To interfere with cell function, many scientists rely on methods that target DNA or RNA due to the ease with which they can be applied. Proteins are usually the final executors of function but are targeted only indirectly by these methods. Recent advances in targeted degradation of proteins based on proteolysis-targeting chimaeras (PROTACs), ubiquibodies, deGradFP (degrade Green Fluorescent Protein) and other approaches have demonstrated the potential of interfering directly at the protein level for research and therapy. Proteins can be targeted directly and very specifically by antibodies, but using antibodies inside cells has so far been considered to be challenging. However, it is possible to deliver antibodies or other proteins into the cytosol using standard laboratory equipment. Physical methods such as electroporation have been demonstrated to be efficient and validated thoroughly over time. The expression of intracellular antibodies (intrabodies) inside cells is another way to interfere with intracellular targets at the protein level. Methodological strategies to target the inside of cells with antibodies, including delivered antibodies and expressed antibodies, as well as applications in the research areas of neurobiology, viral infections and oncology, are reviewed here. Antibodies have already been used to interfere with a wide range of intracellular targets. Disease-related targets included proteins associated with neurodegenerative diseases such as Parkinson’s disease (α-synuclein), Alzheimer’s disease (amyloid-β) or Huntington’s disease (mutant huntingtin [mHtt]). The applications of intrabodies in the context of viral infections include targeting proteins associated with HIV (e.g. HIV1-TAT, Rev, Vif, gp41, gp120, gp160) and different oncoviruses such as human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV) and Epstein-Barr virus, and they have been used to interfere with various targets related to different processes in cancer, including oncogenic pathways, proliferation, cell cycle, apoptosis, metastasis, angiogenesis or neo-antigens (e.g. p53, human epidermal growth factor receptor-2 [HER2], signal transducer and activator of transcription 3 [STAT3], RAS-related RHO-GTPase B (RHOB), cortactin, vascular endothelial growth factor receptor 2 [VEGFR2], Ras, Bcr-Abl). Interfering at the protein level allows questions to be addressed that may remain unanswered using alternative methods. This review addresses why direct targeting of proteins allows unique insights, what is currently feasible in vitro, and how this relates to potential therapeutic applications.

中文翻译：

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在细胞内应用抗体：神经生物学，病毒学和肿瘤学的原理和最新进展。

为了干扰细胞功能，许多科学家都依赖于靶向DNA或RNA的方法，因为它们易于使用。蛋白质通常是功能的最终执行者，但只能通过这些方法间接靶向。基于靶向蛋白水解的嵌合体（PROTAC），泛体抗体，deGradFP（降解绿色荧光蛋白）和其他方法的蛋白质靶向降解的最新进展表明，可以直接在蛋白质水平上进行研究和治疗。蛋白质可以直接且非常特异性地被抗体靶向，但是迄今为止，在细胞内使用抗体一直被认为具有挑战性。但是，可以使用标准实验室设备将抗体或其他蛋白递送到细胞质中。物理方法（例如电穿孔）已被证明是有效的，并且随着时间的流逝得到了彻底的验证。细胞内细胞内抗体（抗体）的表达是在蛋白质水平上干扰细胞内靶标的另一种方法。本文综述了以抗体为靶标的细胞内方法论策略，包括递送的抗体和表达的抗体，以及在神经生物学，病毒感染和肿瘤学研究领域的应用。抗体已经被用来干扰广泛的细胞内靶标。与疾病相关的靶标包括与神经退行性疾病相关的蛋白质，例如帕金森氏病（α-突触核蛋白），阿尔茨海默氏病（淀粉样β）或亨廷顿氏病（突变亨廷顿[mHtt]）。体内抗体在病毒感染中的应用包括靶向与HIV相关的蛋白（例如HIV1-TAT，Rev，Vif，gp41，gp120，gp160）和不同的癌病毒，例如人乳头瘤病毒（HPV），乙型肝炎病毒（HBV），丙型肝炎病毒（HCV）和爱泼斯坦-巴尔病毒，已被用于干扰与癌症不同过程相关的各种靶标，包括致癌途径，增殖，细胞周期，凋亡，转移，血管生成或新抗原（例如p53） ，人类表皮生长因子受体2 [HER2]，信号转导和转录激活因子3 [STAT3]，RAS相关的RHO-GTPase B（RHOB），皮质激素，血管内皮生长因子受体2 [VEGFR2]，Ras，Bcr- Abl）。在蛋白质水平上的干扰使问题得以解决，而使用其他方法可能无法解决这些问题。