Laboratory of Cancer Biology, Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK.
J Cell Sci. 2012 Aug 1;125(Pt 15):3519-27. doi: 10.1242/jcs.099523. Epub 2012 Aug 30.
Actin is an integral component of the cytoskeleton, forming a plethora of macromolecular structures that mediate various cellular functions. The formation of such structures relies on the ability of actin monomers to associate into polymers, and this process is regulated by actin nucleation factors. These factors use monomeric actin pools at specific cellular locations, thereby permitting rapid actin filament formation when required. It has now been established that actin is also present in the nucleus, where it is implicated in chromatin remodelling and the regulation of eukaryotic gene transcription. Notably, the presence of typical actin filaments in the nucleus has not been demonstrated directly. However, studies in recent years have provided evidence for the nuclear localisation of actin nucleation factors that promote cytoplasmic actin polymerisation. Their localisation to the nucleus suggests that these proteins mediate collaboration between the cytoskeleton and the nucleus, which might be dependent on their ability to promote actin polymerisation. The nature of this cooperation remains enigmatic and it will be important to elucidate the physiological relevance of the link between cytoskeletal actin networks and nuclear events. This Commentary explores the current evidence for the nuclear roles of actin nucleation factors. Furthermore, the implication of actin-associated proteins in relaying exogenous signals to the nucleus, particularly in response to cellular stress, will be considered.
肌动蛋白是细胞骨架的重要组成部分，形成了大量的大分子结构，介导各种细胞功能。这些结构的形成依赖于肌动蛋白单体聚合成聚合物的能力，而这一过程受到肌动蛋白成核因子的调节。这些因子在特定的细胞位置利用单体肌动蛋白池，从而在需要时允许快速形成肌动蛋白丝。现在已经确定，肌动蛋白也存在于细胞核中，它参与染色质重塑和真核基因转录的调节。值得注意的是，细胞核中典型的肌动蛋白丝的存在尚未被直接证明。然而，近年来的研究为促进细胞质肌动蛋白聚合的肌动蛋白成核因子的核定位提供了证据。它们在细胞核中的定位表明这些蛋白质介导了细胞骨架和细胞核之间的协作，这可能依赖于它们促进肌动蛋白聚合的能力。这种合作的性质仍然是神秘的，阐明细胞骨架肌动蛋白网络与核事件之间联系的生理相关性将是重要的。本评论探讨了肌动蛋白成核因子在细胞核中作用的现有证据。此外，还将考虑肌动蛋白相关蛋白在将外源信号传递到细胞核中的作用，特别是在应对细胞应激时。
