Schroder Annika L, Songster Livia D, Savich Yahor, Titus Margaret A
Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455.
present address: Driskill Graduate Program in Life Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611.
bioRxiv. 2025 May 29:2025.05.28.656686. doi: 10.1101/2025.05.28.656686.
Migrating cells sense and respond to external chemical and physical cues, enabling them to efficiently reach their destinations. Filopodia are slender actin-filled membrane protrusions implicated in interacting with the extracellular environment in many contexts, such as neuronal growth cone guidance and the capture of prey by immune cells and unicellular organisms. The role of filopodia in chemotactic guidance in fast-moving amoeboid cells has not been well-studied. The social amoeba relies on chemotaxis for development and finding food, making it an excellent system for investigating the role of filopodia in amoeboid chemotaxis. Stimulation of amoebae with the chemoattractant cAMP activates a transient increase of filopodia formation by recruiting the filopodial myosin DdMyo7 to the cell cortex. Filopodia formation is biased towards the source of chemoattractant, yet null cells that lack filopodia exhibit normal directional migration. However, cells either lacking filopodia or having increased numbers of filopodia move more slowly than those with wildtype numbers of filopodia. Thus, while filopodia are dispensable for detection of chemical gradients by amoeboid cells, changes in filopodia number can impact their migration speed possibly due to altering cell-substrate adhesion.
迁移细胞能够感知并响应外部化学和物理信号，从而使其能够高效地到达目的地。丝状伪足是细长的、充满肌动蛋白的膜状突起，在许多情况下都与细胞外环境相互作用有关，比如神经元生长锥导向以及免疫细胞和单细胞生物捕获猎物。丝状伪足在快速移动的阿米巴样细胞的趋化导向中的作用尚未得到充分研究。社会性阿米巴在发育和寻找食物过程中依赖趋化作用，这使其成为研究丝状伪足在阿米巴样趋化作用中作用的绝佳系统。用趋化因子cAMP刺激阿米巴会通过将丝状伪足肌球蛋白DdMyo7招募到细胞皮层，激活丝状伪足形成的短暂增加。丝状伪足的形成偏向于趋化因子的来源，但缺乏丝状伪足的缺失细胞表现出正常的定向迁移。然而，缺乏丝状伪足或丝状伪足数量增加的细胞比具有野生型丝状伪足数量的细胞移动得更慢。因此，虽然丝状伪足对于阿米巴样细胞检测化学梯度并非必不可少，但丝状伪足数量的变化可能会影响其迁移速度，这可能是由于改变了细胞与底物的粘附。
