Veltman Douwe M, van Haastert Peter J M
Department of Biology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
J Cell Sci. 2008 Jan 1;121(Pt 1):120-7. doi: 10.1242/jcs.015602. Epub 2007 Dec 11.
During chemotaxis, pseudopod extensions lead the cell towards the source of attractant. The role of actin-filled pseudopodia at the front of the cell is well recognized, whereas the function of the rear of the cell in chemotaxis and cell-cell interactions is less well known. Dictyostelium cell aggregation is mediated by outwardly propagating waves of extracellular cAMP that induce chemotaxis and cell-cell contacts, resulting in streams of cells moving towards the aggregation centre. Wild-type cells efficiently retract pseudopodia in the rear of the cell during the rising flank of the cAMP wave and have a quiescent cell posterior. This polarization largely remains during the declining flank, which causes cells to continue their chemotactic movement towards the aggregation centre and to form stable streams of moving cells. The dominance of the leading-edge pseudopod rescues chemotaxis during the rising flank of the wave, but the cells move in random directions after the peak of the wave has passed. As a consequence, cell-cell contacts cannot be maintained, and the cell streams break up. The results show that a quiescent rear of the cell increases the efficiency of directional movement and is essential to maintain stable cell-cell contacts.
在趋化作用过程中，伪足延伸引导细胞朝向吸引剂来源。细胞前端充满肌动蛋白的伪足的作用已得到充分认识，而细胞后端在趋化作用和细胞间相互作用中的功能则鲜为人知。盘基网柄菌细胞聚集由细胞外cAMP向外传播的波介导，这些波诱导趋化作用和细胞间接触，导致细胞流向聚集中心移动。野生型细胞在cAMP波上升沿期间能有效缩回细胞后端的伪足，并且细胞后端处于静止状态。这种极化在波下降沿期间基本保持，这使得细胞继续向聚集中心进行趋化运动，并形成稳定的移动细胞流。波上升沿期间前沿伪足的主导作用挽救了趋化作用，但在波峰过后细胞会向随机方向移动。因此，细胞间接触无法维持，细胞流会瓦解。结果表明，细胞静止的后端提高了定向运动的效率，并且对于维持稳定的细胞间接触至关重要。
