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来源：百度文库 编辑：神马品牌网 时间：2024/05/12 19:51:48
Cell clusters follow the leaders
Organogenesis requires the collective movement of large groups of cells during development. According to a new study by Petra Haas and Darren Gilmour (European Molecular Biology Laboratory, Heidelberg, Germany), one such mass transit is directed by a few leader cells that respond to a chemokine signal to guide the trek and keep the marching troops in formation.
The cluster of about 100 cells that forms the posterior lateral line primordium (pLLP), the progenitor of the zebrafish mechanosensory organ, marches down a stripe of the stroma-derived factor 1 (SDF1) chemokine. Time-lapse imaging showed that the tissue's trajectory was controlled by cells that extended filopodia on the leading outer edge of the pLLP. For the column of cells to move, only leader cells required Cxcr4b, the SDF1 receptor; cells on the interior of the pLLP did not need the receptor.
Leaders in pLLP migration seem to get appointed to the post, perhaps by having higher receptor activity, says Gilmour. When wild-type and Cxcr4b-lacking cells were combined in genetic mosaic experiments, the wild-type cells quickly took position on the leading edge to restore proper movement.
"We think the job of guiding will be given to those cells that initially sense the most," Gilmour says. "The cluster is extremely unstable. Whenever it has reduced chemokine signaling, it rolls around, and it is this instability that allows sensing cells to get into a position where they can reinstate order." As few as four transplanted Cxcr4b-expressing cells were able to curb the chaos and generate normal movement in mutant tissue.
Organogenesis requires the collective movement of large groups of cells during development. According to a new study by Petra Haas and Darren Gilmour (European Molecular Biology Laboratory, Heidelberg, Germany), one such mass transit is directed by a few leader cells that respond to a chemokine signal to guide the trek and keep the marching troops in formation.
The cluster of about 100 cells that forms the posterior lateral line primordium (pLLP), the progenitor of the zebrafish mechanosensory organ, marches down a stripe of the stroma-derived factor 1 (SDF1) chemokine. Time-lapse imaging showed that the tissue's trajectory was controlled by cells that extended filopodia on the leading outer edge of the pLLP. For the column of cells to move, only leader cells required Cxcr4b, the SDF1 receptor; cells on the interior of the pLLP did not need the receptor.
Leaders in pLLP migration seem to get appointed to the post, perhaps by having higher receptor activity, says Gilmour. When wild-type and Cxcr4b-lacking cells were combined in genetic mosaic experiments, the wild-type cells quickly took position on the leading edge to restore proper movement.
"We think the job of guiding will be given to those cells that initially sense the most," Gilmour says. "The cluster is extremely unstable. Whenever it has reduced chemokine signaling, it rolls around, and it is this instability that allows sensing cells to get into a position where they can reinstate order." As few as four transplanted Cxcr4b-expressing cells were able to curb the chaos and generate normal movement in mutant tissue.