First Inner Cells

今週、定量生物学の会主催の「Japan Q-Bio week」のシンポジウムがここ遺伝研で開催されていたので一日参加していた。最近自分も少しこういうのに足を踏み入れつつあるので、いろんなタイプの研究を興味深く聞かせてもらった。いくつか、おぉっと思わされた話があったのだが、なかでも自分にとってimpressiveだったものの一つがこれ。

Cortical Tension Allocates the First Inner Cells of the Mammalian Embryo.  Dev. Cell 34: 435–447.

Every cell in our body originates from the pluripotent inner mass of the embryo, yet it is unknown how biomechanical forces allocate inner cells in vivo. Here we discover subcellular heterogeneities in tensile forces, generated by actomyosin cortical networks, which drive apical constriction to position the first inner cells of living mouse embryos. Myosin II accumulates specifically around constricting cells, and its disruption dysregulates constriction and cell fate. Laser ablations of actomyosin networks reveal that constricting cells have higher cortical tension, generate tension anisotropies and morphological changes in adjacent regions of neighboring cells, and require their neighbors to coordinate their own changes in shape. Thus, tensile forces determine the first spatial segregation of cells during mammalian development. We propose that, unlike more cohesive tissues, the early embryo dissipates tensile forces required by constricting cells via their neighbors, thereby allowing confined cell repositioning without jeopardizing global architecture.

マウスの初期胚では、asymmetric divisionではなく、actomyosinが駆動するapical constrictionによるbasal-extrusion likeなallocationによって内側に移動した細胞がinner cell massのはじめの細胞になるという話。今まで考えたことなかったけど、こんなん分かってなかったんやね。シンガポールのDr. NP、なかなか面白い仕事してはりますなぁ。