Underlying mechanisms that ensure actomyosin-mediated directional remodeling of cell-cell contacts for multicellular movement: Tricellular junctions and negative feedback as new aspects underlying actomyosin-mediated directional epithelial morphogenesis: Tricellular junctions and negative feedback as new aspects underlying actomyosin-mediated directional epithelial morphogenesis.

Actomyosin (actin-myosin II complex)-mediated contractile forces are central to the generation of multifaceted uni- and multi-cellular material properties and dynamics such as cell division, migration, and tissue morphogenesis. In the present article, we summarize our recent researches addressing molecular mechanisms that ensure actomyosin-mediated directional cell-cell junction remodeling, either shortening or extension, driving cell rearrangement for epithelial morphogenesis. Genetic perturbation clarified two points concerning cell-cell junction remodeling: an inhibitory mechanism against negative feedback in which actomyosin contractile forces, which are well known to induce cell-cell junction shortening, can concomitantly alter actin dynamics, oppositely leading to perturbation of the shortening; and tricellular junctions as a point that organizes extension of new cell-cell junctions after shortening.

Inhibition of negative feedback for persistent epithelial cell-cell junction contraction by p21-activated kinase 3.

Actin-mediated mechanical forces are central drivers of cellular dynamics. They generate protrusive and contractile dynamics, the latter of which are induced in concert with myosin II bundled at the site of contraction. These dynamics emerge concomitantly in tissues and even each cell; thus, the tight regulation of such bidirectional forces is important for proper cellular deformation.

The Tricellular Junction Protein Sidekick Regulates Vertex Dynamics to Promote Bicellular Junction Extension.

Remodeling of cell-cell junctions drives cell intercalation that causes tissue movement during morphogenesis through the shortening and growth of bicellular junctions. The growth of new junctions is essential for continuing and then completing cellular dynamics and tissue shape sculpting; however, the mechanism underlying junction growth remains obscure. We investigated Drosophila genitalia rotation where continuous cell intercalation occurs to show that myosin II accumulating at the vertices of a new junction is required for the junction growth.

Mechanisms of unusual collective cell movement lacking a free front edge in Drosophila.

The shape and structure of tissues are generated by the dynamic behavior of various cell collectives during morphogenesis. These behaviors include collective cell movement, in which cells move coordinately in a given direction while maintaining cell-cell attachments throughout the collective. For a cell collective to acquire mobility, the cell collective generates forces, and the cells in the front sense extrinsic cues to decide the direction of the movement.

Ubiquitin-Binding Protein CG5445 Suppresses Aggregation and Cytotoxicity of Amyotrophic Lateral Sclerosis-Linked TDP-43 in Drosophila.

Ubiquitin-mediated protein degradation plays essential roles in proteostasis and is involved in the pathogenesis of neurodegenerative diseases in which ubiquitin-positive aberrant proteins accumulate. However, how such aberrant proteins are processed inside cells has not been fully explored. Here, we show that the product of , a previously uncharacterized gene, prevents the accumulation of aggregate-prone ubiquitinated proteins.

Mechanisms of collective cell movement lacking a leading or free front edge in vivo.

Collective cell movement is one of the strategies for achieving the complex shapes of tissues and organs. In this process, multiple cells within a group held together by cell-cell adhesion acquire mobility and move together in the same direction. In some well-studied models of collective cell movement, the mobility depends strongly on traction generated at the leading edge by cells located at the front.

Characterization of the testis-specific proteasome subunit α4s in mammals.

The 26 S proteasome is responsible for regulated proteolysis in eukaryotic cells. It is composed of one 20 S core particle (CP) flanked by one or two 19 S regulatory particles. The CP is composed of seven different α-type subunits (α1-α7) and seven different β-type subunits, three of which are catalytic.

[Rare case report of solitary ganglioneuroma of the transverse colon].

We report herein a rare case of solitary ganglioneuroma occurring in the transverse colon with a brief literature review. A 45-year-old man was diagnosed as having hemorrhoids by a local medical practitioner and referred to our hospital for further examination. He showed neither signs nor symptoms of neurofibromatosis and multiple endocrine neoplasia.