ラメリポリポディアにおけるアクチンフィラメントの回転の単分子スペックル分析
Naoki Watanabe1, Timothy J Mitchison
1Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA. naoki_watanabe@hms.harvard.edu
まとめ
研究者は,アクチンポリメリゼーションを理解するために,細胞ラメリポディアの単一のアクチン分子を追跡しました. アクチン線維の形成は,主にラメリポディアムの先端から離れて発生し,細胞の縁全体で定常の運動学があります.
科学分野:
- 細胞生物学 細胞生物学
- バイオフィジックス 生物物理学
- 分子生物学は分子生物学である.
背景:
- ラメリポディアは,移動と粘着に関与する重要な細胞構造です.
- ラメリポディア内のアクチンダイナミクスは,その機能に不可欠ですが,in vivoで研究するには複雑です.
- アクチンポリメリゼーションの空間的調節を理解することは,細胞運動性研究の鍵です.
研究 の 目的:
- 細胞ラメリポディア内のアクチンポリメリゼーションとデポリメリゼーションの空間的調節を分析する.
- アクチン繊維の運動学と寿命を高空間精度で in vivo で測定する.
- ラメリポディアにおけるアクチンフィラメント生成の主要な部位を解明する.
主な方法:
- 緑色光タンパク質 (GFP) に溶融した単一のアクチン分子を追跡するアプローチを vivo で開発しました.
- 高解像度顕微鏡を用いて,アクチンポリメリゼーションとデポリメリゼーションの動態を監視した.
- 量化されたポリメリゼーション率とアクチンフィラメントの寿命は,ラメリポディア内の異なる場所にある.
主要な成果:
- 観察された基礎アクチンポリメリゼーションとデポリメリゼーションは,ラメリポディア全体で一貫した運動学を持つ.
- ラメリポディアムの先端の1ミクロン以内の強化されたアクチンポリメリゼーションを特定しました.
- ラメリポディアのアクチン繊維の大部分は,先端から離れて発生するポリメリゼーションから発生することを決定しました.
結論:
- ラメリポディアのアクチンフィラメント組成は空間的に調節され,重要な部分は先端から離れています.
- アクチンポリメリゼーションとデポリメリゼーションの動態学は,ラメリポディアム全体でほぼ均一である.
- この研究は,細胞の形状と運動に不可欠なアクチンダイナミクスの空間的制御に関する新しい洞察を提供します.
関連する概念動画
Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Actin Filament Depolymerization
Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
Actin Polymerization and Cell Motility
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Mechanism of Filopodia Formation
Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Mechanism of Lamellipodia Formation
Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
Actin Treadmilling
Actin filaments undergo polymerization and depolymerization from either end. The polymerization and depolymerization rates depend on the cytosolic concentration of free G-actins. The polymerization rate is generally higher at the plus or barbed end, while the depolymerization rate is higher at the minus or pointed end. At a steady state, critical concentration describes the concentration of free G-actin monomers at which the polymerization rate at the plus end is equal to that of the...


