拡散バリアは,偏光ニューロン内の膜タンパク質の分布を維持する

B Winckler¹, P Forscher, I Mellman

¹Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520-8002, USA.

Nature

|March 6, 1999

まとめ

ニューロンは,物理的な障壁のない明確な膜領域を維持します. 特殊な軸索セグメントは,タンパク質の拡散を制限し,新しい拡散障壁として作用します.

科学分野:

細胞生物学細胞生物学
神経科学は神経科学である.
膜バイオフィジックス

背景:

偏極化された細胞は,機能するために非対称な血膜タンパク質分布を必要とします.
皮質細胞は緊密な接点を用いるが,神経細胞には,軸索領域と体幹領域の間の明らかな障壁がない.
膜タンパク質の二極化におけるアクソン初期セグメントの役割は不明である.

研究の目的:

ニューロンにおけるプラズマ膜タンパク質の分極化のメカニズムを調査する.
軸索の初期セグメントに拡散障壁が存在するかどうかを判断する.
ニューロン領域における膜タンパク質の移動性を影響する要因を特定する.

主な方法:

膜タンパク質の横向移動性を測定するために使用される光学ピンチ.
実験では,人工的脂質 (DiI) 拡散とF-アクチンの破壊が行われました.
ディメチル硫酸化物 (DMSO) は,バリア機能を評価するために使用されました.

主要な成果:

特定の膜タンパク質は,軸索の初期セグメントの移動性が著しく低下したことを示した.
F-アクチンの破壊とDMSOによる治療は,この拡散障壁をなくした.
バリアの破壊は,以前に偏光された膜マーカーの再分布につながった.

結論:

軸索の初期セグメントは,膜タンパク質の横向移動を制限する特殊ドメインとして作用します.
このドメインは,細胞と細胞の接触がない場合,拡散障壁として機能します.
タンパク質の不動化は,細胞骨格の構成要素との差異的結合による可能性が高い.

さらに関連する動画

06:22

Lucifer Yellow - A Robust Paracellular Permeability Marker in a Cell Model of the Human Blood-brain Barrier

Published on: August 19, 2019

07:53

Split Retina as an Improved Flatmount Preparation for Studying Inner Nuclear Layer Neurons in Vertebrate Retina

Published on: January 16, 2024

関連する概念動画

02:32

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.

01:24

What are Membranes?

A cell's plasma membrane demarcates the cell's borders and determines the nature of its interaction with the environment. Cells exclude certain substances, take in others, and excrete some others in controlled quantities. The plasma membrane must be flexible to allow certain cells, such as red and white blood cells, to change their shape while passing through narrow capillaries. These are the more obvious plasma membrane functions. In addition, the plasma membrane's surface carries markers that...

01:24

Protein Diffusion in the Membrane

Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...

01:18

Membrane Domains

The membrane domains concentrate specific lipids and proteins at one place within the membrane, which helps in cell signaling, adhesion, and other critical cellular processes. These domains can differ in size, composition, function, and lifespan.
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...

01:22

Enlargement of the Plasma Membrane

Cell division and enlargement are processes that require precise control. The control ensures that cell division cannot proceed unless the cell has grown to a specific size. A spherical, dividing cell requires an approximately 1.6X increase in its surface area to double its volume. The secretory pathway also has a significant role in cell membrane enlargement. Secretory vesicles that bud off from the Golgi apparatus and later fuse with the plasma membrane during exocytosis are a major source of...

00:59

Mechanisms of Membrane Domain Formation

Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...

関連する実験動画