状赤血球の脂質二重層からスペクトルベースの骨格の分離
1Division of Hematology-Oncology, St. Elizabeth's Hospital, Tufts University School of Medicine, Boston, MA 02135.
Science (New York, N.Y.)
|April 26, 1991
まとめ
シクル細胞病は,異常なヘモグロビン (HbS) ポリメリゼーションを伴うもので,細胞の形状の変化を引き起こします. この研究では, sickled 細胞のスペクトルとバンド3の分布を視覚化して,スピキュール形成のメカニズムを明らかにします.
科学分野:
- 細胞生物学 細胞生物学
- 血液学 ヘマトロジ
- バイオフィジックス 生物物理学
背景:
- シクル細胞病 (Sickle cell disease,SCD) は,異常なヘモグロビン (HbS) によって特徴づけられる遺伝的血液疾患である.
- HbSの脱酸素化はポリメリゼーションにつながり,赤血球 (RBC) の形状と機能を変化させます.
- 逆転性形細胞 (RSC) は,脱酸素化時に特徴的な形を形成する.
研究 の 目的:
- 無酸素化RSCにおけるスペクトルおよびバンド3タンパク質の分布を調査する.
- SCDにおけるスピキュール形成の基礎となる分子メカニズムを解明する.
主な方法:
- 免疫光顕微鏡では,
- 免疫電子顕微鏡では,
- スペクトルおよびバンド3タンパク質の抗体ラベル付け
主要な成果:
- 変膜タンパク質であるバンド3は,細胞体全体とスピキュールに沿って検出されました.
- スペクトリン (Spectrin) は,細胞体とスピキュール基に局限した膜骨格タンパク質である.
- スピキュール形成は,HbSのポリメリゼーションとスペクトリン-アクチン網の潜在的な破壊と相関しています.
結論:
- RSCにおけるスピキュール延長は,連続したHbSポリメリゼーションと関連しています.
- このポリメリゼーションにより,脂質二重層が膜下骨格から分離する可能性があります.
- これらの構造的変化を理解することで,SCDの病理生理学に関する洞察が得られます.
関連する概念動画
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
01:15Mechanisms of Membrane-bending
The living membranes are flexible due to their fluid mosaic nature; however, their bending into different shapes is an active process regulated by specific lipids and proteins. The membrane bending can be transient as seen in vesicles or stable for a long time as in microvilli. Cells regulate the size, location, and duration of the membrane curvature.
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
Membrane bending can happen due to intrinsic changes in lipid composition or extrinsic association with different proteins. The proteins involved...
01:32Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
01:39Mechanism 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...
01:16Cell Motility through Blebbing
Blebs are a type of membrane protrusion formed by the internal hydrostatic pressure of the cytoplasm. Blebs are observed in several cell types, including fibroblasts, immune cells, and single-celled organisms like the amoeba. The primary function of blebs is cell locomotion and apoptosis, but they are also found during necrosis and cell division. The life cycle of a bleb comprises an initiation phase followed by the expansion and retraction phases.
Blebbing Through the Matrix
In multicellular...
Blebbing Through the Matrix
In multicellular...
01:19Membrane Asymmetry Regulating Transporters
Enzymes like flippase, floppase, and scramblase transfer phospholipids from one layer to another in the membrane, thereby affecting membrane asymmetry.
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...