フォスホイノシチドシグナル伝達は,O-GlcNAcトランスファーゼとインスリン抵抗性とのリンクを結び付けています
Xiaoyong Yang1, Pat P Ongusaha, Philip D Miles
1Howard Hughes Medical Institute and Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Nature
|February 22, 2008
まとめ
O-GlcNAcトランスファーゼ (OGT) 酵素は,インスリンに反応して細胞膜に結合し,インスリンシグナル伝達経路を変更します. このO-GlcNAcの改変は,インスリン抵抗性や2型糖尿病に寄与する.
科学分野:
- バイオケミストリー バイオケミストリー
- 細胞生物学 細胞生物学
- メタボリック・レギュレーション
背景:
- ヘキソサミンの生物合成経路は,O-リンクベータ-N-アセチルグルコサミン (O-GlcNAc) 改変によって細胞のプロセスを調節する.
- このシステムは栄養センサーとして機能し,代謝状態と細胞の調節を結びつける.
- O-GlcNAcの改変は,信号伝達,転写,およびタンパク質の分解に影響を与える.
研究 の 目的:
- インスリンシグナル伝達におけるO-GlcNAcトランスファーゼ (OGT) の役割を調査する.
- OGTがインスリン経路を変化させるメカニズムを解明する.
- インスリン抵抗性に対するO-GlcNAc変異の貢献を理解する.
主な方法:
- OGTのフォスホイノシチド結合ドメインの特徴.
- インスリン誘導時のOGTの血への徴募の分析.
- インスリンシグナル伝達部位におけるO-GlcNAc変異の評価.
- インスリン感受性および遺伝子発現に対する肝臓OGT過剰発現の影響の評価.
主要な成果:
- OGTは,新しいフォスホイノシチド結合ドメインを持っています.
- インスリンは,OGTを,フォスファディチルニノシトール3,4,5-トリスホスファート経由で血膜に誘導する.
- インスリンシグナル伝達経路のO-GlcNAc変化により,リン酸化が変化し,シグナル伝達が弱まります.
- 肝臓のOGT過剰発現は,インスリン抵抗性,脂質不全,およびインスリン反応性遺伝子発現の障害を引き起こす.
結論:
- 栄養学的ヒントは,O-GlcNAc改変を通じてインスリンシグナル伝達を調節する.
- OGTとフォスホイノシチドの相互作用は,この規制の重要なメカニズムです.
- 異常なO-GlcNAcの改変は,インスリン抵抗性および2型糖尿病の病原化に寄与する.
関連する概念動画
Insulin: The Receptor and Signaling Pathways
Insulin action is mediated through a receptor tyrosine kinase, akin to the IGF-1 receptor. The number of receptors per cell varies significantly, from 40 on erythrocytes to 300,000 on adipocytes and hepatocytes. The insulin receptor consists of linked α/β subunit dimers, forming a heterotetramer glycoprotein with two extracellular α subunits and two β subunits spanning the membrane. The α subunits inhibit the inherent tyrosine kinase activity of the β subunits, but this inhibition is released...
IP3/DAG Signaling Pathway
Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...
cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
PI3K/mTOR/AKT Signaling Pathway
The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast, mTORC2 consists of a rapamycin-insensitive companion...
Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Glucose Homeostasis: Pancreatic Islets and Insulin Secretion
The pancreatic islets comprising only 1%-2% of the volume are highly vascularized and innervated mini-organs. They contain five endocrine cell types, including β cells that secrete insulin, which is synthesized as a single polypeptide chain, preproinsulin, processed to proinsulin, and finally to insulin and C-peptide. This process is complex and regulated, involving the Golgi complex, the endoplasmic reticulum, and the secretory granules of the β cell.
Insulin and C-peptide are co-secreted in...
Insulin and C-peptide are co-secreted in...


