Phosphorylations of BLT1 receptor are necessary for sufficient cell responses at high concentration of leukotriene B4

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K08294
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Biological pharmacy
• Research Institution: Okayama University of Science
• Principal Investigator: Nakamura Motonao 岡山理科大学, 理学部, 教授 (40431762)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: ロイコトリエンB4 / BLT1 / リン酸化 / ユビキチン修飾 / βアレスチン / G蛋白質共役型受容体 / GPCR

Outline of Final Research Achievements

LTB4 receptor type 1 (BLT1) is abundantly expressed in immune cells and plays crucial roles in various inflammatory diseases. We determined two types of BLT1 phosphorylation, basal and ligand-induced, in the C-terminus of human BLT1 using the Phos-tag SDS-PAGE. Ligand-induced phosphorylation occurred at different LTB4 concentrations, and this modification facilitated basal phosphorylation. Because neutrophils migrate through the LTB4 gradient toward inflammatory sites, the degree of phosphorylation could be enhanced in parallel with an increase in LTB4. At high concentrations of LTB4, deficiencies in these two types of phosphorylation impaired chemotaxis and β-hexosaminidase release in CHO-K1 and RBL-2H3 cells, respectively. These results suggest that an LTB4 gradient around inflammatory regions boosts BLT1 phosphorylation in a stepwise manner to facilitate the precise migration of phagocytic and immune cells, and the initiation of local responses, including degranulation.

Free Research Field

脂質生化学

Academic Significance and Societal Importance of the Research Achievements

炎症時、局所で産生されたLTB4は血中に放出され、好中球はこの際のリガンド濃度勾配を頼りに局所へ向かう。これまでこの濃度勾配は遊走の方向指示のみに重要とされてきたが、我々はこれに新たな意義を加える。BLT1を介して好中球に局所応答の開始時期を伝える意義である。低親和性化したBLT1が濃度勾配の中で再活性化されうる高いLTB4濃度に到達することで、この低親和性型を介して高親和性型とは異なる情報伝達が作動し、局所応答が開始されるという考え方である。この仕組みは全く新奇なシグナル伝達調節の発見である。