Regulation of M 2 ‐type pyruvate kinase mediated by the high‐affinity IgE receptors is required for mast cell degranulation

• Published in: British journal of pharmacology Vol. 154; no. 5; pp. 1035 - 1046
• Main Authors: Ryu, H, Walker, J K L, Kim, S, Koo, N, Barak, L S, Noguchi, T, Kang, B Y, Kim, K‐M
• Format: Journal Article
• Language: English
• Published: 01.07.2008
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1038/bjp.2008.148

Background and purpose: M 2 ‐type pyruvate kinase (M 2 PK) was found to interact directly with the ‘ITAM’ region of the γ chain of the high‐affinity IgE receptor (FcɛRI). Our hypothesis was that mast cell degranulation might require the FcɛRI‐mediated inhibition of M 2 PK activity. Experimental approach: In rat basophilic leukaemia (RBL‐2H3) cells, the effects of directly inhibiting M 2 PK or preventing the FcɛRI‐mediated inhibition of M 2 PK (disinhibition) on degranulation was measured by hexosaminidase release. Effects of blocking the FcɛRI‐mediated inhibition of M 2 PK was also assessed in vivo in a mouse model of allergen‐induced airway hyper‐responsiveness. Key results: Activation of FcɛRI in RBL‐2H3 cells caused the rapid phosphorylation of tyrosine residues in M 2 PK, associated with a decrease in M 2 PK enzymatic activity. There was an inverse correlation between M 2 PK activity and mast cell degranulation. FcɛRI‐mediated inhibition of M 2 PK involved Src kinase, phosphatidylinositol 3‐kinase, PKC and calcium. Direct inhibition of M 2 PK potentiated FcɛRI‐mediated degranulation and prevention of the FcɛRI‐mediated inhibition of M 2 PK attenuated mast cell degranulation. Transfection of RBL‐2H3 cells with M 1 PK which prevents FcɛRI‐induced inhibition of M 2 PK, markedly reduced their degranulation and exogenous M 1 PK (i.p.) inhibited ovalbumin‐induced airway hyper‐responsiveness in vivo . Conclusions and implications: We have identified a new control point and a novel biochemical pathway in the process of mast cell degranulation. Our study suggests that the FcɛRI‐mediated inhibition of M 2 PK is a crucial step in responses to allergens. Moreover, the manipulation of glycolytic processes and intermediates could provide novel strategies for the treatment of allergic diseases. British Journal of Pharmacology (2008) 154 , 1035–1046; doi: 10.1038/bjp.2008.148 ; published online 21 April 2008