Mechanisms of suppression of insulin signaling by Na channel blockers

1)局麻药利多卡因和各种寡肽对胰岛素受体(IR)自磷酸化的抑制作用40 mM的利多卡因和4 mM的KIFMK和KIYEK可抑制20%或以上的IR自磷酸化。DIYET和KIQMK对预磷酸化IR的抑制作用弱于KIFMK和KIYEK。2)利多卡因和各种寡肽使预磷酸化IR去磷酸化。40 mM利多卡因和4 mM KIYEK使预磷酸化IR的磷酸化分别减少到35%和30%。3)利多卡因、KIYEK和DIYET荧光光谱分析显示IR激活环肽(AL)与利多卡因或寡肽之间的相互作用对激活IR有去磷酸化作用，由于280 nm激发和303 nm发射，AL的荧光强度降低。相反，没有显示去磷酸化作用的KIFMK增加了信号强度。表面等离子体共振(SPR)实验研究了利多卡因和寡肽对IR的去磷酸化作用。通过改变固定化配体和流动缓冲液进行各种SPR实验后，得出结论：SPR方法不足以分析IR的磷酸化。5)寡肽抑制表皮生长因子受体(EGFR)的自磷酸化研究了寡肽对EGFR自磷酸化的抑制作用，其氨基酸序列与EGFR的自磷酸化位点一致。根据Y1148和Y1173附近氨基酸序列的寡肽被发现有效地抑制了EGFR的自氧化短化。

1)Suppression of autophosphorylation of insulin receptor(IR) by local anesthetic lidocaine and various oligopeptidesThe 40 mM of lidocaine and the 4 mM of oligopeptides, KIFMK and KIYEK, suppressed autophosphorylation of IR below 20% or more. DIYET and KIQMK, suppressed autophosphorylation less effectively than did KIFMK and KIYEK.2)Dephosphorylation of pre-phosphorylated IR by lidocaine and various oligopeptidesThe 40 mM of lidocaine and 4 mM of KIYEK and DIYET decreased phosphorylation of pre-phosphorylated IR to 35 and 30%, respectively. In contrast, KIFMK showed no dephosphorylation effect.3)Interactions between activation loop peptide(AL) of IR and lidocaine or oligopeptides by fluorescence spectraLidocaine, KIYEK, and DIYET, which had dephosphorylation effects on activated IR, reduced fluorescence intensities of AL due to 280 nm excitation and 303 nm emission. In contrast, KIFMK, which showed no dephosphorylation effect, increased the intensities. LPFFD had no effect on the intensities.4)Dephosphorylation effects for IR by lidocaine and oligopeptides as studied by surface plasmon resonance(SPR) experimentsAfter various SPR experiments performed by varying ligands to be immobilized and analytes to be flowed with running buffer, it was concluded that the SPR method is inadequate for analyzing phosphorylation of IR.5)Suppression of autophosphorylation of epidermal growth factor receptor(EGFR) by oligopeptidesSuppression effects of oligopeptides, the amino acid sequences of which followed those of autophosphorylation sites of EGFR, on autophosphorylation of EGFR were studied. The oligopeptides which followed the amino acid sequences around Y1148 and Y1173 were found to effectively suppress autophoshorylation of EGFR.