Multiple signalling pathways involved in β2-adrenoceptor-mediated glucose uptake in rat skeletal muscle cells
Multiple signalling pathways involved in β2-adrenoceptor-mediated glucose uptake in rat skeletal muscle cells
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DOI：
10.1038/sj.bjp.0706626
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发表时间：
2006-02-01
影响因子：
7.3
通讯作者：
Summers, RJ
中科院分区：
文献类型：
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作者：
Nevzorova, J;Evans, BA;Summers, RJ
1β-肾上腺素能受体(AR)激动剂通过β(2)-AR增加大鼠L6细胞对2-脱氧-[H-3]-D-葡萄糖的摄取。β-AR激动剂zinterol(β(2)-AR)和(-)-异丙肾上腺素以浓度依赖的方式增加cAMP积累(pec(50)=9.1+/-0.02和7.8+/-0.02)。霍乱毒素(%max增加141.8+/-2.5%)和cAMP类似物8-溴-cAMP(8BrcAMP)和二丁酰cAMP(DBcAMP)也增加GU(196.8+/-13.5%和196.4+/-17.3%)。2.腺苷环化酶抑制剂2‘，5’-二脱氧腺苷(50mM)显著减少cAMP在津特罗(100nM)上的积聚(109.7±35.0到21.6±4.5pmol井(-1))，或福司可林(10 MU M)(230.1+/-58.0~107.2+/-26.3pmolwell(-1))，并部分抑制zinterol刺激的GU(217+/-26.3~176.1+/-20.4%)。蛋白激酶A(PKA)抑制剂4-氰基-3-甲基异喹啉(100 NM)不能抑制zinterol刺激的GU。PDE4抑制剂罗利普兰(10 MU M)可增加cAMP对zinterol或forsklin的反应，并使gu对zinterol的反应增敏，表明cAMP在GU中的刺激作用。3 cAMP积累研究表明，zinterol延长刺激可使β(2)-AR减敏，而对zinterol的gu反应随时间延长而增加，提示gu可能与受体脱敏有关。4 PTX(100 ng·ml~(-1))可抑制胰岛素或Zinterol刺激的GU，但不能抑制8BR-cAMP或DBcAMP刺激的GU。PI3K抑制剂LY294002(1mU M)可抑制胰岛素(174.9+/-5.9%~142.7+/-2.7%)和Zinterol-(166.9+/-7.6%~141.1+/-8.1%)，但不能抑制8-溴-cAMP刺激的GU。与胰岛素相反，zinterol不能引起Ak.5的磷酸化。5结果表明，L6细胞中的GU涉及三个机制：(1)涉及PI3K的胰岛素依赖途径，(2)β(2)-AR介导的涉及cAMP和PI3K的途径，以及(3)cAMP类似物建议的不依赖受体的途径，使GU增加而不依赖PI3K。PKA似乎对β(2)-AR介导的GU有负性调节作用。
1 beta-adrenoceptor (AR) agonists increase 2-deoxy-[H-3]-D-glucose uptake (GU) via beta(2)-AR in rat L6 cells. The beta-AR agonists, zinterol (beta(2)-AR) and (-)-isoprenaline, increased cAMP accumulation in a concentration-dependent manner (pEC(50) = 9.1 +/- 0.02 and 7.8 +/- 0.02). Cholera toxin (% max increase 141.8 +/- 2.5) and the cAMP analogues, 8-bromo-cAMP (8Br-cAMP) and dibutyryl cAMP (dbcAMP), also increased GU (196.8 +/- 13.5 and 196.4 +/- 17.3%).2 The adenylate cyclase inhibitor, 2',5'-dideoxyadenosine (50 mu M), significantly reduced cAMP accumulation to zinterol ( 100 nM) (109.7+ 35.0 to 21.6 + 4.5 pmol well(-1)), or forskolin ( 10 mu M) (230.1 +/- 58.0 to 107.2 +/- 26.3 pmol well(-1)), and partially inhibited zinterol-stimulated GU (217 +/- 26.3 to 176.1 +/- 20.4%). The protein kinase A(PKA) inhibitor, 4-cyano-3-methylisoquinoline ( 100 nM), did not inhibit zinterol-stimulated GU. The PDE4 inhibitor, rolipram ( 10 mu M), increased cAMP accumulation to zinterol or forskolin, and sensitised the GU response to zinterol, indicating a stimulatory role of cAMP in GU.3 cAMP accumulation studies indicated that the beta(2)-AR was desensitised by prolonged stimulation with zinterol, but not forskolin, whereas GU responses to zinterol increased with time, suggesting that receptor desensitisation may be involved in GU. Receptor desensitisation was not reversed by inhibition of PKA or Gi.4 PTX pretreatment (100 ng ml(-1)) inhibited insulin or zinterol-stimulated but not 8Br-cAMP or dbcAMP-stimulated GU. The PI3K inhibitor, LY294002 ( 1 mu M), inhibited insulin- (174.9 +/- 5.9 to 142.7 +/- 2.7%) and zinterol- (166.9 +/- 7.6 to 141.1 +/- 8.1%) but not 8 Br-cAMP-stimulated GU. In contrast to insulin, zinterol did not cause phosphorylation of Akt.5 The results suggest that GU in L6 cells involves three mechanisms: ( 1) an insulin- dependent pathway involving PI3K, ( 2) a beta(2)-AR-mediated pathway involving both cAMP and PI3K, and ( 3) a receptor-independent pathway suggested by cAMP analogues that increase GU independently of PI3K. PKA appears to negatively regulate beta(2)-AR-mediated GU.