Role of mitochondrial phosphate carrier in metabolism-secretion coupling in rat insulinoma cell line INS-1
Role of mitochondrial phosphate carrier in metabolism-secretion coupling in rat insulinoma cell line INS-1
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DOI：
10.1042/bj20101708
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发表时间：
2011-04-15
影响因子：
4.1
通讯作者：
Inagaki, Nobuya
中科院分区：
文献类型：
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作者：
Nishi, Yuichi;Fujimoto, Shimpei;Inagaki, Nobuya
在胰腺β细胞中，葡萄糖诱导的线粒体ATP产生在胰岛素分泌中起重要作用。线粒体磷酸盐载体PiC是SLC 25（溶质载体家族25）家族的成员，并将P（i）从胞质溶胶转运到线粒体基质中。由于线粒体内P（i）是复合物V（ATP合酶）产生线粒体ATP的重要底物，并影响呼吸链的活性，因此P（i）通过PiC的转运可能是ATP产生的限速步骤。我们使用经操作以通过siRNA（小干扰RNA）降低PiC表达的INS-1细胞来评估PiC在胰腺β细胞中代谢分泌偶联中的作用。相应地，PiC蛋白水平的降低降低了葡萄糖（10 mM）刺激的胰岛素分泌，在10 mM葡萄糖存在下的ATP：ADP比率以及响应于10 mM葡萄糖的细胞内钙浓度的升高，而不影响INS-1细胞中的线粒体膜电位（Δ psi（m））。在使用INS-1细胞的线粒体部分的实验中，在存在1 mM琥珀酸盐的情况下，PiC下调在0.001至10 mM范围内的各种P（i）浓度下降低ATP产生，但在3 mM P（i）下不影响Δ psi（m）。结论：通过PiC向线粒体供应P（i）在INS-1细胞ATP产生和代谢分泌偶联中起着关键作用。
In pancreatic beta-cells, glucose-induced mitochondrial ATP production plays an important role in insulin secretion. The mitochondrial phosphate carrier PiC is a member of the SLC25 (solute carrier family 25) family and transports P(i) from the cytosol into the mitochondrial matrix. Since intramitochondrial P(i) is an essential substrate for mitochondrial ATP production by complex V (ATP synthase) and affects the activity of the respiratory chain, P(i) transport via PiC may be a rate-limiting step for ATP production. We evaluated the role of PiC in metabolism secretion coupling in pancreatic beta-cells using INS-1 cells manipulated to reduce PiC expression by siRNA (small interfering RNA). Consequent reduction of the PiC protein level decreased glucose (10 mM)-stimulated insulin secretion, the ATP:ADP ratio in the presence of 10 mM glucose and elevation of intracellular calcium concentration in response to 10 mM glucose without affecting the mitochondrial membrane potential (Delta psi(m)) in INS-1 cells. In experiments using the mitochondrial fraction of INS-1 cells in the presence of 1 mM succinate, PiC down-regulation decreased ATP production at various P(i) concentrations ranging from 0.001 to 10 mM, but did not affect Delta psi(m) at 3 mM P(i). In conclusion, the P(i) supply to mitochondria via PiC plays a critical role in ATP production and metabolism secretion coupling in INS-1 cells.