Parathyroid hormone stimulation of calcium transport is mediated by dual signaling mechanisms involving protein kinase A and protein kinase C
Parathyroid hormone stimulation of calcium transport is mediated by dual signaling mechanisms involving protein kinase A and protein kinase C
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DOI：
10.1210/en.137.1.13
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发表时间：
1996-01-01
期刊：
影响因子：
4.8
通讯作者：
Gesek, FA
中科院分区：
文献类型：
--
作者：
Friedman, PA;Coutermarsh, BA;Gesek, FA
PTH促进肾远端曲管对钙的吸收。甲状旁腺激素受体能够与腺苷环化酶和磷脂酶C偶联，但目前尚不清楚甲状旁腺素的作用是否需要这两条途径的激活。通过三种途径鉴定刺激远曲小管细胞钙内流的信号通路：确定甲状旁腺素反应形成的第二信使，测定化学或多肽阻滞剂抑制蛋白激酶A(PKA)或蛋白激酶C(PKC)对钙摄取的影响，以及外源性第二信使的加入重建钙转运。PTH促进原代培养的小鼠远端和近端肾小管细胞cAMP的形成。然而，甲状旁腺激素仅刺激近端肾小管细胞形成三磷酸肌醇。用RP-cAMP或cAMP依赖的蛋白激酶抑制剂阻断PKA可抑制PTH刺激的钙摄取。同样，PKC抑制剂，Calphostin C和PKC假底物，抑制PTH诱导的钙摄取。单独添加Forskolin(30 NM)或佛波醇12-肉豆蔻酸酯13-乙酸酯(10 NM)对钙吸收无影响。然而，当联合添加时，钙吸收的刺激程度几乎与PTH浓度相同，后者最大限度地刺激钙运输。我们的结论是，远端曲小管细胞刺激钙摄取需要同时激活PKA和PKC。
PTH stimulates calcium absorption by renal distal convoluted tubules. The PTH receptor is capable of coupling to adenylyl cyclase and phospholipase C. However, it is not known whether the actions of PTH require activation of both pathways. Three approaches were taken to identify the signaling pathways responsible for stimulating calcium entry in distal convoluted tubule cells: second messengers formed in response to PTH were identified, the effects on calcium uptake of inhibiting protein kinase A (PKA) or protein kinase C (PKC) with chemical or peptide blockers were determined, and calcium transport was reconstituted by the addition of exogenous second messengers. PTH increased cAMP formation in primary cultures of mouse distal and proximal tubule cells. However, PTH stimulated inositol trisphosphate formation only in proximal tubule cells. Blocking PKA with Rp-cAMPS or the cAMP-dependent protein kinase inhibitor inhibited PTH-stimulated Ca uptake. Likewise, the PKC inhibitors, calphostin C and PKC pseudosubstrate, inhibited PTH-induced calcium uptake. Addition of forskolin (30 nM) or phorbol 12-myristate 13-acetate (10 nM) alone had no effect on Ca uptake. However, when added in combination, Ca uptake was stimulated to nearly the same extent as with concentrations of PTH that maximally stimulate calcium transport. We conclude that stimulation of calcium uptake by distal convoluted tubule cells requires activation of both PKA and PKC.