Gelsolin modulates phospholipase C activity in vivo through phospholipid binding.
Gelsolin modulates phospholipase C activity in vivo through phospholipid binding.
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DOI：
10.1083/jcb.138.4.811
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发表时间：
1997-08-25
影响因子：
7.8
通讯作者：
Yin, HL
中科院分区：
文献类型：
--
作者：
Sun, HQ;Lin, KM;Yin, HL
凝溶胶蛋白和 CapG 是肌动蛋白调节蛋白，可在激动剂刺激期间响应磷脂酰肌醇 4,5-二磷酸 (PIP2) 和 Ca2+ 来重塑细胞骨架。生理相关的 Ca2+ 升高会增加其对 PIP2 的亲和力，并可促进活化细胞中与 PIP2 的显着相互作用。这可能会在底物可用性水平上影响不同的 PIP2 依赖性信号传导过程。我们发现 CapG 过表达增强了 PDGF 刺激的磷脂酶 Cγ (PLCγ) 活性 (Sun, H.-q., K. Kwiatkowska, D.C. Wooten, and H.L. Yin. 1995. J. Cell Biol. 129:147–156)。在本文中，我们研究了凝溶胶蛋白和 CapG 在活细胞、半完整细胞和体外与另一种 PLC 竞争 PIP2 的能力。我们发现 CapG 和凝溶胶蛋白过度表达可显着抑制缓激肽刺激的 PLCβ。抑制发生在 G 蛋白激活步骤时或之后，因为过度表达也会降低对 NaF 直接 G 蛋白激活的反应。包括凝溶胶蛋白在内的胞浆蛋白从过度表达的细胞中漏出后，缓激肽反应性得以恢复。相反，添加到透化细胞中的外源凝溶胶蛋白以剂量依赖性方式抑制反应。洗脱和回加实验清楚地表明，过量的凝溶胶蛋白是细胞中 PLC 抑制的主要原因。体外实验表明，凝溶胶蛋白和 CapG 既能刺激又能抑制 PLCβ，并且只有含有 PIP2 结合位点的凝溶胶蛋白结构域才有效。通过增加 PIP2 浓度来减轻抑制，其方式与凝溶胶蛋白和 PLCβ 之间对 PIP2 的竞争一致。凝溶胶蛋白和 CapG 对酪氨酸激酶磷酸化 PLCγ 也具有双相作用，尽管它们对 PLCγ 的抑制作用小于 PLCβ。我们的研究结果表明，随着 PIP2 水平和可用性在信号传导过程中发生变化，PIP2 调节蛋白之间的串扰为信号转导级联的正向和负向调节提供了选择性机制。
Gelsolin and CapG are actin regulatory proteins that remodel the cytoskeleton in response to phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ during agonist stimulation. A physiologically relevant rise in Ca2+ increases their affinity for PIP2 and can promote significant interactions with PIP2 in activated cells. This may impact divergent PIP2- dependent signaling processes at the level of substrate availability. We found that CapG overexpression enhances PDGF-stimulated phospholipase Cγ (PLCγ) activity (Sun, H.-q., K. Kwiatkowska, D.C. Wooten, and H.L. Yin. 1995. J. Cell Biol. 129:147–156). In this paper, we examined the ability of gelsolin and CapG to compete with another PLC for PIP2 in live cells, in semiintact cells, and in vitro. We found that CapG and gelsolin overexpression profoundly inhibited bradykinin-stimulated PLCβ. Inhibition occurred at or after the G protein activation step because overexpression also reduced the response to direct G protein activation with NaF. Bradykinin responsiveness was restored after cytosolic proteins, including gelsolin, leaked out of the overexpressing cells. Conversely, exogenous gelsolin added to permeabilized cells inhibited response in a dose-dependent manner. The washout and addback experiments clearly establish that excess gelsolin is the primary cause of PLC inhibition in cells. In vitro experiments showed that gelsolin and CapG stimulated as well as inhibited PLCβ, and only gelsolin domains containing PIP2-binding sites were effective. Inhibition was mitigated by increasing PIP2 concentration in a manner consistent with competition between gelsolin and PLCβ for PIP2. Gelsolin and CapG also had biphasic effects on tyrosine kinase– phosphorylated PLCγ, although they inhibited PLCγ less than PLCβ. Our findings indicate that as PIP2 level and availability change during signaling, cross talk between PIP2-regulated proteins provides a selective mechanism for positive as well as negative regulation of the signal transduction cascade.
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影响因子：
4.8
作者：
Pike, LJ;Casey, L
通讯作者：
Casey, L
影响因子：
2.9
作者：
Singh, SS;Chauhan, A;Chauhan, VPS
通讯作者：
Chauhan, VPS
影响因子：
56.9
作者：
SMRCKA, AV;HEPLER, JR;STERNWEIS, PC
通讯作者：
STERNWEIS, PC
DOI：
10.1083/jcb.128.4.589
发表时间：
1995-02
期刊：
The Journal of cell biology
影响因子：
--
作者：
Muallem S;Kwiatkowska K;Xu X;Yin HL
通讯作者：
Yin HL
DOI：
10.1083/jcb.129.1.147
发表时间：
1995-04
期刊：
The Journal of cell biology
影响因子：
--
作者：
Sun HQ;Kwiatkowska K;Wooten DC;Yin HL
通讯作者：
Yin HL