The intracellular Ca(2+) release channel TRPML1 regulates lower urinary tract smooth muscle contractility.
The intracellular Ca(2+) release channel TRPML1 regulates lower urinary tract smooth muscle contractility.
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DOI：
10.1073/pnas.2016959117
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发表时间：
2020-12-01
影响因子：
11.1
通讯作者：
Earley S
中科院分区：
文献类型：
--
作者：
Griffin CS;Alvarado MG;Yamasaki E;Drumm BT;Krishnan V;Ali S;Nagle EM;Sanders KM;Earley S
TRPML 1（瞬时受体电位粘磷脂1）是一种Ca 2+可渗透的非选择性阳离子通道，定位于晚期内体和溶酶体。在这里，我们研究TRPML 1通道在调节下尿路（LUT）平滑肌细胞（SMC）收缩性的功能。我们发现TRPML 1与肌浆网（SR）中的ryanodine受体（RyRs）形成稳定的信号复合物。我们进一步表明TRPML 1通道对于启动SR膜上的RyR和质膜上的K+通道之间的必需Ca 2+信号负反馈机制是重要的。在小鼠中敲除TRPML 1通道会损害这一通路，导致LUT平滑肌过度收缩和膀胱过度活动症的症状。我们的研究结果表明TRPML 1在LUT功能中起着关键作用。TRPML 1（瞬时受体电位粘磷脂1）是一种Ca 2+可渗透的非选择性阳离子通道，主要定位于晚期内体和溶酶体（LEL）的膜上。通过TRPML 1的细胞内Ca 2+释放被认为是维持囊泡内酸性pH以及LELs成熟、融合和运输的关键。有趣的是，在小鼠（Mcoln 1 −/−）中基因切除TRPML 1诱导了过度扩张/肥大膀胱表型。在这里，我们进一步研究了这一现象，探索TRPML 1通道在调节膀胱和尿道平滑肌细胞（SMC）的Ca 2+信号活性和收缩性的非常规作用。四维（4D）点阵光片活细胞成像显示，在新鲜分离的膀胱平滑肌细胞中的大多数LEL基本上是固定的。超分辨率显微镜显示不同的纳米级共定位LEL表达TRPML 1通道与兰尼碱2型受体（RyR 2）在膀胱平滑肌细胞。通过RyR 2从肌浆网（SR）自发细胞内释放Ca 2+产生局部Ca 2+升高（“Ca 2+火花”），其激活质膜大电导Ca 2+激活的K+（BK）通道，这是调节平滑肌收缩性的关键负反馈机制。这种机制在Mcoln 1 −/−小鼠中受损，表现出膀胱和尿道SMC中自发Ca 2+火花和BK通道活性减少。此外，离体收缩性实验表明，Mcoln 1 −/−小鼠中Ca 2 + spark-BK通道信号的丢失使膀胱和尿道平滑肌过度收缩。排尿活动分析显示Mcoln 1 −/−小鼠的膀胱过度活动。我们的结论是，TRPML 1是至关重要的钙火花信号，从而调节收缩性和功能，在下尿路平滑肌细胞。
TRPML1 (transient receptor potential mucolipin 1) is a Ca2+-permeable, nonselective cation channel that is localized to late endosomes and lysosomes. Here, we investigated the function of TRPML1 channels in regulating lower urinary tract (LUT) smooth muscle cell (SMC) contractility. We found that TRPML1 forms a stable signaling complex with ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR). We further showed that TRPML1 channels are important for initiating an essential Ca2+-signaling negative feedback mechanism between RyRs on SR membranes and K+ channels on the plasma membrane. Knockout of TRPML1 channels in mice impaired this pathway, resulting in LUT smooth muscle hypercontractility and symptoms of overactive bladder. Our findings demonstrate a critical role for TRPML1 in LUT function. TRPML1 (transient receptor potential mucolipin 1) is a Ca2+-permeable, nonselective cation channel that is predominantly localized to the membranes of late endosomes and lysosomes (LELs). Intracellular release of Ca2+ through TRPML1 is thought to be pivotal for maintenance of intravesicular acidic pH as well as the maturation, fusion, and trafficking of LELs. Interestingly, genetic ablation of TRPML1 in mice (Mcoln1−/−) induces a hyperdistended/hypertrophic bladder phenotype. Here, we investigated this phenomenon further by exploring an unconventional role for TRPML1 channels in the regulation of Ca2+-signaling activity and contractility in bladder and urethral smooth muscle cells (SMCs). Four-dimensional (4D) lattice light-sheet live-cell imaging showed that the majority of LELs in freshly isolated bladder SMCs were essentially immobile. Superresolution microscopy revealed distinct nanoscale colocalization of LEL-expressing TRPML1 channels with ryanodine type 2 receptors (RyR2) in bladder SMCs. Spontaneous intracellular release of Ca2+ from the sarcoplasmic reticulum (SR) through RyR2 generates localized elevations of Ca2+ (“Ca2+ sparks”) that activate plasmalemmal large-conductance Ca2+-activated K+ (BK) channels, a critical negative feedback mechanism that regulates smooth muscle contractility. This mechanism was impaired in Mcoln1−/− mice, which showed diminished spontaneous Ca2+ sparks and BK channel activity in bladder and urethra SMCs. Additionally, ex vivo contractility experiments showed that loss of Ca2+ spark–BK channel signaling in Mcoln1−/− mice rendered both bladder and urethra smooth muscle hypercontractile. Voiding activity analyses revealed bladder overactivity in Mcoln1−/− mice. We conclude that TRPML1 is critically important for Ca2+ spark signaling, and thus regulation of contractility and function, in lower urinary tract SMCs.
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影响因子：
16.6
作者：
Dong, Xian-ping;Shen, Dongbiao;Wang, Xiang;Dawson, Taylor;Li, Xinran;Zhang, Qi;Cheng, Xiping;Zhang, Yanling;Weisman, Lois S.;Delling, Markus;Xu, Haoxing
通讯作者：
Xu, Haoxing
影响因子：
2.7
作者：
Brading, AF
通讯作者：
Brading, AF
影响因子：
5.5
作者：
Drumm, Bernard T.;Rembetski, Benjamin E.;Sanders, Kenton M.
通讯作者：
Sanders, Kenton M.
影响因子：
2
作者：
Drake MJ;Fry CH;Hashitani H;Kirschner-Hermanns R;Rahnama'i MS;Speich JE;Tomoe H;Kanai AJ;McCloskey KD
通讯作者：
McCloskey KD
影响因子：
3.6
作者：
Frazier, Elfaridah P.;Peters, Stephan L. M.;Michel, Martin C.
通讯作者：
Michel, Martin C.