Kwong Raymond W M, Perry Steve F
Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
Am J Physiol Cell Physiol. 2015 Jul 1;309(1):C60-9. doi: 10.1152/ajpcell.00053.2015. Epub 2015 May 6.
Hydrogen sulfide (H2S) can act as a signaling molecule for various ion channels and/or transporters; however, little is known about its potential involvement in Ca(2+) balance. Using developing zebrafish (Danio rerio) as an in vivo model system, the present study demonstrated that acute exposure to H2S donors increased Ca(2+) influx at 4 days postfertilization, while chronic (3-day) exposure caused a rise in whole body Ca(2+) levels. The mRNA expression of Ca(2+)-transport-related genes was unaffected by H2S exposure, suggesting that posttranscriptional modifications were responsible for the altered rates of Ca(2+) uptake. Indeed, treatment of fish with the protein kinase A inhibitor H-89 abolished the H2S-mediated stimulation of Ca(2+) influx, suggesting that H2S increased Ca(2+) influx by activating cAMP-protein kinase A pathways. Cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) are two key enzymes in the endogenous synthesis of H2S. Using an antisense morpholino knockdown approach, we demonstrated that Ca(2+) influx was reduced in CBS isoform b (CBSb)- but not in CSE-deficient fish. Interestingly, the reduction in Ca(2+) influx in CBSb-deficient fish was observed only in fish that were acclimated to low-Ca(2+) water (i.e., 25 μM Ca(2+); control: 250 μM Ca(2+)). Similarly, mRNA expression of cbsb but not cse was increased in fish acclimated to low-Ca(2+) water. Results from whole-mount immunohistochemistry further revealed that CBSb was expressed in Na(+)-K(+)-ATPase-rich cells, which are implicated in Ca(2+) uptake in zebrafish larvae. Collectively, the present study suggests a novel role for H2S in promoting Ca(2+) influx, particularly in a low-Ca(2+) environment.
硫化氢（H₂S）可作为多种离子通道和/或转运蛋白的信号分子；然而，其在钙（Ca²⁺）平衡中的潜在作用却鲜为人知。本研究以发育中的斑马鱼（Danio rerio）作为体内模型系统，证明急性暴露于H₂S供体可使受精后4天的Ca²⁺内流增加，而慢性（3天）暴露则导致全身Ca²⁺水平升高。Ca²⁺转运相关基因的mRNA表达不受H₂S暴露的影响，这表明转录后修饰是Ca²⁺摄取速率改变的原因。事实上，用蛋白激酶A抑制剂H - 89处理鱼类可消除H₂S介导的Ca²⁺内流刺激，这表明H₂S通过激活cAMP - 蛋白激酶A途径增加了Ca²⁺内流。胱硫醚β - 合酶（CBS）和胱硫醚γ - 裂解酶（CSE）是内源性H₂S合成中的两种关键酶。使用反义吗啉代敲低方法，我们证明在CBS同工型b（CBSb）缺陷的鱼类中Ca²⁺内流减少，而在CSE缺陷的鱼类中未减少。有趣的是，仅在适应低Ca²⁺水（即25 μM Ca²⁺；对照：250 μM Ca²⁺）的鱼类中观察到CBSb缺陷鱼类的Ca²⁺内流减少。同样，适应低Ca²⁺水的鱼类中cbsb而非cse的mRNA表达增加。全组织免疫组化结果进一步显示，CBSb在富含Na⁺ - K⁺ - ATP酶的细胞中表达，这些细胞与斑马鱼幼虫的Ca²⁺摄取有关。总体而言，本研究表明H₂S在促进Ca²⁺内流方面具有新作用，特别是在低Ca²⁺环境中。
