Zinc-dependent lysosomal enlargement in TRPML1-deficient cells involves MTF-1 transcription factor and ZnT4 (Slc30a4) transporter.
Zinc-dependent lysosomal enlargement in TRPML1-deficient cells involves MTF-1 transcription factor and ZnT4 (Slc30a4) transporter.
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DOI：
10.1042/bj20121506
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发表时间：
2013-04-15
期刊：
影响因子：
--
通讯作者：
Kiselyov K
中科院分区：
文献类型：
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作者：
Kukic I;Lee JK;Coblentz J;Kelleher SL;Kiselyov K
锌对于多种细胞过程至关重要，包括基因表达、分泌和酶活性。细胞锌由锌螯合蛋白和锌转运蛋白控制。最近对溶酶体离子通道 TRPML1 锌渗透性的鉴定，以及 TRPML1 缺陷细胞中锌水平异常的证据，表明 TRPML1 在锌转运中的作用。在这里，我们为这种作用提供了新的证据，并确定了负责它的其他细胞成分。与之前发表的数据一致，当细胞暴露于高浓度的 Zn 时，急性 siRNA 驱动的 TRPML1 敲低 (KD) 会导致 Lysotracker 和 Zn 染色呈阳性的大细胞质囊泡的积累。我们现在表明，暴露于 Zn 的 TRPML1-KD 细胞中的溶酶体增大和 Zn 积累可通过 Zn 敏感转录因子 MTF-1 或 Zn 转运蛋白 ZnT4 的 KD 得到改善。 TRPML1 KD 与细胞质 Zn 的积累以及金属硫蛋白 2a (MT2a) mRNA 转录反应的增强有关。 TRPML1 KD 不会抑制溶酶体分泌，但它确实会延迟 Zn 从溶酶体渗漏到细胞质中。这些数据强调了 TRPML1 在锌代谢中的作用。此外，他们认为 TRPML1 与 ZnT4 协同作用，调节细胞质和溶酶体之间的锌易位。
Zn is critical for a multitude of cellular processes, including gene expression, secretion and enzymatic activities. Cellular Zn is controlled by Zn-chelating proteins and by Zn transporters. The recent identification of Zn permeability of the lysosomal ion channel TRPML1, and the evidence of abnormal Zn levels in cells deficient in TRPML1, suggested a role for TRPML1 in Zn transport. Here we provide new evidence for such a role and identify additional cellular components responsible for it. In agreement with the previously published data, an acute siRNA-driven TRPML1 knockdown (KD) leads to the buildup of large cytoplasmic vesicles positive for Lysotracker and Zn staining, when cells are exposed to high concentrations of Zn. We now show that lysosomal enlargement and Zn buildup in TRPML1-KD cells exposed to Zn are ameliorated by KD of the Zn-sensitive transcription factor MTF-1 or Zn transporter ZnT4. TRPML1 KD is associated with a buildup of cytoplasmic Zn and with enhanced transcriptional response of mRNA for metallothionein 2a (MT2a). TRPML1 KD did not suppress lysosomal secretion, but it did delay Zn leak from the lysosomes into the cytoplasm. These data underscore a role for TRPML1 in Zn metabolism. Furthermore, they suggest that TRPML1 works in concert with ZnT4 to regulate Zn translocation between the cytoplasm and lysosomes.