Department of Molecular Biology, Palladin Institute of Biochemistry National Academy of Sciences of Ukraine, Kyiv, Ukraine.
Department of Molecular Biology, Palladin Institute of Biochemistry National Academy of Sciences of Ukraine, Kyiv, Ukraine.
Arch Biochem Biophys. 2024 Sep;759:110104. doi: 10.1016/j.abb.2024.110104. Epub 2024 Jul 24.
Endoplasmic reticulum stress and synthesis of serine are essential for tumor growth, but the mechanism of their interaction is not clarified yet. The overarching goal of this work was to investigate the impact of ERN1 (endoplasmic reticulum to nucleus signaling 1) inhibition on the expression of serine synthesis genes in U87MG glioblastoma cells concerning the suppression of cell proliferation.
Wild type U87MG glioblastoma cells and their clones with overexpression of transgenes dnERN1 (without cytoplasmic domain of ERN1) and dnrERN1 (with mutation in endoribonuclease of ERN1), and empty vector (as control) were used. The silencing of ERN1 and XBP1 was also used to inhibition of ERN1 and its function. Gene expression was measured by qPCR.
We show that the expression of PSAT1 and several other related to serine synthesis genes is suppressed in cells with ERN1 inhibition by dissimilar mechanisms: PHGDH gene through ERN1 protein kinase, because its expression was resistant to inhibition of ERN1 endoribonuclease, but ATF4 gene via endoribonuclease of ERN1. However, in the control of PSAT1 and PSPH genes both enzymatic activities of ERN1 signaling protein are involved. At the same time, ERN1 knockdown strongly increased SHMT1 expression, which controls serine metabolism and enhances the proliferation and invasiveness of glioma cells. The level of microRNAs, which have binding sites in PSAT1, SHMT1, and PSPH mRNAs, was also changed in cells harboring dnERN1 transgene. Inhibition of ERN1 suppressed cell proliferation and enzymatic activity of PHGDH, a rate-limiting enzyme for serine synthesis.
Changes in the expression of phosphoserine aminotransferase 1 and other genes related to serine synthesis are mediated by diverse ERN1-dependent mechanisms and contributed to suppressed proliferation and enhanced invasiveness of ERN1 knockdown glioblastoma cell.
内质网应激和丝氨酸合成对于肿瘤生长至关重要，但它们相互作用的机制尚不清楚。这项工作的首要目标是研究 ERN1（内质网到细胞核信号 1）抑制对 U87MG 神经胶质瘤细胞丝氨酸合成基因表达的影响，以及对细胞增殖的抑制作用。
使用野生型 U87MG 神经胶质瘤细胞及其过表达转染体 dnERN1（无 ERN1 细胞质结构域）和 dnrERN1（ERN1 内切核酸酶突变）的克隆，以及空载体（作为对照）。还使用 ERN1 和 XBP1 的沉默来抑制 ERN1 及其功能。通过 qPCR 测量基因表达。
我们表明，ERN1 抑制通过不同的机制抑制 PSAT1 和其他几种与丝氨酸合成相关的基因的表达：PHGDH 基因通过 ERN1 蛋白激酶，因为其表达不受 ERN1 内切核酸酶抑制的影响，但 ATF4 基因通过 ERN1 内切核酸酶。然而，在 PSAT1 和 PSPH 基因的控制中，ERN1 信号蛋白的两种酶活性都参与其中。同时，ERN1 敲低强烈增加了 SHMT1 的表达，SHMT1 控制丝氨酸代谢并增强神经胶质瘤细胞的增殖和侵袭性。具有 PSAT1、SHMT1 和 PSPH mRNA 结合位点的 microRNAs 的水平也在携带 dnERN1 转基因的细胞中发生了变化。ERN1 抑制抑制了丝氨酸合成的限速酶 PHGDH 的酶活性和细胞增殖。
磷酸丝氨酸转氨酶 1 和其他与丝氨酸合成相关基因的表达变化是由多种 ERN1 依赖的机制介导的，并有助于抑制 ERN1 敲低神经胶质瘤细胞的增殖和增强其侵袭性。
