The half-life of the transcript encoding the folate receptor alpha in KB cells is reduced by cytosolic proteins expressed in folate-replete and not in folate-depleted cells.
The half-life of the transcript encoding the folate receptor alpha in KB cells is reduced by cytosolic proteins expressed in folate-replete and not in folate-depleted cells.
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KB细胞中编码叶酸受体α的转录物的半衰期会被叶酸充足的细胞中表达的胞浆蛋白缩短，而叶酸耗尽的细胞中则不会。
DOI：
10.1016/s0378-1119(02)00591-7
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发表时间：
2002
期刊：
影响因子：
3.5
通讯作者：
Rothenberg,SheldonP
中科院分区：
文献类型：
--
作者：
Sadasivan,Easwara;Regec,Annette;Rothenberg,SheldonP
KB 细胞是一种转化的人类细胞系，组成型表达高水平的糖基磷脂酰肌醇 (GPI) 锚定叶酸受体蛋白 α (FRα)，因此可以在含有 <1 nM 叶酸的培养基中生长。当从富含叶酸 (FR) 的培养基转移到叶酸缺乏 (FD) 的培养基时，细胞内叶酸减少约 50 倍，而 FRα 的表达增加 6 倍。这种上调是由初始转录率增加 4.5 倍和 mRNA 半衰期延长 2.4 倍介导的，两者共同提供了更高水平的稳态 mRNA 丰度。对 mRNA 的 5' 区域（包括所有非编码序列和 24 nt 编码序列）和仅由编码序列组成的 3' 区域进行 RNA 凝胶位移测定，鉴定出与来自 FR-KB 细胞的胞质蛋白的独特复合物，而在来自 FD-KB 细胞的胞质溶胶中未观察到这种复合物。因此，这些叶酸依赖性胞质反式活性蛋白的表达似乎通过与 5' 和 3' 顺式元件结合来维持 FR-KB 细胞中 mRNA 的较短半衰期，从而降低了该转录物的稳定性。
The KB cell, a transformed human cell line, constitutively expresses a high level of the glycosylphosphatidylinositol (GPI) anchored folate receptor protein α (FRα) and thereby can grow in medium containing <1 nM folate. When transferred from a folate-replete (FR) medium to one folate-deficient (FD), intracellular folate diminishes about 50-fold and expression of the FRα increases 6-fold. This up-regulation is mediated by a 4.5-fold increase in the initial transcription rate and a 2.4-fold prolongation of the mRNA half-life that together provide a higher level of the steady-state mRNA abundance. An RNA gel -shift assay of a 5′ region of the mRNA that includes all of the non-coding and 24 nt of coding sequence, and a 3′ region comprised only of coding sequence, identified unique complexes with cytosolic proteins from the FR-KB cells that were not observed with the cytosol from FD-KB cells. It appears, therefore, that expression of these folate-dependent cytosolic trans-active proteins function to maintain a shorter half-life of the mRNA in the FR-KB cells by binding to 5′ and 3′ cis elements, reducing the stability of this transcript.