Antic D, Lu N, Keene J D
Department of Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Genes Dev. 1999 Feb 15;13(4):449-61. doi: 10.1101/gad.13.4.449.
Human ELAV proteins are implicated in cell growth and differentiation via regulation of mRNA expression in the cytoplasm. In human embryonic teratocarcinoma (hNT2) cells transfected with the human neuronal ELAV-like protein, Hel-N1, neurites formed, yet cells were not terminally differentiated. Cells in which neurite formation was associated with Hel-N1 overexpression, also expressed increased levels of endogenous neurofilament M (NF-M) protein, which distributed along the neurites. However, steady-state levels of NF-M mRNA remained similar whether or not hNT2 cells were transfected with Hel-N1. These findings suggest that turnover of NF-M mRNA was not affected by Hel-N1 expression, despite the fact that Hel-N1 can bind to the 3' UTR of NF-M mRNA and was found directly associated with NF-M mRNA in transfected cells. Analysis of the association of NF-M mRNA with the translational apparatus in Hel-N1 transfectants showed nearly complete recruitment to heavy polysomes, indicating that Hel-N1 caused an increase in translational initiation. Our results suggest that the stability and/or translation of ARE-containing mRNAs can be regulated independently by the ELAV protein, Hel-N1, depending upon sequence elements in the 3' UTRs and upon the inherent turnover rates of the mRNAs that are bound to Hel-N1 in vivo.
人类ELAV蛋白通过调节细胞质中的mRNA表达参与细胞生长和分化。在转染了人类神经元ELAV样蛋白Hel-N1的人类胚胎性畸胎瘤（hNT2）细胞中，形成了神经突，但细胞并未终末分化。神经突形成与Hel-N1过表达相关的细胞，内源性神经丝M（NF-M）蛋白水平也升高，且该蛋白沿神经突分布。然而，无论hNT2细胞是否转染Hel-N1，NF-M mRNA的稳态水平都保持相似。这些发现表明，尽管Hel-N1能与NF-M mRNA的3'UTR结合且在转染细胞中被发现与NF-M mRNA直接相关，但NF-M mRNA的周转不受Hel-N1表达的影响。对Hel-N1转染细胞中NF-M mRNA与翻译装置的关联分析表明，其几乎完全募集到重多聚核糖体上，这表明Hel-N1导致翻译起始增加。我们的结果表明，含ARE的mRNA的稳定性和/或翻译可由ELAV蛋白Hel-N1独立调节，这取决于3'UTR中的序列元件以及体内与Hel-N1结合的mRNA的固有周转速率。
