Coordinate regulation of RARgamma2, TBP, and TAFII135 by targeted proteolysis during retinoic acid-induced differentiation of F9 embryonal carcinoma cells.
Coordinate regulation of RARgamma2, TBP, and TAFII135 by targeted proteolysis during retinoic acid-induced differentiation of F9 embryonal carcinoma cells.
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DOI：
10.1186/1471-2199-2-4
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发表时间：
2001
影响因子：
--
通讯作者：
Davidson I
中科院分区：
文献类型：
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作者：
Perletti L;Kopf E;Carré L;Davidson I
用全反式维甲酸（T-RA）处理小鼠F9胚胎癌细胞诱导分化为原始内胚层型细胞。分化需要全反式和9顺式视黄酸受体（分别为RAR和RXR）的作用，并伴有生长抑制、细胞形态变化、细胞凋亡增加、RARγ2受体的蛋白水解降解以及靶基因的诱导。我们发现，RNA聚合酶II转录因子TFIID亚基TBP和TAFII 135选择性耗尽从分化的F9细胞提取物。相反，TBP和TAFII 135在用蛋白酶体抑制剂处理的分化F9细胞的提取物中容易检测到，表明它们的消失是由于靶向蛋白水解。这种调节途径不限于F9细胞，因为当C2 C12成肌细胞分化成肌管时也可以看到。在F9细胞中靶向TBP和TAFII 135进行蛋白水解与先前报道的RARγ2受体协同发生，并且在已知分化受损或消失的RAR突变F9细胞中延迟或不发生。此外，TAFII 135的异位表达延迟RARγ2受体的蛋白水解，并在早期阶段损害原始内胚层分化，如细胞形态、标记基因的诱导和凋亡反应所证明的。此外，增强的TAFII 135表达诱导了一种新的分化途径，其特征在于出现具有非典型细长形态的cAMP抗性细胞。这些观察结果表明，TBP和TAFII 135的适当定时的蛋白水解是正常F9细胞分化所必需的。因此，除了反式激活因子外，基础转录因子的靶向蛋白水解在响应生理刺激的基因调控中也起重要作用。
Treatment of mouse F9 embryonal carcinoma cells with all-trans retinoic acid (T-RA) induces differentiation into primitive endodermal type cells. Differentiation requires the action of the receptors for all trans, and 9cis-retinoic acid (RAR and RXR, respectively) and is accompanied by growth inhibition, changes in cell morphology, increased apoptosis, proteolytic degradation of the RARγ2 receptor, and induction of target genes. We show that the RNA polymerase II transcription factor TFIID subunits TBP and TAFII135 are selectively depleted in extracts from differentiated F9 cells. In contrast, TBP and TAFII135 are readily detected in extracts from differentiated F9 cells treated with proteasome inhibitors showing that their disappearance is due to targeted proteolysis. This regulatory pathway is not limited to F9 cells as it is also seen when C2C12 myoblasts differentiate into myotubes. Targeting of TBP and TAFII135 for proteolysis in F9 cells takes place coordinately with that previously reported for the RARγ2 receptor and is delayed or does not take place in RAR mutant F9 cells where differentiation is known to be impaired or abolished. Moreover, ectopic expression of TAFII135 delays proteolysis of the RARγ2 receptor and impairs primitive endoderm differentiation at an early stage as evidenced by cell morphology, induction of marker genes and apoptotic response. In addition, enhanced TAFII135 expression induces a novel differentiation pathway characterised by the appearance of cells with an atypical elongated morphology which are cAMP resistant. These observations indicate that appropriately timed proteolysis of TBP and TAFII135 is required for normal F9 cell differentiation. Hence, in addition to transactivators, targeted proteolysis of basal transcription factors also plays an important role in gene regulation in response to physiological stimuli.