Dafachronic acids (DAs) are 3-keto cholestenoic acids bearing a carboxylic acid moiety at the end of the steroid side chain. These compounds interact with the DAF-12 receptor, a ligand-dependent transcription factor that acts as a molecular switch mediating the choice between arrest at diapause or progression to reproductive development and adult lifespan in different nematodes. Recently, we reported that the 27-nor-Δ4-DA was able to directly activate DAF-12 in a transactivation cell-based luciferase assay and rescued the Mig phenotype of daf-9(rh50) Caenorhabditis elegans mutants. In the present paper, to investigate further the relationship between the structure of the steroid side chain and DAF-12 activity, we evaluated the in vitro and in vivo activity of Δ4-DA analogues with modified side chains using transactivation cell-based assays and daf-9(dh6) C. elegans mutants. Our results revealed that introduction of a 24,25-double bond on the cholestenoic acid side chain did not affect DAF-12 activity, whereas shortening the side chain lowered the activity. Most interestingly, the C24 alcohol 24-hydroxy-4-cholen-3-one (6) was an antagonist of the DAF-12 receptor both in vitro and in vivo.
达菲酸(DAs)是一种 3-酮胆甾烯酸,其甾体侧链末端含有一个羧酸分子。这些化合物与 DAF-12 受体相互作用,DAF-12 受体是一种配体依赖性转录因子,在不同线虫中充当介导停滞于休眠期或生殖发育和成虫寿命之间选择的分子开关。最近,我们报道了 27-nor-Δ4-DA 能够在基于荧光素酶的转录激活细胞实验中直接激活 DAF-12,并能挽救 daf-9(rh50) Caenorhabditis elegans 突变体的 Mig 表型。在本文中,为了进一步研究类固醇侧链结构与 DAF-12 活性之间的关系,我们使用基于转录激活细胞的检测方法和 daf-9(dh6) C. elegans 突变体评估了具有修饰侧链的Δ4-DA 类似物的体外和体内活性。我们的研究结果表明,在胆甾烯酸侧链上引入 24、25-双键不会影响 DAF-12 的活性,而缩短侧链则会降低其活性。最有趣的是,C24 醇 24-hydroxy-4-cholen-3-one (6) 在体外和体内都是 DAF-12 受体的拮抗剂。