Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India.
Biochemistry. 2010 Mar 23;49(11):2389-97. doi: 10.1021/bi1001536.
Sphingolipids are essential components of eukaryotic cell membranes and are thought to be involved in a variety of cellular functions. Mycotoxins such as fumonisins can disrupt sphingolipid metabolism, and treatment with fumonisins represents an efficient approach to modulate cellular sphingolipid levels. In this work, we modulated sphingolipid levels in CHO cells stably expressing the human serotonin(1A) receptor by metabolically inhibiting the biosynthesis of sphingolipids using fumonisin B(1). Serotonin(1A) receptors belong to the family of seven-transmembrane domain receptors that couple to G-proteins and are implicated in the generation and modulation of various cognitive, behavioral, and developmental functions. We explored the function of serotonin(1A) receptors under sphingolipid-depleted conditions by monitoring ligand binding, G-protein coupling, and downstream signaling of the receptor. Importantly, our results show that the function of the serotonin(1A) receptor is impaired upon metabolic depletion of sphingolipids, although the membrane receptor level does not exhibit any reduction. Interestingly, we find that the replenishment of sphingolipids using sphingosine results in restoration of ligand binding of serotonin(1A) receptors, demonstrating that the loss of ligand binding due to metabolic depletion of sphingolipids is reversible. These novel results demonstrate that sphingolipids are necessary for ligand binding and downstream signaling of the human serotonin(1A) receptor. We discuss possible mechanisms of specific interaction of sphingolipids with the serotonin(1A) receptor that could involve the proposed "sphingolipid-binding domain" (SBD).
鞘脂是真核细胞膜的重要组成部分，被认为参与多种细胞功能。真菌毒素如伏马菌素可以破坏鞘脂代谢，用伏马菌素处理代表了一种调节细胞鞘脂水平的有效方法。在这项工作中，我们通过用伏马菌素 B1 代谢抑制鞘脂的生物合成来调节稳定表达人 5-羟色胺 (1A) 受体的 CHO 细胞中的鞘脂水平。5-羟色胺 (1A) 受体属于七跨膜域受体家族，与 G 蛋白偶联，与各种认知、行为和发育功能的产生和调节有关。我们通过监测配体结合、G 蛋白偶联和受体下游信号来探索在鞘脂耗尽条件下 5-羟色胺 (1A) 受体的功能。重要的是，我们的结果表明，尽管膜受体水平没有任何降低，但在鞘脂代谢耗尽的情况下，5-羟色胺 (1A) 受体的功能受损。有趣的是，我们发现使用鞘氨醇补充鞘脂可恢复 5-羟色胺 (1A) 受体的配体结合，表明由于鞘脂代谢耗尽导致的配体结合丧失是可逆的。这些新的结果表明，鞘脂是人类 5-羟色胺 (1A) 受体配体结合和下游信号传导所必需的。我们讨论了鞘脂与 5-羟色胺 (1A) 受体特异性相互作用的可能机制，这可能涉及拟议的“鞘脂结合域”（SBD）。
