Max-Planck-Institut für Biologie, Tübingen, Germany.
Pharmazeutisches Institut der Universität Tübingen, Tübingen, Germany.
Cell Signal. 2022 Sep;97:110396. doi: 10.1016/j.cellsig.2022.110396. Epub 2022 Jul 2.
Nine mammalian adenylyl cyclases (AC) are pseudoheterodimers with two hexahelical membrane domains, which are isoform-specifically conserved. Previously we proposed that these membrane domains are orphan receptors (https://doi.org/10.7554/eLife.13098; https://doi.org/10.1016/j.cellsig.2020.109538). Lipids extracted from fetal bovine serum at pH 1 inhibited several mAC activities. Guided by a lipidomic analysis we tested glycerophospholipids as potential ligands. Contrary to expectations we surprisingly discovered that 1-stearoyl-2-docosahexaenoyl-phosphatidic acid (SDPA) potentiated Gsα-activated activity of human AC isoform 3 seven-fold. The specificity of fatty acyl esters at glycerol positions 1 and 2 was rather stringent. 1-Stearoyl-2-docosahexaenoyl-phosphatidylserine and 1-stearoyl-2-docosahexaenoyl-phosphatidylethanolamine significantly potentiated several Gsα-activated mAC isoforms to different extents. SDPA appears not interact with forskolin activation of AC isoform 3. SDPA enhanced Gsα-activated AC activities in membranes from mouse brain cortex. The action of SDPA was reversible. Unexpectedly, SDPA did not affect cAMP generation in HEK293 cells stimulated by isoproterenol, PGE and adenosine, virtually excluding a role as an extracellular ligand and, instead, suggesting an intracellular role. In summary, we discovered a new dimension of intracellular AC regulation by chemically defined glycerophospholipids.
九种哺乳动物的腺苷酸环化酶（AC）是具有两个六螺旋膜结构域的假异源二聚体，这些结构域在同种型特异性上是保守的。我们之前提出这些膜结构域是孤儿受体（https://doi.org/10.7554/eLife.13098；https://doi.org/10.1016/j.cellsig.2020.109538）。在 pH 值为 1 的胎牛血清中提取的脂质会抑制几种 mAC 的活性。在脂质组学分析的指导下，我们测试了甘油磷脂作为潜在的配体。出乎意料的是，我们发现 1-硬脂酰-2-二十二碳六烯酰基-磷酸酰基甘油（SDPA）可使人类 AC 同工型 3 的 Gsα 激活活性增强七倍。甘油 1 位和 2 位的脂肪酸酯特异性相当严格。1-硬脂酰-2-二十二碳六烯酰基-磷酸丝氨酸和 1-硬脂酰-2-二十二碳六烯酰基-磷酸乙醇胺显著增强了几种 Gsα 激活的 mAC 同工型的活性，程度不同。SDPA 似乎不与 AC 同工型 3 的福司可林激活相互作用。SDPA 增强了小鼠大脑皮质膜中 Gsα 激活的 AC 活性。SDPA 的作用是可逆的。出乎意料的是，SDPA 不影响异丙肾上腺素、PGE 和腺苷刺激的 HEK293 细胞中环腺苷酸的生成，几乎排除了其作为细胞外配体的作用，相反，提示其具有细胞内作用。总之，我们发现了化学定义的甘油磷脂对细胞内 AC 调节的新维度。
