Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA.
Division of Research and Development, Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA.
J Alzheimers Dis. 2021;84(4):1747-1762. doi: 10.3233/JAD-215124.
Doublecortin (DCX), a microtubule associated protein, has emerged as a central biomarker of hippocampal neurogenesis. However, molecular mechanisms by which DCX is regulated are poorly understood.
Since sleep is involved with the acquisition of memory and oleamide or 9-Octadecenamide (OCT) is a sleep-inducing supplement in human, we examined whether OCT could upregulate DCX in hippocampal progenitor cells (HPCs).
We employed real-time PCR, western blot, immunostaining, chromatin immunoprecipitation, lentiviral transduction in HPCs, and the calcium influx assay.
OCT directly upregulated the transcription of Dcx in HPCs via activation of peroxisome proliferator-activated receptor α (PPARα), a lipid-lowering transcription factor. We observed that, HPCs of Ppara-null mice displayed significant impairment in DCX expression and neuronal differentiation as compared to that of wild-type mice. Interestingly, treatment with OCT stimulated the differentiation process of HPCs in wild-type, but not Ppara-null mice. Reconstruction of PPARα in mouse Ppara-null HPCs restored the expression of DCX, which was further stimulated with OCT treatment. In contrast, a dominant-negative mutant of PPARα significantly attenuated the stimulatory effect of OCT on DCX expression and suppressed neuronal differentiation of human neural progenitor cells. Furthermore, RNA microarray, STRING, chromatin immunoprecipitation, site-directed mutagenesis, and promoter reporter assay have identified DCX as a new target of PPARα.
These results indicate that OCT, a sleep supplement, directly controls the expression of DCX and suggest that OCT may be repurposed for stimulating the hippocampal neurogenesis.
双皮质素 (DCX) 是一种微管相关蛋白，已成为海马神经发生的核心生物标志物。然而，调控 DCX 的分子机制还知之甚少。
由于睡眠与记忆的获得有关，而油酸酰胺或 9-十八碳烯酰胺 (OCT) 是人类诱导睡眠的补充剂，我们研究了 OCT 是否可以上调海马祖细胞 (HPCs) 中的 DCX。
我们采用实时 PCR、western blot、免疫染色、染色质免疫沉淀、HPCs 中的慢病毒转导和钙内流测定。
OCT 通过激活过氧化物酶体增殖物激活受体 α (PPARα) 直接上调 HPCs 中 Dcx 的转录，PPARα 是一种降脂转录因子。我们观察到，与野生型小鼠相比，Ppara 敲除小鼠的 HPCs 中 DCX 表达和神经元分化明显受损。有趣的是，与野生型小鼠相比，OCT 处理刺激了 Ppara 敲除小鼠的 HPC 分化过程。在 Ppara 敲除小鼠的 HPCs 中重建 PPARα 恢复了 DCX 的表达，OCT 处理进一步刺激了其表达。相反，PPARα 的显性负突变显著减弱了 OCT 对 DCX 表达的刺激作用，并抑制了人神经祖细胞的神经元分化。此外，RNA 微阵列、STRING、染色质免疫沉淀、定点突变和启动子报告基因测定已将 DCX 鉴定为 PPARα 的新靶标。
这些结果表明，作为睡眠补充剂的 OCT 直接控制 DCX 的表达，并表明 OCT 可能被重新用于刺激海马神经发生。
