Ottawa Hospital Research Institute (Neuroscience), Ottawa Brain and Mind Research Institute, 451 Smyth Road, Ottawa, ON K1H-8M5, Canada.
Int J Mol Sci. 2024 Jun 4;25(11):6194. doi: 10.3390/ijms25116194.
Calcium calmodulin-dependent protein kinase (CaMK) mediates calcium-induced neural gene activation. CaMK also inhibits the non-syndromic intellectual disability gene, Freud-1/CC2D1A, a transcriptional repressor of human serotonin-1A (5-HT1A) and dopamine-D2 receptor genes. The altered expression of these Freud-1-regulated genes is implicated in mental illnesses such as major depression and schizophrenia. We hypothesized that Freud-1 is blocked by CaMK-induced phosphorylation. The incubation of purified Freud-1 with either CaMKIIα or CaMKIV increased Freud-1 phosphorylation that was partly prevented in Freud-1-Ser644Ala and Freud-1-Thr780Ala CaMK site mutants. In human SK-N-SH neuroblastoma cells, active CaMKIV induced the serine and threonine phosphorylation of Freud-1, and specifically increased Freud-1-Thr780 phosphorylation in transfected HEK-293 cells. The activation of purified CaMKIIα or CaMKIV reduced Freud-1 binding to its DNA element on the 5-HT1A and dopamine-D2 receptor genes. In SK-N-SH cells, active CaMKIV but not CaMKIIα blocked the Freud-1 repressor activity, while Freud-1 Ser644Ala, Thr780Ala or dual mutants were resistant to inhibition by activated CaMKIV or calcium mobilization. These results indicate that the Freud-1 repressor activity is blocked by CaMKIV-induced phosphorylation at Thr780, resulting in the up-regulation of the target genes, such as the 5-HT1A receptor gene. The CaMKIV-mediated inhibition of Freud-1 provides a novel de-repression mechanism to induce 5-HT1A receptor expression for the regulation of cognitive development, behavior and antidepressant response.
钙调蛋白依赖性蛋白激酶（CaMK）介导钙诱导的神经基因激活。CaMK 还抑制非综合征性智力残疾基因 Freud-1/CC2D1A，它是人类 5-羟色胺-1A（5-HT1A）和多巴胺-D2 受体基因的转录抑制剂。这些 Freud-1 调节基因的表达改变与重度抑郁症和精神分裂症等精神疾病有关。我们假设 Freud-1 被 CaMK 诱导的磷酸化所阻断。纯化的 Freud-1 与 CaMKIIα 或 CaMKIV 孵育会增加 Freud-1 的磷酸化，而 Freud-1-Ser644Ala 和 Freud-1-Thr780Ala CaMK 位点突变体部分阻止了磷酸化。在人类 SK-N-SH 神经母细胞瘤细胞中，活性 CaMKIV 诱导 Freud-1 的丝氨酸和苏氨酸磷酸化，并且在转染的 HEK-293 细胞中特异性增加 Freud-1-Thr780 磷酸化。纯化的 CaMKIIα 或 CaMKIV 的激活降低了 Freud-1 与其 DNA 元件在 5-HT1A 和多巴胺-D2 受体基因上的结合。在 SK-N-SH 细胞中，活性 CaMKIV 而不是 CaMKIIα 阻断了 Freud-1 抑制活性，而 Freud-1 Ser644Ala、Thr780Ala 或双突变体对激活的 CaMKIV 或钙动员的抑制具有抗性。这些结果表明，CaMKIV 诱导的 Thr780 磷酸化阻断了 Freud-1 抑制剂的活性，导致靶基因（如 5-HT1A 受体基因）的上调。CaMKIV 介导的 Freud-1 抑制提供了一种新的去抑制机制，以诱导 5-HT1A 受体表达，从而调节认知发育、行为和抗抑郁反应。
