The ADNP-Mediated Transcriptome Response to Ketamine Impairs the Cytoskeletal Protein Axis.

De novo variants in the Activity-Dependent Neuroprotective Protein (ADNP) gene cause the autistic Helsmoortel-Van der Aa syndrome with patients showing mild to disastrous phenotypes impacting brain functioning, behavior, and organ functions. In this respect, two treatment strategies have been proposed to alleviate symptoms in patients with this syndrome: (1) the ADNP-derived octapeptide investigational drug NAP (davunetide), which enhances ADNP's ability to target cytoskeletal deficits, and (2) subnarcotic levels of ketamine, which are suggested to increase endogenous ADNP mRNA levels. Here, we focus on the perspective of ketamine and investigated the transcriptomic response of low-dose and high-dose ketamine applications at different time points, experimentally controlled by the non-toxic drug NAP, in lymphoblastoid cell lines obtained from individuals with Helsmoortel-Van der Aa syndrome. Transcriptome profiling was performed at baseline conditions, followed by dose (low or high) and time (40 min or 4 h)-dependent ketamine application in patient and control lymphoblastoid cell lines. We showed that ketamine affected ADNP expression levels in a dose- and time-dependent manner with only toxic ketamine concentrations increasing ADNP protein levels. Ketamine application also triggered a transcriptomic response with profound gene expression alterations centered around processes such as immune response-regulating signaling pathways and cell fate commitment at low-dose ketamine, together with organelle assembly and cytoskeletal dysregulation at high doses. A parallel control experiment with NAP under the same experimental conditions did not induce detectable gene expression differences in patient-derived cell lines. The ketamine-induced cytoskeletal alterations were functionally studied using immunoblotting, showing a disturbed expression of α-tubulin, β-actin, and to a minor extent microtubule-associated protein EB3 in patient-derived lymphoblastoid cells. Ketamine upregulates wild-type ADNP transcript and protein levels in a dose- and time-dependent manner in patient-derived lymphoblastoid cell lines from individuals with Helsmoortel-Van der Aa syndrome, while inducing a transcriptomic response that affects key processes including immune system signaling and cytoskeletal organization.