AAV-delivery of diacylglycerol kinase kappa achieves long-term rescue of Fmr1-KO mouse model deficits of fragile X syndrome

Fragile X syndrome (FXS) is the most frequent form of familial intellectual disability. It results from the lack of the RNA binding protein FMRP and is associated with the overactivation of signaling pathways downstream of mGluRI receptors and upstream of mRNA translation. We previously found that diacylglycerol kinase kappa (DGKk) is a main mRNA target of FMRP in cortical neurons. Here we show that diacylglycerol kinase kappa (DGKk), when modified as to become FMRP-independent and delivered into the brain of adolescent mice using adeno-associated viral vectors, corrects brain diacylglycerol and phosphatidic acid homeostasis and the main phenotypic behaviors of the Fmr1-KO mouse model of FXS. Thus, DGKk appears as a key triggering factor of FXS pathomechanism while providing a possible means of intervention for FXS gene therapy. One sentence summary DGKk gene therapy in Fmr1 -KO mouse model ### Competing Interest Statement HM and RT are listed as inventors on a patent describing the AAV construct reported in this manuscript. M.H., and R.L. are full-time employees and hold equity in Lysogene. All other authors declare no competing interests.