Improving cell-specific recombination using AAV vectors in the murine CNS by capsid and expression cassette optimization.

The production of cell-type- and age-specific genetically modified mice is a powerful approach for unraveling unknown gene functions. Here, we present a simple and timesaving method that enables adeno-associated virus (AAV)-mediated cell-type- and age-specific recombination in floxed mice. To achieve astrocyte-specific recombination in floxed Ai14 reporter mice, we intravenously injected blood-brain barrier-penetrating AAV-PHP.eB vectors expressing Cre recombinase (Cre) using the astrocyte-specific mouse glial fibrillary acidic protein (mGfaABC1D) promoter. However, we observed nonspecific neuron-predominant transduction despite the use of an astrocyte-specific promoter. We speculated that subtle but continuous Cre expression in nonastrocytic cells triggers recombination, and that excess production of Cre in astrocytes inhibits recombination by forming Cre-DNA aggregates. Here, we resolved this paradoxical event by dividing a single AAV into two mGfaABC1D-promoter-driven AAV vectors, one expressing codon-optimized flippase (FlpO) and another expressing flippase recognition target-flanked rapidly degrading Cre (dCre), together with switching the neuron-tropic PHP.eB capsid to astrocyte-tropic AAV-F. Moreover, we found that the FlpO-dCre system with a target cell-tropic capsid can also function in neuron-targeting recombination in floxed mice.

Maternal n-7 Unsaturated Fatty Acids Protect the Fetal Brain from Neuronal Degeneration in an Intrauterine Hyperglycemic Animal Model.

We previously reported that glycation induces insulin resistance in the hearts of newborn pups from a gestational diabetes mellitus (GDM) rat model. Administration of n-3 unsaturated fatty acids suppressed glycation and improved signaling in GDM rat pups. In this study, we investigated their effects on cranial neurons using the GDM rat model and PC12 cells derived from rat adrenal pheochromocytomas. Additionally, we examined whether n-3 and n-7 unsaturated fatty acids (cis-palmitoleic acid [CPA] and trans-palmitoleic acid [TPA]) ameliorate the detrimental effects of high glucose exposure on rats. In the neonatal cerebrum of GDM rats, increased levels of advanced glycation end products (AGEs) inhibited Akt phosphorylation; however, CPA and TPA intake during pregnancy ameliorated these abnormalities. Furthermore, exposure to high-glucose-induced apoptosis in PC12 cells compared to the cells cultured in control glucose. PC12 cells exposed to high-glucose with fatty acids exhibited reduced AGE production and apoptosis induction compared to the high-glucose group. These findings suggest that a hyperglycemic environment during pregnancy promotes AGE formation in brain neuronal proteins and induces apoptosis. Both TPA and CPA mitigated these abnormalities; however, CPA is cytotoxic, highlighting its safety in pregnant women.