Glucosylceramide synthase inhibition alleviates aberrations in synucleinopathy models.

Mutations in the glucocerebrosidase gene (GBA) confer a heightened risk of developing Parkinson's disease (PD) and other synucleinopathies, resulting in a lower age of onset and exacerbating disease progression. However, the precise mechanisms by which mutations in GBA increase PD risk and accelerate its progression remain unclear. Here, we investigated the merits of glucosylceramide synthase (GCS) inhibition as a potential treatment for synucleinopathies. Two murine models of synucleinopathy (a Gaucher-related synucleinopathy model, GbaD409V/D409V and a A53T-α-synuclein overexpressing model harboring wild-type alleles of GBA, A53T-SNCA mouse model) were exposed to a brain-penetrant GCS inhibitor, GZ667161. Treatment of GbaD409V/D409V mice with the GCS inhibitor reduced levels of glucosylceramide and glucosylsphingosine in the central nervous system (CNS), demonstrating target engagement. Remarkably, treatment with GZ667161 slowed the accumulation of hippocampal aggregates of α-synuclein, ubiquitin, and tau, and improved the associated memory deficits. Similarly, prolonged treatment of A53T-SNCA mice with GZ667161 reduced membrane-associated α-synuclein in the CNS and ameliorated cognitive deficits. The data support the contention that prolonged antagonism of GCS in the CNS can affect α-synuclein processing and improve behavioral outcomes. Hence, inhibition of GCS represents a disease-modifying therapeutic strategy for GBA-related synucleinopathies and conceivably for certain forms of sporadic disease.

In silico genomic analysis of the human and murine guanylate-binding protein (GBP) gene clusters.

The guanylate-binding proteins (GBPs) were among the first interferon (IFN)-stimulated genes (ISGs) discovered, but until recently, little was known about their functions and even less about the composition of the gene family. Analysis of the promoter of human GBP-1 contributed significantly toward the understanding of Jak-Stat signaling and the delineation of the IFN-gamma activation site (GAS) and IFN-stimulated response element (ISRE) promoter elements. In this study, we have examined the genomic arrangement and composition of the GBPs in both mouse and humans. There are seven GBP paralogs in humans and at least one pseudogene, all of which are located in a cluster of genes on chromosome 1. Five of the six MuGBPs and a GBP pseudogene are clustered in a syntenic region on chromosome 3. The sixth MuGBP, MuGBP-4, and three GBP pseudogenes are located on chromosome 5. As might be expected, the GBPs share similar genomic organizations of introns and exons. Five of the MuGBPs had previously been shown to be coordinately induced by IFNs, and as expected, all of the MuGBPs have GAS and ISRE elements in their promoters. Interestingly, not all of the HuGBPs have GAS and ISRE elements, suggesting that not all GBPs are IFN responsive in humans.