A proteogenomic view of Parkinson's disease causality and heterogeneity.

The pathogenesis and clinical heterogeneity of Parkinson's disease (PD) have been evaluated from molecular, pathophysiological, and clinical perspectives. High-throughput proteomic analysis of cerebrospinal fluid (CSF) opened new opportunities for scrutinizing this heterogeneity. To date, this is the most comprehensive CSF-based proteomics profiling study in PD with 569 patients (350 idiopathic patients, 65 GBA + mutation carriers and 154 LRRK2 + mutation carriers), 534 controls, and 4135 proteins analyzed. Combining CSF aptamer-based proteomics with genetics we determined protein quantitative trait loci (pQTLs). Analyses of pQTLs together with summary statistics from the largest PD genome wide association study (GWAS) identified 68 potential causal proteins by Mendelian randomization. The top causal protein, GPNMB, was previously reported to be upregulated in the substantia nigra of PD patients. We also compared the CSF proteomes of patients and controls. Proteome differences between GBA + patients and unaffected GBA + controls suggest degeneration of dopaminergic neurons, altered dopamine metabolism and increased brain inflammation. In the LRRK2 + subcohort we found dysregulated lysosomal degradation, altered alpha-synuclein processing, and neurotransmission. Proteome differences between idiopathic patients and controls suggest increased neuroinflammation, mitochondrial dysfunction/oxidative stress, altered iron metabolism and potential neuroprotection mediated by vasoactive substances. Finally, we used proteomic data to stratify idiopathic patients into "endotypes". The identified endotypes show differences in cognitive and motor disease progression based on previously reported protein-based risk scores.Our findings not only contribute to the identification of new therapeutic targets but also to shape personalized medicine in CNS neurodegeneration.

Immunohistochemical localization of the calcitonin gene-related peptide binding site in the primate trigeminovascular system using functional antagonist antibodies.

Calcitonin gene-related peptide (CGRP) is a potent vasodilator and a neuromodulator implicated in the pathophysiology of migraine. It binds to the extracellular domains of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein (RAMP) 1 that together form the CGRP receptor. Antagonist antibodies against CGRP and its binding site at the receptor are clinically effective in preventing migraine attacks. The blood-brain barrier penetration of these antagonist antibodies is limited, suggesting that a potential peripheral site of action is sufficient to prevent migraine attacks. To further understand the sites of CGRP-mediated signaling in migraine, we used immunohistochemical staining with recently developed antagonist antibodies specifically recognizing a fusion protein of the extracellular domains of RAMP1 and CLR that comprise the CGRP binding pocket at the CGRP receptor in monkey and man. We confirmed binding of the antagonist antibodies to human vascular smooth muscle cells (VSMCs) of dural meningeal arteries and neurons in the trigeminal ganglion, both of which are likely sites of action for therapeutic antibodies in migraine patients. We further used one of these antibodies for detailed mapping on cynomolgus monkey tissue and found antagonist antibody binding sites at multiple levels in the trigeminovascular system: in the dura mater VSMCs, in neurons and satellite glial cells in the trigeminal ganglion, and in neurons in the spinal trigeminal nucleus caudalis. These data reinforce and clarify our understanding of CGRP receptor localization in a pattern consistent with a role for CGRP receptors in trigeminal sensitization and migraine pathology.

Discovery of Novel Imidazo[4,5-b]pyridines as Potent and Selective Inhibitors of Phosphodiesterase 10A (PDE10A).

We report the discovery of novel imidazo[4,5-b]pyridines as potent and selective inhibitors of PDE10A. The investigation began with our recently disclosed ketobenzimidazole 1, which exhibited single digit nanomolar PDE10A activity but poor oral bioavailability. To improve oral bioavailability, we turned to novel scaffold imidazo[4,5-b]pyridine 2, which not only retained nanomolar PDE10A activity but was also devoid of the morpholine metabolic liability. Structure-activity relationship studies were conducted systematically to examine how various regions of the molecule impacted potency. X-ray cocrystal structures of compounds 7 and 24 in human PDE10A helped to elucidate the key bonding interactions. Five of the most potent and structurally diverse imidazo[4,5-b]pyridines (4, 7, 12b, 24a, and 24b) with PDE10A IC50 values ranging from 0.8 to 6.7 nM were advanced into receptor occupancy studies. Four of them (4, 12b, 24a, and 24b) achieved 55-74% RO at 10 mg/kg po.