Genetic and pathological studies link ␣-synuclein to the etiology of Parkinson's disease (PD), but the normal function of this presynaptic protein remains unknown. ␣-Synuclein, an acidic lipid binding protein, shares high sequence identity with ␤-and ␥-synuclein. Previous studies have implicated synucleins in synaptic vesicle (SV) trafficking, although the precise site of synuclein action continues to be unclear. Here we show, using optical imaging, electron microscopy, and slice electrophysiology, that synucleins are required for the fast kinetics of SV endocytosis. Slowed endocytosis observed in synuclein null cultures can be rescued by individually expressing mouse ␣-, ␤-, or ␥-synuclein, indicating they are functionally redundant. Through comparisons to dynamin knock-out synapses and biochemical experiments, we suggest that synucleins act at early steps of SV endocytosis. Our results categorize ␣-synuclein with other familial PD genes known to regulate SV endocytosis, implicating this pathway in PD.

Synucleins (α, β, γ-synuclein) are a family of abundant presynaptic proteins. α-Synuclein is causally linked to the pathogenesis of Parkinson disease (PD). In an effort to define their physiological and pathological function(s), we investigated the effects of deleting synucleins and overexpressing α-synuclein PD mutations, in mice, on synapse architecture using electron microscopy (EM) and Cryo-Electron Tomography (Cryo-ET). We show that synucleins are regulators of presynapse size and synaptic vesicle (SV) pool organization. Using Cryo-ET, we observed that deletion of synucleins increases SV tethering to the active zone but decreases the inter-linking of SVs by short connectors. These ultrastructural changes were correlated with discrete protein phosphorylation changes in αβγ-synuclein−/− neurons. We also determined that α-synuclein PD mutants (PARK1/hA30P, PARK4/hα-syn) primarily affected presynaptic cytomatrix proximal to the active zone, congruent with previous findings that these PD mutations decrease neurotransmission. Collectively, our results suggest that synucleins are important orchestrators of presynaptic terminal topography.

Preeclampsia (PE) is a complicated obstetric complication characterized by increased blood pressure, decreased trophoblast invasion, and inflammation. The growth arrest-specific 6 (Gas6) protein is known to induce dynamic cellular responses and is elevated in PE. Gas6 binds to the AXL tyrosine kinase receptor and AXL-mediated signaling is implicated in proliferation and migration observed in several tissues. Our laboratory utilized Gas6 to induce preeclamptic-like conditions in pregnant rats. Our objective was to determine the role of Gas6/AXL signaling as a possible model of PE. Briefly, pregnant rats were divided into three groups that received daily intraperitoneal injections (from gestational day 7.5 to 17.5) of phosphate buffered saline (PBS), Gas6, or Gas6 + R428 (an AXL inhibitor administered from gestational day 13.5 to 17.5). Animals dispensed Gas6 experienced elevated blood pressure, increased proteinuria, augmented caspase-3-mediated placental apoptosis, and diminished trophoblast invasion. Gas6 also enhanced expression of several PE-related genes and a number of inflammatory mediators. Gas6 further enhanced placental oxidative stress and impaired mitochondrial respiration. Each of these PE-related characteristics was ameliorated in dams and/or their placentae when AXL inhibition by R428 occurred in tandem with Gas6 treatment. We conclude that Gas6 signaling is capable of inducing PE and that inhibition of AXL prevents disease progression in pregnant rats. These results provide insight into pathways associated with PE that could be useful in the clarification of potential therapeutic approaches.

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The detrimental effects of exposure to tobacco smoke have been confirmed repeatedly over the last several decades. Primary smoking produces the greatest damage; however, secondhand smoke (SHS) is also notably detrimental. More recently the development of electronic cigarettes (eCigs) has introduced a new aspect to the study of smoke exposure. A heating element is used by eCigs to vaporize an oil‐based carrier that contains nicotine and various flavorings. eCig liquid and aerosols have been linked to increased cytotoxicity, inflammation, and production of reactive oxygen species. Negative effects on respiratory health have also been confirmed. Both tobacco smoke and eCig vapor have been found to alter cellular signaling and activate inflammatory responses. Of note, inflammatory pathways include signaling through receptors for advanced glycation end‐products (RAGE). Our objective in this study was to examine effects of acute exposure to eCig vapor compared to SHS in the murine lung. Wild type mice were exposed to vapor containing Apple or Cinnamon flavoring, or to SHS for a period of four days using a nose‐only delivery system (Scireq). Exposure consisted of 30 minutes of eCig vapor or SHS generated by three cigarettes over a period of 30 minutes. Control mice were exposed to room air. Animal use was in accordance with approved IACUC protocols at Brigham Young University. After exposure, lung tissue was collected: the left lung lobe was inflated for histological analysis, and the right lung lobes were snap frozen for protein and RNA analysis. H&E stained lung sections did not show changes in morphology and staining for pulmonary cell types using cell‐specific antibodies (SPC, CCSP, T1a and Fox J1) revealed evidence of cell population alterations potentially explaining increases in pro‐apoptotic cleaved caspase‐3 following exposure. Immunoblotting for RAGE and signaling intermediates activated by RAGE such as NF‐kB and pERK revealed differential expression following eCig or SHS exposure. These results indicate that activation of inflammatory signaling pathways occurs following an acute four‐day exposure. Such signaling in eCig vapor exposed mice has potential to lead to chronic inflammatory disease characteristics with longer exposures potentially leading to chronic obstructive disorders resulting from tobacco smoke exposure. Support or Funding Information This work was supported by a grant from the Flight Attendant’s Medical Research Institute (FAMRI, PRR and JAA) and a BYU Mentoring Environment Grant (JAA and PRR).