Mutations inUBQLN2cause amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerations. However, the mechanism by which the UBQLN2 mutations cause disease remains unclear. Alterations in proteins involved in autophagy are prominent in neuronal tissue of human ALSUBQLN2patients and in a transgenic P497S UBQLN2 mouse model of ALS/FTD, suggesting a pathogenic link. Here, we show UBQLN2 functions in autophagy and that ALS/FTD mutant proteins compromise this function. Inactivation of UBQLN2 expression in HeLa cells reduced autophagic flux and autophagosome acidification. The defect in acidification was rescued by reexpression of wild type (WT) UBQLN2 but not by any of the five different UBQLN2 ALS/FTD mutants tested. Proteomic analysis and immunoblot studies revealed P497S mutant mice and UBQLN2 knockout HeLa and NSC34 cells have reduced expression of ATP6v1g1, a critical subunit of the vacuolar ATPase (V-ATPase) pump. Knockout of UBQLN2 expression in HeLa cells decreased turnover of ATP6v1g1, while overexpression of WT UBQLN2 increased biogenesis of ATP6v1g1 compared with P497S mutant UBQLN2 protein. In vitro interaction studies showed that ATP6v1g1 binds more strongly to WT UBQLN2 than to ALS/FTD mutant UBQLN2 proteins. Intriguingly, overexpression of ATP6v1g1 in UBQLN2 knockout HeLa cells increased autophagosome acidification, suggesting a therapeutic approach to overcome the acidification defect. Taken together, our findings suggest that UBQLN2 mutations drive pathogenesis through a dominant-negative loss-of-function mechanism in autophagy and that UBQLN2 functions as an important regulator of the expression and stability of ATP6v1g1. These findings may have important implications for devising therapies to treatUBQLN2-linked ALS/FTD.

Shikonin has been shown to have properties of improving open wound healing, but it is not known whether shikonin is effective in promoting cardiac repair after myocardial infarction (MI). We hypothesize that shikonin can improve wound healing in infarcted hearts. We created MI models by ligating the coronary artery in mice. We treated the infarcted mice with 5 mg/kg of shikonin a day through oral gavage, or the same volume of distilled water was given to the control group. After seven days of treatment, we documented the heart weight and body weight, and the hearts were photographed and the infarct size was measured. The ratio of heart weight to body weight was calculated.We found that the infarct area in treated mice was significantly smaller than in the control group. While there was no significant difference in body weight between the two groups, but the ratio of heart weight to body weight in the treated group was much smaller than in the control group. In conclusion, shikonin was effective in helping wound healing in the heart after MI. Future studies will be directed to further study how shikonin functions at the cellular level and whether it improves cardiac function.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.