The mitochondrial uniporter is a highly selective calcium channel in the organelle’s inner membrane. Its molecular components include the EF-hand containing proteins mitochondrial calcium uptake 1 (MICU1) and MICU2 and the pore forming subunit mitochondrial calcium uniporter (MCU). We sought to achieve a full molecular characterization of the uniporter holocomplex (uniplex). Quantitative mass spectrometry of affinity-purified uniplex recovered MICU1 and MICU2, MCU and its paralog MCUb, and essential MCU regulator (EMRE), a previously uncharacterized protein. EMRE is a 10 kD, metazoan specific protein with a single transmembrane domain. In its absence, uniporter channel activity was lost despite intact MCU expression and oligomerization. EMRE was required for the interaction of MCU with MICU1 and MICU2. Hence, EMRE is essential for in vivo uniporter current and additionally bridges the calcium-sensing role of MICU1 and MICU2 with the calcium conducting role of MCU.

In our population-based analysis of chronic liver disease mortality in the United States, the decrease in HCV-related mortality coincided with the introduction of direct-acting antiviral therapies, whereas mortality from ALD and nonalcoholic fatty liver disease increased during the same period. Minorities in the United States have disproportionately higher mortality related to chronic liver disease.

Cirrhosis- and HCC-related mortality rates increased between 2007 and 2016 in the US. However, mortality rates in HCV-cirrhosis demonstrated a significant decline from 2014-2016, during the direct-acting antiviral era. Mortality rates for ALD/NAFLD-cirrhosis and HCC have continued to increase, while HBV-cirrhosis-related mortality declined during the 10-year period. Importantly, minorities had a disproportionately higher burden of ESLD-related mortality. This article is protected by copyright. All rights reserved.

Background and Aims In general, physical activity (PA) and nonalcoholic fatty liver disease (NAFLD) have an inverse association. However, studies assessing the impact of the widely accepted Physical Activity Guidelines for Americans (PA Guidelines) on NAFLD are lacking. Approach and Results We performed a serial, cross‐sectional analysis among adults by using the 2007‐2016 US National Health and Nutrition Examination Survey. NAFLD and advanced fibrosis were defined by using various noninvasive panels. A PA questionnaire assessed the leisure‐time PA, occupation‐related PA, transportation‐related PA, and total sitting time as sedentary behavior. PA was categorized according to the PA Guidelines. Of the 24,588 individuals (mean age, 47.4 years; 47.9% males), leisure‐time PA (≥150 minutes per week) demonstrated 40% lower odds of NAFLD, whereas transportation‐related PA was associated with a 33% risk reduction in NAFLD. Analysis of total PA and sitting times simultaneously showed a dose‐response association between sitting time and NAFLD (P for trend < 0.001). Compliance with the PA Guidelines was lower in individuals with NAFLD versus those without NAFLD. The trends in compliance with the PA Guidelines for any type of PA remained stable in individuals with NAFLD except for a downtrend in transportation‐related PA. In contrast, an improvement in compliance with the PA Guidelines for leisure time was noted in the cohort without NAFLD. Although PA demonstrated a 10% stronger association with risk reduction of NAFLD in women, women showed a lower tendency of meeting the PA Guidelines. Trends in total sitting time increased significantly regardless of NAFLD status. Conclusions Sedentary behavior emerged as an independent predictor of NAFLD. Overall compliance with the PA Guidelines was lower in the cohort with NAFLD, with sex‐ and ethnicity‐based differences. Implementation of these observations in clinical practice may improve our understanding as well as clinical outcomes.