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Summary: Translation inhibition is a major but poorly understood mode of action of microRNAs (miRNAs) in plants and animals. In particular, the subcellular location where this process takes place is unknown. Here, we show that the translation inhibition, but not the mRNA cleavage activity, of Arabidopsis miRNAs requires ALTERED MERISTEM PROGRAM1 (AMP1). AMP1 encodes an integral membrane protein associated with endoplasmic reticulum (ER) and ARGONAUTE1, the miRNA effector and a peripheral ER membrane protein. Large differences in polysome association of miRNA target RNAs are found between wild-type and the amp1 mutant for membrane-bound, but not total, polysomes. This, together with AMP1-independent recruitment of miRNA target transcripts to membrane fractions, shows that miRNAs inhibit the translation of target RNAs on the ER. This study demonstrates that translation inhibition is an important activity of plant miRNAs, reveals the subcellular location of this activity, and uncovers a previously unknown function of the ER. PaperClip: Display Omitted [ABSTRACT FROM AUTHOR]

The generation of new adipocytes from precursor cells (adipogenesis) has implications for systemic metabolism and is a commonly used model for studying the process of cell differentiation in vitro. Previous studies from us and others suggested that the peripheral circadian clock can influence adipogenesis in vitro, but the mechanisms driving this activity and the relevance for adipogenesis in vivo are unknown. Here we reveal that mouse adipocyte precursor cells (APCs) contain a circadian clock that oscillates in vivo. We expose context-specific features of the clock in APCs: expression of the canonical core clock component Per1 does not significantly oscillate, whereas the lesser-understood paralog Per3 has a prominent rhythm. We discovered that deletion of Per3 promotes adipogenesis in vivo by a clock output pathway in which PER3 and BMAL1 directly regulate Klf15 expression. These findings demonstrate that Per3 has a major role in the APC clock and regulates adipogenesis in vivo., (Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.)

Mitochondrial dysfunction, inflammation, and mutant bone morphogenetic protein receptor 2 (BMPR2) are associated with pulmonary arterial hypertension (PAH), an incurable disease characterized by pulmonary arterial (PA) endothelial cell (EC) apoptosis, decreased microvessels, and occlusive vascular remodeling. We hypothesized that reduced BMPR2 induces PAEC mitochondrial dysfunction, promoting a pro-inflammatory or pro-apoptotic state. Mice with EC deletion of BMPR2 develop hypoxia-induced pulmonary hypertension that, in contrast to non-transgenic littermates, does not reverse upon reoxygenation and is associated with reduced PA microvessels and lung EC p53, PGC1α and TFAM, regulators of mitochondrial biogenesis, and mitochondrial DNA. Decreasing PAEC BMPR2 by siRNA during reoxygenation represses p53, PGC1α, NRF2, TFAM, mitochondrial membrane potential, and ATP and induces mitochondrial DNA deletion and apoptosis. Reducing PAEC BMPR2 in normoxia increases p53, PGC1α, TFAM, mitochondrial membrane potential, ATP production, and glycolysis, and induces mitochondrial fission and a pro-inflammatory state. These features are recapitulated in PAECs from PAH patients with mutant BMPR2., (Copyright © 2015 Elsevier Inc. All rights reserved.)