Abstract
Macroautophagy (autophagy) is the major intracellular degradation pathway for long-lived proteins and organelles. It helps the cell to survive a spectrum of stressful conditions including starvation, growth factor deprivation and misfolded protein accumulation. Moreover, abnormalities of autophagy play a role in major health problems including cancer and neurodegenerative diseases. Yet, mechanisms controlling autophagic activity are not fully understood. Here, we describe hsa-miR-376b (miR-376b) as a new microRNA (miRNA) regulating autophagy. We showed that miR-376b expression attenuated starvation- and rapamycin-induced autophagy in MCF-7 and Huh-7 cells. We discovered autophagy proteins ATG4C and BECN1 (Beclin 1) as cellular targets of miR-376b. Indeed, upon miRNA overexpression, both mRNA and protein levels of ATG4C and BECN1 were decreased. miR-376b target sequences were present in the 3' UTR of ATG4C and BECN1 mRNAs and introduction of mutations abolished their miR-376b responsiveness. Antagomir-mediated inactivation of the endogenous miR-376b led to an increase in ATG4C and BECN1 levels. Therefore, miR-376b controls autophagy by directly regulating intracellular levels of two key autophagy proteins, ATG4C and BECN1.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3' Untranslated Regions / genetics
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Adaptor Proteins, Signal Transducing / metabolism
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Apoptosis Regulatory Proteins / genetics
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Apoptosis Regulatory Proteins / metabolism*
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Autophagy* / drug effects
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Autophagy-Related Proteins
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Base Sequence
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Beclin-1
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Cell Line, Tumor
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Cysteine Endopeptidases / genetics
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Cysteine Endopeptidases / metabolism*
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Gene Expression Regulation, Neoplastic / drug effects
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Humans
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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MicroRNAs / genetics
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MicroRNAs / metabolism*
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Models, Biological
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Molecular Sequence Data
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Oligoribonucleotides / pharmacology
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Proteolysis / drug effects
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Response Elements / genetics
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Sequestosome-1 Protein
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Sirolimus / pharmacology
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Starvation
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TOR Serine-Threonine Kinases / antagonists & inhibitors*
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TOR Serine-Threonine Kinases / metabolism
Substances
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3' Untranslated Regions
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Adaptor Proteins, Signal Transducing
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Apoptosis Regulatory Proteins
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Autophagy-Related Proteins
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BECN1 protein, human
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Beclin-1
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MIRN376C microRNA, human
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Membrane Proteins
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MicroRNAs
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Oligoribonucleotides
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RNA, Messenger
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SQSTM1 protein, human
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Sequestosome-1 Protein
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MTOR protein, human
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TOR Serine-Threonine Kinases
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ATG4A protein, human
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Cysteine Endopeptidases
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Sirolimus