KRAS-MEK Signaling Controls Ago2 Sorting into Exosomes.
Secretion of RNAs in extracellular vesicles is a newly recognized form of intercellular communication. A potential regulatory protein for microRNA (miRNA) secretion is the critical RNA-induced silencing complex (RISC) component Argonaute 2 (Ago2). Here, we use isogenic colon cancer cell lines to show that overactivity of KRAS due to mutation inhibits localization of Ago2 to multivesicular endosomes (MVEs) and decreases Ago2 secretion in exosomes. Mechanistically, inhibition of mitogen-activated protein kinase kinases (MEKs) I and II, but not Akt, reverses the effect of the activating KRAS mutation and leads to increased Ago2-MVE association and increased exosomal secretion of Ago2. Analysis of cells expressing mutant Ago2 constructs revealed that phosphorylation of Ago2 on serine 387 prevents Ago2-MVE interactions and reduces Ago2 secretion into exosomes. Furthermore, regulation of Ago2 exosomal sorting controls the levels of three candidate miRNAs in exosomes. These data identify a key regulatory signaling event that controls Ago2 secretion in exosomes.
Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Andrew J
AJ
McKenzie
Division of Cancer Cell Research, Kanagawa Cancer Center, Yokohama 241-8515, Japan.
Daisuke
D
Hoshino
Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Nan Hyung
NH
Hong
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.
Diana J
DJ
Cha
Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Veterans Affairs Medical Center, Nashville, TN 37232, USA.
Jeffrey L
JL
Franklin
Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Veterans Affairs Medical Center, Nashville, TN 37232, USA.
Robert J
RJ
Coffey
Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA.
James G
JG
Patton
Department of Cancer Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA. Electronic address: alissa.weaver@vanderbilt.edu.
Alissa M
AM
Weaver
D060565:Argonaute Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D055354:Exosomes / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D057146:Multivesicular Bodies / Q000378:metabolism; D050505:Mutant Proteins / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D021381:Protein Transport; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
C466422:AGO2 protein, human; D060565:Argonaute Proteins; C117307:KRAS protein, human; D035683:MicroRNAs; D050505:Mutant Proteins; C487931:mirnlet7 microRNA, human; D010768:Phosphoserine; D020929:Mitogen-Activated Protein Kinase Kinases; D016283:Proto-Oncogene Proteins p21(ras)
Argonaute; exosomes; extracellular RNA; extracellular vesicles; miRNA; signaling