title: Regulation of Complement-Dependent Cytotoxicity by MicroRNAs miR-200b, miR-200c, and miR-217.
abstract: The impact of microRNAs (miRNAs) known to regulate numerous biologic processes on complement-dependent cytotoxicity (CDC) was investigated in K562 cells. The C5b-9 complex is the executioner of CDC. Cells protect themselves from CDC by C5b-9 elimination, a process involving the mitochondrial chaperone mortalin/GRP75. Potential miR-200 (b and c) and miR-217 regulatory sites were identified in mortalin mRNA. Overexpression of miR-200b/c or miR-217 lowered the expression of mortalin mRNA. miRNA inhibitors for miR-200b, miR-200c, or miR-217 enhanced mortalin mRNA level. Unexpectedly, these miRNA modulators had no significant effect on mortalin protein level. Metabolic labeling analysis demonstrated that, to compensate for reduction in mortalin mRNA level, the cells increased the rate of synthesis of mortalin protein. Cells overexpressing miR-200b/c or miR-217 showed reduced sensitivity to CDC, whereas inhibition of miR-200c and miR-217 enhanced cell death. miR-200b/c overexpression reduced C5b-9 binding and enhanced its release from the cells and promoted mortalin relocation to the plasma membrane. Inhibition of miR-200 (b and c) and miR-217 had no effect on the expression level of the membrane complement-regulatory proteins CD46, CD55, and CD59. However, overexpression of miR-200b/c or miR-217 enhanced expression of CD46 and CD55 (not of CD59). Overall, the data demonstrate miRNA regulation of cell sensitivity to CDC. We identified miR-200b, miR-200c, and miR-217 as regulators of mortalin and, perhaps indirectly, of CD46 and CD55. Cell exposure to a sublytic dose of complement was shown to increase expression of miR-200 (b and c), suggesting that complement C5b-9 exerts a feedback-regulatory effect on these miRNAs.
authors.affiliation: Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Yaron
authors.initials: Y
authors.lastname: Hillman
authors.affiliation: Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Niv
authors.initials: N
authors.lastname: Mazkereth
authors.affiliation: Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Luba
authors.initials: L
authors.lastname: Farberov
authors.affiliation: Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Noam
authors.initials: N
authors.lastname: Shomron
authors.affiliation: Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel lifish@post.tau.ac.il.
authors.forename: Zvi
authors.identifier: 0000-0001-7097-6357
authors.initials: Z
authors.lastname: Fishelson
mesh_terms: D018958:CD55 Antigens / Q000235:genetics; D018957:CD59 Antigens / Q000235:genetics; D045744:Cell Line, Tumor; D015938:Complement Membrane Attack Complex / Q000276:immunology / Q000378:metabolism*; D003165:Complement System Proteins / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D005786:Gene Expression Regulation; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D020014:K562 Cells; D051916:Membrane Cofactor Protein / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D012333:RNA, Messenger
chemical_list: C497857:CD46 protein, human; D018958:CD55 Antigens; D018957:CD59 Antigens; D015938:Complement Membrane Attack Complex; D018840:HSP70 Heat-Shock Proteins; C533896:MIRN200 microRNA, human; C553315:MIRN217 microRNA, human; D051916:Membrane Cofactor Protein; D035683:MicroRNAs; D012333:RNA, Messenger; C080352:mortalin; C051590:CD59 protein, human; D003165:Complement System Proteins