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.

NF‐κB p65 promotes ovarian cancer cell proliferation and migration via regulating mortalin

“…Transcription factors generally regulate gene expression at the transcriptional level, whereas microRNAs act primarily, post‐ transcriptionally. Hillman et al found that miR‐200b/c and miR‐217 can bind to mortalin mRNA and decrease its expression in K562 cells . Our experiments have shown that overexpression of mortalin can partly reverse the proliferation and migration ability of ovarian cancer cells induced by NF‐κB p65 downregulation.…”

Activation of the complement system in an osteosarcoma cell line promotes angiogenesis through enhanced production of growth factors

“…Together, activation of the complement system on U2-OS cells would be mediated by suppression of the negative regulatory proteins of the complement system. Recent studies suggested that microRNA expression would be associated with the expression of complement regulatory proteins 15 , 16 . Therefore, we analyzed the previously reported microRNAs related with CD46 and CD55 in U2-OS cells.…”

Identification and Characterization of MicroRNAs in the Liver of Blunt Snout Bream (Megalobrama amblycephala) Infected by Aeromonas hydrophila

“…Several differentially expressed miRNAs have been found to be immune-related in mammals, such as miR-148/152, miR-101a, miR-141/200c, miR-146b, miR-217 and miR-375 [50,51,52,53,54,55,56]. A previous study demonstrated that the miR-148 and miR-152, two members of miR-148 family, were significantly increased in dendritic cells by TLR agonists, which inhibited the up-regulation of MHC II expression and the production of cytokine via targeting CaMKIIα, and might contribute to immune homeostasis [50].…”

“…miR-141 and miR-200c, belonging to the highly conserved miR-200 family, whose members are considered as tumor suppressors [52], can promote the mesenchymal-epithelial transition, and inhibit cell invasion by suppressing the Zeb2 and Snail1 transcriptional repressor complexes [53]. In addition, miR-200b/c and miR-217 regulate the expression of mortalin and the quantity of MACs (complement membrane attack complex) deposited on the target cells during complement activation to resist complement membrane attack [55], and the decreased miR-375 can activate JAK2-STAT3 pathway and promote the proliferation and migration of gastric epithelial cells in response to Helicobacter pylori infection [56]. Meanwhile, the prediction of target genes indicated that toll-like receptor 5b ( TLR5b ), interleukin-1 receptor I ( IL1RI ), interleukin enhancer binding factor 3a ( ILF3a ) and interleukin-17 receptor B ( IL17R B ) are collectively targeted by miR-217.…”