miR-125b modulates mitochondrial metabolism and dynamics through BIK and MTP18 silencing, respectively. THP-1 cells were transfected with si-DRP1, si-MPT18, si-MFN1, si-BIK, control miRNA (CTRL), miR-125b mimics (miR-125b), or miR-125b antagomir (Anti-125b) and analyzed 48 hours later. (A-B) Cell apoptosis was assessed by measuring cell viability and caspase 3/7 activity. The data are presented as percentage (A) or a fold change (FC) (B) of the cell transfected with control miRNA. Data represent mean ± SD of 4 independent experiments. (C-D) Autophagy was monitored using LC3/p62 immunoblotting to track the conversion of LC3-I into LC3-II and the expression of p62 for autophagic activity. Representative western blot of LC3-I/LC3-II, p62, and β-actin is shown (left), and quantitative analysis of LC3-II and p62 are plotted as mean ± SD of 3 exposures of 2 independent experiments (center and right) (C). Quantification of SQSTM1 mRNA (D) was performed using quantitative reverse transcription polymerase chain reaction. Data represent 2 technical independent experiments. (E) The OCR was measured in real time under basal conditions: oligomycin, ATP-synthetase-inhibited rate; FCCP, uncoupled rate; and rotenone + antimycin A, inhibited rate. The OCR was normalized by number of cells in each condition (n = 6 per group). (F) Representative graphs of quantification of various parameters of mitochondrial respiratory profiles, presented as mean ± SD of 4 independent experiments. (G-H) Monitoring of mitochondrial fusion and fission in cells stained with anti-TOM20 antibodies (n = 8). Representative images of mitochondria stained with TOM20 (left; bars represent 10 μm) and quantification of fluorescence using Cellomics ArrayScan VTi platform (right; n = 20 per experimental replicate) are shown. Results are expressed as mean ± SD. *P < .05; **P < .01; ***P < .001.