Mutations in FASTKD2, a mitochondrial RNA binding protein, have been associated with mitochondrial encephalomyopathy with isolated complex IV deficiency. However, deficiencies related to other oxidative phosphorylation system (OXPHOS) complexes have not been reported. Here, we identified three novel FASTKD2 mutations, c.808_809insTTTCAGTTTTG, homoplasmic mutation c.868C>T, and heteroplasmic mutation c.1859delT/c.868C>T, in patients with mitochondrial encephalomyopathy.Cell-based complementation assay revealed that these three FASTKD2 mutations were pathogenic. Mitochondrial functional analysis revealed that mutations in FASTKD2 impaired the mitochondrial function in patient-derived lymphocytes due to the deficiency in multi-OXPHOS complexes, whereas mitochondrial complex II remained unaffected. Consistent results were also found in human primary muscle cell and zebrafish with knockdown of FASTKD2. Furthermore, we discovered that FASTKD2 mutation is not inherently associated with epileptic seizures, optic atrophy, and loss of visual function. Alternatively, a patient with FASTKD2 mutation can show sinus tachycardia and hypertrophic cardiomyopathy, which was partially confirmed in zebrafish with knockdown of FASTKD2. In conclusion, both in vivo and in vitro studies suggest that loss of function mutation in FASTKD2 is responsible for multi-OXPHOS complexes deficiency, and FASTKD2-associated mitochondrial disease has a high degree of clinical heterogenicity.FASTKD2, metabolic genetic diseases, mitochondrial disease, OXPHOS complex Xiujuan Wei, Miaomiao Du, and Dongxiao Li contributed equally to this study.
Background: Most studies on cell-free DNA (cfDNA) were only for single body fluids; however, the differences in cfDNA distribution between two body fluids are rarely reported. Hence, in this work, we compared the differences in cfDNA distribution between cerebrospinal fluid (CSF) and serum of patients with brain-related diseases. Methods:The fragment length of cfDNA was determined by using Agilent 2100Bioanalyzer. The copy numbers of cell-free mitochondrial DNA (cf-mtDNA) and cellfree nuclear DNA (cf-nDNA) were determined by using real-time quantitative PCR (qPCR) and droplet digital PCR (ddPCR) with three pairs of mitochondrial ND1 and nuclear GAPDH primers, respectively.Results: There were short (~60 bp), medium (~167 bp), and long (>250 bp) cfDNA fragment length distributions totally obtained from CSF and serum using Agilent 2100 Bioanalyzer. The results of both qPCR and ddPCR confirmed the existence of these three cfDNA fragment ranges in CSF and serum. According to qPCR, the copy numbers of long cf-mtDNA, medium, and long cf-nDNA in CSF were significantly higher than in paired serum. In CSF, only long cf-mtDNA's copy numbers were higher than long cf-nDNA. But in serum, the copy numbers of medium and long cf-mtDNA were higher than the corresponding cf-nDNA. Conclusion:The cf-nDNA and cf-mtDNA with different fragment lengths differentially distributed in the CSF and serum of patients with brain disorders, which might serve as a biomarker of human brain diseases.
BACKGROUND Colorimetric biosensors based on DNAzyme provide convenient and selective means for the detection of lead ion (Pb2+), which are critically important to prevent lead exposure and poisoning. However, they still remain challenging because of their limitation of sensitivity (only nmol L‐1 level) and practical application. Herein, we design a highly sensitive, selective, simple, and quantitative platform for direct Pb2+ detection based on the magnetic nano‐DNAzyme in real water samples. RESULTS Magnetic beads were modified with enzyme strand of DNAzyme to work as solid phase carriers and hybridized with DNAzyme's substrate strand/horseradish peroxidase molecules double‐codified gold nanoparticles to form a stable magnetic nano‐DNAzyme complex. Under the optimized reaction conditions, the magnetic nano‐DNAzyme had a quantitative detection range from 102 to 108 pmol L‐1, a limit of detection of 32 pmol L‐1 and high selectivity for Pb2+ over other metal ions with an assay time less than 1 h. In addition, this method showed enhanced pH stability and long service life, and had a potential to detect other metal ions only by changing corresponding DNAzyme specific to them. Finally, the magnetic nano‐DNAzyme platform was demonstrated to work well in direct Pb2+ detection in real water samples. CONCLUSION The magnetic nano‐DNAzyme system for colorimetric detection of Pb2+ showed high sensitivity and selectivity, simple, enhanced pH stability with long service life in practical application. © 2018 Society of Chemical Industry
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