Development of a DNA aptamer for direct and selective homocysteine detection in human serum

l-Homocysteine has been an amino acid intermediate of interest for over 20 years due to its implication in various adverse health conditions, including cardiovascular disease. Here, we report the first in vitro selection and application of high affinity aptamers for the target l-homocysteine. Two novel aptamer sequences were selected following 8 rounds of selection that displayed high affinity binding and selectivity to homocysteine compared to other amino acids. One of the selected aptamers, Hcy 8 (KD = 600 ± 300 nM), was used to develop a gold-nanoparticle biosensor capable of sensitive and selective homocysteine detection in human serum, with a limit of detection of 0.5 μM and a linear range of 0.5-3.0 μM. This biosensor allows rapid detection of free homocysteine in human serum samples at low cost, with little preparation time and could be adapted to be part of a po

Methyltransferase Dnmt3a upregulates HDAC9 to deacetylate the kinase TBK1 for activation of antiviral innate immunity

The DNA methyltransferase Dnmt3a has high expression in terminally differentiated macrophages; however, its role in innate immunity remains unknown. Here we report that deficiency in Dnmt3a selectively impaired the production of type I interferons triggered by pattern-recognition receptors (PRRs), but not that of the proinflammatory cytokines TNF and IL-6. Dnmt3a-deficient mice exhibited enhanced susceptibility to viral challenge. Dnmt3a did not directly regulate the transcription of genes encoding type I interferons; instead, it increased the production of type I interferons through an epigenetic mechanism by maintaining high expression of the histone deacetylase HDAC9. In turn, HDAC9 directly maintained the deacetylation status of the key PRR signaling molecule TBK1 and enhanced its kinase activity. Our data add mechanistic insight into the crosstalk between epigenetic modifications and post-translational modifications in the regulation of PRR signaling and activation of antiviral innate immune responses