Molecular electronics sensors on a scalable semiconductor chip: A platform for single-molecule measurement of binding kinetics and enzyme activity.

For nearly 50 years, the vision of using single molecules in circuits has been seen as providing the ultimate miniaturization of electronic chips. An advanced example of such a molecular electronics chip is presented here, with the important distinction that the molecular circuit elements play the role of general-purpose single-molecule sensors. The device consists of a semiconductor chip with a scalable array architecture. Each array element contains a synthetic molecular wire assembled to span nanoelectrodes in a current monitoring circuit. A central conjugation site is used to attach a single probe molecule that defines the target of the sensor. The chip digitizes the resulting picoamp-scale current-versus-time readout from each sensor element of the array at a rate of 1,000 frames per second. This provides detailed electrical signatures of the single-molecule interactions between the probe and targets present in a solution-phase test sample. This platform is used to measure the interaction kinetics of single molecules, without the use of labels, in a massively parallel fashion. To demonstrate broad applicability, examples are shown for probe molecule binding, including DNA oligos, aptamers, antibodies, and antigens, and the activity of enzymes relevant to diagnostics and sequencing, including a CRISPR/Cas enzyme binding a target DNA, and a DNA polymerase enzyme incorporating nucleotides as it copies a DNA template. All of these applications are accomplished with high sensitivity and resolution, on a manufacturable, scalable, all-electronic semiconductor chip device, thereby bringing the power of modern chips to these diverse areas of biosensing.

Fibrates upregulate TRB3 in lymphocytes independent of PPAR alpha by augmenting CCAAT/enhancer-binding protein beta (C/EBP beta) expression.

Fibrates, which function by binding and activating peroxisome proliferator-activated receptor alpha (PPARalpha), have been used successfully to treat hyperlipidemia and atherosclerosis. Increasing evidence suggests that in addition to their lipid lowering activities these medications also function as immunosuppressive agents. Tribbles is a Drosophila protein that slows cell cycle progression, and its mammalian homolog, TRB3 interferes with insulin-induced activation of AKT. In these studies we demonstrate that fibrates upregulate TRB3 expression in mitogen-activated lymphocytes. Interestingly, in lymphocytes fibrates augment TRB3 expression in both PPARalpha wildtype and knockout mice, suggesting that upregulation of this protein occurs in a PPARalpha-independent manner. Fibrates activate a proximal TRB3 promoter construct and mutation or partial deletion of a potential PPAR response element does not alter the ability of fibrates to drive TRB3 expression. Subsequent studies reveal that fibrates upregulate C/EBPbeta and CHOP in lymphocytes and mutation of potential C/EBPbeta and CHOP consensus sequences abrogates the ability of fibrates to upregulate TRB3 promoter activity. Accordingly, fibrates enhance the recruitment of C/EBPbeta and CHOP to the proximal TRB3 promoter. Finally, TRB3 expression in lymphocytes induces G2 cell cycle delay and cellular depletion. These studies outline a novel PPARalpha-independent mechanism of action of fibrates and document for the first time the expression of TRB3 in activated lymphocytes.