A universal RNAi-based logic evaluator that operates in mammalian cells.

FAS Center for Systems Biology, Harvard University, 7 Divinity Ave., Cambridge, Massachusetts 02138 USA.
Nature Biotechnology (Impact Factor: 39.08). 08/2007; 25(7):795-801. DOI: 10.1038/nbt1307
Source: PubMed

ABSTRACT Molecular automata that combine sensing, computation and actuation enable programmable manipulation of biological systems. We use RNA interference (RNAi) in human kidney cells to construct a molecular computing core that implements general Boolean logic to make decisions based on endogenous molecular inputs. The state of an endogenous input is encoded by the presence or absence of 'mediator' small interfering RNAs (siRNAs). The encoding rules, combined with a specific arrangement of the siRNA targets in a synthetic gene network, allow direct evaluation of any Boolean expression in standard forms using siRNAs and indirect evaluation using endogenous inputs. We demonstrate direct evaluation of expressions with up to five logic variables. Implementation of the encoding rules through sensory up- and down-regulatory links between the inputs and siRNA mediators will allow arbitrary Boolean decision-making using these inputs.

1 Follower
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An AND logic gate based on a synthetic quorum-sensing (QS) module was constructed in a Shewanella oneidensis MR-1 mtrA knockout mutant. The presence of two input signals activated the expression of a periplasmic decaheme cytochrome MtrA to regenerate the extracellular electron transfer conduit, enabling the construction of AND-gated microbial fuel cells.
    Chemical Communications 02/2015; DOI:10.1039/c5cc00026b · 6.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: An important goal of synthetic biology is the rational design and predictable implementation of synthetic gene circuits using standardized and interchangeable parts. However, engineering of complex circuits in mammalian cells is currently limited by the availability of well-characterized and orthogonal transcriptional repressors. Here, we introduce a library of 26 reversible transcription activator-like effector repressors (TALERs) that bind newly designed hybrid promoters and exert transcriptional repression through steric hindrance of key transcriptional initiation elements. We demonstrate that using the input-output transfer curves of our TALERs enables accurate prediction of the behavior of modularly assembled TALER cascade and switch circuits. We also show that TALER switches using feedback regulation exhibit improved accuracy for microRNA-based HeLa cancer cell classification versus HEK293 cells. Our TALER library is a valuable toolkit for modular engineering of synthetic circuits, enabling programmable manipulation of mammalian cells and helping elucidate design principles of coupled transcriptional and microRNA-mediated post-transcriptional regulation.
    Nature Chemical Biology 02/2015; 11(3). DOI:10.1038/nchembio.1736 · 13.22 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Synthetic biology employs traditional engineering concepts in the construction of cells and organisms. One of the most fundamental concepts is feedback, where the activity of a system is influenced by its output. Feedback can imbue the system with a range of desirable properties such as reducing the rise time or exhibiting an ultrasensitive response. Feedback is also commonly found in nature, further supporting the incorporation of feedback into synthetic biological systems. In this review, we discuss the common attributes of negative and positive feedback loops in gene regulatory networks, whether alone or in combination, and describe recent applications of feedback in metabolic engineering, population control, and the development of advanced biosensors. The examples principally come from synthetic systems in the bacterium Escherichia coli and in the budding yeast Saccharomyces cerevisiae, the two major workhorses of synthetic biology. Through this review, we argue that biological feedback represents a powerful yet underutilized tool that can advance the construction of biological systems.
    Chemical Engineering Science 11/2013; 103:79-90. DOI:10.1016/j.ces.2013.02.017 · 2.61 Impact Factor



Leonidas Bleris