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Noise Enhancer and Suppressor Molecules

Weinberger Lab

Long ago, chemists realized that chemical-reaction efficiency could be enhanced not only by catalysts but also by increasing the thermal energy (i.e. kT in the Arrhenius equation).

chemical potential graphIn other words, catalysts deterministically lower activation-energy barriers on potential-energy landscapes (below) but when such deterministic drivers are insufficient to cross the barrier, amplifying thermal fluctuations (e.g. via a Bunsen burner) provides an added perturbation for crossing activation-energy barriers.

Remarkably, this physical-chemistry concept also applies to gene regulation in cell-fate decisions (Dar et al., 2014).  Roughly, the chemical potential-energy landscape can be compared to a Waddington-epigenetic landscape, where transcriptional activators are essentially catalysts and we have identified a class of noise-enhancer compounds that act like biological Bunsen burners. 

waddington landscape graph

As a model system, we focus on HIV, where achieving a cure will require latent virus be reactivated and purged.  Unfortunately, current reactivation schemes are ineffective.  Through screening a small-molecule library for compounds that enhance stochastic gene-expression noise.  These noise-enhancer compounds (already FDA approved) act like Bunsen burners, potentiating transcriptional activators to greatly enhance HIV reactivation.  Moreover, noise-suppressor compounds—effectively equivalent to ‘ice packs’—inhibit reactivation.

Since molecular noise is a fundamental biophysical phenomenon—influencing phenotypes from antibiotic persistence to cellular reprogramming and cancer—noise-modulating molecules could provide a general tool to manipulate diverse cell-fate decisions.

Papers of note: Dar et al. Science 2014. (linked above)