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Ghosh, R. P.

Publications and source records attributed to Ghosh, R. P..

2 recordsLinked to original sources

Spatial resets modulate YAP-dependent transcription

Yes-associated protein 1 (YAP) is a transcriptional regulator with critical roles in mechanotransduction, organ size control, and regeneration. Here, using new tools for real-time visualization of native YAP and target gene transcription dynamics, we show that a cycle of fast exodus of nuclear YAP to the cytoplasm followed by fast reentry to the nucleus ("localization-resets") activates YAP target genes. These "resets" could be induced by calcium signaling, modulation of actomyosin contractility, or mitosis. Using nascent-transcription reporter knock-ins of YAP target genes, we observed a strict association between these resets and downstream transcription. Oncogenically-transformed transformed cell lines lacked localization-resets and instead showed dramatically elevated rates of nucleocytoplasmic shuttling of YAP, suggesting an escape from compartmentalization-based control. The single-cell localization and transcription traces suggest that YAP activity is not a simple linear function of nuclear enrichment and point to a new model of transcriptional activation based on nucleocytoplasmic exchange properties of YAP.

cell biology

A Fluorogenic Array Tag for Temporally Unlimited Single Molecule Tracking

Cellular processes take place over many timescales, prompting the development of precision measurement technologies that cover milliseconds to hours. Here we describe ArrayG, a bipartite fluorogenic system composed of a GFP-nanobody array and monomeric wtGFP binders. The free binders are initially dim but brighten 15 fold upon binding the array, suppressing background fluorescence. By balancing rates of intracellular binder production, photo-bleaching, and stochastic binder exchange on the array, we achieved temporally unlimited tracking of single molecules. Fast (20-180Hz) tracking of ArrayG tagged kinesins and integrins, for thousands of frames, revealed repeated state-switching and molecular heterogeneity. Slow (0.5 Hz) tracking of single histones for as long as 1 hour showed fractal dynamics of chromatin. We also report ArrayD, a DHFR-nanobody-array tag for dual color imaging. The arrays are aggregation resistant and combine high brightness, background suppression, fluorescence replenishment, and extended choice of fluorophores, opening new avenues for seeing and tracking single molecules in living cells.

biophysics