Organization of inner cellular components as reported by a viscosity-sensitive fluorescent Bodipy probe suitable for phasor approach to FLIM

•We developed a new Bodipy-based viscosity-sensitive molecular rotor, BoMe.•We used BoMe to explore viscosity properties in cellulo, via FLIM phasor approach.•BoMe binds to dsDNA both in vitro and in vivo.•We compared intracellular viscosity maps in HGPS cellular model with control cells.•A less viscous nucleoplasm environment in HGPS cell indicates less compact chromatin.

According to the recent developments in imaging strategies and in tailoring fluorescent molecule as probe for monitoring biological systems, we coupled a Bodipy-based molecular rotor (BoMe) with FLIM phasor approach to evaluate the viscosity in different intracellular domains. BoMe rapidly permeates cells, stains cytoplasmic as well as nuclear domains, and its optical properties make it perfectly suited for widely diffused confocal microscopy imaging setups. The capability of BoMe to report on intracellular viscosity was put to the test by using a cellular model of a morbid genetic pathology (Hutchinson-Gilford progeria syndrome, HGPS). Our results show that the nucleoplasm of HGPS cells display reduced viscosity as compared to normal cells. Since BoMe displays significant affinity towards DNA, as demonstrated by an in vitro essay, we hypothesize that genetic features of HGPS, namely the misassembly of lamin A protein within the nuclear lamina, modulates chromatin compaction. This hypothesis nicely agrees with literature data.

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