Biology subjects

Michelatti, D.

Publications and source records attributed to Michelatti, D..

2 recordsLinked to original sources

bioRxiv2025

Metastatic cell plasticity is maintained by SOX9 function during mitosis in breast cancer

Disseminated tumor cells (DTCs) contribute to metastasis formation by adapting to the hostile environmental conditions encountered at the seeded secondary organs. This phenotypic plasticity is supported by the epigenetic reprogramming of cis-regulatory elements (CREs), representing a hallmark of metastatic cells. DTCs can enter a reversible state of cancer dormancy, resulting from their ability to enter quiescence after mitosis and escape immune surveillance. In this respect, mitosis may represent a window of opportunity to increase DTCs fitness by priming CREs, ensuring the reactivation of a dormancy-related transcriptional program while preserving the epigenetic information. By profiling the chromatin changes occurring during the early steps of mitosis, we found that DTCs experience fluctuations in chromatin accessibility at CREs, which are bookmarked by pro-metastatic TFs. Among these, the pro-dormancy TF SOX9 remained associated with mitotic chromatin, facilitating transcriptional reactivation upon exiting mitosis. By dissecting the consequences of degrading SOX9 before mitosis, we found that its priming of dormancy-related CREs, combined with the recruitment of the Mediator kinase module, is instrumental for metastatic cells to enter quiescence and escape NK-mediated immune surveillance. These findings indicate that cancer dormancy is primed during mitosis by pro-metastatic TFs.

molecular biology↗

bioRxiv2024

Chromatin condensates tune nuclear mechano-sensing in Kabuki Syndrome by constraining cGAS activation

Cells and tissue integrity is constantly challenged by the necessity to adapt and respond to mechanical loads. Among the cellular components, the nucleus possesses mechano-sensing and mechanotransduction capabilities, yet the molecular mechanisms involved remain poorly defined. We postulated that the mechanical properties of the chromatin and its compartmentalization into condensates contribute to the nuclear adaptation to external forces, while preserving its integrity. By interrogating the effects of MLL4 loss-of-function in Kabuki Syndrome, we found that the balancing of transcriptional and Polycomb condensates tunes the nuclear responsiveness to external mechanical forces. We showed that MLL4 acts as a chromatin mechano-sensor by clustering into condensates through its Prion-like domain, and its response was regulated by the chromatin context. Furthermore, the mechano-sensing activity of MLL4 condensates is instrumental to withstand the physical challenges that nuclei experience during cell confinement and migration by preserving their integrity. In Kabuki Syndrome persistent rupture of nuclear envelope triggers cGAS-STING activation, which leads to programmed cell death. Ultimately, these results demonstrate the critical role chromatin compartments play in mechano-responses and how they impact pathological conditions by stimulating cGAS-STING signaling.

molecular biology↗