Local Monomer Levels and Established Filaments Potentiate Non-Muscle Myosin 2 Assembly

Quintanilla, M. A.; Patel, H.; Wu, H.; Sochacki, K. A.; Akamatsu, M.; Rotty, J. D.; Korobova, F.; Bear, J. E.; Taraska, J. W.; Oakes, P. W.; Beach, J. R.

doi:10.1101/2023.04.26.538303

bioRxiv · 10.1101/2023.04.26.538303

Local Monomer Levels and Established Filaments Potentiate Non-Muscle Myosin 2 Assembly

Quintanilla, M. A.·Patel, H.·Wu, H.·Sochacki, K. A.·Akamatsu, M.·Rotty, J. D.·Korobova, F.·Bear, J. E.·Taraska, J. W.·Oakes, P. W.·Beach, J. R.

View original source ↗Export metadata ↓

Abstract

The ability to dynamically assemble contractile networks is required throughout cell physiology, yet the biophysical mechanisms regulating non-muscle myosin 2 filament assembly in living cells are lacking. Here we use a suite of dynamic, quantitative imaging approaches to identify deterministic factors that drive myosin filament appearance and amplification. We find that actin dynamics regulate myosin assembly, but that the actin architecture plays a minimal direct role. Instead, remodeling of actin networks modulates the local myosin monomer levels and facilitates assembly through myosin:myosin driven interactions. Using optogenetically controlled myosin, we demonstrate that locally concentrating myosin is sufficient to both form filaments and jump-start filament amplification and partitioning. By counting myosin monomers within filaments, we demonstrate a myosin-facilitated assembly process that establishes sub-resolution filament stacks prior to partitioning into clusters that feed higher-order networks. Together these findings establish the biophysical mechanisms regulating the assembly of non-muscle contractile structures that are ubiquitous throughout cell biology.

Source connections

Published article ↗

Explore related subjects

cell biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Quintanilla, M. A., Patel, H., Wu, H., Sochacki, K. A., Akamatsu, M., Rotty, J. D., Korobova, F., Bear, J. E., Taraska, J. W., Oakes, P. W., Beach, J. R.. 2023-04-27. Local Monomer Levels and Established Filaments Potentiate Non-Muscle Myosin 2 Assembly. https://doi.org/10.1101/2023.04.26.538303

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Sequence context and partner availability specify divergent cell fates from a single transcription factor

Transcription factors drive the gene regulatory networks that control developmental transitions, yet which of their many targets a cell uses remains unresolved. Expressing Cebp, Cebp{beta} or Cebp{delta} identically, alone or with Oct4, Sox2, Klf4 and cMyc, gave four outcomes: adipocyte from fibroblasts and neural stem cells, trophectoderm from embryonic stem cells, and myeloid from B cells. Raising Cebp levels changed how many sites it reached, not which sequence it read: clustered motifs maintained somatic enhancers, while spillover onto low-copy sites created de novo enhancers carrying composites of Cebp and cell-type-restricted partners. In fibroblasts, Cebp also redistributed Oct4, Sox2 and Klf4 from early targets, blocking iPSC formation. Supplying the predicted partners rewrote the output: Spi1 redirected Cebp into parallel adipogenic and myeloid programs, via a transient PpargCD45 state using separate enhancers for each; TFAP2C abolished adipogenic conversion. Motif density and partner composites therefore assemble a factor's instructive output in the receiving cell.

cell biology↗

bioRxiv2026

High-content screening identifies FDA-approved activators of mitophagy

Mitochondrial diseases are highly heterogeneous disorders caused by defects in oxidative phosphorylation, for which only limited therapeutic options are available. The elimination of dysfunctional mitochondria via mitophagy activation is an attractive strategy to treat several mitochondrial diseases, irrespective of the underlying genetic defect. To identify pharmacological activators of this pathway, we performed a high-content screening of 1,971 FDA-approved compounds using cellular reporters of TFEB nuclear translocation and mitophagy. This screening identified 294 compounds that promoted TFEB translocation, nine of which increased the number of mitolysosomes without compromising cell viability or damaging mitochondria. Among the selected compounds, Meptazinol and Ponatinib emerged as the top-ranked mitophagy inducers in fibroblasts from patients with complex I and IV deficiency, respectively, and were prioritised for further characterisation. However, they did not rescue the bioenergetic defect, suggesting that the stimulation of mitophagy per se is not sufficient to ameliorate the OXPHOS defect in mitochondrial diseases. Overall, our findings establish a scalable platform for the identification of pharmacological activators of TFEB and identify candidate compounds for therapeutic modulation of mitophagy.

cell biology↗

bioRxiv2026

Matrix Gla Protein deficiency reveals a previously unrecognized mucosal calcification in the mouse airways

Tracheal calcification is a common finding that is considered to have limited clinical significance when detected most often in elderly individuals. Despite its frequent occurrence, the cellular and molecular mechanisms at the origin of tracheal calcification remain largely unexplored. In this context, we aimed to characterize the development of tracheal calcification, and to determine the role of matrix Gla protein (MGP), a major inhibitor of ectopic calcification whose genetic or pharmacologic deficiency is associated with premature tracheal calcification in humans. We found that wild-type mice undergo an unexpected early physiologic calcification of the tracheal cartilage rings beginning around one month after birth. This calcification progresses in a dynamic rostro-caudal sequence through a process involving terminal differentiation of tracheal chondrocytes. These findings challenge the prevailing view that tracheal cartilage is a permanent hyaline cartilage and instead reveals an early and highly organized physiologic calcification process. Furthermore, our findings further identify MGP as a key regulator of calcification within the respiratory tract. Indeed, MGP deficiency not only markedly accelerates tracheal cartilage calcification through a similar pattern and mechanism but also induces a previously unrecognized calcification of the tracheal mucosa, a lesion absent in wild-type mice. These alterations could partly explain the respiratory manifestations observed in MGP-deficient patients having Keutel syndrome, which include dyspnea, cough, stridor, and recurrent infections, symptoms previously being mainly attributed to calcification of the tracheal cartilage rings.

cell biology↗