Identification of a mechanochemical checkpoint and negative feedback loop regulating branching morphogenesis
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Updated: Jun 19, 2026

Image-Based Methods to Study Membrane Trafficking Events in Stomatal Lineage Cells
Published on: May 12, 2023
William P Daley1, Kathryn M Gulfo, Sharon J Sequeira
1Graduate program in Molecular, Cellular, Developmental, and Neural Biology, Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA.
Abstract:
Cleft formation is the initial step in submandibular salivary gland (SMG) branching morphogenesis, and may result from localized actomyosin-mediated cellular contraction. Since ROCK regulates cytoskeletal contraction, we investigated the effects of ROCK inhibition on mouse SMG ex vivo organ cultures. Pharmacological inhibitors of ROCK, isoform-specific ROCK I but not ROCK II siRNAs, as well as inhibitors of myosin II activity stalled clefts at initiation. This finding implies the existence of a mechanochemical checkpoint regulating the transition of initiated clefts into progression-competent clefts. Downstream of the checkpoint, clefts are rendered competent through localized assembly of fibronectin promoted by ROCK I/myosin II. Cleft progression is primarily mediated by ROCK I/myosin II-stimulated cell proliferation with a contribution from cellular contraction. Furthermore, we demonstrate that FN assembly itself promotes epithelial proliferation and cleft progression in a ROCK-dependent manner. ROCK also stimulates a proliferation-independent negative feedback loop to prevent further cleft initiations. These results reveal that cleft initiation and progression are two physically and biochemically distinct processes.
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