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    • Y-27632 Dihydrochloride: Selective ROCK Inhibitor for Cyt...

    2025-11-01

    Y-27632 Dihydrochloride: Selective ROCK Inhibitor for Cytoskeletal and Stem Cell Research

    Executive Summary: Y-27632 dihydrochloride is a small-molecule inhibitor that selectively targets Rho-associated protein kinases ROCK1 and ROCK2, demonstrating an IC50 of approximately 140 nM for ROCK1 and a Ki of 300 nM for ROCK2 in kinase assays (ApexBio A3008). It exhibits over 200-fold selectivity toward ROCK isoforms compared to kinases such as PKC, PKA, MLCK, and PAK, minimizing off-target effects. Inhibition of ROCK signaling by Y-27632 disrupts Rho-mediated stress fiber assembly and modulates G1/S cell cycle progression, making it a tool for cytoskeletal, proliferation, and stem cell viability studies. The compound is functionally validated for in vitro and in vivo research, including suppression of tumor invasion and metastasis in mouse models (Chandra et al. 2023). Stock solutions are stable below -20°C, and the compound is highly soluble in DMSO, ethanol, and water with appropriate preparation protocols.

    Biological Rationale

    ROCK1 and ROCK2 are serine/threonine kinases that act as downstream effectors of the small GTPase RhoA. These kinases regulate cytoskeletal organization, cell contractility, migration, and proliferation. Dysregulation of the Rho/ROCK pathway is implicated in cancer progression, fibrosis, and stem cell viability decline. Y-27632 dihydrochloride enables targeted inhibition of ROCK1/2, permitting dissection of Rho-mediated cellular processes while avoiding off-target kinase interference (ApexBio A3008). The compound’s selectivity and cell permeability make it suitable for both basic and translational studies involving stress fiber dynamics, stem cell expansion, and tumor invasion mechanisms.

    Mechanism of Action of Y-27632 dihydrochloride

    Y-27632 dihydrochloride is a reversible, ATP-competitive inhibitor that binds to the catalytic site of ROCK1 and ROCK2. The compound inhibits substrate phosphorylation with an IC50 of ~140 nM for ROCK1 and a Ki of 300 nM for ROCK2 under standard in vitro kinase assay conditions (25°C, Tris-HCl buffer, pH 7.5) (product page). Selectivity profiling demonstrates >200-fold lower activity for PKC, MLCK, PKA, and PAK versus ROCK isoforms, as measured by radiolabeled substrate assays. Inhibition of ROCK activity leads to decreased phosphorylation of downstream effectors such as myosin light chain (MLC) and LIM kinase, resulting in disrupted actin stress fiber formation, altered cell shape, and impaired contractility. Y-27632 also impedes cell cycle progression at G1/S and interferes with cytokinesis. These activities are confirmed in both mammalian cell culture and animal models.

    Evidence & Benchmarks

    • Y-27632 inhibits ROCK1 with an IC50 of ~140 nM and ROCK2 with a Ki of 300 nM in purified enzyme assays (ApexBio, product page).
    • It shows >200-fold selectivity for ROCK isoforms over PKC, cAMP-dependent protein kinase, MLCK, and PAK (ApexBio, link).
    • In vitro, Y-27632 suppresses Rho-mediated stress fiber formation in cultured mammalian cells at 10 μM under standard conditions (37°C, 5% CO2) (A3008).
    • Y-27632 reduces proliferation of prostatic smooth muscle cells in a concentration-dependent manner in cell culture (ApexBio, link).
    • In mouse models, Y-27632 administration reduces tumor invasion and metastasis, as measured by histopathological analysis (Chandra et al. 2023, DOI).
    • The compound enhances stem cell viability in organoid and primary cell cultures by suppressing dissociation-induced apoptosis (internal article).

    Applications, Limits & Misconceptions

    Y-27632 dihydrochloride is widely used as a cell-permeable ROCK inhibitor in the following contexts:

    • Dissection of Rho/ROCK signaling pathways in cytoskeletal dynamics.
    • Enhancement of human pluripotent stem cell and organoid viability by inhibition of anoikis.
    • Suppression of tumor cell invasion and migration in cancer research.
    • Study of cell cycle progression and cytokinesis in mammalian cells.
    • Facilitation of primary cell and epithelial organoid culture.

    This article extends previous site coverage by providing quantitative evidence and clarifying solubility and selectivity parameters, supplementing the mechanistic focus in this workflow guide and offering updated in vivo data beyond the scope of next-gen insights article.

    Common Pitfalls or Misconceptions

    • Y-27632 is not effective against non-ROCK kinases such as PKC or MLCK at recommended concentrations (<10 μM).
    • The compound should not be used as a general anti-mitotic; it specifically disrupts cytokinesis via ROCK inhibition, not by targeting DNA replication or spindle assembly.
    • Long-term storage of Y-27632 in solution, even at -20°C, can lead to degradation; always prepare fresh aliquots for critical experiments.
    • Effects observed in vitro may not fully translate to in vivo models due to pharmacokinetic differences.
    • Y-27632 does not inhibit α-synuclein aggregation in Parkinson’s models; its use is limited to ROCK pathway modulation (Chandra et al. 2023, DOI).

    Workflow Integration & Parameters

    Y-27632 dihydrochloride is supplied as a solid (SKU: A3008) and should be stored desiccated at 4°C or below. For solution preparation, it is soluble at ≥111.2 mg/mL in DMSO, ≥17.57 mg/mL in ethanol, and ≥52.9 mg/mL in water. Solubility may be improved by warming to 37°C or using an ultrasonic bath. Stock solutions can be kept at -20°C for several months, but avoid prolonged storage in solution. Typical working concentrations range from 1–10 μM for cell culture applications. For in vivo mouse models, refer to published dosing regimens (e.g., 10–30 mg/kg IP injection) and adjust based on pharmacodynamics and toxicity studies. For further workflow guidance and troubleshooting, see the Y-27632 dihydrochloride product page and the translational applications article, which contextualizes Y-27632 within current oncology and regenerative medicine pipelines.

    Conclusion & Outlook

    Y-27632 dihydrochloride remains the reference standard for selective, cell-permeable inhibition of ROCK1 and ROCK2 in cytoskeletal, stem cell, and cancer research. Its robust selectivity, validated efficacy across in vitro and in vivo systems, and compatibility with diverse experimental workflows make it a critical tool for dissecting Rho/ROCK signaling. Ongoing innovations in disease modeling and regenerative medicine continue to expand its applications, but its use should be guided by validated protocols and clear understanding of its selectivity parameters.