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D WuDunn, J Haydon; Fluid Shear Stress Stimulates NF-B nuclear Translocation in Bovine Trabecular Meshwork Cells . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1039.
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Purpose: To determine if certain fluid shear stress conditions will elicit the tissue-specific stress response that characterizes glaucomatous trabecular meshwork (TM). This stress response is mediated by the transcription factor, nuclear factor ΚB (NF-ΚB). Methods: Bovine TM cells were subjected to fluid shear stress using a parallel plate flow chamber under various flow conditions and durations. NF-ΚB activation was assessed by immunofluorescence using polyclonal antibodies against NF-ΚB p65 (RelA). Presence of nuclear staining indicated NF-ΚB activation and translocation. Results: NF-ΚB translocation occurred during low-frequency (0.05 cycles/sec) pulsatile flow at mean shear stress levels of 0.25 (see Figure), 0.5, and 1.5 dynes/cm2. In the Figure, nuclear staining is present in cells exposed to flow for 7 hours (left) but is absent in control cells under static conditions (right). This indicates that, under these shear stress conditions, NF-ΚB has translocated from the cytoplasm to the nuclear compartment where it will activate various target genes. In contrast, non-pulsatile flow at these shear stress levels (0.25, 0.5, 1.5 dynes/cm2) did not result in NF-ΚB nuclear staining during the initial 24 hours of flow. Furthermore, non-pulsatile high flow (5-12 dynes/cm2) shear stress for 30-120 minutes induced no or little change in NF-ΚB immunostaining compared to static controls. NF-ΚB translocation was not observed following sustained 10% mechanical stretch during the initial 24 hours. View OriginalDownload SlideView OriginalDownload Slide Conclusion: Pulsatile shear stress at levels modestly elevated over physiological levels (about 0.05 dynes/cm2) induces NF-ΚB activation, which is a critical step in the stress response identified in glaucomatous trabecular meshwork.
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