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Substrate Stiffness and Microtopography in PIP 2 Regulation of the Actin Cytoskeleton in Primary Cardiac Fibroblasts
Author(s) -
Mkrtschjan Michael,
Li Jieli,
Russell Brenda
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1029.4
Subject(s) - vinculin , wound healing , fluorescence recovery after photobleaching , cytoskeleton , actin , actin cytoskeleton , lamellipodium , cell migration , chemistry , biophysics , materials science , cell , medicine , biology , membrane , surgery , biochemistry
Following tissue injury, fibroblasts are one of the primary responding cell types in the wound healing process. Upon myocardial infarction, local fibroblasts divide and increase collagen secretion, leading to cardiac fibrosis. In this study, the effect of the mechanical environment, through substrate stiffness and three‐dimensional topography, is examined in relation to the distribution and levels of phosphatidylinositol 4,5‐bisphosphate (PIP 2 ) in primary neonatal rat ventricular fibroblasts. PIP 2 is a membrane component and known regulator of the actin cytoskeleton. Substrates possessing 10 µm high microprojections are fabricated from polydimethylsiloxane to a stiffness of either 100 kPa or 400 kPa (Young's Modulus). A 3‐fold cellular decrease (P<.001) in PIP 2 is found between flat‐soft substrates and flat‐polystyrene culture dishes. Additionally, microprojections are shown to blunt PIP 2 by a similar amount within each stiffness condition. Fluorescence recovery after photobleaching, yielding the rate constant K frap , allows study of actin dynamics in the various micromechanical conditions. A 4‐fold decrease (P<.0001) is found between actin dynamics within lamellipodia to those within stress cables, correlating to a migrating or an anchored cell. This difference in dynamics coincides with an increased redistribution of PIP 2 to the lamella in migrating cells. An improved understanding of the intracellular lipid mechanisms involved in wound healing could aid in prevention of maladaptive scarring following major injury. Funded by NIH HL62426, T32HL07692