title: Mechanosensitive kinases regulate stiffness-induced cardiomyocyte maturation.
abstract: Cells secrete and assemble extracellular matrix throughout development, giving rise to time-dependent, tissue-specific stiffness. Mimicking myocardial matrix stiffening, i.e. ~10-fold increase over 1 week, with a hydrogel system enhances myofibrillar organization of embryonic cardiomyocytes compared to static hydrogels, and thus we sought to identify specific mechanosensitive proteins involved. Expression and/or phosphorylation state of 309 unique protein kinases were examined in embryonic cardiomyocytes plated on either dynamically stiffening or static mature myocardial stiffness hydrogels. Gene ontology analysis of these kinases identified cardiogenic pathways that exhibited time-dependent up-regulation on dynamic versus static matrices, including PI3K/AKT and p38 MAPK, while GSK3β, a known antagonist of cardiomyocyte maturation, was down-regulated. Additionally, inhibiting GSK3β on static matrices improved spontaneous contraction and myofibril organization, while inhibiting agonist AKT on dynamic matrices reduced myofibril organization and spontaneous contraction, confirming its role in mechanically-driven maturation. Together, these data indicate that mechanically-driven maturation is at least partially achieved via active mechanosensing at focal adhesions, affecting expression and phosphorylation of a variety of protein kinases important to cardiomyogenesis.
authors.affiliation: Department of Bioengineering, University of California, San Diego, CA 92093.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Young
authors.affiliation: Department of Bioengineering, University of California, San Diego, CA 92093.
authors.forename: Kyle
authors.initials: K
authors.lastname: Kretchmer
authors.affiliation: Department of Material Science Program, University of California, San Diego, CA 92093.
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Ondeck
authors.affiliation: Department of Pharmacology, University of California, San Diego, CA 92093.
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Zambon
authors.affiliation: 1] Department of Bioengineering, University of California, San Diego, CA 92093 [2] Department of Material Science Program, University of California, San Diego, CA 92093 [3] Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Engler
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000235:genetics; D002642:Chick Embryo; D005786:Gene Expression Regulation; D020935:MAP Kinase Signaling System / Q000235:genetics*; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D011494:Protein Kinases / Q000096:biosynthesis*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D015398:Signal Transduction; D046888:Tissue Array Analysis; D059289:Vascular Stiffness / Q000235:genetics*
chemical_list: D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt