title: Alpha actinin-1 regulates cell-matrix adhesion organization in keratinocytes: consequences for skin cell motility.
abstract: The migration of keratinocytes in wound healing requires coordinated activities of the motility machinery of a cell, the cytoskeleton, and matrix adhesions. In this study, we assessed the role of alpha actinin-1 (ACTN1), one of the two alpha actinin isoforms expressed in keratinocytes, in skin cell migration via a small hairpin RNA-mediated knockdown approach. Keratinocytes deficient in ACTN1 exhibit changes in their actin cytoskeleton organization, a loss in front-rear polarity, and impaired lamellipodial dynamics. They also display aberrant directed motility and move slower compared with their wild-type counterparts. Moreover, they have abnormally arranged matrix adhesion sites. Specifically, the focal adhesions in ACTN1 knockdown keratinocytes are not organized as distinct entities. Rather, focal adhesion proteins are arranged in a circle subjacent to cortical fibers of actin. In the same cells, hemidesmosome proteins arrange in cat paw patterns, more typical of confluent, stationary cells, and β4 integrin dynamics are reduced in knockdown cells compared with control keratinocytes. In summary, our data suggest a mechanism by which ACTN1 determines the motility of keratinocytes by regulating the organization of the actin cytoskeleton, focal adhesion, and hemidesmosome proteins complexes, thereby modulating cell speed, lamellipodial dynamics, and directed migration.
authors.affiliation: Department of Eye and Vision Science, Institute of Ageing and Chronic Diseases, University of Liverpool, Liverpool, UK.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Hamill
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
authors.forename: Sho
authors.initials: S
authors.lastname: Hiroyasu
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
authors.forename: Zachary T
authors.initials: ZT
authors.lastname: Colburn
authors.affiliation: Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.
authors.forename: Rosa V
authors.initials: RV
authors.lastname: Ventrella
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington, USA.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Hopkinson
authors.affiliation: Department of Biological Sciences, University of Memphis, Memphis, Tennessee, USA.
authors.forename: Omar
authors.initials: O
authors.lastname: Skalli
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington, USA. Electronic address: jcr.jones@vetmed.wsu.edu.
authors.forename: Jonathan C R
authors.initials: JCR
authors.lastname: Jones
mesh_terms: D000185:Actinin / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000256:Adenoviridae / Q000378:metabolism; D002465:Cell Movement; D002469:Cell Separation; D003599:Cytoskeleton / Q000378:metabolism; D016109:Epidermolysis Bullosa, Junctional / Q000378:metabolism; D005434:Flow Cytometry; D022002:Hemidesmosomes / Q000378:metabolism; D006801:Humans; D039663:Integrin beta4 / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology*; D011554:Pseudopodia / Q000378:metabolism; D012867:Skin / Q000378:metabolism*; D014945:Wound Healing
chemical_list: D000199:Actins; D039663:Integrin beta4; D000185:Actinin