title: Regulation of cell proliferation by ERK and signal-dependent nuclear translocation of ERK is dependent on Tm5NM1-containing actin filaments.
abstract: ERK-regulated cell proliferation requires multiple phosphorylation events catalyzed first by MEK and then by casein kinase 2 (CK2), followed by interaction with importin7 and subsequent nuclear translocation of pERK. We report that genetic manipulation of a core component of the actin filaments of cancer cells, the tropomyosin Tm5NM1, regulates the proliferation of normal cells both in vitro and in vivo. Mouse embryo fibroblasts (MEFs) lacking Tm5NM1, which have reduced proliferative capacity, are insensitive to inhibition of ERK by peptide and small-molecule inhibitors, indicating that ERK is unable to regulate proliferation of these knockout (KO) cells. Treatment of wild-type MEFs with a CK2 inhibitor to block phosphorylation of the nuclear translocation signal in pERK resulted in greatly decreased cell proliferation and a significant reduction in the nuclear translocation of pERK. In contrast, Tm5NM1 KO MEFs, which show reduced nuclear translocation of pERK, were unaffected by inhibition of CK2. This suggested that it is nuclear translocation of CK2-phosphorylated pERK that regulates cell proliferation and this capacity is absent in Tm5NM1 KO cells. Proximity ligation assays confirmed a growth factor-stimulated interaction of pERK with Tm5NM1 and that the interaction of pERK with importin7 is greatly reduced in the Tm5NM1 KO cells.
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Galina
authors.initials: G
authors.lastname: Schevzov
authors.affiliation: Cellular and Genetic Medicine Unit, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Kee
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Vanessa B
authors.initials: VB
authors.lastname: Sequeira
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Jeff
authors.initials: J
authors.lastname: Hook
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia Sydney Medical School, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Coombes
authors.affiliation: Cellular and Genetic Medicine Unit, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Lucas
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Justine R
authors.initials: JR
authors.lastname: Stehn
authors.affiliation: Kinghorn Cancer Centre, Cancer Research Program, Garvan Institute of Medical Research, Darlinghurst, Sydney, NSW 2010, Australia.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Musgrove
authors.affiliation: Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Cretu
authors.affiliation: Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6160.
authors.forename: Richard
authors.initials: R
authors.lastname: Assoian
authors.affiliation: Neurodegeneration and Repair Laboratory, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Fath
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Tamar
authors.initials: T
authors.lastname: Hanoch
authors.affiliation: Department of Biological Regulation, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Rony
authors.initials: R
authors.lastname: Seger
authors.affiliation: Cancer and Hematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.
authors.forename: Irina
authors.initials: I
authors.lastname: Pleines
authors.affiliation: Cancer and Hematology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Kile
authors.affiliation: Cellular and Genetic Medicine Unit, University of New South Wales, Australia, Sydney, NSW 2052, Australia.
authors.forename: Edna C
authors.initials: EC
authors.lastname: Hardeman
authors.affiliation: Oncology Research Unit, School of Medical Sciences, University of New South Wales, Australia, Sydney, NSW 2052, Australia p.gunning@unsw.edu.au.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Gunning
mesh_terms: D008841:Actin Cytoskeleton / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D021581:Active Transport, Cell Nucleus; D000818:Animals; D047390:Casein Kinase II / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D010766:Phosphorylation; D014335:Tropomyosin / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C498783:TPM3 protein, human; C411923:Tpm3 protein, mouse; D014335:Tropomyosin; D047390:Casein Kinase II; D020929:Mitogen-Activated Protein Kinase Kinases