title: Differential expression and cellular localization of ERKs during organogenic nodule formation from internodes of Humulus lupulus var. Nugget.
abstract: The expression and subcellular localization of extracellular signal-regulated kinase 1 or 2 (ERK1/2) homologues (HLERK1/2) during the process of organogenic nodule formation in Humulus lupulus var. Nugget was studied using antibodies specific for ERK1 and ERK2, and for phosphorylated mitogen-activated protein kinases (MAPKs). The increase in HLERK levels, detected by Western blotting 12 hours after wounding suggests their involvement in response to the wounding treatment applied for morphogenesis induction. In dividing cambial cells, occurring in between 4 and 7 days after morphogenesis induction, as well as in dividing prenodular cells (15 days after induction) HLERK1 and/or 2 were localized in the nucleus. However, as soon as nodular cells start proliferating to form shoot meristems, HLERK1 and 2 were detected in the cytoplasm and not in the nucleus. The data reported account for a differential expression and activation of HLERK1 and HLERK2 throughout the process of nodule formation and plantlet regeneration. HLERK1 appears to be expressed in the stages of nodule formation and plantlet regeneration, playing a possible role in controlling cell proliferation and differentiation. HLERK2 may be induced as a response to reactive oxygen species (ROS) generated by wounding of internodes as its expression is reduced in liquid medium with less oxygen availability compared to solid medium. However, addition of a ROS inhibitor to the liquid medium does not result in a further decrease in the HLERK2 level.
authors.affiliation: Laboratory of Plant Biotechnology-ICAT, Campus of Science Faculty of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal. mfsilva@fc.ul.pt
authors.forename: Marta
authors.initials: M
authors.lastname: Sousa Silva
authors.forename: Ana
authors.initials: A
authors.lastname: Margarida Fortes
authors.forename: Pilar
authors.initials: P
authors.lastname: Sanchéz Testillanob
authors.forename: Maria del Carmen
authors.initials: Mdel C
authors.lastname: Risueño
authors.forename: Maria
authors.initials: M
authors.lastname: Salom'e Pais
mesh_terms: D018506:Gene Expression Regulation, Plant; D027582:Humulus / Q000201:enzymology* / Q000254:growth & development; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3