title: Expression and knockdown of zebrafish folliculin suggests requirement for embryonic brain morphogenesis.
abstract: Birt-Hogg-Dubé syndrome (BHD) is a dominantly inherited familial cancer syndrome characterised by the development of benign skin fibrofolliculomas, multiple lung and kidney cysts, spontaneous pneumothorax and susceptibility to renal cell carcinoma. BHD is caused by mutations in the gene encoding Folliculin (FLCN). Little is known about what FLCN does in a healthy individual and how best to treat those with BHD. As a first approach to developing a vertebrate model for BHD we aimed to identify the temporal and spatial expression of flcn transcripts in the developing zebrafish embryo. To gain insights into the function of flcn in a whole organism system we generated a loss of function model of flcn by the use of morpholino knockdown in zebrafish.
  
  
  
  flcn is expressed broadly and upregulated in the fin bud, somites, eye and proliferative regions of the brain of the Long-pec stage zebrafish embryos. Together with knockdown phenotypes, expression analysis suggest involvement of flcn in zebrafish embryonic brain development. We have utilised the zFucci system, an in vivo, whole organism cell cycle assay to study the potential role of flcn in brain development. We found that at the 18 somite stage there was a significant drop in cells in the S-M phase of the cell cycle in flcn morpholino injected embryos with a corresponding increase of cells in the G1 phase. This was particularly evident in the brain, retina and somites of the embryo. Timelapse analysis of the head region of flcn morpholino injected and mismatch control embryos shows the temporal dynamics of cell cycle misregulation during development.
  
  
  
  In conclusion we show that zebrafish flcn is expressed in a non-uniform manner and is likely required for the maintenance of correct cell cycle regulation during embryonic development. We demonstrate the utilisation of the zFucci system in testing the role of flcn in cell proliferation and suggest a function for flcn in regulating cell proliferation in vertebrate embryonic brain development.
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. E.Kenyon@sussex.ac.uk.|Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton, UK. E.Kenyon@sussex.ac.uk.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Kenyon
authors.affiliation: Department of Dermatology and GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: Monique N H
authors.initials: MN
authors.lastname: Luijten
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Harmeet
authors.initials: H
authors.lastname: Gill
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Matthew
authors.initials: M
authors.lastname: Rawlings
authors.affiliation: Department of Biosciences, College of Science, Swansea University, Swansea, SA2 8PP, Wales, UK.
authors.forename: James C
authors.initials: JC
authors.lastname: Bull
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Yavor
authors.initials: Y
authors.lastname: Hadzhiev
authors.affiliation: School of Medicine and School of Life Sciences, University of Dundee, Dow Street, Dundee, UK.|Institute of Medical Biology, Immunos, 8A Biomedical Grove, Singapore, Singapore.
authors.forename: Maurice A M
authors.initials: MA
authors.lastname: van Steensel
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Eamonn
authors.initials: E
authors.lastname: Maher
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Mueller
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000378:metabolism; D002453:Cell Cycle; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D012160:Retina / Q000254:growth & development / Q000378:metabolism; D019170:Somites / Q000254:growth & development / Q000378:metabolism; D059008:Time-Lapse Imaging; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation; D015027:Zebrafish / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D029961:Zebrafish Proteins; C000622228:flcn protein, zebrafish
keywords: Birt-Hogg-Dubé syndrome (BHD); Brain; Cell cycle; Folliculin; Zebrafish; flcn; zFucci