PgmNr Z6015: marsyas: a zebrafish mutant in GBF1 showing defects in epithelial integrity.

Authors:
Thomas A. Hawkins 1 ; Liana Goodings 1 ; Patrick Toolan-Kerr 1 ; Richard J. Poole 1 ; Rodrigo M. Young 1 ; Heather L. Stickney 1 ; Florencia Cavodeassi 2 ; Quenten P. Schwartz 3 ; Stephen W. Wilson 1


Institutes
1) Div. Biosciences, UCL, London, UK; 2) Centro de Biologia Molecular Severo Ochoa, Universidad Autonoma de Madrid, Madrid, Spain; 3) Center for Cancer Biology, University of South Australia, Adelaide, Australia.


Abstract:

The zebrafish mutant marsyas (mrys) was identified through a screen for skin defects using the vital dye R18 at 3dpf.  mrys mutants display skin defects from 36hpf with the outer layer of skin cells sloughing off from the basal layer and ineffective formation of all fins. mrys mutants also have defective blood vessel formation, displaying bleeds across their circulatory system concurrent with defects in the skin.  Apico-basal polarity of epidermal cells appears unaffected.

Initial bulked-segregant mapping indicated a lesion on chromosome 13 and subsequent whole genome sequencing identified a premature stop codon in GBF1 (golgi brefeldin-A resistance factor 1).  This lesion was confirmed by high-resolution mapping.  We are currently attempting phenocopy and rescue of the phenotype to confirm the mutation as causative.

GBF1 is an ArfGEF implicated in the entry of vesicles to the cis-golgi, feeding primarily the exocytosis pathway of vesicle trafficking although it is also implicated in endocytosis by some studies.  The drosophila GBF1 mutant gartenzwerg has defects in tracheal and other tubular structure formation, suggesting a comparable phenotype.

We are currently carrying out further phenotypic analysis, including cell-autonomy tests, electron microscopy and GFP tagging of golgi and other organelles to closely examine the phenotype.  Our primary question concerns whether the phenotypes we observe originate from a failure of the vesicular delivery of protein(s) important for epithelial integrity or whether the phenotype is caused by defective balance between membrane compartments of epithelial cells.



ZFIN Genetics Index
1. gbf1