A general role for Rab27a in secretory cells.
Vesicular transport is a complex multistep process regulated by distinct Rab GTPases. Here, we show for the first time that an EGFP-Rab fusion protein is fully functional in a mammalian organism. We constructed a PAC-based transgenic mouse, which expresses EGFP-Rab27a under the control of endogenous Rab27a promoter. The EGFP-Rab27a transgene was fully functional and rescued the two major defects of the ashen Rab27a knockout mouse. We achieved cell-specific expression of EGFP-Rab27a, which faithfully followed the pattern of expression of endogenous Rab27a. We found that Rab27a is expressed in an exceptionally broad range of specialized secretory cells, including exocrine (particularly in mucin- and zymogen-secreting cells), endocrine, ovarian, and hematopoietic cells, most of which undergo regulated exocytosis. We suggest that Rab27a acts in concert with Rab3 proteins in most regulated secretory events. The present strategy represents one way in which the complex pattern of expression and function of proteins involved in specialized cell types may be unraveled.
Tolmachova
Tanya
T
Cell and Molecular Biology, Division of Biomedical Sciences, Faculty of Medicine, Imperial College London, London SW7 2AZ, United Kingdom.
Anders
Ross
R
Stinchcombe
Jane
J
Bossi
Giovanna
G
Griffiths
Gillian M
GM
Huxley
Clare
C
Seabra
Miguel C
MC
D000818:Animals; D002478:Cells, Cultured; D004702:Endocrine Glands / Q000166:cytology / Q000378:metabolism*; D005088:Exocrine Glands / Q000166:cytology / Q000378:metabolism*; D005089:Exocytosis / Q000502:physiology; D005260:Female; D041981:Gastrointestinal Tract / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic / Q000378:metabolism; D008854:Microscopy, Electron; D010053:Ovary / Q000166:cytology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014018:Tissue Distribution; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D000075745:rab27 GTP-Binding Proteins; D049452:Green Fluorescent Proteins; C512962:Rab27a protein, mouse; D020691:rab GTP-Binding Proteins; D020692:rab3 GTP-Binding Proteins