Snakeskin, a membrane protein associated with smooth septate junctions, is required for intestinal barrier function in Drosophila.
Septate junctions (SJs) are the membrane specializations observed between epithelial cells in invertebrates. SJs play a crucial role in epithelial barrier function by restricting the free diffusion of solutes through the intercellular space. In arthropod species, two morphologically different types of SJs have been described: pleated septate junctions (pSJs) and smooth septate junctions (sSJs), which are specific to ectodermal and endodermal epithelia, respectively. In contrast to the recent identification of pSJ-related proteins, the molecular constituents of sSJs are mostly unknown. Here, we report the discovery of a new sSJ-specific membrane protein, designated 'Snakeskin' (Ssk). Ssk is highly concentrated in sSJs in the Drosophila midgut and Malpighian tubules. Lack of Ssk expression is embryonically lethal in Drosophila and results in defective sSJ formation accompanied by abnormal morphology of midgut epithelial cells. We also show that the barrier function of the midgut to a fluorescent tracer is impaired in ssk-knockdown larvae. These results suggest that Ssk is required for the intestinal barrier function in Drosophila.
Division of Cell Biology, Department of Physiology and Cell Biology, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan.
Yuichi
Y
Yanagihashi
Tadao
T
Usui
Yasushi
Y
Izumi
Shigenobu
S
Yonemura
Motoyuki
M
Sumida
Shoichiro
S
Tsukita
Tadashi
T
Uemura
Mikio
M
Furuse
D000595:Amino Acid Sequence; D000818:Animals; D004330:Drosophila / Q000737:chemistry / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004475:Ectoderm / Q000196:embryology / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology* / Q000196:embryology; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D019108:Tight Junctions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; D008565:Membrane Proteins; C577654:Ssk protein, Drosophila