VAMP7 modulates ciliary biogenesis in kidney cells.
Epithelial cells elaborate specialized domains that have distinct protein and lipid compositions, including the apical and basolateral surfaces and primary cilia. Maintaining the identity of these domains is required for proper cell function, and requires the efficient and selective SNARE-mediated fusion of vesicles containing newly synthesized and recycling proteins with the proper target membrane. Multiple pathways exist to deliver newly synthesized proteins to the apical surface of kidney cells, and the post-Golgi SNAREs, or VAMPs, involved in these distinct pathways have not been identified. VAMP7 has been implicated in apical protein delivery in other cell types, and we hypothesized that this SNARE would have differential effects on the trafficking of apical proteins known to take distinct routes to the apical surface in kidney cells. VAMP7 expressed in polarized Madin Darby canine kidney cells colocalized primarily with LAMP2-positive compartments, and siRNA-mediated knockdown modulated lysosome size, consistent with the known function of VAMP7 in lysosomal delivery. Surprisingly, VAMP7 knockdown had no effect on apical delivery of numerous cargoes tested, but did decrease the length and frequency of primary cilia. Additionally, VAMP7 knockdown disrupted cystogenesis in cells grown in a three-dimensional basement membrane matrix. The effects of VAMP7 depletion on ciliogenesis and cystogenesis are not directly linked to the disruption of lysosomal function, as cilia lengths and cyst morphology were unaffected in an MDCK lysosomal storage disorder model. Together, our data suggest that VAMP7 plays an essential role in ciliogenesis and lumen formation. To our knowledge, this is the first study implicating an R-SNARE in ciliogenesis and cystogenesis.
Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America.
Christina M
CM
Szalinski
Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America ; Ciência sem Fronteiras, CNPq, Brasilia, Brazil.
Anatália
A
Labilloy
Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America.
Jennifer R
JR
Bruns
Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America ; Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America.
Ora A
OA
Weisz
D000818:Animals; D002460:Cell Line; D002923:Cilia / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D007668:Kidney / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D020033:Protein Isoforms; D021381:Protein Transport; D050683:R-SNARE Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats
D020033:Protein Isoforms; D050683:R-SNARE Proteins