A soluble sulfogalactosyl ceramide mimic promotes Delta F508 CFTR escape from endoplasmic reticulum associated degradation.
AdaSGC binds Hsc70s to inhibit ATPase activity. Using single-turnover assays, adaSGC, a soluble SGC mimic, preferentially inhibited Hsp40-activated Hsc70 ATP hydrolysis (Ki approximately 10 microM) to reduce C-terminal Hsc70-peptide binding and, potentially, chaperone function. ERAD of misfolded Delta F508 CFTR requires Hsc70-Hsp40 chaperones. In transfected baby hamster kidney (BHK) cells, adaSGC increased Delta F508CFTR ERAD escape, and after low-temperature glycerol rescue, maturation, and iodide efflux. Inhibition of SGC biosynthesis reduced Delta F508CFTR but not wtCFTR expression, whereas depletion of other glycosphingolipids had no affect. WtCFTR transfected BHK cells showed increased SGC synthesis compared with Delta F508CFTR/mock-transfected cells. Partial rescue of Delta F508CFTR by low-temperature glycerol increased SGC synthesis. AdaSGC also increased cellular endogenous SGC levels. SGC in the lung, liver, and kidney was severely depleted in Delta F508CFTR compared with wtCFTR mice, suggesting a role for CFTR in SGC biosynthesis.
Park
Hyun-Joo
HJ
Research Institute, Division of Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
Mylvaganum
Murugesapillai
M
McPherson
Anne
A
Fewell
Sheara W
SW
Brodsky
Jeffrey L
JL
Lingwood
Clifford A
CA
D000218:Adamantane / Q000737:chemistry / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics* / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005699:Galactosylceramides / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D006028:Glycosphingolipids / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D051379:Mice; D011485:Protein Binding; D014162:Transfection
D005699:Galactosylceramides; D006028:Glycosphingolipids; D050883:HSC70 Heat-Shock Proteins; C093349:cystic fibrosis transmembrane conductance regulator delta F508; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate; D000218:Adamantane