TY - JOUR

T1 - The tissue-specific Rep8/UBXD6 tethers p97 to the endoplasmic reticulum membrane for degradation of misfolded proteins

AU - Madsen, Louise

AU - Kriegenburg, Franziska

AU - Lages Lino Vala, Andrea

AU - Best, Diana

AU - Prag, Søren

AU - Hofmann, Kay

AU - Seeger, Michael

AU - Adams, Ian R

AU - Hartmann-Petersen, Rasmus

N1 - Artikel ID: e25061

PY - 2011

Y1 - 2011

N2 - The protein known as p97 or VCP in mammals and Cdc48 in yeast is a versatile ATPase complex involved in several biological functions including membrane fusion, protein folding, and activation of membrane-bound transcription factors. In addition, p97 plays a central role in degradation of misfolded secretory proteins via the ER-associated degradation pathway. This functional diversity of p97 depends on its association with various cofactors, and to further our understanding of p97 function it is important that these cofactors are identified and analyzed. Here, we isolate and characterize the human protein named Rep8 or Ubxd6 as a new cofactor of p97. Mouse Rep8 is highly tissue-specific and abundant in gonads. In testes, Rep8 is expressed in post-meiotic round spermatids, whereas in ovaries Rep8 is expressed in granulosa cells. Rep8 associates directly with p97 via its UBX domain. We show that Rep8 is a transmembrane protein that localizes to the ER membrane with its UBX domain facing the cytoplasm. Knock-down of Rep8 expression in human cells leads to a decreased association of p97 with the ER membrane and concomitantly a retarded degradation of misfolded ER-derived proteasome substrates. Thus, Rep8 tethers p97 to the ER membrane for efficient ER-associated degradation.

AB - The protein known as p97 or VCP in mammals and Cdc48 in yeast is a versatile ATPase complex involved in several biological functions including membrane fusion, protein folding, and activation of membrane-bound transcription factors. In addition, p97 plays a central role in degradation of misfolded secretory proteins via the ER-associated degradation pathway. This functional diversity of p97 depends on its association with various cofactors, and to further our understanding of p97 function it is important that these cofactors are identified and analyzed. Here, we isolate and characterize the human protein named Rep8 or Ubxd6 as a new cofactor of p97. Mouse Rep8 is highly tissue-specific and abundant in gonads. In testes, Rep8 is expressed in post-meiotic round spermatids, whereas in ovaries Rep8 is expressed in granulosa cells. Rep8 associates directly with p97 via its UBX domain. We show that Rep8 is a transmembrane protein that localizes to the ER membrane with its UBX domain facing the cytoplasm. Knock-down of Rep8 expression in human cells leads to a decreased association of p97 with the ER membrane and concomitantly a retarded degradation of misfolded ER-derived proteasome substrates. Thus, Rep8 tethers p97 to the ER membrane for efficient ER-associated degradation.

KW - Adenosine Triphosphatases

KW - Blotting, Western

KW - Cell Cycle Proteins

KW - Cytoplasm

KW - Endoplasmic Reticulum

KW - Endoplasmic Reticulum-Associated Degradation

KW - Erythrocytes

KW - Humans

KW - Immunoprecipitation

KW - In Situ Hybridization

KW - Melanoma

KW - Proteasome Endopeptidase Complex

KW - Protein Binding

KW - Protein Folding

KW - Protein Processing, Post-Translational

KW - Proteins

KW - RNA, Messenger

KW - Real-Time Polymerase Chain Reaction

KW - Tumor Cells, Cultured

KW - Two-Hybrid System Techniques

KW - Ubiquitin

KW - Ubiquitin-Protein Ligases

U2 - 10.1371/journal.pone.0025061

DO - 10.1371/journal.pone.0025061

M3 - Journal article

C2 - 21949850

VL - 6

JO - PLoS ONE

JF - PLoS ONE

SN - 1932-6203

IS - 9

ER -