The palmitoyl acyltransferase HIP14 shares a high proportion of interactors with huntingtin: implications for a role in the pathogenesis of Huntington's disease.
HIP14 is the most highly conserved of 23 human palmitoyl acyltransferases (PATs) that catalyze the post-translational addition of palmitate to proteins, including huntingtin (HTT). HIP14 is dysfunctional in the presence of mutant HTT (mHTT), the causative gene for Huntington disease (HD), and we hypothesize that reduced palmitoylation of HTT and other HIP14 substrates contributes to the pathogenesis of the disease. Here we describe the yeast two-hybrid (Y2H) interactors of HIP14 in the first comprehensive study of interactors of a mammalian PAT. Unexpectedly, we discovered a highly significant overlap between HIP14 interactors and 370 published interactors of HTT, 4-fold greater than for control proteins (P = 8 × 10(-5)). Nearly half of the 36 shared interactors are already implicated in HD, supporting a direct link between HIP14 and the disease. The HIP14 Y2H interaction set is significantly enriched for palmitoylated proteins that are candidate substrates. We confirmed that three of them, GPM6A, and the Sprouty domain-containing proteins SPRED1 and SPRED3, are indeed palmitoylated by HIP14; the first enzyme known to palmitoylate these proteins. These novel substrates functions might be affected by reduced palmitoylation in HD. We also show that the vesicular cargo adapter optineurin, an established HTT-binding protein, co-immunoprecipitates with HIP14 but is not palmitoylated. mHTT leads to mislocalization of optineurin and aberrant cargo trafficking. Therefore, it is possible that optineurin regulates trafficking of HIP14 to its substrates. Taken together, our data raise the possibility that defective palmitoylation by HIP14 might be an important mechanism that contributes to the pathogenesis of HD.
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Stefanie L
SL
Butland
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Shaun S
SS
Sanders
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Mandi E
ME
Schmidt
Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin-Buch 13125, Germany.
Sean-Patrick
SP
Riechers
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
David T S
DT
Lin
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Dale D O
DD
Martin
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Kuljeet
K
Vaid
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Rona K
RK
Graham
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4.
Roshni R
RR
Singaraja
Neuroproteomics, Max Delbrueck Center for Molecular Medicine, Berlin-Buch 13125, Germany mrh@cmmt.ubc.ca conibear@cmmt.ubc.ca ewanker@mdc-berlin.de.
Erich E
EE
Wanker
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4 mrh@cmmt.ubc.ca conibear@cmmt.ubc.ca ewanker@mdc-berlin.de.
Elizabeth
E
Conibear
Centre for Molecular Medicine and Therapeutics, Department of Medical Genetics, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada V5Z 4H4 mrh@cmmt.ubc.ca conibear@cmmt.ubc.ca ewanker@mdc-berlin.de.
Michael R
MR
Hayden
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins; D002522:Chlorocebus aethiops; D053263:Gene Regulatory Networks; D057809:HEK293 Cells; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D054878:Lipoylation; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins; D058977:Molecular Sequence Annotation; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D035582:Transcription Factor TFIIIA / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C484158:GPM6A protein, human; C086055:HTT protein, human; D000071058:Huntingtin Protein; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C409460:OPTN protein, human; D012097:Repressor Proteins; C504812:SPRED1 protein, human; C511416:SPRED3 protein, human; D035582:Transcription Factor TFIIIA; D000217:Acyltransferases; C473038:ZDHHC17 protein, human