GISP binding to TSG101 increases GABA receptor stability by down-regulating ESCRT-mediated lysosomal degradation.
The neuron-specific G protein-coupled receptor interacting scaffold protein (GISP) is a multidomain, brain-specific protein derived from the A-kinase anchoring protein-9 gene. We originally isolated GISP as an interacting partner for the GABA(B) receptor subunit GABA(B1). Here, we show that the protein tumour susceptibility gene 101 (TSG101), an integral component of the endosomal sorting machinery that targets membrane proteins for lysosomal degradation, also interacts with GISP. TSG101 co-immunoprecipitates with GISP from adult rat brain, and using GST pull-downs, we identified that the eighth coiled-coiled region of GISP is critical for TSG101 association. Intriguingly, although there is no direct interaction between GISP and the GABA(B2) subunit, their co-expression in HEK293 cells increases levels of GABA(B2). GISP also inhibits TSG101-dependent GABA(B2) down-regulation in human embryonic kidney 293 cells whereas over-expression of a mutant GISP lacking the TSG101 binding domain has no effect on GABA(B2) degradation. These data suggest that GISP can function as a negative regulator of TSG101-dependent lysosomal degradation of transmembrane proteins in neurons to promote receptor stability.
Kantamneni
Sriharsha
S
Department of Anatomy, MRC Centre for Synaptic Plasticity, School of Medical Sciences, University of Bristol, Bristol, UK.
Holman
David
D
Wilkinson
Kevin A
KA
Corrêa
Sônia A L
SA
Feligioni
Marco
M
Ogden
Simon
S
Fraser
William
W
Nishimune
Atsushi
A
Henley
Jeremy M
JM
D054758:A Kinase Anchor Proteins; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D011963:Receptors, GABA-A / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism; D000099177:Tsg101 Protein
D054758:A Kinase Anchor Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D014157:Transcription Factors; D005680:gamma-Aminobutyric Acid; D000099177:Tsg101 Protein; C486537:Akap9 protein, rat; C485504:Gabbr2 protein, mouse; C502185:Gabrb2 protein, rat