Disease-associated mutations affect GPR56 protein trafficking and cell surface expression

Jin, Zhaohui; Tietjen, Ian; Bu, Le; Liu-Yesucevitz, Liqun; Gaur, Shantanu; Walsh, Christopher A.; Piao, Xiangshu

doi:10.1093/hmg/ddm144

Cited by 113 publications

(131 citation statements)

References 55 publications

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“…GPR56 from these transfected cells was solubilized in 1% Triton X-100, immunoprecipitated with the C-terminal antibody, and visualized on Western blot analyses using a commercially available antibody to detect the GPR56 NT. The GPR56 NT was visualized in these Western blot analyses as an approximately 75-kDa band that, upon deglycosylation, decreased in size to 37 kDa, consistent with past reports (8,9). As shown in Fig.…”

Section: Gpr56 Is Processed Into Two Fragments That Remainsupporting

confidence: 90%

The N Terminus of the Adhesion G Protein-coupled Receptor GPR56 Controls Receptor Signaling Activity

Paavola

Stephenson

Ritter

et al. 2011

Journal of Biological Chemistry

160

205

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GPR56 is an adhesion G protein-coupled receptor that plays a key role in cortical development. Mutations to GPR56 in humans cause malformations of the cerebral cortex, but little is known about the normal function of the receptor. We found that the large N terminus (NT) of GPR56 is cleaved from the rest of the receptor during processing but remains non-covalently associated with the seven-transmembrane region of the receptor, as indicated by coimmunoprecipitation of the two GPR56 fragments from both transfected cells and native tissue. We also found that truncation of the GPR56 NT results in constitutive activation of receptor signaling, as revealed by increased GPR56-stimulated signaling upon transfection of HEK-293 cells with truncated GPR56, greatly enhanced binding of ␤-arrestins by truncated GPR56 relative to the full-length receptor, extensive ubiquitination of truncated GPR56, and cytotoxicity induced by truncated GPR56 that could be rescued by cotransfection of cells with ␤-arrestin 2. Furthermore, we found that the GPR56 NT is capable of homophilic trans-trans interactions that enhance receptor signaling activity. On the basis of these findings, we suggest a model of receptor activation in which the large N terminus of GPR56 constrains receptor activity but N-terminal interactions (GPR56 NT with an extracellular ligand and/or GPR56 NT homophilic trans-trans associations) can remove this inhibitory influence of the N terminus to activate receptor signaling.During the development of the cerebral cortex, neuronal precursors proliferate in the ventricular and subventricular zones that line the cerebral cavity and then migrate outward to make connections with other neurons. Given the billions of cells involved and the requirements for temporal and spatial precision, it is perhaps not surprising that many different types of problems can arise during this process. Abnormalities in cortical development can lead to a range of distinct neurodevelopmental disorders, some of which are caused by mutations to a single gene. For example, bilateral frontoparietal polymicrogyria is a condition in which patients exhibit profound cognitive abnormalities and seizures because of disordered cortical connectivity in the frontoparietal area. Bilateral frontoparietal polymicrogyria is an autosomal recessive syndrome that results from mutations in the orphan receptor GPR56 (1). Thus, insights into the natural function of GPR56 might shed light on the specific pathology underlying bilateral frontoparietal polymicrogyria and also lead to new insights about the fundamental mechanisms controlling cortical development.GPR56 is a member of the adhesion family of G proteincoupled receptors (GPCRs) 2 , which are characterized by extremely large extracellular N termini (NT) exhibiting homology to adhesion proteins (2). There are approximately 30 adhesion GPCRs, all of which are still considered to be orphan receptors. Almost all members of the adhesion GPCR family possess an N-terminal region known as a "GPCR proteolytic site" or GPS dom...

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Section: Gpr56 Is Processed Into Two Fragments That Remainsupporting

confidence: 90%

The N Terminus of the Adhesion G Protein-coupled Receptor GPR56 Controls Receptor Signaling Activity

Paavola

Stephenson

Ritter

et al. 2011

Journal of Biological Chemistry

160

205

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“…Complete ECD dissociation to reveal β-strand-13 would be a very energy-intensive process, although aGPCR ECD "shedding" from membranes was documented (21). Known aGPCR ligands include collagen subtypes and other components of the insoluble extracellular matrix (10,11,13).…”

Section: Discussionmentioning

confidence: 99%

Adhesion G protein-coupled receptors are activated by exposure of a cryptic tethered agonist

Stoveken¹,

Hajduczok²,

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

227

385

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The large class of adhesion G protein-coupled receptors (aGPCRs) bind extracellular matrix or neighboring cell-surface ligands to regulate organ and tissue development through an unknown activation mechanism. We examined aGPCR activation using two prototypical aGPCRs, GPR56 and GPR110. Active dissociation of the noncovalently bound GPR56 or GPR110 extracellular domains (ECDs) from the respective seven-transmembrane (7TM) domains relieved an inhibitory influence and permitted both receptors to activate defined G protein subtypes. After ECD displacement, the newly revealed short N-terminal stalk regions of the 7TM domains were found to be essential for G protein activation. Synthetic peptides comprising these stalks potently activated GPR56 or GPR110 in vitro or in cells, demonstrating that the stalks comprise a tethered agonist that was encrypted within the ECD. Establishment of an aGPCR activation mechanism provides a rational platform for the development of aGPCR synthetic modulators that could find clinical utility toward aGPCR-directed disease.

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“…3B, available at www.jneurosci.org as supplemental material) (Xu et al, 2006;Jin et al, 2007). Western blot analysis with an antibody against the C terminus of GPR56 C failed to detect any signal in Gpr56 Ϫ/Ϫ mouse brain, in contrast with wild-type and heterozygous brains, confirming that the targeting strategy results in a true null allele (supplemental Fig.…”

Section: Loss Of Gpr56 Leads To Regional Lamination Defectsmentioning

confidence: 79%

GPR56 Regulates Pial Basement Membrane Integrity and Cortical Lamination

Li¹,

Jin²,

Koirala³

et al. 2008

J. Neurosci.

214

242

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GPR56 is a member of the family of adhesion G-protein-coupled receptors that have a large extracellular region containing a GPS (G-protein proteolytic site) domain. Loss-of-function mutations in the GPR56 gene cause a specific human brain malformation called bilateral frontoparietal polymicrogyria (BFPP). BFPP is a radiological diagnosis and its histopathology remains unclear. This study demonstrates that loss of the mouse Gpr56 gene leads to neuronal ectopia in the cerebral cortex, a cobblestone-like cortical malformation. There are four crucial events in the development of cobblestone cortex, namely defective pial basement membrane (BM), abnormal anchorage of radial glial endfeet, mislocalized Cajal-Retzius cells, and neuronal overmigration. By detailed time course analysis, we reveal that the leading causal events are likely the breaches in the pial BM. We show further that GPR56 is present in abundance in radial glial endfeet. Furthermore, a putative ligand of GPR56 is localized in the marginal zone or overlying extracellular matrix. These observations provide compelling evidence that GPR56 functions in regulating pial BM integrity during cortical development.

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Disease-associated mutations affect GPR56 protein trafficking and cell surface expression

Cited by 113 publications

References 55 publications

The N Terminus of the Adhesion G Protein-coupled Receptor GPR56 Controls Receptor Signaling Activity

The N Terminus of the Adhesion G Protein-coupled Receptor GPR56 Controls Receptor Signaling Activity

Adhesion G protein-coupled receptors are activated by exposure of a cryptic tethered agonist

GPR56 Regulates Pial Basement Membrane Integrity and Cortical Lamination

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