Identification of a Point Mutation Impairing the Binding between Aquaporin-4 and Neuromyelitis Optica Autoantibodies

Pisani, Francesco; Mola, Maria Grazia; Simone, Laura; Rosito, Stefania; Alberga, Domenico; Mangiatordi, Giuseppe Felice; Lattanzi, Gianluca; Frigeri, Antonio; Svelto, María; Nicchia, Grazia Paola

doi:10.1074/jbc.m114.582221

Cited by 27 publications

(30 citation statements)

References 43 publications

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“…Beyond the wild type (WT), three different engineered mutants were investigated: D 69 E, D 69 H and M 70 V. The latter was employed as a negative control, since such mutation is known not to affect the NMO-IgG epitope unlike the other MTs [25]. A synoptic view is reported in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…In our investigation, the tautomeric state of histidine 69 was univocally assigned on the basis of the hydrogen bond network predictable from the X-ray of AQP0 (PDB codes 1YMG and 2B6P). Indeed, this was the rationale inspiring the mutations at position 69 [25] since NMO-IgGs did not recognize chimeras made by AQP0 transmembrane domains [24]. The pretreatment of such crystals using the protein preparation module available from the Schrödinger Suite 2013 [35] returned hydrogen bonded to carbon δ of H69.…”

Section: From X-ray Structure To Model System Preparationmentioning

confidence: 99%

“…Focusing our attention on residue T62, the Calpha AV values closest to WT (31.37 ± 0.66 Å) are exhibited by D 69 E (31.39 ± 1.73 Å) and M 70 V [25] where we first hypothesized that the effect of the point mutation in 69 is transferred to residues upstream the mutation, including T62. We do not report significant differences in the C-alpha AV distances between WT and D69E.…”

Section: C-alpha Av Distancesmentioning

confidence: 99%

“…In this respect, a coauthored recent work [25] has shown that the mutation of an aspartate in position 69 (D69) impairs the binding between AQP4 and NMO-IgG leaving the water channel function unaltered as well as the formation of the OAPs. Based on 20 ns MD simulations, we speculated that the replacement of D69 with a histidine was responsible for an increased mobility of loop A, with the consequent disruption of the conformational epitopes.…”

Section: Introductionmentioning

confidence: 99%

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Challenging AQP4 druggability for NMO-IgG antibody binding using molecular dynamics and molecular interaction fields

Mangiatordi

Alberga

Siragusa

et al. 2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Neuromyelitis optica (NMO) is a multiple sclerosis-like immunopathology disease affecting optic nerves and the spinal cord. Its pathological hallmark is the deposition of a typical immunoglobulin, called NMO-IgG, against the water channel Aquaporin-4 (AQP4). Preventing NMO-IgG binding would represent a valuable molecular strategy for a focused NMO therapy. The recent observation that aspartate in position 69 (D69) is determinant for the formation of NMO-IgG epitopes prompted us to carry out intensive Molecular Dynamics (MD) studies on a number of single-point AQP4 mutants. Here, we report a domino effect originating from the point mutation at position 69: we find that the side chain of T62 is reoriented far from its expected position leaning on the lumen of the pore. More importantly, the strength of the H-bond interaction between L53 and T56, at the basis of the loop A, is substantially weakened. These events represent important pieces of a clear-cut mechanistic rationale behind the failure of the NMO-IgG binding, while the water channel function as well as the propensity to aggregate into OAPs remains unaltered. The molecular interaction fields (MIF)-based analysis of cavities complemented MD findings indicating a putative binding site comprising the same residues determining epitope reorganization. In this respect, docking studies unveiled an intriguing perspective to address the future design of small drug-like compounds against NMO. In agreement with recent experimental observations, the present study is the first computational attempt to elucidate NMO-IgG binding at the molecular level, as well as a first effort toward a less elusive AQP4 druggability.

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Section: Resultsmentioning

confidence: 99%

Section: From X-ray Structure To Model System Preparationmentioning

confidence: 99%

Section: C-alpha Av Distancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Challenging AQP4 druggability for NMO-IgG antibody binding using molecular dynamics and molecular interaction fields

Mangiatordi

Alberga

Siragusa

et al. 2015

Biochimica et Biophysica Acta (BBA) - Biomembranes

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“…In a healthy large intestine the presence of AQP3-4 and AQP8 transcripts has been confirmed with the use of RT-PCR and Northern blot analysis (M a and Verkman 1999;Elkjaer et al 2001). It seems that such a specific distribution pattern of aquaporins makes them one of key players crucial for the physiological regulation of several processes including the most important one, the production and reabsorption of fluid (King et al 2000), but also of dietary fat processing (M a et al 2001), gut inflammatory disorders (Zhao et al 2014), tumour development (Papadopoulos and Saadoun 2014), or even autoimmune diseases (Pisani et al 2014). Recent studies suggest that aquaporins may serve as an attractive novel drug target with a potential clinical application (Frigeri et al 2007).…”

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confidence: 90%

Immunohistochemical localization of aquaporin 4 (AQP4) in the porcine gastrointestinal tract

2015

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The water channel aquaporin-4 (AQP4) is a protein widely expressed on plasma membrane of a variety of epithelial cells. In this study we investigated the expression of AQP4 in the gastrointestinal tract of the pig using immunohistochemical staining. We found no presence of AQP4 in the different regions of the pig stomach. In the porcine small intestine moderate immunoreactivity to AQP4 was detected in enterocytes (along the villi and in the bottom of the crypts), duodenal Brunner's glands and in enteric ganglia in cells lying in close vicinity to myenteric as well as submucous neurons. In superficial epithelial cells of the colonic mucosa as well as of caecal and colonic glands a very strong immunoreactivity to AQP4 was found. Both in the myenteric and submucous ganglia of the large intestine AQP4-positive cells surrounding enteric neurons were observed. We concluded that AQP4 expression in the porcine gastrointestinal tract showed some species-dependent differences in relation to other species. Based on the presented distribution pattern of AQP4, it is likely that the aquaporin plays a role in mucous (but not acid) secretion and intestinal absorptive processes in the pig. Aquaporins, gut, small intestine, large intestine, pig

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Translational readthrough generates new astrocyte AQP4 isoforms that modulate supramolecular clustering, glial endfeet localization, and water transport

Bellis

Pisani

Mola

et al. 2017

Glia

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Regulation of water homeostasis is a central feature of central nervous system pathophysiology. In this context, several lines of evidence suggest a crucial role for the water channel aquaporin-4 (AQP4) and its plasma membrane supramolecular organization as the key element. Here, we demonstrate the expression in tissues of additional isoforms of AQP4 characterized by a C-terminal extension generated by programmed translational readthrough. These extended isoforms (AQP4ex) display a perivascular polarization and expression in dystrophin-dependent pools. AQP4ex reduces supramolecular clustering tendency and allows AQP4 interactions with syntrophin. Furthermore, site-directed mutagenesis of two serines in the extended C-terminus of AQP4ex showed potential regulation of water permeability by phosphorylation. Finally, AQP4ex expression can be positively modulated by gentamicin treatment, demonstrating the possibility of regulating the AQP4 translational readthrough frequency. This novel regulatory mechanism could have important pathophysiological implications for conditions in which alternations have been reported in AQP4 structure.

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Identification of a Point Mutation Impairing the Binding between Aquaporin-4 and Neuromyelitis Optica Autoantibodies

Abstract: Background: Neuromyelitis optica autoantibodies target the aquaporin-4 (AQP4) aggregate named orthogonal arrays of particles (OAP

Cited by 27 publications

References 43 publications

Challenging AQP4 druggability for NMO-IgG antibody binding using molecular dynamics and molecular interaction fields

Challenging AQP4 druggability for NMO-IgG antibody binding using molecular dynamics and molecular interaction fields

Immunohistochemical localization of aquaporin 4 (AQP4) in the porcine gastrointestinal tract

Translational readthrough generates new astrocyte AQP4 isoforms that modulate supramolecular clustering, glial endfeet localization, and water transport

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