Altering the Modular Architecture of Galectins Affects its Binding with Synthetic α-Dystroglycan O-Mannosylated Core M1 Glycoconjugates In situ.

The multifunctionality of galectins helps regulate a broad range of fundamental cellular processes via cis-binding and trans-bridging activities and has gained widespread attention with respect to the importance of the natural specificity/selectivity of this lectin family to its glycoconjugate receptors. Combining galectin (Gal)-1, -3, -4, and -9 variant test panels, achieved via rational protein engineering, and a synthetic α-dystroglycan (DG) O-Mannosylated core M1 glycopeptide library, a detailed comparative analysis was performed, utilizing microarray experiments to delineate the design-functionality relationships within this lectin family. Enhancement of prototype Gal-1 and chimera-type Gal-3 cis-binding toward the prepared ligands is possible by transforming these lectins into tandem-repeat type and prototypes, respectively. Furthermore, Gal-1 variants demonstrated improved trans-bridging capabilities between core M1 α-DG glycopeptides and laminins in microarray, suggesting the possible translational applications of these galectin variants in the treatment of some forms of α-dystroglycanopathy.

Exploring the In situ pairing of human galectins toward synthetic O-mannosylated core M1 glycopeptides of α-dystroglycan.

Dystroglycan (DG), which constitutes a part of the dystrophin-glycoprotein complex, connects the extracellular matrix to the cytoskeleton. The matriglycans presented by the extracellular α-DG serve as a contact point with extracellular matrix proteins (ECM) containing laminin G-like domains, providing cellular stability. However, it remains unknown whether core M1 (GlcNAcß1-2Man) structures can serve as ligands among the various O-Mannosylated glycans. Therefore, based on the presence of N-acetylLactosamine (LacNAc) in this glycan following the core extension, the binding interactions with adhesion/growth-regulatory galectins were explored. To elucidate this process, the interaction between galectin (Gal)-1, -3, -4 and -9 with α-DG fragment 372TRGAIIQTPTLGPIQPTRV390 core M1-based glycopeptide library were profiled, using glycan microarray and nuclear magnetic resonance studies. The binding of galectins was revealed irrespective of its modular architecture, adding galectins to the list of possible binding partners of α-DG core M1 glycoconjugates by cis-binding (via peptide- and carbohydrate-protein interactions), which can be abrogated by α2,3-sialylation of the LacNAc units. The LacNAc-terminated α-DG glycopeptide interact simultaneously with both the S- and F-faces of Gal-1, thereby inducing oligomerization. Furthermore, Gal-1 can trans-bridge α-DG core M1 structures and laminins, which proposed a possible mechanism by which Gal-1 ameliorates muscular dystrophies; however, this proposal warrants further investigation.

Synthetic glycopeptides reveal specific binding pattern and conformational change at O-mannosylated position of α-dystroglycan by POMGnT1 catalyzed GlcNAc modification.

Structural and functional effects of core M1 type glycan modification catalyzed by protein O-linked mannose ß1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) were investigated using a core M1 glycoform focused library of an α-dystroglycan fragment, 372TRGAIIQTPTLGPIQPTRV390. Evanescent-field fluorescence-assisted microarray system illuminated the specific binding pattern of plant lectins that can discriminate the glycan structure of core M1 glycan of the library. The comparative NMR analysis of synthetic glycopeptide having different length of the O-mannosylated glycans revealed a conformational change of the peptide backbone along with core M1 disaccharide formation. No long-range NOE signals of glycan-amino acid nor inter amino acid indicate the conformational change is induced by steric hindrance of core M1, the sole 1,2-O-modified form among protein binding sugar residue found in mammals.

Total anomalous pulmonary venous connection with a ductus arteriosus aneurysm in a neonate: report of a case.

We performed successful emergency surgery on a 1-day-old infant to repair a total anomalous pulmonary venous connection (TAPVC) and a ductus arteriosus aneurysm (DAA) diagnosed by two-dimensional echocardiography. We anastomosed the common pulmonary venous chamber to the left atrium and ligated the pulmonary end of the DAA. Echocardiography and cardiac catheterization done 3 months later showed that the DAA had regressed. To the best of our knowledge, this is the first report describing the successful repair of a supracardiac TAPVC with a DAA.

Simultaneous repair of pectus excavatum and tetralogy of fallot: report of a case.

We report an 18-month-old boy with the association of pectus excavatum and tetralogy of Fallot (TOF). We successfully performed simultaneous pectus repair using sternal elevation without any prosthetic support and total correction of TOF after a prior modified Blalock-Taussig shunt. Retracting a divided costo-sternal complex with a rectus abdominal flap away from the operative field before the cardiac operation provided excellent surgical exposure. The modified Blalock-Taussig shunt prior to the combined repair prevented life-threatening hypoxic spells during dissection of the deformed sternum and costochondral cartilages before institution of cardiopulmonary bypass.

Absent pulmonary valve associated with tetralogy of Fallot and complete atrioventricular septal defect: report of a case.

A male infant with an extremely rare combination of absent pulmonary valve, tetralogy of Fallot and atrioventricular septal defect presented without symptoms of respiratory distress or congestive heart failure. He underwent successful primary repair at the age of 5 months. The procedure consisted of double-patch repair of the atrioventricular septal defect and right ventricular outflow tract reconstruction with a monocusp transannular patch. Resection or plication of a dilated pulmonary artery was not required. The patient is doing well without any symptoms 5 years after repair.