Production of panels of monoclonal antibodies by the hybridoma method

Characterization of 65 epitope-specific dystrophin monoclonal antibodies in canine and murine models of duchenne muscular dystrophy by immunostaining and western blot

Epitope-specific monoclonal antibodies can provide unique insights for studying cellular proteins. Dystrophin is one of the largest cytoskeleton proteins encoded by 79 exons. The absence of dystrophin results in Duchenne muscular dystrophy (DMD). Over the last two decades, dozens of exon-specific human dystrophin monoclonal antibodies have been developed and successfully used for DMD diagnosis. Unfortunately, the majority of these antibodies have not been thoroughly characterized in dystrophin-deficient dogs, an outstanding large animal model for translational research. To fill the gap, we performed a comprehensive study on 65 dystrophin monoclonal antibodies in normal and dystrophic dogs (heart and skeletal muscle) by immunofluorescence staining and western blot. For comparison, we also included striated muscles from normal BL10 and dystrophin-null mdx mice. Our analysis revealed distinctive species, tissue and assay-dependent recognition patterns of different antibodies. Importantly, we identified 15 antibodies that can consistently detect full-length canine dystrophin in both immunostaining and western blot. Our results will serve as an important reference for studying DMD in the canine model.

Endosomal location of dopamine receptors in neuronal cell cytoplasm

Five subtypes of dopamine receptor exist in two subfamilies: two D(1)-like (D(1) and D(5)) and three D(2)-like (D(2), D(3) and D(4)). We produced novel monoclonal antibodies against all three D(2)-like receptors and used them to localize receptors in Ntera-2 (NT-2) cells, the human neuronal precursor cell line. Most of the immunostaining for all three receptors colocalized with mannose-6-phosphate receptor, a marker for late endosomes formed by internalization of the plasma membrane. This result was obtained with antibodies against three different epitopes on the D(3) receptor, to rule out the possibility of cross-reaction with another protein, and controls without primary antibody or in the presence of competitor antigen were completely negative. In rat cerebral cortex and hippocampus, some of the dopamine receptor staining was found in similar structures in neuronal cell cytoplasm. Only some of the neurons were positive for dopamine receptors and the pattern was consistent with previously-reported patterns of innervation by dopamine-producing neurons. Endosomal dopamine receptors may provide a useful method for identifying cell bodies of dopamine-responsive neurons to complement methods that detect only active receptors in the neuronal cell membrane.