Goodpasture antigen-binding protein, the kinase that phosphorylates the goodpasture antigen, is an alternatively spliced variant implicated in autoimmune pathogenesis.
The non-collagenous C-terminal domain of the alpha(3) chain of collagen IV is the autoantigen in Goodpasture disease, an autoimmune disorder described only in humans. Specific N-terminal phosphorylation is a biological feature unique to the human domain when compared with other homologous domains lacking immunopathogenic potential. We have recently cloned from a HeLa-derived cDNA library a novel serine/threonine kinase (Goodpasture antigen-binding protein (GPBP)) that phosphorylates the N-terminal region of the human domain (Raya, A. Revert, F, Navarro, S. and Saus J. (1999) J. Biol. Chem. 274, 12642-12649). We show here that the pre-mRNA of GPBP is alternatively spliced in human tissues an…
The expression of the Goodpasture antigen-binding protein (ceramide transporter) in adult rat brain
The Goodpasture antigen-binding protein (GPBP) plays a critical role in brain development. Knockdown of GPBP leads to loss of myelinated tracts in the central nervous system and to extensive apoptosis in the brain during early embryogenesis. GPBP was initially identified as a protein associated with the autoantigen in Goodpasture autoimmune syndrome, where it was shown to be a kinase that regulates type IV collagen organization. GPBP isoforms bind and transport ceramide from the endoplasmic reticulum to the Golgi apparatus and are therefore also known as ceramide transporters (CERT). Ceramide dysregulation is involved in autoimmunity and neurodegenerative disorders. In order to analyze the …
Goodpasture Antigen-binding Protein Is a Soluble Exportable Protein That Interacts with Type IV Collagen
Goodpasture-antigen binding protein (GPBP) is a nonconventional Ser/Thr kinase for basement membrane type IV collagen. Various studies have questioned these findings and proposed that GPBP serves as transporter of ceramide between the endoplasmic reticulum and the Golgi apparatus. Here we show that cells expressed at least two GPBP isoforms resulting from canonical (77-kDa) and noncanonical (91-kDa) mRNA translation initiation. The 77-kDa polypeptide interacted with type IV collagen and localized as a soluble form in the extracellular compartment. The 91-kDa polypeptide and its derived 120-kDa polypeptide associated with cellular membranes and regulated the extracellular levels of the 77-kD…
An in vitro and in vivo study of peptide-functionalized nanoparticles for brain targeting: The importance of selective blood-brain barrier uptake
Targeted delivery of drugs across endothelial barriers remains a formidable challenge, especially in the case of the brain, where the blood-brain barrier severely limits entry of drugs into the central nervous system. Nanoparticle-mediated transport of peptide/protein-based drugs across endothelial barriers shows great potential as a therapeutic strategy in a wide variety of diseases. Functionalizing nanoparticles with peptides allows for more efficient targeting to specific organs. We have evaluated the hemocompatibilty, cytotoxicity, endothelial uptake, efficacy of delivery and safety of liposome, hyperbranched polyester, poly(glycidol) and acrylamide-based nanoparticles functionalized wi…
Clonal heterogeneity of thymic B cells from early-onset myasthenia gravis patients with antibodies against the acetylcholine receptor
Myasthenia gravis (MG) with antibodies against the acetylcholine receptor (AChR-MG) is considered as a prototypic autoimmune disease. The thymus is important in the pathophysiology of the disease since thymus hyperplasia is a characteristic of early-onset AChR-MG and patients often improve after thymectomy. We hypothesized that thymic B cell and antibody repertoires of AChR-MG patients differ intrinsically from those of control individuals. Using immortalization with Epstein Barr Virus and Toll-like receptor 9 activation, we isolated and characterized monoclonal B cell lines from 5 MG patients and 8 controls. Only 2 of 570 immortalized B cell clones from MG patients produced antibodies agai…