TY - JOUR T1 - Structural modeling of a novel CAPN5 mutation that causes uveitis and neovascular retinal detachment. JF - PLoS One Y1 - 2015 A1 - Bassuk, Alexander G A1 - Yeh, Steven A1 - Wu, Shu A1 - Martin, Daniel F A1 - Tsang, Stephen H A1 - Gakhar, Lokesh A1 - Mahajan, Vinit B KW - Base Sequence KW - Calpain KW - Computational Biology KW - DNA Primers KW - Female KW - Fluorescein Angiography KW - Humans KW - Models, Molecular KW - Molecular Sequence Data KW - Mutation, Missense KW - Pedigree KW - Phenotype KW - Protein Conformation KW - Retinal Detachment KW - Sequence Analysis, DNA KW - Tomography, Optical Coherence KW - Uveitis KW - Vitreoretinopathy, Proliferative AB -

CAPN5 mutations have been linked to autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV), a blinding autoimmune eye disease. Here, we link a new CAPN5 mutation to ADNIV and model the three-dimensional structure of the resulting mutant protein. In our study, a kindred with inflammatory vitreoretinopathy was evaluated by clinical eye examinations, DNA sequencing, and protein structural modeling to investigate the disease-causing mutation. Two daughters of an affected mother demonstrated symptoms of stage III ADNIV, with posterior uveitis, cystoid macular edema, intraocular fibrosis, retinal neovascularization, retinal degeneration, and cataract. The women also harbored a novel guanine to thymine (c.750G>T, p.Lys250Asn) missense mutation in exon 6 of CAPN5, a gene that encodes a calcium-activated cysteine protease, calpain-5. Modeling based on the structures of all known calpains revealed the mutation falls within a calcium-sensitive flexible gating loop that controls access to the catalytic groove. Three-dimensional modeling placed the new mutation in a region adjacent to two previously identified disease-causing mutations, all three of which likely disrupt hydrogen bonding within the gating loop, yielding a CAPN5 with altered enzymatic activity. This is the third case of a CAPN5 mutation leading to inherited uveitis and neovascular vitreoretinopathy, suggesting patients with ADNIV features should be tested for CAPN5 mutations. Structural modeling of novel variants can be used to support mechanistic consequences of the disease-causing variants.

VL - 10 IS - 4 U1 - http://www.ncbi.nlm.nih.gov/pubmed/25856303?dopt=Abstract ER - TY - JOUR T1 - Calpain-5 mutations cause autoimmune uveitis, retinal neovascularization, and photoreceptor degeneration. JF - PLoS Genet Y1 - 2012 A1 - Mahajan, Vinit B A1 - Skeie, Jessica M A1 - Bassuk, Alexander G A1 - Fingert, John H A1 - Braun, Terry A A1 - Daggett, Heather T A1 - Folk, James C A1 - Sheffield, Val C A1 - Stone, Edwin M KW - Amino Acid Sequence KW - Base Sequence KW - Calpain KW - Cell Line KW - Cells, Cultured KW - Choroid Diseases KW - Exome KW - Exons KW - Eye Diseases, Hereditary KW - Female KW - Gene Expression KW - Genetic Linkage KW - Humans KW - Male KW - Models, Molecular KW - Molecular Sequence Data KW - Mutation KW - Pedigree KW - Phenotype KW - Photoreceptor Cells, Vertebrate KW - Protein Conformation KW - Protein Transport KW - Retinal Degeneration KW - Sequence Alignment AB -

Autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) is an autoimmune condition of the eye that sequentially mimics uveitis, retinitis pigmentosa, and proliferative diabetic retinopathy as it progresses to complete blindness. We identified two different missense mutations in the CAPN5 gene in three ADNIV kindreds. CAPN5 encodes calpain-5, a calcium-activated cysteine protease that is expressed in retinal photoreceptor cells. Both mutations cause mislocalization from the cell membrane to the cytosol, and structural modeling reveals that both mutations lie within a calcium-sensitive domain near the active site. CAPN5 is only the second member of the large calpain gene family to cause a human Mendelian disorder, and this is the first report of a specific molecular cause for autoimmune eye disease. Further investigation of these mutations is likely to provide insight into the pathophysiologic mechanisms of common diseases ranging from autoimmune disorders to diabetic retinopathy.

VL - 8 IS - 10 ER - TY - JOUR T1 - Collagen XVIII mutation in Knobloch syndrome with acute lymphoblastic leukemia. JF - American journal of medical genetics. Part A Y1 - 2010 A1 - Mahajan, Vinit B A1 - Olney, Ann Haskins A1 - Garrett, Penny A1 - Chary, Ajit A1 - Dragan, Ecaterina A1 - Lerner, Gary A1 - Murray, Jeffrey A1 - Bassuk, Alexander G KW - Base Sequence KW - Child KW - Child, Preschool KW - Collagen Type XVIII KW - DNA Mutational Analysis KW - Encephalocele KW - Eye Abnormalities KW - Family KW - Female KW - Humans KW - Infant KW - Magnetic Resonance Imaging KW - Male KW - Molecular Sequence Data KW - Mutation KW - Pedigree KW - Precursor Cell Lymphoblastic Leukemia-Lymphoma KW - Retinal Detachment AB -

Knobloch syndrome (KNO) is caused by mutations in the collagen XVIII gene (COL18A1) and patients develop encephalocele and vitreoretinal degeneration. Here, we report an El Salvadorian family where two sisters showed features of KNO. One of the siblings also developed acute lymphoblastic leukemia. DNA sequencing of COL18A1 revealed a homozygous, 2-bp deletion (c3514-3515delCT) in exon 41, which leads to abnormal collagen XVIII and deficiency of its proteolytic cleavage product endostatin. KNO patients with mutations in COL18A1 may be at risk for endostatin-related conditions including malignancy.

VL - 152A IS - 11 U1 - http://www.ncbi.nlm.nih.gov/pubmed/20799329?dopt=Abstract ER - TY - JOUR T1 - Creatine kinase, an ATP-generating enzyme, is required for thrombin receptor signaling to the cytoskeleton. JF - Proceedings of the National Academy of Sciences of the United States of America Y1 - 2000 A1 - Mahajan, V B A1 - Pai, K S A1 - Lau, A A1 - Cunningham, D D KW - Adenosine Triphosphate KW - Animals KW - Base Sequence KW - Calcium KW - Creatine Kinase KW - Cytoskeleton KW - Oligonucleotides, Antisense KW - Rats KW - Receptor, PAR-1 KW - Receptors, Thrombin KW - Signal Transduction KW - Two-Hybrid System Techniques AB -

Thrombin orchestrates cellular events after injury to the vascular system and extravasation of blood into surrounding tissues. The pathophysiological response to thrombin is mediated by protease-activated receptor-1 (PAR-1), a seven-transmembrane G protein-coupled receptor expressed in the nervous system that is identical to the thrombin receptor in platelets, fibroblasts, and endothelial cells. Once activated by thrombin, PAR-1 induces rapid and dramatic changes in cell morphology, notably the retraction of growth cones, axons, and dendrites in neurons and processes in astrocytes. The signal is conveyed by a series of localized ATP-dependent reactions directed to the actin cytoskeleton. How cells meet the dynamic and localized energy demands during signal transmission is unknown. Using the yeast two-hybrid system, we identified an interaction between PAR-1 cytoplasmic tail and the brain isoform of creatine kinase, a key ATP-generating enzyme that regulates ATP within subcellular compartments. The interaction was confirmed in vitro and in vivo. Reducing creatine kinase levels or its ATP-generating potential inhibited PAR-1-mediated cellular shape changes as well as a PAR-1 signaling pathway involving the activation of RhoA, a small G protein that relays signals to the cytoskeleton. Thrombin-stimulated intracellular calcium release was not affected. Our results suggest that creatine kinase is bound to PAR-1 where it may be poised to provide bursts of site-specific high-energy phosphate necessary for efficient receptor signal transduction during cytoskeletal reorganization.

VL - 97 IS - 22 U1 - http://www.ncbi.nlm.nih.gov/pubmed/11050237?dopt=Abstract ER - TY - JOUR T1 - Connectin: a homophilic cell adhesion molecule expressed on a subset of muscles and the motoneurons that innervate them in Drosophila. JF - Cell Y1 - 1992 A1 - Nose, A A1 - Mahajan, V B A1 - Goodman, C S KW - Amino Acid Sequence KW - Animals KW - Base Sequence KW - Cell Adhesion Molecules KW - Cloning, Molecular KW - Connectin KW - DNA KW - Drosophila KW - Molecular Sequence Data KW - Motor Neurons KW - Muscle Proteins KW - Muscles KW - Protein Kinases KW - Sequence Alignment AB -

Each abdominal hemisegment in the Drosophila embryo contains a stereotyped array of 30 muscles, each specifically innervated by one or a few motoneurons. We screened 11,000 enhancer trap lines, isolated several expressing beta-galactosidase in small subsets of muscle fibers prior to innervation, and identified two of these as inserts in connectin and Toll, members of the leucine-rich repeat gene family. Connectin contains a signal sequence, ten leucine-rich repeats, and a putative phosphatidylinositol membrane linkage; in S2 cells, connectin can mediate homophilic cell adhesion. Connectin is expressed on the surface of eight muscles, the motoneurons that innervate them, and several glial cells along the pathways leading to them. During synapse formation, the protein localizes to synaptic sites; afterward, it largely disappears. Thus, connectin is a novel cell adhesion molecule whose expression suggests a role in target recognition.

VL - 70 IS - 4 U1 - http://www.ncbi.nlm.nih.gov/pubmed/1505024?dopt=Abstract ER -