Dysbindin, short for dystrobrevin-binding protein 1, is a protein constituent of the dystrophin-associated protein complex (DPC) of skeletal muscle cells. It is also a part of BLOC-1, or biogenesis of lysosome-related organelles complex 1. Dysbindin was discovered by the research group of Derek Blake via yeast two-hybrid screening for binding partners of α-dystrobrevin. [5] In addition, dysbindin is found in neural tissue of the brain, particularly in axon bundles and especially in certain axon terminals, notably mossy fiber synaptic terminals in the cerebellum and hippocampus. [5] In humans, dysbindin is encoded by the DTNBP1 gene. [5]
Much interest in dysbindin has arisen through pedigree-based family-association studies of families with a history of schizophrenia, where a strong association was found between expression of a particular dysbindin allele and a clinical expression of schizophrenia. [6] However, the genetic link between dysbindin and schizophrenia has not been established in all the case control samples tested and this implies that there are different genetic subtypes of schizophrenia with different disease allele frequencies in different populations. This phenomenon is called genetic locus heterogeneity and is typical of all common disorders with a strong genetic component. A further complication is that it is highly likely that there are several or many different mutations within the dysbindin gene that are responsible for schizophrenia. This complexity is called disease allele heterogeneity and is a further reason that genetic associations are found with different markers in the dysbindin gene when different samples are studied.
Genetically caused dysbindin-related mechanisms causing brain dysfunction are not fully known, but in one study, schizophrenic patients carrying the high-risk haplotype demonstrated visual processing deficits. [7] In another work, damping down the DTNBP1 expression led to an increase in cell surface dopamine D2-receptor levels. [8]
Mutation in the DTNBP1 gene was also shown to cause Hermansky–Pudlak syndrome type 7. [9]
In drosophila, dysbindin has been shown to be essential for neural plasticity. [10]
Dysbindin has been shown to interact with SNAPAP, [11] MUTED [11] and PLDN. [11]
Heřmanský–Pudlák syndrome is an extremely rare autosomal recessive disorder which results in oculocutaneous albinism, bleeding problems due to a platelet abnormality, and storage of an abnormal fat-protein compound. It is considered to affect around 1 in 500,000 people worldwide, with a significantly higher occurrence in Puerto Ricans, with a prevalence of 1 in 1800. Many of the clinical research studies on the disease have been conducted in Puerto Rico.
BLOC-1 or biogenesis of lysosome-related organelles complex 1 is a ubiquitously expressed multisubunit protein complex in a group of complexes that also includes BLOC-2 and BLOC-3. BLOC-1 is required for normal biogenesis of specialized organelles of the endosomal-lysosomal system, such as melanosomes and platelet dense granules. These organelles are called LROs which are apparent in specific cell-types, such as melanocytes. The importance of BLOC-1 in membrane trafficking appears to extend beyond such LROs, as it has demonstrated roles in normal protein-sorting, normal membrane biogenesis, as well as vesicular trafficking. Thus, BLOC-1 is multi-purposed, with adaptable function depending on both organism and cell-type.
AP-3 complex subunit beta-1 is a protein that in humans is encoded by the AP3B1 gene.
SNARE-associated protein Snapin is a protein that in humans is encoded by the SNAPIN gene.
Pallidin is a protein that in humans is encoded by the PLDN gene.
Hermansky–Pudlak syndrome 1 protein is a protein that in humans is encoded by the HPS1 gene.
AP-3 complex subunit mu-1 is a protein that in humans is encoded by the AP3M1 gene.
Hermansky–Pudlak syndrome 4 protein is a protein that in humans is encoded by the HPS4 gene.
Hermansky–Pudlak syndrome 3 protein is a protein that in humans is encoded by the HPS3 gene.
Hermansky–Pudlak syndrome 5 protein is a protein that in humans is encoded by the HPS5 gene.
Biogenesis of lysosome-related organelles complex 1 subunit 2 is a protein that in humans is encoded by the BLOC1S2 gene.
Biogenesis of lysosome-related organelles complex 1 subunit 1 is a protein that in humans is encoded by the BLOC1S1 gene.
Protein Muted homolog is a protein that in humans is encoded by the MUTED gene.
Vacuolar protein sorting-associated protein 33A is a protein that in humans is encoded by the VPS33A gene.
Dystrobrevin alpha is a protein that in humans is encoded by the DTNA gene.
Protein cappuccino homolog is a protein that in humans is encoded by the CNO gene.
Hermansky–Pudlak syndrome 6 (HPS6), also known as ruby-eye protein homolog (Ru), is a protein that in humans is encoded by the HPS6 gene.
Dystrobrevin beta is a protein which in humans is encoded by the DTNB gene.
BLOC-3 or biogenesis of lysosome-related organelles complex 3 is a ubiquitously expressed multisubunit protein complex.
P14 deficiency is a rare autosomal recessive disease characterized as a primary immunodeficiency syndrome. This disease was first identified within a white Mennonite family by Professor Bodo Grimbacher and Professor Christoph Klein’s teams in 2006. Four out of 15 offspring in this family showed symptoms including short stature, recurrent infection of Streptococcus pneumonia, and dysfunction of cells that contain specific lysosome-related organelles, including cytotoxic T cells, melanocytes, and neutrophil granulocytes.