Spleen-specific isoforms of Pax5 and Ataxin-7 as potential proteomic markers of lymphoma-affected spleen

Co-Localization and Interaction of Pax5 with Iba1 in Brain of Mice

The Pax5, a B-cell-Specific Activator Protein (BSAP) and redox-sensitive transcription factor, is expressed in the immune-privileged brain, B-lymphocytes, lymph nodes and spleen. PAX5-mediated immune pathway has also been described in the progression of Glioblastoma multiforme. However, the status of Pax5 and its role in brain immunity are not yet elucidated. In silico analysis of Pax5 interacting proteins predicts its interaction with proteins of cell proliferation, differentiation of hematopoietic cells, neurogenesis and several cell signalling pathways. Promoter analysis shows multiple binding sites for Pax5 in promoter of ionized calcium-binding adapter molecule 1 (Iba1). Like Iba1, Pax5 is also associated with inflammatory and immune response, activation of leukocyte and remodelling of actin cytoskeleton. Therefore, localization and interaction of Pax5 with Iba1 in brain of mice were studied using Chromatin Immunoprecipitation (ChIP), Co-Immunoprecipitation (Co-IP) and Immuno-fluorescence assay. The Pax5- and Iba1-positive cells were observed in cerebral cortex, cerebellum, olfactory bulb, hippocampus, and ventricles of brain. The co-localization of Pax5 and Iba1 was evident in microglia in almost all evaluated regions of brain. In some regions, Pax5- and Iba1-positive were distinctly compartmentalized. The Pax5a/b interacts with Iba1 and binds to its regulatory sequences. Results indicate Pax5-associated activities of Iba1 in microglia in brain of mice.

Intrinsic Disorder in Proteins with Pathogenic Repeat Expansions

Intrinsically disordered proteins and proteins with intrinsically disordered regions have been shown to be highly prevalent in disease. Furthermore, disease-causing expansions of the regions containing tandem amino acid repeats often push repetitive proteins towards formation of irreversible aggregates. In fact, in disease-relevant proteins, the increased repeat length often positively correlates with the increased aggregation efficiency and the increased disease severity and penetrance, being negatively correlated with the age of disease onset. The major categories of repeat extensions involved in disease include poly-glutamine and poly-alanine homorepeats, which are often times located in the intrinsically disordered regions, as well as repeats in non-coding regions of genes typically encoding proteins with ordered structures. Repeats in such non-coding regions of genes can be expressed at the mRNA level. Although they can affect the expression levels of encoded proteins, they are not translated as parts of an affected protein and have no effect on its structure. However, in some cases, the repetitive mRNAs can be translated in a non-canonical manner, generating highly repetitive peptides of different length and amino acid composition. The repeat extension-caused aggregation of a repetitive protein may represent a pivotal step for its transformation into a proteotoxic entity that can lead to pathology. The goals of this article are to systematically analyze molecular mechanisms of the proteinopathies caused by the poly-glutamine and poly-alanine homorepeat expansion, as well as by the polypeptides generated as a result of the microsatellite expansions in non-coding gene regions and to examine the related proteins. We also present results of the analysis of the prevalence and functional roles of intrinsic disorder in proteins associated with pathological repeat expansions.