Biology subjects

Rincon-Limas, D. E.

Publications and source records attributed to Rincon-Limas, D. E..

3 recordsLinked to original sources

bioRxiv2025

Progressive Supranuclear Palsy PERK haplotype B selectively translates DLX1 promoting tau toxicity

The unfolded protein response (UPR) sensor PERK exists in two haplotypes termed A and B. PERK-B uniquely confers increased risk for tauopathies like progressive supranuclear palsy (PSP), but the mechanisms distinguishing its function from PERK-A and contributing to its association with tau pathology are not known. Here, we developed a controlled cellular model for a pair-wise comparison of the two PERK haplotypes, finding their UPR functions nearly indistinguishable. However, a careful examination employing puromycin-based proteomics revealed that a subset of mRNA translation events were permissible under PERK-B, but not PERK-A, dependent UPR. Critically, one of the targets that escaped PERK-B suppression was the transcription factor DLX1, which has been genetically linked to PSP risk. Here, we found a shift in the solubility of DLX1 in human PSP brain tissue, and report that silencing of DLX-1 reduced the aggregation of tau in mammalian cells. Furthermore, silencing of the fly homolog of DLX1 was sufficient to decrease tau-induced toxicity, in vivo. Our results detail the haplotype-specific PERK-B/DLX-1 pathway as a novel driver of tau pathology in cells, flies, and likely human brain, revealing new insights into PSP pathogenesis and potential therapeutic targets.

neuroscience↗

bioRxiv2023

Amyloid fibril proteomics of AD brains reveals modifiers of aggregation and toxicity

BackgroundThe accumulation of amyloid beta (A{beta}) peptides in fibrils is prerequisite for Alzheimers disease (AD). Our understanding of the proteins that promote A{beta} fibril formation and mediate neurotoxicity has been limited due to technical challenges in isolating pure amyloid fibrils from brain extracts. MethodsTo investigate how amyloid fibrils form and cause neurotoxicity in AD brain, we developed a robust biochemical strategy. We benchmarked the success of our purifications using electron microscopy, amyloid dyes, and a large panel of A{beta} immunoassays. Tandem mass-spectrometry based proteomic analysis workflows provided quantitative measures of the amyloid fibril proteome. These methods allowed us to compare amyloid fibril composition from human AD brains, three amyloid mouse models, transgenic A{beta}42 flies, and A{beta}42 seeded cultured neurons. ResultsAmyloid fibrils are primarily composed by A{beta}42 and unexpectedly harbor A{beta}38 but generally lack A{beta}40 peptides. Multidimensional quantitative proteomics allowed us to redefine the fibril proteome by identifying 17 new amyloid-associated proteins. Notably, we confirmed 126 previously reported plaque-associated proteins. We validated a panel of these proteins as bona fide amyloid-interacting proteins using antibodies and orthogonal proteomic analysis. One metal-binding chaperone metallothionein-3 is tightly associated with amyloid fibrils and modulates fibril formation in vitro. Lastly, we used a transgenic A{beta}42 fly model to test if knock down or over-expression of fibril-interacting gene homologues modifies neurotoxicity. Eight RNAi lines suppressed and 11 enhanced A{beta}42 toxicity. ConclusionsThese discoveries and subsequent confirmation indicate that fibril-associated proteins play a key role in amyloid formation and AD pathology.

neuroscience↗

bioRxiv2019

NCBP2-mediated apoptosis contributes to developmental defects of the schizophrenia-associated 3q29 deletion

The 1.6 Mbp deletion on chromosome 3q29 is associated with a range of neurodevelopmental disorders, including schizophrenia, autism, microcephaly, and intellectual disability. Despite its importance towards neurodevelopment, the role of individual genes, genetic interactions, and disrupted biological mechanisms underlying the deletion have not been thoroughly characterized. Here, we used quantitative methods to assay Drosophila melanogaster and Xenopus laevis models with tissue-specific individual and pairwise knockdown of 14 homologs of genes within the 3q29 region. We identified developmental, cellular, and neuronal phenotypes for multiple homologs of 3q29 genes, potentially due to altered apoptosis and cell cycle mechanisms during development. Using the fly eye, we screened for 314 pairwise knockdowns of homologs of 3q29 genes and identified 44 interactions between pairs of homologs and 34 interactions with other neurodevelopmental genes. Interestingly, NCBP2 homologs in Drosophila (Cbp20) and X. laevis (ncbp2) enhanced the phenotypes of homologs of the other 3q29 genes, leading to significant increases in apoptosis that disrupted cellular organization and brain morphology. These cellular and neuronal defects were rescued with overexpression of the apoptosis inhibitors Diap1 and xiap in both models, suggesting that apoptosis is one of several potential biological mechanisms disrupted by the deletion. NCBP2 was also highly connected to other 3q29 genes in a human brain-specific interaction network, providing support for the relevance of our results towards the human deletion. Overall, our study suggests that NCBP2-mediated genetic interactions within the 3q29 region disrupt apoptosis and cell cycle mechanisms during development. AUTHOR SUMMARYRare copy-number variants, or large deletions and duplications in the genome, are associated with a wide range of neurodevelopmental disorders. The 3q29 deletion confers an increased risk for schizophrenia, autism, and microcephaly. To understand the conserved biological mechanisms that are disrupted by this deletion, we systematically tested 14 individual homologs and 314 pairwise interactions of 3q29 genes for neuronal, cellular, and developmental phenotypes in Drosophila melanogaster and Xenopus laevis models. We found that multiple homologs of genes within the deletion region contribute towards developmental defects, such as larval lethality and disrupted cellular organization. Interestingly, we found that NCBP2 acts as a key modifier gene within the region, enhancing the developmental phenotypes of each of the homologs for other 3q29 genes and leading to disruptions in apoptosis and cell cycle pathways. Our results suggest that multiple genes within the 3q29 region interact with each other through shared mechanisms and jointly contribute to neurodevelopmental defects.

genomics↗