Biology subjects

Abreu, C. M.

Publications and source records attributed to Abreu, C. M..

4 recordsLinked to original sources

bioRxiv2024

CDR2 is a dynein adaptor recruited by kinectin to regulate ER sheet organization

The endoplasmic reticulum (ER) relies on the microtubule cytoskeleton for distribution and re-modelling of its extended membrane network, but how microtubule-based motors contribute to ER organization remains unclear. Using biochemical and cell-based assays, we identify cerebellar degeneration-related protein 2 (CDR2) and its paralog CDR2-like (CDR2L), onconeural antigens with poorly understood functions, as ER adaptors for cytoplasmic dynein-1 (dynein). We demonstrate that CDR2 is recruited by the integral ER membrane protein kinectin (KTN1) and that double knockout of CDR2 and CDR2L enhances KTN1-dependent ER sheet stacking, reversal of which by exogenous CDR2 requires its dynein-binding CC1 box motif. Exogenous CDR2 expression additionally promotes CC1 box-dependent clustering of ER sheets near centrosomes. CDR2 competes with the eEF1B{beta} subunit of translation elongation factor 1 for binding to KTN1, and eEF1B{beta} knockdown increases endogenous CDR2 levels on ER sheets, inducing their centrosome-proximal clustering. Our study describes a novel molecular pathway that implicates dynein in ER sheet organization and may be involved in the pathogenesis of paraneoplastic cerebellar degeneration.

cell biology↗

bioRxiv2023

RNA landscapes of brain tissue and brain tissue-derived extracellular vesicles in simian immunodeficiency virus (SIV) infection and SIV-related central nervous system pathology

IntroductionAntiretroviral treatment regimens can effectively control HIV replication and some aspects of disease progression. However, molecular events in end-organ diseases such as central nervous system (CNS) disease are not yet fully understood, and routine eradication of latent reservoirs is not yet in reach. Brain tissue-derived extracellular vesicles (bdEVs) act locally in the source tissue and may indicate molecular mechanisms in HIV CNS pathology. Regulatory RNAs from EVs have emerged as important participants in HIV disease pathogenesis. Using brain tissue and bdEVs from the simian immunodeficiency virus (SIV) model of HIV disease, we profiled messenger RNAs (mRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), seeking to identify possible networks of RNA interaction in SIV infection and neuroinflammation. MethodsPostmortem occipital cortex tissue were collected from pigtailed macaques: uninfected controls and SIV-infected subjects (acute phase and chronic phase with or without CNS pathology). bdEVs were separated and characterized in accordance with international consensus standards. RNAs from bdEVs and source tissue were used for sequencing and qPCR to detect mRNA, miRNA, and circRNA levels ResultsMultiple dysregulated bdEV RNAs, including mRNAs, miRNAs, and circRNAs, were identified in acute infection and chronic infection with pathology. Most dysregulated mRNAs in bdEVs reflected dysregulation in their source tissues. These mRNAs are disproportionately involved in inflammation and immune responses, especially interferon pathways. For miRNAs, qPCR assays confirmed differential abundance of miR-19a-3p, let-7a-5p, and miR-29a-3p (acute SIV infection), and miR- 146a-5p and miR-449a-5p (chronic with pathology) in bdEVs. In addition, target prediction suggested that several circRNAs that were differentially abundant in source tissue might be responsible for specific differences in small RNA levels in bdEVs during SIV infection. ConclusionsRNA profiling of bdEVs and source tissues reveals potential regulatory networks in SIV infection and SIV-related CNS pathology.

neuroscience↗

bioRxiv2022

Longitudinal characterization of circulating extracellular vesicles and small RNA during simian immunodeficiency virus infection and antiretroviral therapy

ObjectivesLatent infection by human immunodeficiency virus (HIV) hinders viral eradication despite effective antiretroviral treatment (ART), Amongst proposed contributors to viral latency are cellular small RNAs that have also been proposed to shuttle between cells in extracellular vesicles (EVs). Thus, we profiled EV small RNAs during different infection phases to understand the potential relationship between these EV-associated small RNAs and viral infection. DesignA well characterized simian immunodeficiency virus (SIV)/macaque model of HIV was used to profile EV-enriched blood plasma fractions harvested during pre-infection, acute infection, latent infection/ART treatment, and rebound after ART interruption. MethodsMeasurement of EV concentration, size distribution, and morphology was complemented with qPCR array for small RNA expression, followed by individual qPCR validations. Iodixanol density gradients were used to separate EV subtypes and virions. ResultsPlasma EV particle counts correlated with viral load and peaked during acute infection. However, SIV gag RNA detection showed that virions did not fully explain this peak. EV microRNAs miR-181a, miR-342-3p, and miR-29a decreased with SIV infection and remained downregulated in latency. Interestingly, small nuclear RNA U6 had a tight association with viral load peak. ConclusionsThis study is the first to monitor how EV concentration and EV small RNA expression change dynamically in acute viral infection, latency, and rebound in a carefully controlled animal model. These changes may also reveal regulatory roles in retroviral infection and latency.

microbiology↗

bioRxiv2017

Shu complex SWS1-SWSAP1 is required for mouse meiotic recombination in concert with the BRCA2 C terminus

Homology recognition and DNA-strand invasion ensure faithful homolog pairing and segregation during the first meiotic division1. RAD51 and DMC1 recombinases catalyze these steps2, with BRCA2 promoting their assembly into nuclear foci3. The recently identified human SWS1-SWSAP1 complex, related to the Shu complex in yeast, promotes RAD51 focus formation in cell lines4,5. We show here that mouse SWS1-SWSAP1 is critical for meiotic homologous recombination (HR) by promoting the assembly of RAD51 and DMC1 on early recombination intermediates. Absence of the complex perturbs meiotic progression in males and females and both sexes are sterile, although a fraction of meiocytes form crossovers. Remarkably, loss of the DNA damage checkpoint kinase CHK2 rescues fertility specifically in females without rescuing crossover numbers. Unlike the Shu complex, the BRCA2 C terminus (known to be required for RAD51 stabilization6,7) is dispensible for RAD51 and DMC1 focus formation. However, concomitant loss of the BRCA2 C terminus aggravates the meiotic defects in Shu mutant spermatocytes. These results point to a complex interplay of factors that ensure recombinase function and hence meiotic progression in the mouse.

genetics↗