Biology subjects

Teixeira, V.

Publications and source records attributed to Teixeira, V..

6 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

In vitro ALPK1 kinase assay reveals new insights into ADP-heptose sensing pathway and kinase activity of disease-associated ALPK1 mutants

Alpha-protein kinase 1 (ALPK1) is a pathogen recognition receptor that detects ADP-heptose (ADPH), a lipopolysaccharide biosynthesis intermediate, recently described as a pathogen-associated molecular pattern in Gram-negative bacteria. ADPH binding to ALPK1 activates its kinase domain and triggers TIFA phosphorylation on threonine 9. This leads to the assembly of large TIFA oligomers called TIFAsomes, activation of NF-{kappa}B and pro-inflammatory gene expression. Furthermore, mutations in ALPK1 are associated with inflammatory syndromes and cancers. While this kinase is of growing medical interest, only few tools are available to characterize its activity. Here, we describe a versatile non-radioactive ALPK1 in vitro kinase assay based on protein thiophosphorylation. We confirm that ALPK1 phosphorylates TIFA T9 and show that T2, T12 and T19 are also weakly phosphorylated by ALPK1. Interestingly, we find that ALPK1 itself is phosphorylated in response to ADPH recognition during Shigella flexneri and Helicobacter pylori infection and that disease-associated ALPK1 mutants exhibit altered kinase activity. In particular, T237M and V1092A mutations associated with ROSAH syndrome and spiradenoma/spiradenocarcinoma respectively, exhibit enhanced ADPH-induced kinase activity and constitutive assembly of TIFAsomes. Altogether, this study provides new insights into the ADPH sensing pathway and a new tool for measuring the activity of ALPK1.

immunology↗

bioRxiv2022

An anti-steatosis response regulated by oleic acid through lipid droplet-mediated ERAD enhancement

Although excessive lipid accumulation is a hallmark of obesity-related pathologies, some lipids are beneficial. Oleic acid (OA), the most abundant monounsaturated fatty acid (FA), promotes health and longevity. Here we show that OA benefits C. elegans by activating the endoplasmic reticulum (ER)-resident transcription factor SKN-1A (Nrf1/NFE2L1) in a lipid homeostasis response. SKN-1A/Nrf1 is cleared from the ER by the ER-associated degradation (ERAD) machinery and stabilized when proteasome activity is low, and canonically maintains proteasome homeostasis. Unexpectedly, OA increases nuclear SKN-1A levels independently of proteasome activity, through lipid droplet (LD)-mediated enhancement of ERAD. In turn, SKN-1A reduces steatosis by reshaping the lipid metabolism transcriptome, and mediates longevity from OA provided through endogenous accumulation, reduced H3K4 trimethylation, or dietary supplementation. Our findings reveal a surprising mechanism of FA signal transduction, and a lipid homeostasis pathway that provides strategies for opposing steatosis and aging, and may mediate benefits of the OA-rich Mediterranean diet.

cell biology↗

bioRxiv2021

Hierarchical reactivation of transcription during mitosis-to-G1 transition by Brn2 and Ascl1 in neural stem cells

During mitosis, chromatin condensation is accompanied by a global arrest of transcription. Recent studies suggest transcriptional reactivation upon mitotic exit occurs in temporally coordinated waves, but the underlying regulatory principles have yet to be elucidated. In particular, the contribution of sequence-specific transcription factors (TFs) remains poorly understood. Here we report that Brn2, an important regulator of neural stem cell identity, associates with condensed chromatin throughout cell division, as assessed by live-cell imaging of proliferating neural stem cells. By contrast, the neuronal fate determinant Ascl1 dissociates from mitotic chromosomes. ChIP-seq analysis reveals that Brn2 mitotic-chromosome binding does not result in sequence-specific interactions prior to mitotic exit, relying mostly on electrostatic forces. Nevertheless, surveying active transcription using single-molecule RNA-FISH against immature transcripts, indicates the differential presence of TF near chromatin when exiting mitosis is associated with early (anaphase) versus late (early G1) reactivation of key targets of Brn2 and Ascl1, respectively. Moreover, by using a mitotic-specific dominant negative approach, we show that competing with Brn2 binding during mitotic exit reduces the transcription of its target gene Nestin. Our study shows an important role for differential binding of TFs to mitotic chromosomes, governed by their electrostatic properties, in defining the temporal order of transcriptional reactivation during mitosis-to-G1 transition.

developmental biology↗

bioRxiv2020

Dynein-dynactin segregate meiotic chromosomes in C. elegans spermatocytes

The dynactin complex is an essential co-factor of the microtubule-based motor dynein. Dynein-dynactin have well-documented roles in spindle assembly and positioning during C. elegans female meiosis and embryonic mitosis, while dynein-dynactins contribution to male meiosis has not been investigated. Here, we characterize the G33S mutation in DNC-1s N-terminal microtubule binding domain, which corresponds to G59S in the human dynactin subunit p150/Glued that causes motor neuron disease. In spermatocytes, dnc-1(G33S) delays spindle assembly and penetrantly inhibits anaphase spindle elongation in meiosis I, which prevents homologous chromosome segregation and generates aneuploid sperm with an extra centrosome. Consequently, embryos produced by dnc-1(G33S) hermaphrodites exhibit a high incidence of tetrapolar mitotic spindles, yet dnc-1(G33S) embryos with bipolar spindles proceed through early mitotic divisions without errors in chromosome segregation. Deletion of the DNC-1 N-terminus shows that defective meiosis in dnc-1(G33S) spermatocytes is not due to DNC-1s inability to interact with microtubules. Rather, our results suggest that the DNC-1(G33S) protein, which is aggregation-prone in vitro, is less stable in spermatocytes than the early embryo, resulting in different phenotypic severity in the two dividing tissues. Thus, the unusual hypomorphic nature of the dnc-1(G33S) mutant reveals that dynein-dynactin drive meiotic chromosome segregation in spermatocytes and illustrates that the extent to which protein misfolding leads to loss of function can vary significantly between cell types.

cell biology↗

bioRxiv2020

Metagenome-assembled genomes from Monte Cristo Cave (Diamantina, Brazil) reveal prokaryotic lineages as functional models for life on Mars

Although several studies have explored microbial communities in different terrestrial subsurface ecosystems, little is known about the diversity of their metabolic processes and survival strategies. The advance of bioinformatic tools is allowing the description of novel and not-yet cultivated microbial lineages in different ecosystems, due to the genome reconstruction approach from metagenomic data. The recovery of genomes has the potential of revealing novel lifestyles, metabolic processes and ecological roles of microorganisms, mainly in ecosystems that are largely unknown, and in which cultivation could be not viable. In this study, through shotgun metagenomic data, it was possible to reconstruct several genomes of cultivated and not-yet cultivated prokaryotic lineages from a quartzite cave, located in Minas Gerais state, Brazil, which showed to possess a high diversity of genes involved with different biogeochemical cycles, including reductive and oxidative pathways related to carbon, sulfur, nitrogen and iron. Tree genomes were selected, assigned as Truepera sp., Ca. Methylomirabilis sp. and Ca. Koribacter sp. based on their lifestyles (radiation resistance, anaerobic methane oxidation and potential iron oxidation) for pangenomic analysis, which exhibited genes involved with different DNA repair strategies, starvation and stress response. Since these groups have few reference genomes deposited in databases, our study adds important genomic information about these lineages. The combination of techniques applied in this study allowed us to unveil the potential relationships between microbial genomes and their ecological processes with the cave mineralogy, as well as to discuss their implications for the search for extant lifeforms outside our planet, in silica- and iron-rich environments, especially on Mars.

microbiology↗