Biology subjects

Martin-Cofreces, N. B.

Publications and source records attributed to Martin-Cofreces, N. B..

3 recordsLinked to original sources

bioRxiv2026

A single Omicron mutation reshapes ORF3a-driven host-cell remodelling

SARS-CoV-2 ORF3a remodels host membranes, but the structural basis and metabolic consequences of this process remain unclear. Here, we combine complementary imaging approaches to define ORF3a function at nanometric scale, identifying underlying mechanisms, and determining how Omicron variant rewire this activity. ORF3a from the ancestral Wuhan strain disrupts Golgi cisternae, drives the formation of ORF3a dense vesicles, remodels mitochondrial architecture, and promotes lipid droplet expansion. Multi-omics analyses further reveal selective triacylglycerol accumulation linked to DGAT1 upregulation, which we validate pharmacologically through DGAT1 inhibition. In contrast, Omicron ORF3a variant, despite carrying only the Thr223Ile substitution within the {beta}7-{beta}8 loop at the bottom of the cytosolic domain, induced a dramatic phenotypic shift: ORF3a localizes to multivesicular bodies, preserves Golgi architecture, and fails to induce lipid accumulation. All together, these results identify ORF3a as a regulator of membrane organization and lipid homeostasis, showing how minimal sequence variation rewires host-cell remodelling. Graphical TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/742305v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@135032borg.highwire.dtl.DTLVardef@1633d4borg.highwire.dtl.DTLVardef@4d4115org.highwire.dtl.DTLVardef@1ebdf65_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

In-gel protein digestion using acidic methanol produces a highly selective methylation of glutamic 1 acid residues.

Mass-tolerant open search methods allow the high-throughput analysis of modified peptides by mass spectrometry. These techniques have paved the way to unbiased analysis of post-translational modifications (PTMs) in biological contexts, as well as of chemical modifications produced during the manipulation of protein samples. In this work, we have analyzed in-depth a wide variety of samples of different biological origin, including cells, extracellular vesicles, secretomes, centrosomes and tissue preparations, using Comet-ReCom, a recently improved version of the open search engine Comet-PTM. Our results demonstrate that glutamic acid residues undergo intensive methyl esterification when protein digestion is performed using in-gel techniques, but not using gel-free approaches. This effect was highly specific to Glu and was not found for other methylable residues such as Asp.

systems biology↗

bioRxiv2023

Phosphatases of regenerating liver balance F-actin rearrangements during T cell activation through WD repeat containing protein 1

Phosphatases of regenerating liver (PRLs) have been proposed to regulate actin dynamics in lymphoid cells. However, the mechanism mediating this role remained unknown. Here we showed the interaction of the PRLs with the actin regulator WD repeat containing protein 1 (WDR1). The interaction of the PRLs with WDR1 was dependent on F-actin integrity and the proper recruitment of the PRLs to cell membranes through the CAAX motif. Endogenous PRLs and WDR1 were distributed to the Immunological Synapse (IS) and perturbed expression of PRL-1 or PRL-2 by CRISPR/Cas9 mediated genome editing showed that the PRLs were required for proper distribution of WDR1 to filamentous (F)-actin at the IS. Further, perturbed expression of the PRLs or WDR1 resulted in defective IS assembly with deregulated F-actin rearrangements, altered positioning of LFA-1, and reduced IL-2 production. Interestingly, balanced expression of PRLs was required for accumulation of CD3{varepsilon} at the IS and early activating signalling. We propose that PRLs regulate early T cell signalling and are required for proper F-actin dynamics by regulating the WDR1 access to F-actin networks. As a consequence, PRLs regulate LFA-1 positioning at the IS and proper cytokine secretion.

immunology↗