Biology subjects

Velazquez, M. A.

Publications and source records attributed to Velazquez, M. A..

3 recordsLinked to original sources

bioRxiv2025

Structural and mechanistic insights into translation initiation on the enterovirus Type 1 IRES

Enteroviruses are a diverse group of pathogens that cause over one billion human infections annually. Upon cell entry, translation of the viral genome is directed by an internal ribosome entry site (IRES) within the 5' untranslated region. Despite early identification of the Type 1 poliovirus IRES, the structural and mechanistic basis for its activity remains poorly understood due to its size, flexibility and dependence on multiple host cell factors. Here, we reconstitute human translation initiation on a model poliovirus IRES and examine 48S complexes by cryo-electron microscopy. Our structures reveal how IRES domain IVc contacts ribosomal proteins uS19 and uS13, whilst a conserved GNRA tetraloop engages with the initiator tRNA during start-codon recognition. Disruption of these interfaces impairs IRES-dependent translation and viral replication. Together, our results provide new structural and mechanistic insights into initiation on the Type 1 IRES and reveal conserved RNA-RNA interactions critical for enterovirus translation.

molecular biology↗

bioRxiv2024

The embryo-derived protein PDI is highly conserved among placental mammals and alters the function of the endometrium in species with different implantation strategies.

Pregnancy establishment in mammals requires a complex sequence of events, including bi-lateral embryo-maternal communication, leading up to implantation. This is the time when most pregnancy loss occurs in mammals (including humans and food production species) and dysregulation in embryo-maternal communication contributes to pregnancy loss. Embryo-derived factors modify the function of the endometrium for pregnancy success. We hypothesise that these previously unexplored conceptus-derived proteins may be involved in altering the function of the endometrium to facilitate early pregnancy events in mammals with different early pregnancy phenotypes. Here, we show that protein disulphide-isomerase (PDI) is a highly conserved protein among mammals, and provide evidence for a species-specific roles for PDI in endometrial function in mammals with different implantation strategies. We show how PDI alters the endometrial transcriptome in human and bovine in vitro in a species-specific manner, and using a microfluidic approach we demonstrate that it alters the secretome capability of the endometrium. We also provide evidence from in vitro assays using human-derived cells that MNS1, a transcript commonly downregulated in response to PDI in human and bovine endometrial epithelial cells, may be involved in the attachment (but not invasion) phase of implantation. We propose that the trophoblast-derived protein PDI, is involved in supporting the modulation of the uterine luminal fluid secreted by the endometrium to support conceptus nourishment, and also in the process of embryo attachment to the uterine lumen for pregnancy success in mammals. SIGNIFICANCE STATEMENTWe provide evidence that a highly conserved protein (PDI) alters the endometrial transcriptome in a species- and cell-specific manner. Exposure of endometrial epithelia to PDI altered genes belonging to immune modulatory, pro-inflammatory, and adhesion-pathways. One transcript, MNS1, was commonly downregulated in endometrial epithelia from species with superficial (bovine) and invasive (human) implantation morphologies. Knockdown of MNS1 expression in humans epithelia altered the ability of human trophoblast BeWo spheroids to attach suggesting a mechanism by which PDI affects implantation in human and bovine. In addition, using a microfluidics approach we have shown that PDI alters the secretome in a species-specific manner demonstrating PDI alters a key function of the endometrium in mammals.

developmental biology↗

bioRxiv2020

The role of CAPG in molecular communication between the embryo and the uterine endometrium: Is its function conserved in species with different implantation strategies?

During the pre-implantation period of pregnancy in eutherian mammals, changes to the uterine endometrium are required (both at the transcriptional and protein level) to facilitate the endometrium becoming receptive to an implanting embryo. We know that the developing conceptus (embryo and extraembryonic membranes) produces proteins during this developmental stage. We hypothesised that this common process in early pregnancy in eutheria may be facilitated by highly conserved conceptus-derived proteins such as macrophage capping protein CAPG. More specifically, we propose that CAPG may share functionality in modifying the transcriptome of the endometrial epithelial cells to facilitate receptivity to implantation in species with different implantation strategies, such as human and bovine. A recombinant bovine form of CAPG (91% sequence identity between bovine and human) was produced and bovine endometrial epithelial (bEECs) and stromal (bESCs) cells and human endometrial epithelial cells (hEECs) were cultured for 24 h with or without rbCAPG. RNA sequencing and quantitative real-time PCR analysis was used to assess the transcriptional response to rbCAPG (Control, vehicle, CAPG 10, 100, 1000 ng/ml: n=3 biological replicates per treatment per species). Treatment of bEECs with CAPG resulted in changes to 1052 transcripts (629 increased and 423 decreased) compared to vehicle controls, including those previously only identified as regulated by interferon-tau, the pregnancy recognition signal in cattle. Treatment of hEECs with bovine CAPG increased expression of transcripts previously known to interact with CAPG in different systems (CAPZB, CAPZA2, ADD1 and ADK) compared with vehicle controls (P<0.05). In conclusion, we have demonstrated that CAPG, a highly conserved protein in eutherian mammals elicits a transcriptional response in the endometrial epithelium in two species with different implantation strategies that may facilitate uterine receptivity.

physiology↗