Biology subjects

Burgos, M.

Publications and source records attributed to Burgos, M..

6 recordsLinked to original sources

bioRxiv2024

Sox9 prevents retinal degeneration and is required for limbal stem cell differentiation in the adult mouse eye

Sox9 is a transcription factor with multiple roles during development and in adult organ homeostasis. In the adult eye, Sox9 expression persists in several cell types, including the retinal pigmented epithelium cells and the Muller glial cells, as well as in the limbal and corneal basal epithelia. To uncover the role of Sox9 in these cell types, we induced the deletion of the gene in adult mice. We found that, after Sox9 ablation, mutant mice undergo a severe process of retinal degeneration characterized by the loss of Muller glial cells and complete depletion of the photoreceptors layer. Moreover, by combining single-cell RNA sequencing and Sox9 lineage tracing, we found that Sox9 is expressed in a basal limbal stem cell population with the ability to form two types of long-lived cell clones involved in stem cell maintenance and homeostasis. Mosaic analysis of Sox9 positive and negative cells confirmed that the gene is essential for limbal stem cell differentiation. Our results show that Sox9 is required for the maintenance of retinal integrity and for limbal stem cell differentiation in the adult mouse eye.

developmental biology↗

bioRxiv2023

Passive surveillance for shrimp pathogens in Penaeus vannamei submitted from 3 Regions of Latin America

Multiple PCR analyzes were performed using 19 different primer sets to open and broaden the search spectrum for shrimp pathogens. In addition, multiple primer pairs for 10 pathogens were compared to see if there were differences in selectivity or sensitivity among them. Some pathogens that did not present histological lesions were detected. The most important outcome was that selection of appropriate primers was the most critical factor in obtaining reliable results. We found high variability in results among primers and we learned it was prudent to seasonally assess among them for the best set selection. It is important to understand that a PCR positive test result alone does not confirm the presence of a viable pathogen or a disease state. Nor, as might be expected, does it mean that the positive PCR test results will be necessarily accompanied by histological lesions characteristic of the targeted pathogen. However, the use of appropriately selected primers sets can reveal whether there is an evolution in the result spectrum over time and if some pathogens disappear or reappear or new ones emerge. In general, most shrimp presented coinfections that consisted of the presence of WzSV8, DHPV, chronic midgut inflammation and tubule distension/epithelial atrophy consistent with Pir A/B toxicity. Also included were RLB/NHPB, microsporidia, striated muscle necrosis, gregarines in the hindgut caecum (gametocyte stage, and not associated with tegumental glands but glands that line the mouth and anus) and encysted, presumed nematode larvae. WzSV8 was newly discovered in gonads. Histological changes and the presence of spheroids in the lymphoid organ were considered as healthy host responses of often unidentified cause.

pathology↗

bioRxiv2023

An improved PDE6D inhibitor combines with Sildenafil to synergistically inhibit KRAS mutant cancer cell growth

The trafficking chaperone PDE6D (or PDE) was proposed as a surrogate target for K-Ras, leading to the development of a series of inhibitors that block its prenyl-binding pocket. These inhibitors suffered from low solubility and intracellular potency, preventing their clinical development. Here we developed a highly soluble PDE6D inhibitor (PDE6Di), Deltaflexin3, which has the currently lowest off-target activity, as we demonstrate in dedicated assays. We further increased the K-Ras focus, by exploiting that PKG2-mediated phosphorylation of Ser181 lowers K-Ras binding to PDE6D. Thus, the combination of Deltaflexin3 with the approved PKG2-activator Sildenafil synergistically inhibits cell- and microtumor growth. However, the overall cancer survival of the high PDE6D/ low PKG2 target population is higher than of the group with the opposite signature. Our results therefore suggest re-examining the interplay between PDE6D and K-Ras in cancer, while recommending the development of PDE6Di that plug, rather than stuff the hydrophobic pocket of PDE6D. SignificanceCombinations of a novel PDE6D inhibitor with Sildenafil synergistically focus the inhibition on K-Ras, however, survival data of the target population suggest an interplay of K-Ras and PDE6D that needs further exploration.

biochemistry↗

bioRxiv2023

Complete male-to-female sex reversal in XY mice lacking the miR-17~92 cluster

In mammals, sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads1 2. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation3 4 5. Despite this strong genetic component, the involvement of non-coding regulation in determining mammalian sex remains unclear6. Here we show that the deletion of a single microRNA cluster, miR-17[~]92, induces complete primary male-to-female sex reversal in XY mice. Time-course analyses revealed that Sry is heterochronically expressed, showing a delay in XY miR-17[~]92 knockout gonads, which subsequently activate the ovarian genetic program. Bulk and single cell RNA-seq analyses showed that Sertoli cell differentiation is reduced, delayed and unable to sustain the testicular fate. This disrupted differentiation results from a transient state of sex ambiguity in pre-supporting cells, which is later resolved towards the ovarian fate. Consistent with known mechanisms of miRNA-mediated gene regulation, the expression of miR-17[~]92 target genes is not stabilized in undifferentiated XY mutant gonads, affecting concomitantly the fine regulation of gene networks with critical roles in developing gonads. Our results demonstrate that microRNAs are key components for mammalian sex determination, controlling the timing of Sry expression and Sertoli cell differentiation.

developmental biology↗

bioRxiv2022

Cell adhesion and immune response, two main functions altered in the transcriptome of seasonally regressed testes of two mammalian species

In species with seasonal breeding, male specimens undergo substantial testicular regression during the non-breeding period of the year. However, the molecular mechanisms that control this biological process are largely unknown. Here, we report a transcriptomic analysis on the Iberian mole, Talpa occidentalis, in which the desquamation of live, non-apoptotic germ cells is the major cellular event responsible for testis regression. By comparing testes at different reproductive states (active, regressing and inactive), we demonstrate that the molecular pathways controlling the cell adhesion function in the seminiferous epithelium, such as the MAPK, ERK and TGF-{beta} signalling, are altered during the regression process. In addition, inactive testes display a global upregulation of genes associated with immune response, indicating a selective loss of the "immune privilege" that normally operates in sexually active testes. Interspecies comparative analyses using analogous data from the Mediterranean pine vole, a rodent species where testis regression is controlled by halting meiosis entry, revealed a common gene expression signature in the regressed testes of these two evolutionary distant species. Our study advances in the knowledge of the molecular mechanisms associated to gonadal seasonal breeding, highlighting the existence of a conserved transcriptional program of testis involution across mammalian clades. Research HighlightsBy comparing the trascriptomes of the testes from males of the iberian mole, Talpa occidentalis (order Eulipotyphla), captured at different stages of the seasonal breeding cycle of this species, we show that two main functions are altered during seasonal testis regression: cell adhesion and immune response. The fact that the same functions alre also altered in the Mediterranean pine vole, Microtus duodecimcostatus (order Rodentia), evidences the existence of a conserved transcriptional program of testis regression across mammalian clades.

molecular biology↗

bioRxiv2020

p.E152K-STIM1 mutation deregulates Ca2+ signaling contributing to chronic pancreatitis.

Since deregulation of intracellular Ca2+ can lead to intracellular trypsin activation and STIM1 (stromal interaction molecule-1) protein is the main regulator of Ca2+ homeostasis in pancreatic acinar cells, we explored the Ca2+ signaling in 37 STIM1 variants found in three pancreatitis patient cohorts. Extensive functional analysis of one particular variant, p.E152K, identified in three patients, provided a plausible link between dysregulated Ca2+ signaling within pancreatic acinar cells and chronic pancreatitis susceptibility. Specifically, p.E152K, located within the STIM1 EF-hand and sterile -motif domain, increased the release of Ca2+ from the endoplasmic reticulum in patient-derived fibroblasts and transfected HEK293T cells. This event was mediated by altered STIM1-sarco/endoplasmic reticulum calcium transport ATPase (SERCA) interactions and enhanced SERCA pump activity leading to increased Store Operated Calcium Entry (SOCE). In the pancreatic AR42J cells expressing the p.E152K variant, Ca2+-signaling perturbations correlated with defects in trypsin activation and secretion, and increased cytotoxicity after cholecystokinin stimulation. Summary statementp.E152K-STIM1 variant found in pancreatitis patients leads to intracellular changes in calcium homeostasis through SERCA interaction, enabling intracellular trypsin activation and pancreatic acinar cell death.

cell biology↗