Biology subjects

Robledo, M.

Publications and source records attributed to Robledo, M..

7 recordsLinked to original sources

bioRxiv2026

Nicotiana tabacum and Vitis vinifera as suitable growth-chamber models for microinjection-based studies of Xylella fastidiosa

Xylella fastidiosa is one of the most important plant pathogens worldwide, infecting more than 700 plant species and causing major economic losses in affected agricultural regions. In the absence effective curative treatments under field conditions, experimental research is essential. However, research efforts are severely constrained by strict phytosanitary regulations and the pathogen's restricted geographic distribution, as well as its demanding culture requirements. To the best of our knowledge, no studies have compared different host infection models under controlled growth-chamber conditions. To address these limitations, we developed and compared a microinjection-based inoculation protocol across herbaceous and woody hosts maintained in biosafety growth chambers. Stems of Vitis vinifera, Nicotiana tabacum, N. benthamiana, and Medicago sativa were inoculated with X. fastidiosa by microinjection and maintained under controlled growth-chamber conditions. Pathogen establishment was assessed by qPCR analysis of petiole tissue, together with disease progression, plant growth, and leaf scorch development. Approximately one month after inoculation, bacterial detection rates reached 100% in V. vinifera and 80% in N. tabacum. Both species subsequently exhibited measurable disease development, whereas bacterial establishment and phenotypic responses were less consistent in N. benthamiana and M. sativa.

plant biology↗

bioRxiv2025

A single small RNA shapes multiple symbiotic traits in rhizobia

Bacterial small non-coding RNAs (sRNAs) remain understudied in the ecologically crucial nitrogen (N2)-fixing root-nodule Rhizobium-legume symbiosis. The only known rhizobial RNA regulator with broad symbiotic influence is the N-responsive trans-acting sRNA NfeR1, identified in the alfalfa symbiont Sinorhizobium meliloti. To pinpoint NfeR1 function, we profiled its RNA targets using MS2 affinity purification coupled with RNA sequencing (MAPS) in N stressed bacteria, a condition that drives nodulation. NfeR1 targets distinct regions of numerous mRNAs and sRNAs via three redundant anti-Shine-Dalgarno motifs, with silencing as major regulatory outcome. Target mRNAs span pathways differentially regulated throughout symbiosis, including N metabolism, motility, stress adaptation, and cell cycle control. Notably, NfeR1 modulates cell morphology and DNA replication by pervasive regulation of cell cycle mRNAs. It also silences gdhA, repressing glutamine dehydrogenase-dependent N assimilation and enhancing nodulation gene expression, further fine-tuned by a novel RNA feedback loop between NfeR1 and the dual-function sRNA SmelC549. Our findings position NfeR1 as a central hub within a structurally and functionally complex RNA network that coordinates N signaling and symbiotic performance in S. meliloti.

microbiology↗

bioRxiv2025

A genetic signature predicts aggressive paraganglioma sensitivity to dual PI3K-CDK4/6 inhibition therapy

Effective medical therapies for metastatic paraganglioma (mPPGL) are currently lacking, leading to dismal prognosis. Building on our knowledge of molecular mechanisms driving PPGL progression, we assessed the therapeutic potential of targeting two critical processes: PI3K signaling and cell cycle regulation. The efficacy of buparlisib (PI3Ki) and ribociclib (CDK4/6i), individually and combined, was assessed in vitro using PPGL cell lines, rat- and patient-derived primary cells, and in vivo using PPGL cells-derived mouse xenografts. The combination therapy demonstrated superior antitumor activity compared to single agents, particularly in vivo. Mechanistically, the efficacy of the combination therapy was associated to the downregulation of FOXM1-controlled genes implicated in mitotic spindle assembly and chromosomal segregation, leading to mitotic catastrophe. Data mining and qRT-PCR showed this genetic signature to be upregulated in human mPPGLs. This suggests that aggressive PPGLs exhibit heightened vulnerability to dual PI3K and CDK4/6 inhibition, offering a promising therapeutic avenue for these challenging cancers.

cancer biology↗

bioRxiv2025

Identification of a novel papillary renal cell carcinoma molecular subtype characterized by HIF-pathway over-activation

PurposePapillary renal cell carcinoma (pRCC), the second most common subtype of renal cancer, exhibits heterogeneity in molecular features and response to targeted therapies, including antiangiogenic drugs. Discovering molecular biomarkers able to stratify pRCC patients into clinically relevant subgroups and understanding the underlying mechanisms are urgently needed to advance precision medicine. Here, we molecularly dissect a large pRCC series through the expression of the targets of hypoxia inducible factors (HIF), master regulators of angiogenesis, metabolic reprogramming and immune microenvironment. Experimental DesignWe merged and analyzed multi-omic and clinical data of 346 patients derived from two pRCC series (TCGA-KIRP and a Spanish metastatic series). Altered pathways and differences in tumor microenvironment were identified through tumor transcriptomic analyses. Tumor metabolome analysis was performed in selected cases. ResultsMolecular revision of driver mutations classified 302 patients as pRCC, while uncovering misclassified cases. Analysis of HIF targets gene expression identified a subset of pRCC tumors with increased HIF activity (31%; "HIF-active"). These tumors were characterized by high hypoxia scores, increased angiogenesis, low expression of Krebs cycle genes and mitochondrial activity, high immune infiltration and increased epithelial-mesenchymal transition (P<0.0001; each feature) and they were associated with increased metastasis risk and worse overall survival (P<0.005). Metabolome analyses revealed that HIF-active tumors accumulated L-2-hydroxyglutarate (L-2-HG), an oncometabolite that leads to pseudohypoxia by inhibiting HIF prolyl hydroxylases and preventing HIF degradation. L-2-HG-accumulation agreed with diminished L2HGDH expression, associated with losing one copy of the gene and low expression of PPARGC1A, which regulates its transcription. ConclusionsHIF-pathway overactivation defines a pseudohypoxic pRCC molecular subgroup characterized by high angiogenesis, immune infiltration and aggressive features. These findings advance our understanding of pRCC diversity, revealing potential clues for the variable response of patients to targeted therapies and paving the way to more personalized pRCC treatments.

cancer biology↗

bioRxiv2025

Vertical transmission of core endophytes through the seeds

Plant-associated microorganisms, particularly endophytes, are essential for plant health and development. Endophytic microbiota is intimately associated with host plants colonizing various tissues, including seeds. Seed endophytes are particularly noteworthy because of their potential for vertical transmission. This pathway may play a role in the long-term establishment and evolution of stable bacteria-host interactions across plant generations. Hundreds of seed-bacteria associations have been recently uncovered; however, most seem to be transient or unspecific. While it is known that microorganisms can be transmitted from plant tissues to seeds and from seeds to seedlings, the experimental confirmation of bacterial transfer through successive plant generations remains unreported. In this study, we identified Pantoea as the unique core endophytic bacteria inhabiting the endosperms of 24 wheat seed samples originally harvested in different worldwide locations. Remarkably, Pantoea is the genus with the highest relative average abundance in wheat seeds (61%) and also in germinated seedlings grown under gnotobiotic conditions (30%). In the field, it was the only genus dwelling roots, shoots, spikes and seeds of 4 different wheat varieties tested and its abundance progressively increased across these tissues. This genuine pattern of vertical enrichment, which was not found in other common wheat-associated taxa, suggests a role in the transfer of these endophytic bacteria through the seeds. To confirm intergenerational transmission, parental plants were inoculated with labelled Pantoea isolates, which specifically colonized the next generations of Poaceae plants, experimentally demonstrating bacterial vertical inheritance to the offspring generations and suggesting transmission specificity.

microbiology↗

bioRxiv2022

Cytoplasmic HIF-2α correlates to proliferation and predicts worse outcome in sympathetic paraganglioma

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors. PGLs can further be divided into sympathetic (sPGLs) and head-and-neck (HN-PGLs). There are virtually no treatment options, and no cure, for metastatic PCCs and PGLs (PPGLs). Here, we composed a tissue microarray (TMA) consisting of 149 PPGLs, reflecting clinical features and presenting as a useful resource. Mutations in the pseudohypoxic marker EPAS1/HIF-2 correlates to an aggressive tumor phenotype. We show that HIF-2 unexpectedly localized to the cytoplasm in PPGLs. This subcompartmentalized protein expression differed between tumor subtypes, and strongly correlated to proliferation. Half of all sPGLs were metastatic at time of diagnosis. Cytoplasmic HIF-2 was strongly expressed in metastatic sPGLs and predicted poor outcome in this subgroup. We propose that cytoplasmic HIF-2 expression serves as a useful clinical marker to differentiate subtypes and predicting outcome, and hence can be used for improved targeted treatment in PPGLs.

cancer biology↗

bioRxiv2019

CcnA, a novel non-coding RNA regulating the bacterial cell cycle

Bacteria are powerful models for understanding how cells divide and accomplish global regulatory programs. In Caulobacter crescentus, a cascade of essential master regulators supervises the correct and sequential activation of DNA replication, cell division and development of different cell types. Among them, the response regulator CtrA plays a crucial role coordinating all those functions. Here, for the first time we describe the role of a novel factor named CcnA, a cell cycle regulated ncRNA located at the origin of replication, presumably activated by CtrA and responsible for the accumulation of CtrA itself. In addition, CcnA may be also involved in the inhibition of translation of the S-phase regulator, GcrA, by interacting with its 5 untranslated region (5-UTR). Performing in vitro experiments and mutagenesis, we propose a mechanism of action of CcnA based on liberation (ctrA) or sequestration (gcrA) of their ribosome-binding site (RBS). Finally, its role may be conserved in other alphaproteobacterial species, such as Sinorhizobium meliloti, representing indeed a potentially conserved process modulating cell cycle in Caulobacterales and Rhizobiales.

microbiology↗