Biology subjects

Castellano, D.

Publications and source records attributed to Castellano, D..

At least 19 recordsLinked to original sources

bioRxiv2025

CD44v6 Drives Tumor Aggressiveness and Chemoresistance in Bladder Cancer

Bladder cancer is a fast-moving and recurrent malignancy where survival hinges on early detection and precise risk stratification. The search for robust biomarkers is urgent, and CD44v6 has emerged as a compelling candidate. In this study, we reveal that CD44v6 is not merely a marker but a driver of urothelial carcinoma aggressiveness. Through integrated clinical and functional analyses, we show that high CD44v6 expression is strongly associated with poor patient outcomes. Mechanistic investigations demonstrate that CD44v6 amplifies the proliferative, migratory, and invasive potential of bladder cancer cells, while conferring marked resistance to cisplatin. These findings position CD44v6 at the intersection of tumor progression and therapeutic failure, underscoring its value as both a prognostic biomarker and a promising therapeutic target. Targeting CD44v6 could pave the way for strategies that curb disease aggressiveness and overcome chemoresistance in bladder cancer.

cancer biology↗

bioRxiv2025

ConfuseNN: Interpreting convolutional neural network inferences in population genomics with data shuffling

Convolutional neural networks (CNNs) have become powerful tools for population genomic inference, yet understanding which genomic features drive their performance remains challenging. We introduce ConfuseNN, a method that systematically shuffles input haplotype matrices to disrupt specific population genetic features and evaluate their contribution to CNN performance. By sequentially removing signals from linkage disequilibrium, allele frequency, and other population genetic patterns in test data, we evaluate how each feature contributes to CNN performance. We applied ConfuseNN to three published CNNs for demographic history and selection inference, confirming the importance of specific data features and identifying limitations of network architecture and of simulated training and testing data design. ConfuseNN provides an accessible biologically motivated framework for interpreting CNN behavior across different tasks in population genetics, helping bridge the gap between powerful deep learning approaches and traditional population genetic theory.

genetics↗

bioRxiv2025

Transcription start sites experience a high influx of heritable variants fuelled by early development

Mutations drive evolution and genetic diversity, but the impact of transcription on germline mutagenesis remains poorly understood. Here, we identify a hypermutation phenomenon at transcription start sites in the human germline, spanning several hundred base pairs in both directions. We link this TSS mutational hotspot to divergent transcription, RNA polymerase II stalling, R-loops, and mitotic--but not meiotic--double-strand breaks, revealing a recombination-independent mechanism distinct from known processes. Notably, the hotspot is absent in de novo mutation data. We reconcile this by showing that TSS mutations are significantly enriched with early mosaic variants often filtered out in de novo mutation calls, indicating that the hotspot arises during early embryogenesis. Mutational signature analysis reinforces these findings and implicates alternative non-homologous end joining and maternal mutation clusters. Our study provides the first detailed description of a germline TSS mutation hotspot, with broad evolutionary and biomedical implications.

genomics↗

bioRxiv2024

Satellite glial contact enhances differentiation and maturation of human induced sensory neurons

Sensory neurons generated from induced pluripotent stem cells (iSNs) are used to model human peripheral neuropathies, however current differentiation protocols produce sensory neurons with an embryonic phenotype. Peripheral glial cells contact sensory neurons early in development and contribute to formation of the canonical pseudounipolar morphology, but these signals are not encompassed in current iSN differentiation protocols. Here, we show that terminal differentiation of iSNs in co-culture with rodent Dorsal Root Ganglion satellite glia (rSG) advances their differentiation and maturation. Co-cultured iSNs develop a pseudounipolar morphology through contact with rSGs. This transition depends on semaphorin-plexin guidance cues and on glial gap junction signaling. In addition to morphological changes, iSNs terminally differentiated in co-culture exhibit enhanced spontaneous action potential firing, more mature gene expression, and increased susceptibility to paclitaxel induced axonal degeneration. Thus, iSNs differentiated in coculture with rSGs provide a better model for investigating human peripheral neuropathies.

neuroscience↗

bioRxiv2024

Scalable Hypothalamic Arcuate Neuron Differentiation from Human Pluripotent Stem Cells Suitable for Modeling Metabolic and Reproductive Disorders

The hypothalamus, composed of several nuclei, is essential for maintaining our bodys homeostasis. The arcuate nucleus (ARC), located in the mediobasal hypothalamus, contains neuronal populations with eminent roles in energy and glucose homeostasis as well as reproduction. These neuronal populations are of great interest for translational research. To fulfill this promise, we used a robotic cell culture platform to provide a scalable and chemically defined approach for differentiating human pluripotent stem cells (hPSCs) into pro-opiomelanocortin (POMC), somatostatin (SST), tyrosine hydroxylase (TH) and gonadotropin-releasing hormone (GnRH) neuronal subpopulations with an ARC-like signature. This robust approach is reproducible across several distinct hPSC lines and exhibits a stepwise induction of key ventral diencephalon and ARC markers in transcriptomic profiling experiments. This is further corroborated by direct comparison to human fetal hypothalamus, and the enriched expression of genes implicated in obesity and type 2 diabetes (T2D). Genome-wide chromatin accessibility profiling by ATAC-seq identified accessible regulatory regions that can be utilized to predict candidate enhancers related to metabolic disorders and hypothalamic development. In depth molecular, cellular, and functional experiments unveiled the responsiveness of the hPSC-derived hypothalamic neurons to hormonal stimuli, such as insulin, neuropeptides including kisspeptin, and incretin mimetic drugs such as Exendin-4, highlighting their potential utility as physiologically relevant cellular models for disease studies. In addition, differential glucose and insulin treatments uncovered adaptability within the generated ARC neurons in the dynamic regulation of POMC and insulin receptors. In summary, the establishment of this model represents a novel, chemically defined, and scalable platform for manufacturing large numbers of hypothalamic arcuate neurons and serves as a valuable resource for modeling metabolic and reproductive disorders.

developmental biology↗

bioRxiv2024

Non-hypermutator cancers access driver mutations through reversals in germline mutational bias

Cancer is an evolutionary disease driven by mutations in asexually-reproducing somatic cells. In asexual microbes, bias reversals in the mutation spectrum can speed adaptation by increasing access to previously undersampled beneficial mutations. By analyzing tumors from 20 tissues, along with normal tissue and the germline, we demonstrate this effect in cancer. Non-hypermutated tumors reverse the germline mutation bias and have consistent spectra across tissues. These spectra changes carry the signature of hypoxia, and they facilitate positive selection in cancer genes. Hypermutated and non-hypermutated tumors thus acquire driver mutations differently: hypermutated tumors by higher mutation rates and non-hypermutated tumors by changing the mutation spectrum to reverse the germline mutation bias.

cancer biology↗

bioRxiv2023

Comprehensive Landscape of Non-muscle Invasive Bladder Cancer Tumour Microenvironment and Prognostic value of Cancer-Associated Myofibroblasts

BACKGROUNDNon-muscle-invasive bladder cancer (NMIBC) poses clinical challenges due to its high recurrence and progression rates. While Bacillus Calmette-Guerin (BCG) remains as the gold standard treatment for high-risk NMIBC, recent irruption of anti-PD-1/PD-L1 drugs claims for a comprehensive understanding of the tumour microenvironment (TME) of these tumors. METHODSThe present prospective study consisted on the analysis 98 fresh NMIBC samples, tumor and non-pathological tissue, via flow cytometry. Final analysis included distribution of 11 cell types and the expression of PD-L1 in 66 tumor and 62 non-pathological tissue biopsies from 73 NMIBC patients (84.4% paired samples). The results were validated using publicly available transcriptomic data, and histology. RESULTSIn comparison to non-pathological tissue, the TME of NMIBC presented microvascular alterations, increased cancer-associated fibroblast (CAF) and myofibroblast (myoCAF) presence, and varied immune cell distribution. Heterogeneous PD-L1 expression was observed across subsets, with cancer cells as primary potential anti-PD-L1 binding targets. Unbiased analysis revealed that myoCAF and M2-like macrophages are enriched in high grade NMIBC tumors, but only myoCAF were associated with higher rates of progression and recurrence, as we confirmed in three independent transcriptomic cohorts (888 total patients). We further validated the prognostic value of myoCAFs by tissue micro-array. CONCLUSIONThis comprehensive analysis provides a roadmap to establish the full landscape of the NMIB[C]s TME, highlighting myoCAFs as potential prognostic markers. FUNDINGThis study was funded by FC AECC (INVES222946GARC), Consejeria de Educacion, Ciencia y Universidades de la CAM (2018-T2/BMD-10342), Hoffmann-La Roche, Ministerio de Ciencia e Innovacion (INMUNOEPIBLA) and ISCIII/FEDER (CIBERONC CB16/12/00489)

cancer biology↗

bioRxiv2022

Shifts in mutation bias promote mutators by altering the distribution of fitness effects

Recent experimental evidence demonstrates that shifts in mutational biases, for example increases in transversion frequency, can change the distribution of fitness effects of mutations (DFE). In particular, reducing or reversing a prevailing bias can increase the probability that a de novo mutation is beneficial. It has also been shown that mutator bacteria are more likely to emerge if the beneficial mutations they generate have a larger effect size than observed in the wildtype. Here, we connect these two results, demonstrating that mutator strains that reduce or reverse a prevailing bias have a positively-shifted DFE, which in turn can dramatically increase their emergence probability. Since changes in mutation rate and bias are often coupled through the gain and loss of DNA repair enzymes, our results predict that the invasion of mutator strains will be facilitated by shifts in mutation bias that offer improved access to previously under-sampled beneficial mutations.

evolutionary biology↗

bioRxiv2022

Extraordinary selection on the human X chromosome associated with archaic admixture

The X chromosome in non-African human populations shows less diversity and less Neanderthal introgression than expected under the standard neutral model. We analyzed 162 X chromosomes from human males worldwide and discovered 14 chromosomal regions where haplotypes of several hundred kilobases rapidly rose to high frequencies in non-Africans. These observations cannot be explained by neutral genetic drift in realistic demographic scenarios and are only consistent with partial selective sweeps produced by strong selection. Using an approach for inferring individual Neanderthal-derived haplotypes, which do not rely on an archaic reference genome, we further discover that the swept haplotypes are devoid of the archaic ancestry otherwise typical of the affected chromosomal regions. The ancient Ust-Ishim male carries its expected proportion of these haplotypes, implying that the sweeps must have occurred between 45,000 and 55,000 years ago. Finally, we find that the chromosomal positions of sweeps overlap previously reported hotspots of selection in great ape evolution. We propose that this puzzling combination of observations points to a general mechanism of positive selection unique to the X chromosome.

evolutionary biology↗

bioRxiv2022

Detection of Domestication Signals through the Analysis of the Full Distribution of Fitness Effects using Forward Simulations and Polygenic Adaptation

Domestication is a process marked by complex interactions between demographic changes and selective pressures, which together shape genetic diversity. While the phenotypic outcomes of domestication are well documented, its genetic basis--particularly the dynamics of selection-- remain less well understood. To investigate these dynamics, we performed simulations designed to approximate the demographic history of large domestic mammals. These simulations used selection coefficients as a modeling tool to represent changes in selection pressures, recognizing that such coefficients are abstractions rather than direct representations of biological reality. Specifically, we analyzed site frequency spectra (SFS) under varying distributions of fitness effects (DFE) and proportions of mutations with divergent selective pressures. Our results show that the discretized deleterious DFE can be reliably inferred from the SFS of a single population, but reconstructing the beneficial DFE and demographic history remains challenging, even when using the joint SFS of both populations. We further developed a novel joint DFE inference model to estimate the proportion of mutations with divergent selection coefficients (pc), although we found that signals of classic hard sweeps can mimic increases in pc, complicating interpretation. These findings underscore both the utility and limitations of DFE inference and highlight the need for caution when interpreting demographic histories in domesticated populations based on such modeling assumptions.

evolutionary biology↗

bioRxiv2022

Shisa7-dependent regulation of GABAA receptor single-channel gating kinetics

GABAA receptors (GABAARs) mediate the majority of fast inhibitory transmission throughout the brain. Although it is widely known that pore-forming subunits critically determine receptor function, it is unclear whether their single-channel properties are modulated by GABAAR-associated transmembrane proteins. We previously identified Shisa7 as a GABAAR auxiliary subunit that modulates the trafficking, pharmacology, and kinetic properties of these receptors. In particular, Shisa7 accelerates receptor deactivation; however, the underlying mechanisms by which Shisa7 controls GABAAR kinetics have yet to be determined. Here we have performed single-channel recordings and find that while Shisa7 does not change channel slope conductance, it reduces the frequency of openings. Importantly, Shisa7 modulates GABAAR gating by decreasing the duration and open probability (Po) within bursts. Kinetic analysis of dwell times, activation modeling, and macroscopic simulations indicate that Shisa7 accelerates GABAAR deactivation by governing the time spent between close and open states during gating. Together, our data provide a mechanistic basis for how Shisa7 controls GABAAR gating kinetics and reveal for the first time that GABAAR single-channel properties can be modulated by an auxiliary subunit. These findings shed light on processes that shape the temporal dynamics of GABAergic transmission.

neuroscience↗

bioRxiv2021

Characterization of plasma circulating small extracellular vesicles in patients with metastatic solid tumors and newly diagnosed brain metastasis.

PurposeNearly 40% of the advanced cancer patients will present brain metastases during the course of their disease, with a 2-year life expectancy of less than 10%. Immune system impairment, including the modulation of both STAT3 and PD-L1, is one of the hallmarks of brain metastases. Liquid biopsy could offer several advantages in brain metastases management, such as the possibility of non-invasive dynamic monitoring. Extracellular vesicles (EVs) have been recently proposed as novel biomarkers especially useful in liquid biopsy due to their secretion in biofluids and their role in cell communication during tumor progression. Materials and MethodsThe main aim of this work was to characterize the size and protein cargo of plasma circulating EVs in patients with solid tumors and their correlation with newly diagnosed brain metastases, in addition to their association with other relevant clinical variables. ResultsWe analyzed circulating EVs in the plasma of 123 patients: 42 patients with brain metastases, 50 without brain metastases and 31 healthy controls. Patients with newly diagnosed brain metastases had a lower number of circulating EVs in the plasma and a higher protein concentration in small EVs (sEVs) compared to patients without brain metastases and healthy controls. Interestingly, melanoma patients with brain metastases presented decreased STAT3 activation and increased PD-L1 levels in circulating sEVs compared to patients without central nervous system metastases. ConclusionsDecreased STAT3 activation and increased PD-L1 in plasma circulating sEVs identify melanoma patients with brain metastasis. Statement of translational relevanceBrain metastases are critical for outcomes and quality of life in almost 50% of oncological patients, generally associated with a poor short-term prognosis. Early or preventive diagnosis of this complication represents an unmet need. There is a necessity of discovering new biomarkers that could aid to predict disease outcome. In this study, we analyzed plasma circulating extracellular vesicles (EVs) from a cohort of 92 patients with different solid tumors (lung, breast, kidney cancer and melanoma) and found that newly diagnosed patients with brain metastases presented lower number of circulating particles and a higher protein concentration in small extracellular vesicles (sEVs) compared to patients without brain metastases and healthy controls. Out of all groups analyzed, melanoma patients with brain metastases presented decreased STAT3 activation and increased PD-L1 levels in circulating sEVs compared to patients without central nervous system metastases. The data presented in this work suggest that circulating sEVs may represent the immunosuppressive status of newly diagnosed brain metastases characterized by the reduced phospho-STAT3 (pSTAT3) and increased PD-L1, although the origin of these molecules found in circulating sEVs remains to be uncovered.

cancer biology↗

bioRxiv2021

Shisa7 phosphorylation regulates GABAergic transmission and neurodevelopmental behaviors

GABA-A receptors (GABAARs) are crucial for development and regulation of the central nervous system. Altered GABAergic signaling is hypothesized to be involved in the pathophysiology of neurodevelopmental disorders. Nevertheless, how aberrant cellular and molecular mechanisms affect GABAARs in these diseases remain elusive. Recently, we identified Shisa7 as a GABAAR auxiliary subunit that modulates GABAAR trafficking, kinetics, and pharmacology, and discovered a phosphorylation site in Shisa7 (S405) critical for extrasynaptic 5-GABAAR trafficking and tonic inhibition. However, the role of S405 phosphorylation in the regulation of synaptic inhibition, plasticity, and behavior remains unknown. Here, we found that expression of a phospho-null mutant (Shisa7 S405A) in heterologous cells and neurons diminishes 2-GABAAR trafficking. Subsequently, we generate a Shisa7 S405A knock-in (KI) mouse line that displays reduced surface expression of GABAARs in hippocampal neurons. Importantly, both synaptic and tonic inhibition are decreased in KI mice. Moreover, chemically induced inhibitory long-term potentiation is impaired, highlighting a critical role of Shisa7 S405 in GABAergic plasticity. Lastly, KI mice exhibit enhanced locomotor activity and grooming associated with neurodevelopmental disorders. Collectively, our study reveals a phosphorylation site critical for Shisa7-dependent trafficking of synaptic and extrasynaptic GABAARs which contributes to behavioral endophenotypes displayed in neurodevelopmental disorders.

neuroscience↗

bioRxiv2021

Distinct regulation of tonic GABAergic inhibition by NMDA receptor subtypes

Tonic inhibition mediated by extrasynaptic {gamma}-aminobutyric acid type A receptors (GABAARs) play important roles in the regulation of various brain functions. However, the regulatory mechanisms for tonic inhibition remain largely unknown. Here we report distinct actions of GluN2A- and GluN2B-containing subtypes of NMDA receptors (NMDARs) on tonic inhibition in hippocampal neurons. Mechanistically, GluN2A- and GluN2B-containing NMDARs play differential roles in 5-GABAAR internalization. Additionally, GluN2A-, but not GluN2B-, containing receptors are required for the homeostatic potentiation of tonic inhibition. In an acute seizure model induced by kainic acid, tonic inhibition is decreased during acute seizures, while it is increased 24 h later, and these alterations are dependent on the distinct GluN2-containing NMDARs. Collectively, these data reveal a critical link between NMDARs and extrasynaptic GABAARs in both physiological and pathological conditions.

neuroscience↗

bioRxiv2019

Immunohistochemistry-based taxonomical classification of bladder cancer predicts response to neoadjuvant chemotherapy

Platinum-based neoadjuvant chemotherapy (NAC) increases the survival of patients with organ-confined urothelial bladder cancer (UBC). Because not all patients benefit from treatment, NAC has not been widely applied in the clinical setting. There is strong evidence, based on retrospective studies, that patients with Basal/Squamous (BASQ)-like tumours present with more advanced disease and have worse prognosis; global transcriptomics can identify tumour subtypes associated with response to NAC. We aimed to investigate whether tumour immunohistochemical (IHC) subtyping predicts NAC response. Patients with muscle-invasive UBC having received platinum-based NAC were identified in two hospitals in Spain. Tissue microarrays were constructed; RNA and DNA were extracted from full sections. Nanostring analysis and immunohistochemistry to identify BASQ-like tumours and mutational analysis of UBC oncogenes. We used hierarchical clustering to classify 126 tumours and adjusted logistic regression to assess association with treatment response. Outcomes were progression-free survival and disease-specific survival; univariable and multivariate Cox regression models were applied. We found very high concordance between mRNA and protein for the 4 markers analyzed. We identified three main subgroups: BASQ-like (FOXA1/GATA3 low; KRT5/6/14 high), Luminal-like (FOXA1/GATA3 high; KRT5/6/14 low), and mixed-cluster (FOXA1/GATA3 high; KRT5/6 high; KRT14 low). Patients with BASQ-like tumours were more likely to achieve a pathological response to NAC, displaying a disease-specific survival similar to that of the remaining patients. In conclusion, patients with BASQ-like tumours - identified through simple and robust immunohistochemistry - have a higher likelihood of undergoing a pathological complete response to NAC. Prospective validation in independent series is required.\n\nNovelty and impactNeoadjuvant chemotherapy is an important component of the management of patietns with muscle-invasive bladder cancer but improved stratification is necessary. This retrospective study shows that patients with BASQ-like tumors can be identified using immunohistochemistry on paraffin-embedded tissue and are 4-fold more likely to achieve a pathological complete response to platinum-based NAC. The disease-specific survival of patients with BASQ-like tumours treated with NAC was not different from that of other tumour subtypes.

pathology↗

bioRxiv2019

Comparison of the full distribution of fitness effects of new amino acid mutations across great apes

The distribution of fitness effects (DFE) is central to many questions in evolutionary biology. However, little is known about the differences in DFEs between closely related species. We use more than 9,000 coding genes orthologous one-to-one across great apes, gibbons, and macaques to assess the stability of the DFE across great apes. We use the unfolded site frequency spectrum of polymorphic mutations (n = 8 haploid chromosomes per population) to estimate the DFE. We find that the shape of the deleterious DFE is strikingly similar across great apes. We confirm that effective population size (Ne) is a strong predictor of the strength of negative selection, consistent with the Nearly Neutral Theory. However, we also find that the strength of negative selection varies more than expected given the differences in Ne between species. Across species, mean fitness effects of new deleterious mutations co-varies with Ne, consistent with positive epistasis among deleterious mutations. We find that the strength of negative selection for the smallest populations: bonobos and western chimpanzees, is higher than expected given their Ne. This may result from a more efficient purging of strongly deleterious recessive variants in these populations. Forward simulations confirm that these findings are not artifacts of the way we are inferring Ne and DFE parameters. All findings are replicated using only GC-conservative mutations, thereby confirming that GC-biased gene conversion is not affecting our conclusions.

evolutionary biology↗

bioRxiv2019

Viruses rule over adaptation in conserved human proteins

Adaptive evolution often involves fast-evolving proteins, and the fastest-evolving proteins in primates include antiviral proteins engaged in an arms race with viruses 1-3. Even though fast-evolving antiviral proteins are the most studied cases of primate host adaptation against viruses, viruses predominantly interact with host proteins that are broadly conserved between distant species in order to complete their replication cycle 4. Broadly conserved proteins are generally viewed as playing a negligible role in adaptive evolution. Here, we used a dataset of ~4,500 human proteins known to physically interact with viruses (VIPs for Virus-Interacting Proteins), to test the involvement of broadly conserved proteins in adaptive evolution against viruses. We found that VIPs conserved between animals and fungi have experienced not only high rates of adaption, but also strong adaptive events. Broadly conserved proteins that do not interact with viruses experienced very little adaptation. As a result, the arms race with viruses explains more than 75% of adaptation in the most phylogenetically conserved subset of the human proteome. Our results imply that broadly conserved proteins have played a significant role in adaptation, and that viruses were likely one of very few selective pressures that were able to force the conserved, central pillars of host cellular functions to adapt during evolution.

evolutionary biology↗

bioRxiv2018

Strong selective sweeps before 45,000BP displaced archaic admixture across the human X chromosome

The X chromosome in non-African populations has less diversity and less Neanderthal introgression than expected. We analyzed X chromosome diversity across the globe and discovered seventeen chromosomal regions, where haplotypes of several hundred kilobases have recently reached high frequencies in non-African populations only. The selective sweeps must have occurred more than 45,000 years ago because the ancient Ust-Ishim male also carries its expected proportion of these haplotypes. Surprisingly, the swept haplotypes are entirely devoid of Neanderthal introgression, which implies that a population without Neanderthal admixture contributed the swept haplotypes. It also implies that the sweeps must have happened after the main interbreeding event with Neanderthals about 55,000 BP. These swept haplotypes may thus be the only genetic remnants of an earlier out-of-Africa event.\n\nOne Sentence SummaryAfter humans expanded out of Africa, the X chromosome experienced a burst of extreme natural selection that removed Neanderthal admixture.

genomics↗