Alejandro López-Saavedra

Neuronal differentiation is a highly regulated process in which morphogens establish cellular identities through coordinated transcriptional programs. However, the contribution of physiologically derived metabolites to human neural development remains poorly understood. β-hydroxybutyrate (bhb) has been recognized as an inflammatory, epigenetic, energetic, and neuroprotective regulator. We differentiated midbrain floor plate neural precursor cells (mfNPC) from human embryonic stem cells to generate midbrain organoids (MBOs), which were exposed to bhb. Although dopaminergic differentiation occurred in control MBOs, treatment with 1 mM bhb for 16 days significantly increased both the number of Tyrosine hydroxylase-positive (TH⁺) neurons, and the corresponding transcripts assessed by bulk RNA sequencing. Such transcriptomic profiling revealed modest but consistent bhb-associated changes in trophic, neuronal and dopaminergic transcripts. To further characterize these changes, we performed gene set enrichment analysis using curated cell phenotypes-associated transcriptional programs. These analyses indicated that bhb treatment is associated with shifts in the enrichment scores of dopaminergic programs in day 16 MBOs. At the epigenomic level, we used CUT&RUN assays to map H3K27 acetylation, and the selected candidates H3K27ac regions after bhb treatment were linked to their closest neighboring genes, suggesting positive enrichment of neural and dopaminergic gene ontology categories at both time points. Unsupervised analysis of H3K27ac-enriched regions revealed three major clusters detected across differentiation, although present in both control and bhb-treated MBOs. Motif enrichment analysis of clustering regions identified distinct predicted transcription factor binding motifs in mfNPC and MBOs. Finally, we integrated this motif analysis, enhancer annotation, and our transcriptomic data on a web platform, Enhancer Network Explorer, to explore relationships between H3K27ac profiles, transcriptional changes and bhb exposure during human MBOs differentiation. Together, our results indicate that bhb treatment is associated with increased TH-positive cell abundance and with population-level changes related to neurodevelopmental transcriptional programs. These findings suggest that bhb might support early human midbrain differentiation and provide a starting point for future studies addressing the mechanisms linking metabolic cues, chromatin-associated regulation and dopaminergic differentiation.

The with-no-lysine (K) (WNK) kinases regulate processes such as cell volume and epithelial ion transport through the modulation of cation chloride cotransporters such as the NaCl cotransporter (NCC) present in the distal convoluted tubule (DCT) of the kidney. Recently, the interaction of WNKs with nuclear receptor binding protein 1 (NRBP1) and transforming growth factor–β–stimulated clone 22 domain (TSC22D) proteins was reported. Here, we explored the effect of NRBP1 and TSC22Ds on WNK signaling in vitro and in the DCT. TSC22D1.1, TSC22D2, and NRBP1 are localized in DCT WNK bodies, which are cytoplasmic biomolecular condensates associated with WNK activation. In HEK293 cells, long TSC22D isoforms and NRBP1 increase WNK4 activity. DCT-specific NRBP1-knockout mice have reduced NCC phosphorylation and activate a compensatory response. Thus, NRBP1 and long TSC22D proteins are positive modulators of WNK signaling and modulate Na ⁺ reabsorption in the kidney. NRBP1 and TSC22Ds likely influence WNK signaling in other tissues, affecting various physiological processes.

Triple-negative breast cancer (TNBC) is highly aggressive and lacks targeted therapies, posing a major challenge in oncology. Traditional two-dimensional (2D) cell cultures fail to capture the tumor microenvironment’s complexity, whereas three-dimensional (3D) cultures provide a more accurate model of tumor biology. We developed an advanced 3D culture system for TNBC cell lines BT-20 and MDA-MB-231, enhancing the hanging-drop method with Matrigel to restore essential extracellular matrix interactions. Confocal imaging showed MDA-MB-231 cells forming clusters typical of aggressive carcinoma, while BT-20 cells organized into duct-like structures. Molecular analysis of PI3K and β-catenin target genes revealed distinct expression patterns, with PI3K overexpressed and β-catenin downregulated in 3D cultures. Moreover, β-catenin distribution in the 3D cell culture closely resembles its pattern in tissue. These findings underscore the value of 3D models in understanding TNBC progression and in supporting the exploration of novel therapeutic strategies.

With-no-lysine kinases regulate the phosphorylation and activity of the Na⁺-Cl^– and Na⁺-K⁺-2Cl^– cotransporters. This pathway is modulated by arginine vasopressin (AVP). However, the link between AVP and WNK signaling remains unknown. Here, we show that AVP activates WNK4 through increased phosphorylation at putative protein kinase A-regulated sites and decreases its dephosphorylation by protein phosphatase 1. This work increases our understanding of the signaling pathways mediating AVP actions in the kidney.

Chemoresistance to standard neoadjuvant treatment commonly occurs in locally advanced breast cancer, particularly in the luminal subtype, which is hormone receptor-positive and represents the most common subtype of breast cancer associated with the worst outcomes. Identifying the genes associated with chemoresistance is crucial for understanding the underlying mechanisms and discovering effective treatments. In this study, we aimed to identify genes linked to neoadjuvant chemotherapy resistance in 62 retrospectively included patients with luminal breast cancer. Whole RNA sequencing of 12 patient biopsies revealed 269 differentially expressed genes in chemoresistant patients. We further validated eight highly correlated genes associated with resistance. Among these, solute carrier family 12 member 1 (SLC12A1) and glutamate ionotropic AMPA type subunit 4 (GRIA4), both implicated in ion transport, showed the strongest association with chemoresistance. Notably, SLC12A1 expression was downregulated, while protein levels of glutamate receptor 4 (GLUR4), encoded by GRIA4, were elevated in patients with a worse prognosis. Our results suggest a potential link between SLC12A1 gene expression and GLUR4 protein levels with chemoresistance in luminal breast cancer. In particular, GLUR4 protein could serve as a potential target for drug intervention to overcome chemoresistance.

Background: The identification of histopathology in metastatic non-seminomatous testicular germ cell tumors (TGCT) before post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) holds significant potential to reduce treatment-related morbidity in young patients, addressing an important survivorship concern. Aim: To explore this possibility, we conducted a study investigating the role of computed tomography (CT) radiomics models that integrate clinical predictors, enabling personalized prediction of histopathology in metastatic non-seminomatous TGCT patients prior to PC-RPLND. In this retrospective study, we included a cohort of 122 patients. Methods: Using dedicated radiomics software, we segmented the targets and extracted quantitative features from the CT images. Subsequently, we employed feature selection techniques and developed radiomics-based machine learning models to predict histological subtypes. To ensure the robustness of our procedure, we implemented a 5-fold cross-validation approach. When evaluating the models’ performance, we measured metrics such as the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, precision, and F-score. Result: Our radiomics model based on the Support Vector Machine achieved an optimal average AUC of 0.945. Conclusions: The presented CT-based radiomics model can potentially serve as a non-invasive tool to predict histopathological outcomes, differentiating among fibrosis/necrosis, teratoma, and viable tumor in metastatic non-seminomatous TGCT before PC-RPLND. It has the potential to be considered a promising tool to mitigate the risk of over- or under-treatment in young patients, although multi-center validation is critical to confirm the clinical utility of the proposed radiomics workflow.

Persistent high-risk human papillomavirus infection is the main risk factor for cervical cancer establishment, where the viral oncogenes E6 and E7 promote a cancerous phenotype. Metabolic reprogramming in cancer involves alterations in glutamine metabolism, also named glutaminolysis, to provide energy for supporting cancer processes including migration, proliferation, and production of reactive oxygen species, among others. The aim of this work was to analyze the effect of HPV16 E6 and E7 oncoproteins on the regulation of glutaminolysis and its contribution to cell proliferation. We found that the E6 and E7 oncoproteins exacerbate cell proliferation in a glutamine-dependent manner. Both oncoproteins increased the levels of transporter SNAT1, as well as GLS2 and GS enzymes; E6 also increased LAT1 transporter protein levels, while E7 increased ASCT2 and xCT. Some of these alterations are also regulated at a transcriptional level. Consistently, the amount of SNAT1 protein decreased in Ca Ski cells when E6 and E7 expression was knocked down. In addition, we demonstrated that cell proliferation was partially dependent on SNAT1 in the presence of glutamine. Interestingly, SNAT1 expression was higher in cervical cancer compared with normal cervical cells. The high expression of SNAT1 was associated with poor overall survival of cervical cancer patients. Our results indicate that HPV oncoproteins exacerbate glutaminolysis supporting the malignant phenotype.

During mitosis, many cellular structures are organized to segregate the replicated genome to the daughter cells. Chromatin is condensed to shape a mitotic chromosome. A multiprotein complex known as kinetochore is organized on a specific region of each chromosome, the centromere, which is defined by the presence of a histone H3 variant called CENP-A. The cytoskeleton is re-arranged to give rise to the mitotic spindle that binds to kinetochores and leads to the movement of chromosomes. How chromatin regulates different activities during mitosis is not well known. The role of histone post-translational modifications (HPTMs) in mitosis has been recently revealed. Specific HPTMs participate in local compaction during chromosome condensation. On the other hand, HPTMs are involved in CENP-A incorporation in the centromere region, an essential activity to maintain centromere identity. HPTMs also participate in the formation of regulatory protein complexes, such as the chromosomal passenger complex (CPC) and the spindle assembly checkpoint (SAC). Finally, we discuss how HPTMs can be modified by environmental factors and the possible consequences on chromosome segregation and genome stability.

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm defined by the presence of t(9;22) translocation whose origin has been associated with the tridimensional genome organization. This rearrangement leads to the fusion of BCR and ABL1 genes giving rise to a chimeric protein with constitutive kinase activity. Imatinib, a tyrosine kinase inhibitor (TKI), is used as a first-line treatment for CML, though approximately 40% of CML patients do not respond. Here, using structured illumination microscopy (SIM) and 3D reconstruction, we studied the 3D organization patterns of the ABL1 and BCR genes, and their chromosome territories (CTs) CT9 and CT22, in CD34+ cells from CML patients that responded or not to TKI. We found that TKI resistance in CML is associated with high levels of structural disruption of CT9 and CT22 in CD34+ cells, increased CT volumes (especially for CT22), intermingling between CT9 and CT22, and open-chromatin epigenetic mark in CT22. Altogether our results suggest that large-scale disruption of CT9 and CT22 correlates with the clinical response of CML patients, which could be translated into a potential prognostic marker of response to treatment in this disease and provide novel insights into the mechanisms underlying resistance to TKI in CML.

Tuberculosis remains a serious threat worldwide. For this reason, it is necessary to identify agents that shorten the duration of treatment, strengthen the host immune system, and/or decrease the damage caused by the infection. Statins are drugs that reduce plasma cholesterol levels and have immunomodulatory, anti-inflammatory and antimicrobial effects. Although there is evidence that statins may contribute to the containment of Mycobacterium tuberculosis infection, their effects on peripheral blood mononuclear cells (PBMCs) involved in the immune response have not been previously described. Using PBMCs from 10 healthy subjects infected with M. tuberculosis H37Rv, we analyzed the effects of simvastatin on the treatment of the infections in an in vitro experimental model. Direct quantification of M. tuberculosis growth (in CFU/mL) was performed. Phenotypes and cell activation were assessed via multi-color flow cytometry. Culture supernatant cytokine levels were determined via cytokine bead arrays. The induction of apoptosis and autophagy was evaluated via flow cytometry and confocal microscopy. Simvastatin decreased the growth of M. tuberculosis in PBMCs, increased the proportion of NKT cells in culture, increased the expression of co-stimulatory molecules in monocytes, promoted the secretion of the cytokines IL-1β and IL-12p70, and activated apoptosis and autophagy in monocytes, resulting in a significant reduction in bacterial load. We also observed an increase in IL-10 production. We did not observe any direct antimycobacterial activity. This study provides new insight into the mechanism through which simvastatin reduces the mycobacterial load in infected PBMCs. These results demonstrate that simvastatin activates several immune mechanisms that favor the containment of M. tuberculosis infection, providing relevant evidence to consider statins as candidates for host-directed therapy. They also suggest that future studies are needed to define the roles of statin-induced anti-inflammatory mechanisms in tuberculosis treatment.