Artículos (Biología Celular)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10814

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Uncoupling of nutrient sensing and cell size control by specific defects in ceramide structure
(The Company of Biologists, 2026-05-26) Quesada-Márquez, José Ignacio; Serrano Caravaca, Ana María; Alcaide Gavilán, María; Lucena Hernández, Rafael; Biología Celular; Junta de Andalucía; European Union (UE)
Ceramides are essential structural lipidswhose chemical diversity arises from variations in acyl-chain length and sphingoid-base modifications, yet how these structural features couple metabolic state to growth regulation remains unclear. In Saccharomyces cerevisiae, the target of rapamycin complex 2 (TORC2)–Ypk1/2 signaling axis coordinates plasma membrane homeostasis with cellular growth; however, the lipidderived signals modulating this pathway are not fully defined. Here, we establish that the elongation of very long-chain fatty acids (VLCFAs), specifically to C26, is a critical determinant of the nutrient-dependent regulation of TORC2 activity. Based on a molecular caliper model for acyl-chain determination, we show that the TORC2–Ypk1 axis is specifically tuned to detect the successful completion of C26-VLCFA synthesis. Disrupting VLCFA elongation (elo3Δ) triggers constitutive TORC2 hyperactivation and a failure to reduce cell size in response to nutrient limitation. By expressing mammalian ceramide synthases (CerS1–CerS4), we demonstrate that TORC2 nutrient sensing is specifically tuned to acyl-chain length. While CerS1, CerS3, and CerS4 restore the rapid, nutrient-induced downregulation of TORC2, CerS2 expression phenocopies the elo3Δ mutant, exhibiting a total kinetic failure to inhibit TORC2 signaling upon nutrient shift. Notably, cells producingC18 ceramides (GhLag1) maintained size control despite elevated TORC2 activity, revealing that ceramide-dependent signaling intensity and the physical execution of size regulation can be uncoupled. We further demonstrate that while sphingoid-base hydroxylation is required for the execution of size remodeling, it is dispensable for nutrient sensing; sur2Δ mutants exhibited severe size defects despite maintaining statistically normal, nutrient-responsive TORC2 signaling. Overall, our findings reveal a functional hierarchy where the proteinmediated caliper measurement of VLCFA length serves as the primary sensor for TORC2 nutrient responsiveness, while subsequent lipid modifications govern the biophysical execution of cell size control.
A natural programmable metamaterial controls 3D curvature of compound eyes
(Nature, 2026-06-30) Garrido García, Juan; Walther, Rhian F.; Torres-Tirado, Jesús; Andrés San Román, Jesús Ángel; Sanz Herrera, José Antonio; Pichaud, Franck; Casares, Fernando; Escudero Cuadrado, Luis María; Biología Celular; Mecánica de Medios Continuos y Teoría de Estructuras; Matemática Aplicada I; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
Panoramic vision of the convex compound eyes, common to insects and crustaceans, relies on micrometer-scale curvature variations. These variations generate specialized visual zones adapted to specific tasks, including detecting prey, mates, or predators. However, how such fine-scale curvature is encoded during development remains unknown. We find in Drosophila melanogaster that the basal surface of the developing retina is organized as a supracellular triangular mesh where the size of these triangles is distributed in a speciesspecific 2D pattern. Functional experiments using genetic perturbations, together with computational modeling, support the notion that this pattern guides adult eye local curvature. A similar pattern in the Drosophilamauritania developing retina indicates an evolutionary conservation of this mechanism. Our findings identify a mechanism of morphogenesis where fine-scale 3D curvature is programmed in the 2D patterning of a tissue with metamaterial properties. This mechanism provides a framework for designing shapeprogrammable 3D biological surfaces, with broad implications from synthetic morphogenesis to clinical applications.
Decoding the Mechanism of Action of a Parasite TGFβ Antagonist Inspires the Creation of Cell-Type-Specific TGFβ Modulators
(Wiley, 2026) Dinther, Maarten van; Schwartze, Tristin; Zhang, Jiying; Fan, Kun; Zon, Gerard van der; Power, Luke; Hinck, Cynthia S.; Ciancia, Claire; González Prieto, Román; Dijke, Peter ten; Biología Celular; Wellcome Trust
Heligmosomoides polygyrus, a mouse parasite, modulates host immunity by secreting modular transforming growth factor-β (TGFβ) mimics (TGMs). The agonist TGM1 interacts with TGFBR1, TGFBR2, and the co-receptor CD44 through domains D1/2, D3, and D4/5, respectively. In contrast, the antagonist TGM6, which lacks D1/2, but retains TGFBR2 binding through D3, targets different cells compared to TGM1. The TGM6 co-receptor is unknown. Using X-ray crystallography and binding studies, we show that TGM6 preferentially binds mouse TGFBR2 over human TGFBR2, and that this is essential for its antagonistic function. We identified low-density lipoprotein receptor-related protein 1 (LRP1) and betaglycan (TGFBR3) as co-receptors for TGM6. LRP1 enhances TGM6 efficacy and is required for its antagonistic effect by promoting TGFBR2 lysosomal degradation, whereas betaglycan counteracts TGM6 in a TGFBR2-dependent manner. The modular organization of TGMs enabled us to design TGM1/6 chimeras or TGM-D3 fusion with an affibody that recognizes a specific cell-surface receptor, thereby altering cell-type specificity and functionality. Furthermore, we developed a TGFBR2 nanobody that, on its own, has no inhibitory effect but, when fused to a receptor antibody, antagonizes TGFβ by blocking TGFβ receptor interaction in a cell-selective manner. Thus, we designed programmable agents that modulate TGFβ signaling only in co-receptor-expressing cells.
Crossing and metabolism of tyrosol and hydroxytyrosol by implementing an in vitro blood-brain barrier model of human primary cells
(Royal Society of Chemistry (RSC), 2026) Gulabrai-Díaz, Sonia; Escudero-López, Blanca; Río Mercado, Carmen del; Montaner, Joan; Berzaghi, Marta; Mena, Pedro; Troncoso González, Ana María; Hornedo Ortega, Ruth; Biología Celular; Nutrición y Bromatología, Toxicología y Medicina Legal
There is mounting evidence that the neuroprotective benefits associated with olive oil consumption are related to the presence of the phenolic alcohols tyrosol (Tyr) and hydroxytyrosol (HT). In vitro blood–brain barrier (BBB) models are considered indispensable platforms for the mechanistic assessment of compound permeability. However, it is important to note that most of these models offer only a limited representation of BBB physiology. The aim of the present study was to develop a human triculture (human brain microvascular endothelial cells (HBMECs), astrocytes and pericytes) BBB model to evaluate the permeability of dietary bioactives. In particular, the crossing of Tyr and HT through the BBB and the BBB's potential to further metabolize these bioactives were evaluated. Different seeding densities of HBMECs and the presence/absence of fibronectin as extracellular matrix were considered. 1 × 105 cells and fibronectin coating of the apical transwell surface yielded higher TEER values and improved barrier integrity. Immunocytochemical analysis further confirmed the well-defined ZO-1 localisation at the cell–cell junctions. After 96 h of the establishment of the triculture, the human-origin BBB (ho-BBB) model presented the optimal barrier conditions for the execution of permeability studies. The transport of Tyr and HT (at two different concentrations, 1 and 10 µM) across the ho-BBB was evaluated by UPLC-MS/MS. Our results proved that the ho-BBB was more permeable to HT (high permeability) than Tyr (medium permeability), as determined by calculating transport percentages and apparent permeability coefficients (Papp). This study provides the first evidence that HBMECs can metabolize HT, transforming it into HT-3′-sulfate and HT-4′-sulfate.
The postnatal expression of transcripts and proteins in the corpus callosum, as well as its myelinization, is affected by the congenital absence of AQP4
(Springer, 2026-03-31) Mayo León, Francisco; González Vinceiro, Lourdes; Hiraldo González, Laura; Torres Rubio, Ismael; Calle-Castillejo, Claudia; Sobh-Doush, Elaheh; Ramírez Lorca, Reposo; Echevarría Irusta, Miriam; Biología Celular; Fisiología Médica y Biofísica; Ministerio de Economía y Competitividad (MINECO). España; Instituto de Salud Carlos III; European Union (UE); Junta de Andalucía
During postnatal development in mice there is a marked switch in the expression of AQP4 from white to grey matter regions. A microglial population, CD11c+, which has been shown to be involved in normal postnatal development of the corpus callosum (CC), prolongs its expression in this tissue in the absence of AQP4. Here, we investigated the correlation between the levels of AQP4 expression during the early postnatal period and the expression of marker genes related to oligodendrogenesis in the mouse CC. A microarray transcriptomic analysis of the CC of wild-type (WT) and AQP4-KO (KO) mice was performed, validation of differentially expressed genes was done by RT-qPCR, and protein expression was analyzed by immunofluorescence. Overexpression of genes associated with microglia and astrocytes and inhibition of genes associated with mature oligodendrocytes were observed in the KO animal compared to the WT. GFAP and CD11c signals were significantly higher in the CC of the KO animal, as was the number of OPCs (OLIG2+/PDGFRa+). However, the number of mature oligodendrocytes (OLIG2+/CC1+) was reduced in the KO mice, indicating a failure of the oligodendrogenesis process that results in a significant reduction in the number of myelinated axons in the CC of the KO animal. This mouse model of congenital AQP4 deficiency, which shows defects in the maturation of its oligodendrocytes in the CC, provides insight into the role of AQP4 in demyelinating pathology and could help in the development of new diagnostic and/or therapeutic strategies for such diseases.
Discovery and Development of a Potent LIMK2 Isoform-Specific Degrader
(American Chemical Society, 2026-05-01) Abdul Azeez, Kamal Rayees; Saraswati, Hayuningbudi; Mosler, Thorsten; Hanke, Thomas; Ho, Hung xuan; Neder, Noah; Sivashanmugam, Saran Aswathaman; Heinz, Marcel; Prieto García, Cristian; Knapp, Stefan; Biología Celular; Federal Ministry of Education and Research. Germany; European Union (UE)
The LIM kinases (LIMK1/2) are key mediators in signaling cascades that regulate actin cytoskeleton dynamics via cofilin phosphorylation. Dysregulation of these pathways and overexpression of LIMKs are implicated in disease development, including cancer, Fragile X syndrome, and glaucoma. Positioned downstream of actin-regulating Rho GTPase signaling pathways, LIM kinases are attractive drug targets. Here, we targeted LIMKs with PROTACs to disrupt both catalytically and noncatalytically mediated functions. Despite employing a dual LIMK1/2 inhibitor warhead and high structural conservation between the two human LIM kinases, we discovered isoform-specific LIMK2 degradation by initial PROTACs that we optimized into a highly potent and selective LIMK2 degrader. Cell-based assays and structural analysis indicated that isoform specificity was likely driven by favorable orientation bias and/or lysine accessibility, along with enhanced ternary complex formation. We comprehensively characterized the PROTAC as a chemical probe that induces isoform-specific degradation, offering a powerful alternative to conventional reversible pan-LIMK inhibitors.
The high-density lipoprotein lipidome in metabolic syndrome: A systematic review
(Wiley, 2026) Grao Cruces, Elena; García‐Jiménez, Gabriel; Martín Rubio, María Esther; Mocciaro, Gabriele; Osto, Elena; Montserrat de la Paz, Sergio; Varela Pérez, Lourdes María; Biología Celular; Bioquímica Médica y Biología Molecular e Inmunología; Instituto de Biomedicina de Sevilla (IBIS); Consejo Superior de Investigaciones Científicas (CSIC)
Background: Metabolic syndrome (MetS) is a cluster of cardiovascular risk fac-tors, including low high-density lipoprotein cholesterol (HDL-C) levels. AlthoughHDL-C is an established cardiovascular biomarker, in MetS this marker capturesonly a fraction of the profound alterations occurring within HDL particles. Thecardiometabolic role of HDLs in MetS remains insufficiently understood be-cause the functional properties and molecular components of HDLs, rather thanHDL-C alone, are likely key determinants of cardiovascular risk. Since the early2000s, research has revealed that HDL particles comprise over 280 proteins andmore than 300 lipid species, underscoring their biological complexity. Moreover,HDL composition and function are extensively remodelled in MetS, highlightingthe importance of characterising the differences in HDL composition betweenhealth and disease. In this systematic review, we aimed to examine differences inthe HDL lipidome between MetS patients and healthy controls.Methods: A comprehensive literature search was conducted in MEDLINE,Cochrane Library, and Web of Science. The PRISMA guidelines for systematicreviews were followed, and four records met the eligibility criteria.Results: Overall, the HDL lipidome was markedly different in MetS comparedwith healthy individuals. MetS was consistently associated with higher levels of triacylglycerides (TAGs) and phosphatidylinositol, alongside lower levels of sev-eral key lipid families, indicating a broad remodelling of HDL composition.Conclusions: These findings indicate that the HDL lipidome is substantiallyaltered in MetS, with potential consequences for HDL functionality. Althoughthe mechanistic implications remain to be fully elucidated, TAG enrichmentmay contribute to lower HDL levels and changes in HDL surface lipids may im-pair essential functions such as cholesterol efflux. Further studies are neededto validate these patterns and determine their impact on HDL function andcardiometabolic risk
BiaPy: accessible deep learning on bioimages
(2025-04-29) Franco-Barranco, Daniel; Andrés San Román, Jesús Ángel; Hidalgo-Cenalmor, Ivan; Backová, Lenka; González-Marfil, Aitor; Caporal, Clément; Chessel, Anatole; Gómez Gálvez, Pedro; Escudero Cuadrado, Luis María; Wei, Donglai; Muñoz-Barrutia, Arrate; Arganda-Carreras, Ignacio; Biología Celular
Computational Analysis of SOD1-G93A Mouse Muscle Biomarkers for Comprehensive Assessment of ALS Progression
(Wiley, 2025-03-31) Gómez Gálvez, Pedro; Navarro Garrido, Victoria; Castro, Ana M.; Paradas, Carmen; Escudero Cuadrado, Luis María; Biología Celular
Aims To identify potential image biomarkers of neuromuscular disease by analysing morphological and network-derived features in skeletal muscle biopsies from a murine model of amyotrophic lateral sclerosis (ALS), the SOD1G93A mouse and wild-type (WT) controls at distinct stages of disease progression. Methods Using the NDICIA computational framework, we quantitatively evaluated histological differences between skeletal muscle biopsies from SOD1G93A and WT mice. The process involved the selection of a subset of features revealing these differences. A subset of discriminative features was selected to characterise these differences, and their temporal dynamics were assessed across disease stages. Results Our findings demonstrate that muscle pathology in the mutant model evolves from early alterations in muscle fibre arrangement, detectable at the presymptomatic stage through graph theory features, to the subsequent development of the typical morphological pattern of neurogenic atrophy at more advanced disease stages. Conclusions Our assay identifies a neurogenic signature in mutant muscle biopsies, even when the disease is phenotypically imperceptible.
IMPDH inhibition enhances cytarabine efﬁcacy inSAMHD1-expressing leukaemia cells via guaninenucleotide depletion
(Wiley, 2026-02-19) Yagüe Capilla, Miriam; Dirks, Christopher; Eiden, Caroline; Fesenmayer, Sonja K.; Hormann, Femke M.; Klootsema, Yolande; Lilienthal, Ingrid; Zhang, Si Min; Herold, Nikolas; Rudd, Sean G.; Biología Celular
The nucleoside analogue cytarabine (ara-C) is part of standard treatment against acute myeloid leukaemia (AML). The efficacy of this therapy is dependent upon accumulation of the active triphosphate metabolite ara-CTP, which mis-incorporates into genomic DNA, triggering cell death. The deoxyribonucleoside triphosphate triphosphohydrolase (dNTPase) SAMHD1 can hydrolyse ara-CTP and thereby convert the active metabolite back to its inactive prodrug form. This constitutes a barrier to treatment efficacy and thus strategies to target SAMHD1 are warranted. SAMHD1 activity is allosterically regulated by nucleotides, which are synthesised in cells via distinct pathways. We screened a collection of drugs targeting nucleotide biosynthetic enzymes and identified that inhibition of inosine-50-monophosphate dehydrogenase (IMPDH), responsible for catalysing the rate-limiting step in guanine nucleotide biosynthesis, sensitises AML cell lines to ara-C in a SAMHD1-dependent manner. We show that approved drugs inhibiting IMPDH—mycophenolic acid and ribavirin—imbalance deoxyribonucleoside triphosphate pools and increase ara-C efficacy in SAMHD1-proficient, but not deficient, leukaemic cells. Altogether, we provide insight into SAMHD1 regulation in leukaemic cells and show how this process can be exploited by approved drugs to improve ara-C therapy.
Rho GTPases signaling mediates aggressiveness and differentiation in neuroblastoma tumors
(Springer Nature, 2026-01-10) Gómez Muñoz, María Ángeles; Ojeda Puertas, Mónica; Luna-Ramírez, Luis; Amador Álvarez, Aida; Rodríguez-Prieto, Ismael; Cordero-Varela, Juan A.; Pardal Redondo, Ricardo; Vega Moreno, Francisco Manuel; Biología Celular; Fisiología Médica y Biofísica; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Ministerio de Ciencia e Innovación (MICIN). España; European Union (UE)
Background: Neuroblastoma (NB) is a pediatric cancer with highly variable outcomes, necessitating improved understanding of the molecular pathways driving its progression. Intratumor cellular heterogeneity related to neural differentiation has emerged as a defining characteristic that can explain its aggressive behavior. Although recurrent driver mutations are not typically observed in these tumors, Rho GTPases signaling genes have been identified as frequently mutated in aggressive NB cases. Rho GTPases are key regulators of cell morphology, migration, and differentiation, yet their role in NB remains underexplored. This study aims to comprehensively evaluate the expression and clinical significance of Rho GTPase signaling networks in NB tumors. Methods: We analyzed the expression profiles of Rho GTPases, their regulators, and effectors, across multiple NB patient cohorts. Gene expression correlations with clinical parameters were assessed, and bioinformatics analyses were employed to identify gene expression patterns and interactions in tumors. Functional studies were performed in NB cell lines and in vivo models to validate the role of key Rho GTPases, including Cdc42, in NB progression and differentiation. Results: Our analysis revealed widespread dysregulation of Rho GTPase signaling in NB tumors. Specific GTPases, such as RHOA or RHOV, were upregulated in advanced disease stages, while others, including RHOB, RHOU and CDC42, were downregulated and associated to poor prognosis. A minimal Rho-related gene signature was identified as a strong predictor of NB patient survival. Functional validation highlighted Cdc42 as a key regulator of NB differentiation, where its downregulation was necessary for maintaining the malignant, undifferentiated phenotype of NB cells. We also identified ARHGAP31/CdGAP as a critical regulator of Cdc42 in NB progenitor cells, suggesting a mechanism for Cdc42 suppression in aggressive NB. Conclusions: An important role for Rho GTPase signaling in NB progression is revealed, providing a foundation for further exploration of Rho GTPase-targeted therapies in NB. In particular, Cdc42 signaling intervene in the balance between differentiation and stemness in NB cells, suggesting specific signaling events controlling the identity and plasticity of NB cells.
Fatty acid composition of isoenergetic meals drives distinct postprandial immunometabolic responses in healthy adults: A randomized crossover pilot study
(Elsevier, 2026-04) Márquez Parada, Elvira; Torrecillas López, María; Corell Almuraza, Alfredo; González de la Rosa, Teresa; Barrera Chamorro, Luna; Bermúdez Pulgarín, Beatriz; Claro Cala, Carmen María; Montserrat de la Paz, Sergio; Bioquímica Médica y Biología Molecular e Inmunología; Biología Celular; Farmacología, Pediatría y Radiología; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
The postprandial period represents a critical and dynamic phase during which dietary components can acutely influence metabolic and immune functions. While the chronic effects of dietary fat quality are well characterized, their immediate postprandial immunometabolic impact remains poorly understood. To investigate the acute effects of energy-matched test meals enriched in saturated (SFA), monounsaturated (MUFA), or omega-3 long-chain polyunsaturated fatty acids (ω3-LCPUFA), compared to a fat-free control, on systemic metabolic and immune parameters in healthy adults. In this randomized, crossover pilot study, ten healthy participants consumed four test meals separated by 2-week washouts. Blood samples were collected at fasting, 2–3 h (peak), and 5–6 h (late phase) postprandially. Biochemical and immunological biomarkers were assessed. Statistical analyses included two-way repeated-measures ANOVA, linear mixed models, and area under the curve (AUC/iAUC) calculations. MUFA- and ω3-LCPUFA-enriched meals induced significantly greater postprandial changes in glucose, triacylglycerides, LDL-C, and C-peptide compared to the SFA and fat-free meals, particularly at the late postprandial phase. These effects were confirmed by AUC and iAUC analyses. In contrast, although transient changes in immune cell counts and humoral markers were observed over time, no significant differences between fat types were detected in postprandial immune responses. In healthy adults, the fatty acid composition of energy-matched meals acutely modulates key metabolic pathways in a fat-type-specific manner, whereas systemic immune parameters remain largely unchanged. These preliminary findings suggest a functional dissociation between postprandial metabolic and immune response and underscore the need to more sensitive or compartment-specific immune readouts in future nutritional research.
Human iPSC-derived APOE4/4 Alzheimer´s disease astrocytes exhibit a senescent and pro-inflammatory state that compromises neuronal support
(BioMed Central, 2025-12-12) Cáceres Palomo, Laura; Sánchez Mejías, Elisabeth; Trujillo Estrada, Laura; Pérez Moreno, Juan José; López Oliva, Elba; Lim, Tau En; DeFlitch, Leah; Vitorica Ferrández, Francisco Javier; García León, Juan Antonio; Gutiérrez, Antonia; Biología Celular; Bioquímica y Biología Molecular; Instituto de Salud Carlos III; European Union (UE)
Alzheimer´s disease (AD) is dominated by a complex cellular pathology which involves most brain cell types with glial cells increasingly recognized as playing fundamental roles in neurodegeneration. Astrocytes, which perform essential functions in preserving brain homeostasis, present a reactive phenotype in the AD brains with still unknown consequences. In this study, we generated and characterized human induced pluripotent stem cell (hiPSC)-derived astrocytes from AD patients harboring the APOE4/4 genotype, the greatest genetic risk factor for late-onset AD. Disease astrocytes showed a reactive phenotype. In addition, they showed altered mitochondrial network including perinuclear clustering of mitochondria, enhanced mitochondrial fusion and higher production of reactive oxygen species which, unexpectedly, were coincident with increased oxidative phosphorylation and glycolysis. As these mitochondrial features are related to the acquisition of cell senescence, we evaluated this at the transcriptome level and found that these AD-derived astrocytes significantly upregulated gene signatures of cellular senescence and displayed a senescence-associated secretory phenotype (SASP). To verify this finding, we observed senescence-related DNA damage response in a significant proportion of cells in the cerebral cortex of AD patients, with most of these cells being astrocytes. Finally, we confirmed that this astrocytic senescent and proinflammatory phenotype is associated with a reduced neuronal support, evidencing that APOE4/4 AD astrocytes present intrinsic features that may compromise brain homeostasis and promote neurodegeneration. Addressing the causes and consequences of this astrocytic dysfunctionality should help to elucidate novel therapeutic targets able to modify the neurodegeneration present in AD.
Neuroprotection with Bioactive Compounds
(MDPI, 2026-10-30) Río Mercado, Carmen del; Segura Carretero, Antonio; Biología Celular
Analysis and removal of matrine in liquorice raw materials by good manufacturing practices
(Elsevier, 2026-01-13) Millán Linares, Carmen; Martín Rubio, María Esther; Biología Celular
The quinolizidine alkaloids matrine and its N-oxide oxymatrine, naturally occurring in plants of the genus Sophora, have recently been detected sporadically in liquorice (Glycyrrhiza sp.) products. This contamination is primarily attributed to the morphological similarity between the liquorice plant and Sophora species (sp.) leading to confusion during harvesting. While the use of matrine as a pesticide has been reported, the primary concern stems from its unintentional presence in liquorice products. The detection of matrine in liquorice raised concerns due to some studies suggesting potential genotoxic activity of matrine and oxymatrine. An LC-MS/MS measurement (QuPPe-PO-Method) was successfully developed and applied used for the identification of matrine/SOP 2887 by SGS in 31 samples selected throughout the liquorice production process. No contamination was obtained in any of the samples analyzed after the application of the internal process model designed by Mafco Worldwide LLC. Microscopic and spectroscopic analysis of the manually separated plants demonstrated not only the effectiveness of the procedure for the control of matrine contamination but also showed for the first time that between the two species can be a valuable and less costly alternative or complementary methodology to quantitative methods.
Ceramide sorting into non-vesicular transport is independent of acyl chain length in budding yeast
(Elsevier, 2024-01) Schlarmann, Philipp; Hanaoka, Kazuki; Ikeda, Atsuko; Muñiz Guinea, Manuel; Funato, Kouichi; Biología Celular
The transport of ceramide from the endoplasmic reticulum (ER) to the Golgi is a key step in the synthesis of complex sphingolipids, the main building blocks of the plasma membrane. In yeast, ceramide is transported to the Golgi either through ATP-dependent COPII vesicles of the secretory pathway or by ATP-independent non-vesicular transport that involves tethering proteins at ER-Golgi membrane contact sites. Studies in both mammalian and yeast cells reported that vesicular transport mainly carries ceramide containing very long chain fatty acids, while the main mammalian non-vesicular ceramide transport protein CERT only transports ceramides containing short chain fatty acids. However, if non-vesicular ceramide transport in yeast similarly favors short chain ceramides remained unanswered. Here we employed a yeast GhLag1 strain in which the endogenous ceramide synthase is replaced by the cotton-derived GhLag1 gene, resulting in the production of short chain C18 rather than C26 ceramides. We show that block of vesicular transport through ATP-depletion or the use of temperature-sensitive sec mutants caused a reduction in inositolphosphorylceramide (IPC) synthesis to similar extent in WT and GhLag1 backgrounds. Since the remaining IPC synthesis is a readout for non-vesicular ceramide transport, our results indicate that non-vesicular ceramide transport is neither blocked nor facilitated when only short chain ceramides are present. Therefore, we propose that the sorting of ceramide into non-vesicular transport is independent of acyl chain length in budding yeast.
Targeting IMPDH to inhibit SAMHD1 in KMT2A-rearranged leukaemia
(Taylor & Francis Inc., 2025-12-15) Klootsema, Yolande; Tsesmetzis, Nikolaos; Sharma, Sushma; Hofmann, Sophia; Thier, Jonas; Dirks, Christopher; Hormann, Femke M.; Yagüe Capilla, Miriam; Herold, Nikolas; Biología Celular; Swedish Society for Medical Research; Swedish Cancer Society; Swedish Childhood Cancer Foundation; Swedish Society of Medicine; Sjöberg Foundation; Swedish Research Council
Cytarabine (ara-C) and fludarabine (F-ara-A) are key drugs in leukaemia treatment. SAMHD1 is known to confer resistance to ara-C and F-ara-A, and we previously identified ribonucleotide reductase inhibitors as indirect SAMHD1 inhibitors in a phenotypic screen. The inosine monophosphate dehydrogenase (IMPDH) inhibitor mycophenolic acid (MPA) was also a hit in this screen. IMPDH inhibitors (IMPDHi) have previously shown efficacy against KMT2A-rearranged (KMT2Ar) acute myeloid leukaemia (AML). We investigated whether IMPDH inhibition could enhance the effect of ara-C and F-ara-A in AML cell lines and primary AML samples, and whether this effect was linked to KMT2A status. We found that sensitivity to IMPDHi was independent of KMT2A status. IMPDHi synergized with ara-C and F-ara-A in a SAMHD1-dependent manner in a subset of AML cells, but not in acute lymphoblastic leukaemia cell lines. Mechanistically, IMPDHi depleted allosteric SAMHD1 activators GTP and dGTP, thereby increasing active triphosphate metabolites in SAMHD1-proficient, but not SAMHD1-deficient, cells. Our findings suggest that the addition of IMPDHi to ara-C and F-ara-A may have therapeutic benefits in some AML cases.
Mechanisms of growth-dependent regulation of the Gin4 kinase
(American Society for Cell Biology, 2025-07-28) Méndez Díaz, Francisco; Sánchez -Godínez, David; Solano, Francisco; Jasani, Akshi; Alcaide Gavilán, María; Prichard, Beth E.; Kellogg, Douglas R.; Biología Celular; University of California Santa Cruz, Santa Cruz, CA, United States
Cell cycle progression is dependent upon cell growth. Cells must therefore translate growth into a proportional signal that indicates when there has been sufficient growth for cell cycle progression. In budding yeast, the protein kinase Gin4 is required for normal control of bud growth and undergoes gradual multi-site hyperphosphorylation and activation that are dependent upon bud growth and correlated with the extent of growth. Together, these observations suggest that Gin4 functions in mechanisms that measure cell growth. Here, we searched for signals that link Gin4 hyperphosphorylation to cell growth. We found that Elm1, a yeast homolog of mammalian Lkb1 kinases, is sufficient in vitro to induce full hyperphosphorylation of Gin4, and likely works by stimulating extensive autophosphorylation of Gin4. We further discovered that casein kinase I, encoded by the YCK1 and YCK2 genes, is required for growth-dependent phosphorylation of Gin4. Yck1/2 are delivered to the growing plasma membrane by post-Golgi vesicles that drive membrane growth, and they are required for normal control of growth. The data suggest that delivery of Yck1/2 to the plasma membrane could play an important role in generating a growth-dependent signal that provides a measure of bud growth.
Casein kinase 1 controls components of a TORC2 signaling network in budding yeast
(The Company of Biologists, 2024-12-20) Lucena Hernández, Rafael; Jasani, Akshi; Anastasia, Steph; Kellogg, Douglas; Alcaide Gavilán, María; Biología Celular
Tor kinases play diverse and essential roles in control of nutrient signaling and cell growth. These kinases are assembled into two multiprotein complexes known as TORC1 and TORC2. In budding yeast, TORC2 relays nutrient-dependent signals that strongly influence growth rate and cell size. However, the mechanisms that control TORC2 signaling are poorly understood. Activation of TORC2 requires Mss4, a phosphatidylinositol 4-phosphate 5-kinase that recruits and activates downstream targets of TORC2. Localization of Mss4 to the plasma membrane is thought to be controlled by phosphorylation, and previous work has suggested that yeast homologs of casein kinase 1, Yck1 and Yck2 (referred to here collectively as Yck1/2), Control phosphorylation of Mss4. Here, we generated a new analog-sensitive allele of YCK2 and used it to test whether Yck1/2 influence localization of Mss4 or signaling in the TORC2 network. We found that Yck1/2 strongly influence Mss4 phosphorylation and localization, as well as influencing regulation of multiple components of the TORC2 network. However, inhibition of Yck1/2 causes mild effects on the best-characterized signaling axis in the TORC2 pathway, suggesting that Yck1/2 might play a larger role in influencing less well-understood aspects of TORC2 signaling.
Very long-chain fatty acids drive 1-deoxySphingolipid toxicity
(Nature Research, 2025-11-26) Majcher, Adam; Karsai, Gergely; Yusifov, Elkhan; Schaettin, Martina; Malagola, Ermanno; Horvath, Peter J.; Li, Jinmei; Rodríguez Gallardo, Sofía; Dubey, Raghvendra; Hornemann, Thorsten; Biología Celular; Swiss National Science Foundation (SNFS)
1-Deoxysphingolipids (1-deoxySLs) are atypical sphingolipids formed when serine palmitoyltransferase incorporates L-alanine instead of L-serine. Elevated 1-deoxySLs are associated with hereditary sensory neuropathy type 1 and diabetic neuropathy, but the molecular basis of their toxicity remains unclear. Here we show that toxicity is mediated by very long-chain (VLC) 1-deoxy-dihydroceramides (1-deoxyDHCer), particularly nervonyl-1-deoxyDHCer (m18:0/24:1) and lignoceryl-1-deoxyDHCer (m18:0/24:0). Using a CRISPR interference screen, we identify ELOVL1 and CERS2 as essential enzymes driving the formation of these toxic species. Genetic modulation or pharmacological inhibition of ELOVL1 prevents VLC 1-deoxyDHCer accumulation, rescuing the toxicity in cellular and neuronal models. Mechanistic studies reveal that m18:0/24:1 disrupts mitochondrial integrity and induces the mitochondrial permeability transition pore formation and BAX activation, leading to cell death. These findings establish a direct link between 1-deoxySL chemical structure and cytotoxicity and highlight ELOVL1 inhibition as a potential therapeutic strategy for 1-deoxySL-associated diseases.

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