Biology subjects

de Lazaro, I.

Publications and source records attributed to de Lazaro, I..

7 recordsLinked to original sources

bioRxiv2025

Cardiomyocyte-specific plakophilin-2 loss is sufficient to induce aging and senescence of nonmyocytes. Relevance to arrhythmogenic cardiomyopathy.

IntroductionPathogenic variants in PKP2 are the most common cause of familial arrhythmogenic right ventricular cardiomyopathy (ARVC). ObjectiveTo test whether PKP2 deficiency only in cardiomyocytes is sufficient to provoke premature aging and pro-inflammatory senescence in non-myocytes, cardiac resident cells. MethodsWe studied mice with cardiomyocyte-specific, tamoxifen-activated loss of PKP2 (PKP2cKO) using conventional and multiplex imaging, cytokine arrays, epigenetic clocks, spatial transcriptomics, expansion and structured illumination microscopy, and correlative data analysis. We examined non-myocytes and cardiomyocytes for premature aging and senescence. ResultsWe observed senescence-associated heterochromatin foci (SAHFs) and p21 staining in non-myocytes. Cytokines in media of non-myocyte cells were consistent with senescence-associated secretory phenotype (SASP). Epigenetic clocks identified premature aging. Multiplex immunohistochemistry showed non-myocyte cells in niches, intermingled with cardiomyocytes. Spatial transcriptomics showed over-representation of SASP-related transcripts, predominantly in myocyte-rich areas of the left ventricle. SAHFs, p21 staining and increased epigenetic age were not found in cardiomyocytes from PKP2cKO hearts, though we observed structural features associated to premature aging. Cross-reference analysis showed correlation between the PKP2cKO cardiac proteome and that of mice 5 or 6 times their chronological age, as well as transcriptional signatures of neurodegenerative diseases. ConclusionLoss of PKP2 expression only in adult cardiac myocytes is sufficient to induce pro-inflammatory senescence in non-myocytes, and overall premature cardiac aging. This is the first study to intersect cellular senescence and premature aging in desmosomal arrhythmogenic cardiomyopathies. We speculate that cell-agnostic molecular signatures, biomarkers, and pharmacology of senescence and of neurodegenerative diseases may be relevant to diagnose or treat PKP2-ARVC. UNSTRUCTURED ABSTRACTPathogenic variants in PKP2 are the most common cause of familial arrhythmogenic right ventricular cardiomyopathy. We used the PKP2cKO model (cardiomyocyte-specific, tamoxifen-activated PKP2 knockout) to examine whether PKP2 deficiency only in cardiomyocytes is sufficient to provoke premature aging and pro-inflammatory senescence in non-myocyte, cardiac resident cells. Through a variety of methods, we identified senescence-associated heterochromatin foci (SAHFs), p21 staining, and cytokines consistent with senescence-associated secretory phenotype (SASP) in cells and media of non-myocytes. Epigenetic clocks identified premature aging. Spatial transcriptomics showed over-representation of SASP-related transcripts, predominantly in myocyte-rich areas of the left ventricle. SAHFs, p21 staining and epigenetics suggesting advanced age were not found in cardiomyocytes, though we observed structural features associated to premature aging. Cross-reference analysis showed correlation between the PKP2cKO cardiac proteome and that of mice 5 or 6 times their chronological age, as well as transcriptional signatures of neurodegenerative diseases. HIGHLIGHTSO_LIPKP2-ARVC is a leading cause of sudden unexpected death in the young. C_LIO_LIThe molecular path from the variant of a gene to the clinical disease remains unclear. An inflammatory component has been postulated. C_LIO_LIWe show that loss of PKP2 only in myocytes is sufficient to induce a pro-inflammatory senescence in non-myocytes and premature aging of cardiac cells. C_LIO_LISimilarities to the molecular profile of neurodegenerative diseases and novel paths to therapy are discussed. C_LI

physiology↗

bioRxiv2022

Matrix viscoelasticity controls spatio-temporal tissue organization

The spatio-temporal patterning of multicellular tissues is driven by the collective dynamics of cell proliferation and active movement. These processes are mediated by the extracellular matrix environment via a combination of biomolecular and physical cues. Here we show that the passive viscoelastic properties of the matrix that encapsulate a proliferating ball of cells (e.g. a developing organoid) play a critical role in guiding tissue organization in space and time. By varying the viscoelasticity of well-defined model matrices, we show how a spheroidal tissue of breast epithelial cells breaks symmetry and forms finger-like protrusions that invade the matrix. A computational model allows us to recapitulate these observations and leads to a phase diagram that demarcates the regions of morphological stability and instability as a function of matrix viscoelasticity, tissue viscosity, cell motility and cell division rate. Experiments that use biomolecular manipulations to independently vary these parameters confirm our predictions. To further test our theory, we also study the self-organization of an in-vitro intestinal organoid and show that the morphological changes of this system also fits within our paradigm. Altogether, our studies demonstrate the role of stress relaxation mechanisms in determining the dynamics of tissue growth and the symmetry breaking instabilities associated with branching, a fundamental process in morphogenesis and oncogenesis, and suggest ways of controlling tissue form using the extracellular matrix.

biophysics↗

bioRxiv2021

Induced reprogramming of adult murine cardiomyocytes to pluripotency in vivo

Partial cell reprogramming has been demonstrated in certain mouse tissues by in situ overexpression of Oct3/4, Klf4, Sox2 and cMyc (OKSM) transcription factors, and can induce rejuvenation and/or augment regeneration. Reprogramming of adult cardiomyocytes has been elusive until recently, but its success could help overcome the lack of endogenous regenerative capacity of the mammalian myocardium. Here, we generated cardiomyocyte-specific, doxycycline-inducible, reprogrammable mice and demonstrated that sustained OKSM induction reprograms cardiomyocytes fully into teratoma-forming pluripotent cells. However, we also showed that cyclic OKSM upregulation induces significant decrease of epigenetic age in the cardiomyocytes without de-differentiation or reacquisition of pluripotency. In mice with progressive heart failure, cardiomyocyte epigenetic rejuvenation correlated with stabilization of systolic heart function. These findings confirm that OKSM can reprogram adult mouse cardiomyocytes to different states depending on the duration of their expression, and provide further evidence that partially reprogrammed cardiomyocytes may contribute to ameliorate cardiac disease.

developmental biology↗

bioRxiv2019

Transient Reprogramming of Neonatal Cardiomyocytes to a Proliferative Dedifferentiated State

Zebrafish and urodele amphibians are capable of extraordinary myocardial regeneration thanks to the ability of their cardiomyocytes to undergo transient dedifferentiation and proliferation. Somatic cells can be temporarily reprogrammed to a proliferative, dedifferentiated state through transient expression of Oct3/4, Sox2, Klf4 and c-Myc (OSKM) transcription factors. Here, we utilized an OSKM-encoding non-integrating vector to induce transient reprogramming of mammalian cardiomyocytes in vitro. Reprogramming factor expression in neonatal rat cardiomyocytes triggered rapid cell dedifferentiation characterized by downregulation of cardiomyocyte specific gene and protein expression, sarcomere dis-assembly and loss of autorhythmic contractile activity. Concomitantly, a significant increase in cell cycle related gene expression and Ki67 positive cells was observed, indicating that dedifferentiated cardiomyocytes possess an enhanced proliferative capacity. A small proportion of cardiomyocytes progressed through mesenchymal to epithelial transition, further indicating the initiation of cell reprogramming. However, complete reprogramming to a pluripotent-like state was not achieved for the duration of the study (20 days), both in standard and embryonic stem cell culture media conditions. The transient nature of this partial reprogramming response was confirmed as cardiomyocyte-specific cell morphology, gene expression and contractile activity were recovered by day 15 after viral transduction. Further investigations into the complete downstream biological effects of ectopic OSKM expression in cardiomyocytes and the fate of these reprogrammed cells are warranted. Our results to date suggest that transient reprogramming could be a feasible strategy to recapitulate regenerative mechanisms of lower vertebrates and inform direct gene therapy approaches to cardiac regenerative medicine.

cell biology↗

bioRxiv2018

Graphene Oxide as 2D Platform for Complexation and Intracellular Delivery of siRNA

The development of efficient and safe nucleic acid delivery vectors remains an unmet need holding back translation of gene therapy approaches into bedside. Graphene oxide (GO) could help bypass such bottleneck thanks to its large surface area, versatile chemistry and biocompatibility, which could overall enhance transfection efficiency while abolishing some of the limitations linked to the use of viral vectors. Here, we aimed to assess the capacity of bare GO, without any further surface modification, to complex a short double-stranded nucleic acid of biological relevance (siRNA) and mediate its intracellular delivery. GO formed stable complexes with siRNA at 10:1, 20:1 and 50:1 GO:siRNA mass ratios. Complexation was further corroborated by atomistic molecular dynamics simulations. GO:siRNA complexes were promptly internalized in a primary mouse cell culture, as early as 4 h after exposure. At this time point, intracellular siRNA levels were comparable to those provided by a lipid-based transfection reagent that achieved significant gene silencing. Time-lapse tracking of internalized GO and siRNA evidenced a sharp decrease of intracellular siRNA from 4 to 12 h, while GO was sequestered in large vesicles, which may explain the lack of biological effect (i.e. gene silencing) achieved by GO:siRNA complexes. This study underlines the potential of non-surface modified GO flakes to act as 2D siRNA delivery platforms, without the need for cationic functionalization, but warrants further vector optimization to allow effective release of the nucleic acid and achieve efficient gene silencing.

bioengineering↗

bioRxiv2018

Exposure to graphene oxide sheets alters the expression of reference genes used for real-time RT-qPCR normalization

Backgroundstudies that unravel the interactions between thin, 2D graphene oxide (GO) sheets and the biological milieu, including cells and tissues, are multiplying quickly as the biomedical applications of those and other 2D materials continue to be explored. Many of such studies rely on real-time RT-qPCR as a powerful, yet relatively simple technique to determine gene expression. However, a systematic investigation of potential GO-induced changes in the expression of reference genes, crucial for appropriate normalization of qPCR data that ensures reliability of the results, is still lacking. In this study, we aimed to cover this gap by investigating the stability of the expression of ten (10) candidate reference genes upon exposure to increasing, but subtoxic, concentrations of GO, with two established algorithms (Bestkeeper and NormFinder). The study was performed in a human cancer cell line (MCF7) and in mouse, non-cancerous primary cells (mouse embryonic fibroblasts, MEFs), to assess different behaviors between cell types.\n\nResultsBestkeeper and NormFinder algorithms evidenced significant deviations in the expression of various reference genes. Ribosomal proteins scored among the most significantly dysregulated targets in both cell types. Expression of ACTB and GAPDH, the most frequent calibrators in real-time RT-qPCR studies, was also affected, although differences existed between cell lines.\n\nConclusionsthis study illustrates the need to validate reference genes for appropriate real-time RT-qPCR normalization, according to specific experimental conditions, when GO-cell interactions occur.

molecular biology↗

bioRxiv2017

Non-viral induction of transient cell reprogramming in skeletal muscle to enhance tissue regeneration

Somatic cells can be reprogrammed to pluripotency in vivo by overexpression of defined transcription factors. While their sustained expression triggers tumorigenesis, transient reprogramming induces pluripotency-like features and proliferation only temporarily, without teratoma formation. We sought to achieve transient reprogramming within mouse skeletal muscle with a localized injection of plasmid DNA (pDNA) and hypothesized that this would enhance regeneration after severe injury. Intramuscular administration of reprogramming pDNA rapidly upregulated pluripotency (Nanog, Ecat1, Rex1) and early myogenesis genes (Pax3) in the healthy gastrocnemius of various mouse strains. Mononucleated cells expressing such markers appeared promptly in clusters among myofibers, but proliferated only transiently and did not lead to the generation of teratomas. Nanog was also upregulated in the gastrocnemius when reprogramming factors were administered 7 days after laceration of its medial head. Enhanced tissue regeneration after reprogramming was manifested by the accelerated appearance of centro-nucleated myofibers and reduced fibrosis. These results suggest that in vivo transient reprogramming may constitute a novel strategy towards the acceleration of regeneration following muscle injury, based on the induction of transiently-proliferative, pluripotent-like cells in situ. Further research to achieve clinically meaningful functional regeneration is warranted.

developmental biology↗