Biology subjects

Naveiras, O.

Publications and source records attributed to Naveiras, O..

10 recordsLinked to original sources

bioRxiv2025

Molecular Regulation and Physiological Role of 1 GOLPH3-mediated Golgi retention

The Golgi complex serves as the central hub of the biosynthetic pathway, where anterograde and retrograde trafficking converge. How cargo and Golgi-resident proteins traverse this organelle has long been debated. Recent studies have identified a molecular machinery that sorts resident proteins into retrograde-directed COPI vesicles during cisternal maturation. Golgi phosphoprotein 3 (GOLPH3) is a key component of this system; however, its physiological relevance and regulatory mechanisms remain poorly defined. Here, we show that GOLPH3 depletion in mice disrupts both protein and lipid glycosylation, causes partially penetrant embryonic lethality, and severely impairs growth and bone mineralization. At the molecular level, we find that GOLPH3 is regulated by functionally antagonistic S-acylation events that control the topology of its membrane association. To mediate retrograde trafficking of Golgi-resident glycosyltransferases, GOLPH3 must bind their cytosolic tails. This occurs via a negatively charged surface region, which is correctly oriented only in one of the S-acylated GOLPH3 conformations. Together, these findings reveal a lipid-mediated regulatory mechanism for intra-Golgi trafficking and establish the critical role of GOLPH3 in vertebrate development.

cell biology↗

bioRxiv2025

Wnt-dependent spatiotemporal reprogramming ofbone marrow niches drives fibrosis

Bone marrow fibrosis is the most extensive matrix remodeling of the microenvironment and can include de novo formation of bone (osteosclerosis). Spatiotemporal information on the contribution of distinct bone marrow niche populations to this process is incomplete. We demonstrate that fibrosis-inducing hematopoietic cells cause profibrotic reprogramming of perivascular CXCL12 abundant reticular (CAR) progenitor cells resulting in loss of their hematopoiesis-support and upregulation of osteogenic and pro-apoptotic programs. In turn, peritrabecular osteolineage cells (OLCs) are activated in an injury-specific, Wnt-dependent manner, comparable to skeletal repair. OLCs fuel bone marrow fibrosis through their expansion and skewed differentiation, resulting in osteosclerosis and expansion of Ly6a+ fibroblasts. NCAM1 expression marks peritrabecular OLCs and their expansion into the central marrow is specific for fibrosis in mice and patients. Peritrabecular stromal b-catenin expression is linked to fibrosis in patients and inhibition of Wnt signaling reduces bone marrow fibrosis and osteosclerosis, possibly being a clinically relevant therapeutic target.

molecular biology↗

bioRxiv2024

A three-dimensional ex vivo model recapitulates in vivo features and unravels increased drug resistance in childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) preferentially localizes in the bone marrow (BM) and displays recurrent patterns of medullary and extra-medullary involvement. Leukemic cells exploit their niche for propagation and survive selective pressure by chemotherapy in the BM microenvironment, suggesting the existence of protective mechanisms. Here, we established a three-dimensional (3D) BM mimic with human mesenchymal stromal cells and endothelial cells that resemble vasculature-like structures to explore the interdependence of leukemic cells with their microenvironment. This model recapitulates recurrent topologic differences between B-cell and T-cell precursor ALL, whereby B-ALL interacts more closely with the mesenchymal compartment. Migration versatility was found to be associated with subtype, consistent with increased motility observed in T-ALL in vivo. Single-cell RNA signatures revealed similarities to profiles from in vivo patient derived xenografts, suggesting relevant states ex vivo. Furthermore, enhanced migration, adherence and cell cycle heterogeneity was visualized in our co-culture model. Finally, drug response profiling experiments in this 3D system reproduced established response patterns and indicated that drug resistant leukemic subpopulations may be detected more faithfully compared to information from two-dimensional models.

cancer biology↗

bioRxiv2024

Impaired erythroid maturation in murine embryos upon loss of the preeclampsia-associated serine protease prostasin

In humans, the membrane-bound serine protease prostasin encoded by Prss8 is associated with preeclampsia, a gestational hypertension disorder affecting blood supply of the placenta. Mice deficient in Prss8 resulted in the death of embryos at embryonic day (E) 14.5 and it was characterized by impaired placental labyrinth maturation and vascularization. A pale phenotype was observed in these embryos, suggesting ineffective erythropoiesis. Thus, in this study we analyzed this phenotype further in Prss8-/- embryos at E11.5 and E12.5. We found a reduced number of fetal erythroblasts in placenta, yolk sac and fetal liver of Prss8-/- embryos, while the reticulocyte number was increased, suggesting a defective terminal erythroid differentiation. Further, single-cell RNA sequencing (scRNA-seq) analyses of aorta-gonad-mesonephros (AGM) revealed an upregulation of several ribosomal genes associated with Diamond-Blackfan anemia in erythroid cells of Prss8-/- (KO) embryos. These cells showed a lower capacity to maturate into erythrocytes in vivo and in vitro, despite hematopoietic cells (HSCs) being produced normally. We suggested prostasin influenced erythropoiesis in a cell-extrinsic manner, since Prss8 expression was not detected in erythroid cells but highly expressed in ectoderm-like cells within the AGM. Congruently, while yolk sac-derived cells displayed no erythroid maturation defect in vitro, the yolk sac vascular remodeling in KO embryos was impaired as evidenced by reduced secondary branching likely as a consequence of the reduced blood flow. Our findings unveiled a novel role for this serine protease in terminal maturation of erythrocytes in the fetal liver and open new research avenues for understanding the physiological mechanism of prostasin and its pathological implications. Key PointsO_LIPrss8 deficiency causes transcriptional changes in erythroid progenitor cells in the AGM leading to impaired embryonic erythropoiesis C_LIO_LIOverexpression of Rpl and Rps genes by erythroid cells lacking Prss8 leads to defective erythropoiesis and embryonic lethality C_LI

developmental biology↗

bioRxiv2024

Loss of H3K9 trimethylation leads to premature aging

Aging is the major risk factor for most human diseases and represents a major socio-economical challenge for modern societies. Despite its importance, the process of aging remains poorly understood. Epigenetic dysregulation has been proposed as a key driver of the aging process. Modifications in transcriptional networks and chromatin structure might be central to age-related functional decline. A prevalent feature described during aging is the overall reduction in heterochromatin, specifically marked by the loss of repressive histone modification, Histone 3 lysine 9 trimethylation (H3K9me3). However, the role of H3K9me3 in aging, especially in mammals, remains unclear. Here we show using a novel mouse strain, (TKOc), carrying a triple knockout of three methyltransferases responsible for H3K9me3 deposition, that the inducible loss of H3K9me3 in adulthood results in premature aging. TKOc mice exhibit reduced lifespan, lower body weight, increased frailty index, multi-organ degeneration, transcriptional changes with significant upregulation of transposable elements, and accelerated epigenetic age. Our data strongly supports the concept that the loss of epigenetic information directly drives the aging process. These findings reveal the importance of epigenetic regulation in aging and suggest that interventions targeting epigenetic modifications could potentially slow down or reverse age-related decline. Understanding the molecular mechanisms underlying the process of aging will be crucial for developing novel therapeutic strategies that can delay the onset of age-associated diseases and preserve human health at old age specially in rapidly aging societies.

physiology↗

bioRxiv2023

The bile acid receptor TGR5 regulates the hematopoietic support capacity of the bone marrow niche

The gut is an emerging regulator of bone marrow (BM) hematopoiesis, with several signaling molecules involved in this communication. Among them, bile acids (BAs) act as a relay between the microbiota and the rest of the body through the activation of specific receptors, including Takeda G protein-coupled receptor 5 (TGR5). TGR5 has potent regulatory effects in immune cells, but its role in the BM as a primary immune organ remains unknown. Here, we demonstrate that TGR5 is expressed in hematopoietic progenitors and BM stromal progenitors. TGR5 deficiency did not affect steady-state hematopoiesis but led to impaired short-term progenitor reconstitution and reduced regulated bone marrow adipose tissue (BMAT) in young male mice, but not in female mice. The reduction in BMAT was accompanied by an enrichment in BM adipocyte progenitors and was associated with enhanced hematopoietic recovery upon BM transplantation into Tgr5-/- recipients. Moreover, its reduction was associated with lower myeloid-to-lymphoid progenitor ratios in obese and in aged Tgr5-/- male mice, resembling more those of lean or young controls. Our results indicate that TGR5 is essential for maintaining a balanced BM microenvironment in a sex-dependent manner and open the possibility of modulating stromal hematopoietic support by acting on TGR5 signaling. Impact statementTGR5 loss-of-function reduced regulated bone marrow adipose tissue in male mice, without affecting that of females at homeostasis, and accelerated myeloid recovery upon bone marrow transplantation. These data highlight TGR5 as a new player in the bone marrow microenvironment.

cell biology↗

bioRxiv2023

MarrowDLD: a microfluidic method for label-free retrieval of fragile bone marrow cells

Functional bone marrow studies have focused primarily on hematopoietic progenitors, leaving limited knowledge about other fragile populations, such as bone marrow adipocytes (BMAds) and megakaryocytes. The isolation of these cells is challenging due to rupture susceptibility and large size. We introduce here a label-free cytometry microsystem, MarrowDLD, based on deterministic lateral displacement. MarrowDLD enables the isolation of fragile cells based on intrinsic size properties while preserving their viability and functionality. Bone marrow adipocytes, obtained from mouse and human stromal line differentiation, as well as megakaryocytes, from primary human CD34+ hematopoietic stem and progenitor cells, were used for validation. Precise micrometer-range separation cutoffs were adapted for each cell type. Cells were sorted directly in culture media, without pre-labeling steps, and with real-time imaging for quality control. At least 106 cells were retrieved intact per sorting round. Our method outperformed two FACS instruments in purity and yield, particularly for large cell size fractions. MarrowDLD represents a non-destructive sorting tool for fragile cells, facilitating the separation of phenotypically pure populations of BMAds and megakaryocytes to further investigate their physiological and pathological roles.

bioengineering↗

bioRxiv2023

Induction of mitophagy reverts age-associated decline of the hematopoietic and immune systems

Aging compromises hematopoietic and immune system functions, making elderly individuals especially susceptible to hematopoietic failure, infections and tumor development and thus representing an important medical target for a broad range of diseases. During aging, hematopoietic stem cells (HSCs) lose their blood reconstitution capability and commit preferentially toward myeloid lineage (myeloid-bias). These processes are accompanied by an aberrant accumulation of mitochondria in HSCs. The administration of the mitophagy-inducer Urolithin-A re-establishes the correct mitochondrial homeostasis in HSCs and completely restores the blood reconstitution capability of "old" HSCs. Moreover, Urolithin-A supplemented food restores lymphoid compartments, boosts HSCs function and improves the immune response to viral infection in old mice. Altogether our results demonstrate that targeting mitophagy reverts aging phenotype in the hematopoietic and immune system.

immunology↗

bioRxiv2023

Adrenal extramedullary hematopoiesis as an inducible model of the adult hematopoietic niche

Hematopoietic Stem and Progenitor Cells (HSPCs) reside in the hematopoietic niche, a structure that regulates the balance of cellular quiescence, self-renewal and commitment in a demand-adapted manner. The bone marrow (BM) hematopoietic niche is formed by several cellular players, mainly endothelial cells, osteoblasts, adipocytes, and stromal cells. While the BM niche forms a complex structure, evidence exists for simpler, albeit functional, extramedullary hematopoietic niches. However, the composition of what constitutes the simplest unit of an HSPC supportive microenvironment remains largely unknown. Here, we show that the adult adrenal gland can be transformed into a hematopoietic supportive environment. Upon splenectomy and hormonal stimulation, the adult adrenal gland can be induced to recruit and host HSPC function, including serial transplantation. Furthermore, the adrenal stroma contains a CXCL12+ population, reminiscent of BM CXCL12-Abundant Reticular (CAR) cells. Mirroring this, we found CXCL12+ cells in patient samples obtained from a local cohort of myelolipoma, a benign adrenal tumor composed of adipose and hematopoietic tissue that constitutes the most common site of extramedullary hematopoiesis specific to the adult. We present our model as a novel tool to increase our understanding of the physiology of hematopoietic support and to facilitate the development of a boneless niche model.

cell biology↗

bioRxiv2022

Raman microspectroscopy reveals unsaturation heterogeneity at the lipid droplet level and validates an in vitro model of bone marrow adipocyte subtypes

Bone marrow adipocytes (BMAds) constitute the most abundant stromal component of adult human bone marrow. Two subtypes of BMAds have been described, the more labile regulated adipocytes (rBMAds) and the more stable constitutive adipocytes (cBMAds), which develop earlier and are more resilient to environmental and metabolic disruptions. In vivo, rBMAds are enriched in saturated fatty acids, contain smaller lipid droplets (LDs) and more readily provide hematopoietic support than their cBMAd counterparts. Mouse models have been used for BMAds research, but isolation of primary BMAds presents many challenges, and thus in vitro models remain the current standard to study nuances of adipocyte differentiation. No in vitro model has yet been described for the study of rBMAds/cBMAds. Here, we present an in vitro model of BM adipogenesis with differential rBMAd and cBMAd-like characteristics. We used OP9 BM stromal cells derived from a (C57BL/6xC3H)F2-op/op mouse, which have been extensively characterized as feeder layer for hematopoiesis research. We observed similar canonical adipogenesis transcriptional signatures for spontaneously-differentiated (sOP9) and induced (iOP9) cultures, while fatty acid composition and desaturase expression of Scd1 and Fads2 differed at the population level. To resolve differences at the single adipocyte level we tested Raman microspectroscopy and show it constitutes a high-resolution method for studying adipogenesis in vitro in a label-free manner, with resolution to individual LDs. We found sOP9 adipocytes have lower unsaturation ratios, smaller LDs and higher hematopoietic support than iOP9 adipocytes, thus functionally resembling rBMAds, while iOP9 more closely resembled cBMAds. Validation in human primary samples confirmed a higher unsaturation ratio for lipids extracted from stable cBMAd-rich sites (femoral head upon hip-replacement surgery) versus labile rBMAds (iliac crest after chemotherapy). As a result, the 16:1/16:0 fatty acid unsaturation ratio, which was already shown to discriminate BMAd subtypes in rabbit and rat marrow, was validated to discriminate cBMAds from rBMAd in both the OP9 model in vitro system and in human samples. We expect our model will be useful for cBMAd and rBMAd studies, particularly where isolation of primary BMAds is a limiting step.

cell biology↗