Biology subjects

Velloso, L. A.

Publications and source records attributed to Velloso, L. A..

10 recordsLinked to original sources

bioRxiv2025

E4BP4 Safeguards Brown Fat Mitochondria from Obesity-Induced Fragmentation via Ceramide Repression

Brown adipose tissue (BAT) counteracts obesity-related metabolic dysfunction through both thermogenic and non-thermogenic means. However, substantial evidence indicates that obesity negatively affects BAT mitochondrial morphology and oxidative capacity, impairing systemic energy homeostasis. Motivated by this apparent contradiction, we investigated the relationship between obesity and mitochondrial dynamics, as the underlying mechanisms remain incompletely understood. Here, we identified E4BP4 as a transcriptional repressor that prevents obesity-induced mitochondrial fragmentation and oxidative dysfunction by inhibiting ceramide synthesis in brown fat. Specifically, E4BP4 interacts with PRDM16 to repress Cers6 mRNA expression and consequently reduces C16:0 ceramide levels by binding to a 65 kb upstream enhancer region of the Cers6 gene. Notably, the preservation of mitochondrial integrity in BAT by E4BP4 gain-of-function improves systemic glucose homeostasis, independent of weight loss. Collectively, our findings establish E4BP4 as a molecular safeguard against obesity-induced mitochondrial fragmentation and oxidative dysfunction, primarily by suppressing ceramide synthesis in brown fat.

physiology↗

bioRxiv2024

CETP expression in females increases body metabolism under both cold exposure and thermoneutrality contributing to a leaner phenotype

Susceptibility to obesity differs depending on the genetic background and housing temperatures. We have recently reported that CETP expressing female mice are leaner due to increased lipolysis, brown adipose tissue (BAT) activity and body energy expenditure compared to non-transgenic (NTg) littermates under standard housing temperature (22{degrees}C). The aim of this study is to evaluate how CETP expression affect body temperature, composition and metabolism during cold exposure (4{degrees}C) and thermoneutrality (30{degrees}C). When submitted to cold, CETP mice maintained rectal temperature, body weight and food intake similarly to NTg mice along acute or chronic exposure to 4{o}C. The body oxygen consumption in response to an isoproterenol challenge was 21% higher at 22{o}C, and 41% higher after 7 days of cold exposure in CETP than in NTg mice. In addition, BAT biopsies from CETP mice showed reduced lipid content and increased basal oxygen consumption rates. Under thermoneutrality (30{o}C), when BAT activity is inhibited, CETP mice showed higher rectal and tail temperatures, increased food intake and increased energy expenditure. Lean mass was elevated and fat mass reduced in CETP mice kept at 30{o}C. In this thermoneutrality condition, soleus muscle, but not gastrocnemius or liver of CETP mice showed increased mitochondrial respiration rates. These data indicate that CETP expression confers a greater capacity of elevating body metabolic rates at both cold exposure, through BAT activity, and at thermoneutrality, through increased muscle metabolism. Thus, the CETP expression levels in females should be considered as a new influence in the contexts of obesity and metabolic disorders propensity. NEW & NOTEWORTHYWe demonstrate here that CETP expression in females increases body metabolism under cold (4{o}C) and thermoneutrality (30{o}C). Since this has also been shown at 22{o}C, it seems a constitutive feature of CETP expression. Brown adipose tissue and red fiber muscle contribute to the overall high metabolism and leaner phenotype of CETP mice. Elevated mitochondrial respiration rates were demonstrated in these tissues. Thus, CETP is a new relevant variable in the context of obesity and metabolic disorders. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/623058v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@19ed73org.highwire.dtl.DTLVardef@3458acorg.highwire.dtl.DTLVardef@a9896forg.highwire.dtl.DTLVardef@7e1138_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

CXCR3-expressing myeloid cells recruited to the hypothalamus protect against diet-induced body mass gain and metabolic dysfunction

Microgliosis is an important component of diet-induced hypothalamic inflammation in obesity. A few hours after the introduction of a high-fat diet, the mediobasal hypothalamus resident microglia undergo morphological and functional changes toward an inflammatory phenotype. If the consumption of large amounts of dietary fats persists for long periods, bone marrow- derived myeloid cells are recruited and integrated into a new landscape of hypothalamic microglia. However, it is currently unknown what are the transcriptional signatures and specific functions exerted by either resident or recruited subsets of hypothalamic microglia. Here, the elucidation of the transcriptional signatures revealed that resident microglia undergo only minor changes in response to dietary fats; however, under the consumption of a high-fat diet, there are major transcriptional differences between resident and recruited immune cells with major impact on chemotaxis. In addition, in CCR2+ recruited peripheral immune cells, there are major transcriptional differences between females and males with important impact on transcripts involved in neurodegeneration and thermogenesis. The chemokine receptor CXCR3 emerged as one of the components of chemotaxis with the greatest difference between recruited and resident microglia, and thus, was elected for further intervention. The hypothalamic immunoneutralization of CXCL10, one of the ligands for CXCR3, resulted in increased body mass gain and reduced energy expenditure, particularly in females. Furthermore, the chemical inhibition of CXCR3 resulted in a much greater change in phenotype with increased body mass gain, reduced energy expenditure, increased blood leptin, glucose intolerance, and reduced insulin. Thus, this study has elucidated the transcriptional differences between resident microglia and recruited immune cells in diet-induced obesity, identifying chemokines as a relevant subset of genes undergoing regulation. In addition, we showed that a subset of recruited immune cells expressing CXCR3 has a protective, rather than a detrimental role in the metabolic outcomes promoted by the consumption of a high-fat diet, thus, establishing a new concept in obesity-associated hypothalamic inflammation.

neuroscience↗

bioRxiv2022

A Diabetic Mice Model For Studying Skin Wound Healing

Advances in wound treatment depend on the availability of suitable animal models. All animal models try to reflect human wound healing problems. For acute wounds, it is easier to obtain adequate animal models, however, for chronic wounds such as those found in individuals with diabetic foot ulcer, approximations of the clinical picture become a challenge. Nowadays, the key points of wound healing processes are better understood, and therefore, therapeutic strategies can be developed to manipulate wound repair. Research efforts involves the development of therapies to aid in the treatment of impaired wound healing and, to improving normal wound healing to drive a process close to regenerative. To achieve a better animal model that is more appropriate for studying wound healing, six-week- old male C57BL/6 mice were separated into groups fed a Chow and High-Fat Diet for 0.5, 3, and 6 months, when part of the animals were induced to diabetes by streptozotocin. Then, mice were submitted to metabolic, molecular, and morphological analyses. We show that this model results in a severe metabolic phenotype with insulin resistance, reduced insulin expression, and glucose intolerance associated with obesity and, more importantly, skin changes. Furthermore, the skin phenotype, both structurally and transcriptionally, overlapped with conditions found in elderly patients with DM that reproduce the phenotype of most patients who develop diabetic foot ulcers.

physiology↗

bioRxiv2022

A comprehensive dimensional reduction framework to learn single-cell phenotypic topology uncovers T cell diversity

Reconstructing and investigating the geometry underlying data is a fundamental task in single-cell analysis, yet no unified framework exists for learning, evaluating, and diagnosing representations that faithfully preserve it. We present TopoMetry, a geometry-aware framework that learns intrinsic coordinate systems directly from the data and refines them into high-fidelity spectral scaffolds. These scaffolds capture both local neighborhoods and global structure, supporting downstream analysis such as clustering and visualization. In benchmarks across diverse single-cell datasets, TopoMetry preserved geometry more reliably than standard workflows and revealed biological signals otherwise obscured, including unexpected transcriptional diversity among T cells and links between RNA-defined subpopulations and clonal expansion. The full analysis can be executed with a single line of code to generate a comprehensive report, making the framework both powerful and accessible. Beyond individual findings, TopoMetry warrants a shift of focus from static two-dimensional projections to the systematic learning and evaluation of geometry itself, enabling more accurate exploration of cellular diversity.

bioinformatics↗

bioRxiv2020

Glutamic acid promotes hair growth in mice

Glutamic Acid is the main excitatory neurotransmitter in neurons. Abnormal distributions of the glutamic acid receptors have been shown in hyper proliferative models such as psoriasis and skin regeneration. However, the biological function of glutamic acid in the skin remains unclear. Using ex vivo, in vivo and in silico approaches, we showed for the first time that exogenous glutamic acid promotes hair growth and keratinocyte proliferation. Topical application of glutamic acid decreased expression of genes related to apoptosis signaling in the skin. Also, we showed Glutamic acid increased viability and proliferation in cultured human keratinocyte. For the first time, we identified the excitotoxic GA concentration and we provided evidence for the existence of a novel skin signaling pathway mediated by a neurotransmitter controlling keratinocyte and hair follicle proliferation. In perspective, we anticipate our results could be the starting point to elucidate how exogenous glutamic acid from food intake or even endogenous GA from neuropsychiatric disorders modulate skin diseases.

pharmacology and toxicology↗

bioRxiv2020

A smartphone app for individual anesthetic calculation decreased anesthesia-related mortality in mice

Annually, millions of animals are used for experimental purposes. Despite the recommended anesthetic doses being well-known worldwide, the final amounts applied to mice could be different than those calculated. Here, we developed, tested, and validated a mobile app where researchers and operators were able to use personal devices to process body weight, calculate a master anesthetic cocktail, and then apply the individual volume to each mouse. Our objective was to refine anesthesia procedures using information technologies. Our data showed that the "Labinsane" mobile app decreased anesthetic-related deaths upon using weight-adjusted doses of ketamine and xylazine. Also, we validated that the Labinsane mobile app matched all calculations of anesthetic doses. To our knowledge, this is the first report with hundreds of anesthetized mice records and validation and implementation of a mobile app to solve an old but transversal challenge for researchers working with experimental mice.

pharmacology and toxicology↗

bioRxiv2020

POMC-specific knockdown of Tril reduces body adiposity and increases hypothalamic leptin responsiveness

In a public dataset of transcripts differentially expressed in selected neuronal subpopulations of the arcuate nucleus, we identified TLR4-interactor with leucine-rich repeats (Tril) as a potential candidate for mediating the harmful effects of a high-fat diet in proopiomelanocortin (POMC) neurons. The non-cell-specific inhibition of Tril in the arcuate nucleus resulted in reduced hypothalamic inflammation, protection against diet-induced obesity associated with increased whole-body energy expenditure and increased systemic glucose tolerance. The inhibition of Tril, specifically in POMC neurons, resulted in a trend for protection against diet-induced obesity, increased energy expenditure and increased hypothalamic sensitivity to leptin. Thus, Tril emerges as a new component of the complex mechanisms that promote hypothalamic dysfunction in experimental diet-induced obesity.

neuroscience↗

bioRxiv2020

Demonstration of re-epithelialization in a bioprinted human skin equivalent wound model

ObjectiveThe development of an in vitro platform for modeling human skin injury and the re-epithelization process. ApproachA fibrin provisional matrix (FPM) was installed into a wound facsimile of a bioprinted human skin equivalent (HSE). A mixture of plasma-derived fibrinogen-containing factor XIII, fibronectin, thrombin, and macrophages (an FPM "bioink") was extruded into the wound site. The surrounding in vitro tissue culture became a source of keratinocytes to achieve wound closure by a re-epithelialization process signaled by the FPM. ResultsAn in vitro analog of wound closure and re-epithelialization by keratinocytes occurred over the FPM after a normal migration initiation at 3 days. InnovationA physiologic mixture of macrophage/fibrinogen/fibronectin that supports macrophage differentiation was applied to a mechanically wounded, bioprinted dermal tissue. We developed a transitional culture medium to mimic the changing microenvironment during the initial phases of wound healing. As a reference, we temporally compared our in vitro model with a murine skin wound healing. ConclusionThis co-culture model was shown to temporally synchronize a re-epithelization process for initiation of keratinocyte migration from a surrounding tissue and the migration process over the top of an FPM. A future study of the analogous subepithelial healing pathway is envisioned using the same in vitro bioprinted tissue study platform for co-culture of keratinocytes, melanocytes, fibroblasts, endothelial cells, and macrophages using more specialized FPMs.

bioengineering↗

bioRxiv2020

Three-Dimensional (3D) Fibronectin Nano-Array Presented on Fibrin Matrix Accelerates Mice Skin Wound Healing

Plasma fibrinogen (F1) and fibronectin (pFN) polymerize to form a fibrin clot that is both a hemostatic and provisional matrix for wound healing. About 90% of plasma F1 has a homodimeric pair of {gamma} chains ({gamma}{gamma}F1) and 10% has a heterodimeric pair of {gamma} and more acidic {gamma} chains ({gamma}{gamma}F1). We have synthesized a novel fibrin matrix exclusively from a 1:1 (molar ratio) complex of {gamma}{gamma}F1 and pFN in the presence of highly active thrombin and recombinant Factor XIII (rFXIIIa). In this matrix, the fibrin nanofibers were wrapped with periodic 200-300 nm wide pFN nanobands (termed {gamma}{gamma}F1:pFN fibrin). In contrast, fibrin made from 1:1 mixture of {gamma}{gamma}F1 and pFN formed a sporadic distribution of "pFN droplets" (termed {gamma}{gamma}F1 +pFN fibrin). The {gamma}{gamma}F1:pFN fibrin enhanced the adhesion of primary human umbilical vein endothelium cells (HUVECs) relative to the {gamma}{gamma}F1+FN fibrin. Three dimensional (3D) culturing showed that the {gamma}{gamma}F1:pFN complex fibrin matrix enhanced the proliferation of both HUVECs and primary human fibroblasts. HUVECs in the 3D {gamma}{gamma}F1:pFN fibrin exhibited a starkly enhanced vascular morphogenesis while an apoptotic growth profile was observed in the {gamma}{gamma}F1 +pFN fibrin. Relative to {gamma}{gamma}F1 +pFN fibrin, mouse dermal wounds that were sealed by {gamma}{gamma}F1:pFN fibrin exhibited accelerated and enhanced healing. This study suggests that a 3D pFN nano-array presented on a fibrin matrix can promote wound healing.

bioengineering↗