Biology subjects

Colarusso, P.

Publications and source records attributed to Colarusso, P..

4 recordsLinked to original sources

bioRxiv2024

Redox Signaling Mediates Differentiation of Adipose Progenitors in Response to Inflammatory Cytokines in the Adipose Tissue Secretome

Adipogenesis, the terminal differentiation of adipose progenitor cells (APCs), is critical in maintaining the functional integrity of adipose depots under obesogenic conditions. It is thought that a signal arising from the adipose microenvironment triggers APC differentiation; yet the identity and source of the signal remains unknown. This study sought to uncover the signal responsible for activating adipogenesis. Redox signaling was shown to influence adipogenesis in primary murine APCs treated with pharmacologic agents to manipulate the levels of reactive oxygen species (ROS). Increased generation of superoxide (O2-) and hydrogen peroxide (H2O2) via redox cyclers amplified both early and late APC differentiation, while ROS scavengers and antioxidants blunted differentiation. The impact of specifically targeting H2O2 with the antioxidant, catalase, or a catalase inhibitor, was restricted to lipid accumulation in late adipogenesis. Protein was concentrated from conditioned media of adipose tissue explants cultured ex vivo to capture signals within the adipose secretome. Differentiation was enhanced in APCs cultured in the presence of the adipose secretome, an effect that was diminished with scavenging of ROS and amplified when the secretome was collected from mice fed a high fat diet for 8 weeks. Proteomic analysis revealed that the adipose secretome from animals on a high fat diet was enriched in pathways related to immune cell-mediated inflammation, with interleukin 6 (IL-6) as a central regulator of differentially expressed proteins. A multiplex assay to measure cytokines confirmed higher IL-6 in the adipose secretome of high fat-fed animals. Exposure of APCs to IL-6 increased adipogenesis, while treatment of APCs with an IL-6 blocking antibodies diminished the adipogenic effect of the adipose secretome. Together, these findings substantiate a role for redox signaling in the regulation of adipogenesis and identify IL-6 as a novel activator of adipogenesis that may mediate APC differentiation via generation of ROS under obesogenic conditions.

systems biology↗

bioRxiv2024

Mycobacterium avium subspecies paratuberculosis targets M cells in enteroid-derived monolayers through interactions with β1 integrins

Paratuberculosis is a global infectious disease caused by the bacterium, Mycobacterium avium subspecies paratuberculosis (MAP). MAP infection of ruminants triggers progressive wasting disease characterized by granulomatous lymphadenitis, enteritis, and severe intestinal pathology that often requires early culling of the animal. The resulting economic burden is significant and MAP exposure in the workplace constitutes a significant zoonotic risk. While it has been established the MAP propagates within resident intestinal immune cells, including macrophages and dendritic cells, significantly less is known about how it attaches, enters and traverses the epithelium. The current paradigm suggests MAP infects the small intestinal epithelium by targeting both enterocytes and M cells, with a potential tropism for the latter. In the current study, we employed emerging enteroid technology to identify the target cells for MAPs entry into the small intestinal epithelium. We generated mouse enteroid-derived monolayers with functional M cells capable of transcytosis. Upon exposure to MAP, the bacteria were detected within both enterocytes and M cells. Following quantification, it was apparent that MAP exhibited tropism for M cells. Complementary studies using the Caco-2/Raji-B co-culture system provided similar results, wherein MAP was found primarily in cells expressing functional M cell markers. Since other mycobacteria have been shown to initiate cell attachment and entry by using a fibronectin-bridging process, we tested whether these interactions were involved in MAPs targeting of M cells. We found that MAPs M cell tropism was significantly enhanced in the presence of fibronectin and that this effect was abolished when monolayers were pretreated with an integrin-blocking peptide. Taken together, our data indicate the MAP preferentially targets M cells and that this process involves a fibronectin-bridging process. Furthermore, our data suggest that targeting M cell-associated integrins could provide a mechanism to reduce MAP infection and transmission within livestock herds. Author SummaryIn the current study, we sought to determine the target cell for Mycobacterium avium subspecies paratuberculosis (MAP), which is the causative agent of Johnes disease (JD, also termed paratuberculosis) in ruminants. While MAP primarily infects domestic ruminants including cattle, sheep, goats, and deer, it has also been shown to infect wildlife throughout the world, including cats, rabbits, badgers, and wood mice. Given the significant economic burden of MAP infections in livestock, its role in the pathogenesis of JD has been the focus of much research. However, the broad diversity of MAP-susceptible hosts and reservoirs observed calls into question the true scope of MAP infection and transmission and the true number of susceptible hosts. Furthermore, MAP constitutes a zoonotic threat that some have linked to intestinal pathologies, including Crohns disease. To date, it is still not known exactly how MAP attaches, enters and traverses the small intestinal epithelium to eventually propagate within resident macrophages and dendritic cells to cause eventual disease. To address this question, we developed a model of the small intestinal epithelium, from mouse enteroids, that contained functional M cells. We found that MAP selectivity enters M cells and that this involves fibronectin-bridging process that targets M cell-associated {beta}1-integrins.

cell biology↗

bioRxiv2023

A novel genetic fluorescent reporter to visualize mitochondrial nucleoids

Mitochondria contain their own genome (mtDNA), which is present in hundreds of copies per cell and organized into nucleoid structures that are distributed throughout the dynamic mitochondrial network. Beyond encoding essential protein subunits for oxidative phosphorylation, mtDNA can also serve as a signalling molecule when it is present into the cytosol. Despite the importance of this genome, there are still many unknowns with respect to its regulation. To study mtDNA dynamics in living cells, we have developed a genetic fluorescent reporter, mt-HI-NESS, which is based on the HI-NESS reporter that uses the bacterial H-NS DNA binding domain. Here, we describe how this reporter can be used to image mtDNA nucleoids for live cell imaging without affecting the replication or expression of the mtDNA. In addition to demonstrating the adaptability of the mt-HI-NESS reporter for multiple fluorescent proteins, we also emphasize important factors to consider during the optimization and application of this reporter.

cell biology↗

bioRxiv2022

Potentiation of Adipogenesis by Reactive Oxygen Species is a Unifying Mechanism in the Pro-adipogenic Properties of Bisphenol A and its New Structural Analogues.

AimsStructural analogues of bisphenol A (BPA), including BPS and BPF, are emerging environmental toxicants as their presence in the environment is rising since new regulatory restrictions were placed on BPA-containing infant products. The adipogenesis-enhancing effect of bisphenols may explain the link between human exposure and metabolic disease; however, underlying molecular pathways remain unresolved. ResultsExposure to BPS, BPF, BPA or ROS generators enhanced lipid droplet formation and expression of adipogenic markers after induction of differentiation in adipose-derived progenitors isolated from mice. RNAseq analysis in BPS-exposed progenitors revealed modulation in pathways regulating adipogenesis and responses to oxidative stress. ROS was higher in bisphenol-exposed cells, while co-treatment with antioxidants attenuated adipogenesis and abolished the effect of BPS. There was a loss of mitochondria membrane potential in BPS-exposed cells and mitochondria-derived ROS contributed to potentiation of adipogenesis by BPS and its analogues. Male mice exposed to BPS during gestation had higher whole-body adiposity, as measured by TD-NMR, while postnatal exposure had no impact on adiposity in either sex. InnovationThese findings support existing evidence showing a role for ROS in regulating adipocyte differentiation and are the first to highlight ROS as a unifying mechanism that explains the pro-adipogenic properties of BPA and its structural analogues. ConclusionROS act as signaling molecules in the regulation of adipocyte differentiation and mediate bisphenol-induced potentiation of adipogenesis.

molecular biology↗