Biology subjects

Palmisano, R.

Publications and source records attributed to Palmisano, R..

4 recordsLinked to original sources

bioRxiv2025

Swiprosin-1/EFhd2 promotes mitochondrial spare capacity in response to immobilized antigen in B cells via microtubule stabilization

B cells can recognize soluble and membrane bound antigens, enabling them to initiate and execute versatile immune responses. This study examines Swiprosin-1/EFhd2 (EFhd2) in regulating mitochondrial function and organization in B cells during B cell receptor (BCR) activation and immune synapse formation. Using EFhd2 knockout (KO) and wild-type (WT) murine B cells, we assessed mitochondrial abundance, membrane potential, and respiratory capacity using soluble anti-IgM and anti-CD40/IL-4 stimulation. EFhd2KO B cells exhibit more functional mitochondria and mitochondrial spare capacity selectively in activated but not in resting cells. This phenotype changed absolutely upon BCR synapse formation: While activated WT B cells enhance basal mitochondrial respiration, ATP production and maximal respiration, with large increments of spare capacity, EFhd2KO B cells fail completely to do so. Actin depolymerization and microtubule destabilization impair functional mitochondrial upregulation in WT but not in EFhd2KO B cells, while microtubule stabilization restores full spare capacity in EFhd2KO B cells at the BCR synapse. Live-cell imaging reveals that EFhd2KO B cells fail to organize mitochondria, microtubules, and BCRs symmetrically. Super-resolution 3D imaging shows that WT B cells condense mitochondria at the synapse, whereas EFhd2KO B cells display dispersed, unorganized mitochondria and BCR clusters. EFhd2 re-expression restores mitochondrial polarization in EFhd2KO B cells, confirming its role in coordinating mitochondrial positioning. These findings highlight EFhd2 as a key integrator of cytoskeletal and mitochondrial functions for optimal B cell responses to membrane bound antigens. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=174 HEIGHT=200 SRC="FIGDIR/small/637645v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1844c37org.highwire.dtl.DTLVardef@a7b9eaorg.highwire.dtl.DTLVardef@19ec265org.highwire.dtl.DTLVardef@1eca7fb_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

When Mechanical Stress Matters: Generation of Polyploid Giant Cancer Cells in Tumor-like Microcapsules

In this work, we studied the generation and rising of polyploid cancer cells as a product of mechanical stress. To this purpose, MCF7 breast cancer cells were cultured on 2D (i.e. flasks, or flat hydrogels), and in 3D milieus (i.e. Spheroids, or immobilized within alginate-gelatin microbeads, named in this work as tumor-like microcapsules), and further analyzed by biophysical and genetic methods (i.e. single-cell Traction Force Microscopy and RNA-seq respectively). Our results show that MCF7 cells preconditioned onto 2D surfaces exhibit a low number of polynucleated cells, while their culture in 3D environments triggered their progressive generation with time. Genetic studies enabled us to determine that polyploid cells found in tumor-like microcapsules are likely originated by cell-cell fusion and disrupted cytokinesis, showing most of the genetic markers for Polyploid Giant Cancer Cell, while cells cultured as spheroids seem to be likely generated by other mechanisms, such as cell cannibalisms, entosis, or emperipolesis. Our outcomes strongly suggest that both mechanical stress and confinement are required to stimulate cell polyploidy, which can be easily addressed by the immobilization of breast cancer cells in tumor-like microcapsules.

bioengineering↗

bioRxiv2022

How enhancers regulate wavelike gene expression patterns: A novel enhancer prediction and live reporter system identifies an enhancer associated with the arrest of pair-rule waves in Tribolium

A key problem in development is to understand how genes turn on or off at the right place and right time during embryogenesis. Such decisions are made by non-coding sequences called enhancers. Much of our models of how enhancers work rely on the assumption that genes are activated de novo as stable domains across embryonic tissues. Such view has been strengthened by the intensive landmark studies of the early patterning of the anterior-posterior (AP) axis of the Drosophila embryo, where indeed gene expression domains seem to arise more or less stably. However, careful analysis of gene expressions in other model systems (including the AP patterning in vertebrates and short-germ insects like the beetle Tribolium castaneum) painted a different, very dynamic view of gene regulation, where genes are oftentimes expressed in a wavelike fashion. How such gene expression waves are mediated at the enhancer level is so far unclear. Here we establish the AP patterning of the short-germ beetle Tribolium as a model system to study dynamic and temporal pattern formation at the enhancer level. To that end, we established an enhancer prediction system in Tribolium based on time- and tissue-specific ATAC-seq and an enhancer live reporter system based on MS2 tagging. Using this experimental framework, we discovered several Tribolium enhancers, and assessed the spatiotemporal activities of some of them in live embryos. We found our data consistent with a model in which the timing of gene expression during embryonic pattern formation is mediated by a balancing act between enhancers that induce rapid changes in gene expressions (that we call dynamic enhancers) and enhancers that stabilizes gene expressions (that we call static enhancers).

developmental biology↗

bioRxiv2021

GraviKit: an easy-to-implement microscope add-on for observation of gravitation dependent processes

One of the most important environmental cues for living organisms is gravity and many developmental processes depend on it. However, when it comes to light microscopy, a majority of studies on these processes work with their objects of interest placed perpendicular to their natural orientation. One reason for that is probably that light microscopes with the required horizontal beampath are either costly or require advanced technical skills. To circumvent these obstacles and make imaging of gravity-dependent processes with a horizontal beampath possible for any lab we developed GraviKit. It converts a standard inverted research microscope into an imaging device with a horizontal beampath with a stage that rotates the sample around the optical axis. Like this, the direction of gravity can be freely chosen during an imaging experiment. The system is easy to implement and suitable for multi-user environments.

developmental biology↗