Biology subjects

Leo, L.

Publications and source records attributed to Leo, L..

4 recordsLinked to original sources

bioRxiv2026

Rapid receptor internalization potentiates CD7-targeted lipid nanoparticles for efficient mRNA delivery to T cells and in vivo CAR T-cell engineering

Targeted lipid nanoparticles (tLNPs) enable efficient mRNA delivery to T cells, allowing for in situ generation of chimeric antigen receptor (CAR) T cells without ex vivo manipulation. This strategy has shown promising therapeutical efficacy in preclinical studies of cardiac fibrosis, cancer, and autoimmune diseases. While multiple T-cell surface receptors have been targeted across studies for tLNP-mediated in vivo CAR T-cell generation and exhibit diverse efficiencies, their comparative performance and the mechanisms underlying these differences remain unclear. Here, we systematically compared tLNPs with antibody-based moieties targeting T-cell receptors including CD2, CD4, CD5, CD7, CD8, or a CD4/8 dual-targeting combination under identical conditions, assessing their mRNA delivery efficiency in human T cells and PBMCs in vitro, and subsequently validating the best performer in vivo in humanized mice. Among all moieties tested, CD7-targeting tLNPs achieved the highest mRNA delivery to T cells and efficiently generated functional CAR T cells in vivo. Mechanistic analysis revealed that receptor internalization, rather than the receptor abundance, is the primary determinant of delivery efficiency, a property intrinsic to each receptor and largely independent of antibody clone. These findings provide a rational framework for selecting optimal targeting moiety to enable highly efficient in vivo CAR T-cell engineering. HighlightsO_LITargeting CD7 outperforms other receptors for tLNP-mRNA delivery to T cells C_LIO_LIReceptor abundance does not predict tLNP-mRNA delivery efficiency C_LIO_LIReceptor internalization kinetics governs tLNP-mRNA delivery efficiency C_LIO_LICD7-targeting LNP-mRNA enables efficient in vivo CAR T-cell engineering C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/701374v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@9c2c4eorg.highwire.dtl.DTLVardef@120ced7org.highwire.dtl.DTLVardef@eb9b5forg.highwire.dtl.DTLVardef@25b6f7_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Neuronal progenitors suffer genotoxic stress in the Drosophila clock mutant per0.

The physiological role and the molecular architecture of the circadian clock in fully developed organisms are well established. Yet, we have a limited understanding about the function of the clock during ontogenesis. We have used a null mutant (per0) of the clock gene period (per) in Drosophila melanogaster to ask whether PER may play a role during normal brain development. In 3rd instar larvae, we have observed that absence of functional per results in increased genotoxic stress compared to wild type controls. We have detected increased double strand DNA breaks in the central nervous system and chromosome aberrations in dividing neuronal precursor cells. We have demonstrated that reactive oxygen species (ROS) are causal to the genotoxic effect and that expression of PER in glia is necessary and sufficient to suppress such a phenotype. Finally, preliminary evidence indicates that absence of PER may result in less condensed chromatin, which may contribute to DNA damage.

genetics↗

bioRxiv2024

A centromere-derived retroelement RNA localizes in cis and is a core element of the transcriptional landscape of Drosophila centromeres

Centromeres depend on chromatin containing the conserved histone H3 variant CENP-A for function and inheritance, while the role of centromeric DNA repeats remains unclear. Retroelements are prevalent at centromeres across taxa and represent a potential mechanism for promoting transcription to aid in CENP-A incorporation or for generating RNA transcripts to maintain centromere integrity. Here, we probe into the transcription and RNA localization of the centromere-enriched retroelement G2/Jockey-3 (hereafter referred to as Jockey-3) in Drosophila melanogaster, currently the only in vivo model with assembled centromeres. We find that Jockey-3 is a major component of the centromeric transcriptome and produces RNAs that localize to centromeres in metaphase. Leveraging the polymorphism of Jockey-3 and a de novo centromere system, we show that these RNAs remain associated with their cognate DNA sequences in cis, suggesting they are unlikely to perform a sequence-specific function at all centromeres. We show that Jockey-3 transcription is positively correlated with the presence of CENP-A, and that recent Jockey-3 transposition events have occurred preferentially at CENP-A-containing chromatin. We propose that Jockey-3 contributes to the epigenetic maintenance of centromeres by promoting chromatin transcription, while inserting preferentially within these regions, selfishly ensuring its continued expression and transmission. Given the conservation of retroelements as centromere components through evolution, our findings have broad implications in understanding this association in other species.

cell biology↗

bioRxiv2018

Removing neural correlations improves population sensitivity in MT/MST in response to random dot stimuli

The study of neuronal responses to random-dot motion patterns has provided some of the most valuable insights into how the activity of neurons is related to perception. In the opposite directions of motion paradigm, the motion signal strength is decreased by manipulating the coherence of random dot patterns to examine how well the activity of single neurons represents the direction of motion. To extend this paradigm to populations of neurons, studies have used modelling based on data from pairs of neurons, but several important questions require further investigation with larger neuronal datasets. We recorded neuronal populations in the middle temporal (MT) and medial superior temporal (MST) areas of anaesthetized marmosets with electrode arrays, while varying the coherence of random dot patterns in two opposite directions of motion (left and right). Using the spike rates of simultaneously recorded neurons, we decoded the direction of motion at each level of coherence with linear classifiers. We found that the presence of correlations had a detrimental effect to decoding performance, but that learning the correlation structure produced better decoding performance compared to decoders that ignored the correlation structure. We also found that reducing motion coherence increased neuronal correlations, but decoders did not need to be optimized for each coherence level. Finally, we showed that decoder weights depend of left-right selectivity at 100% coherence, rather than the preferred direction. These results have implications for understanding how the information encoded by populations of neurons is affected by correlations in spiking activity.\n\nSignificance StatementMany studies have examined how the spiking activity of single neurons can encode stimulus features, such the direction of motion of visual stimuli. However, majority of such studies to date have only recorded from a small number of neurons at the same time, meaning that one cannot adequately account for the trial-to-trial correlations in spiking activity between neurons. Using multi-channel recordings, we were able to measure the neuronal correlations, and their effects on population coding of stimulus features. Our results have implications on the way which neural populations must be readout in order to maximize information.

neuroscience↗