Biology subjects

Francesconi, M.

Publications and source records attributed to Francesconi, M..

6 recordsLinked to original sources

bioRxiv2024

A single giant cell at the origin of an evolutionary innovation

Key innovations play a central role in the diversification of lineages, yet our understanding of the mechanisms underlying their emergence remains fragmented. The propelling fan is a key innovation associated with the diversification of Rhagovelia water striders into fast flowing streams. Here, we show that a single giant cell is responsible for the development of the fan throughout embryogenesis. RNA interference against the fan-specific gene family gsha/mogsha depleted the fan in the embryo but did not alter the giant cell, indicating that these genes are not required for specifying the identity of this cell. gsha/mogsha instead seem to activate the expression of cuticular genes during early development, suggesting a role of these genes in regulating the accumulation of fan structural proteins. We also show that Hox genes act to block the giant cell in the fore- and rear-legs, thus restricting its fate to the mid-legs - the pair of legs that generates movement on water. In addition, Hox expression is specifically excluded from the giant cell, thus allowing the expression of the fans developmental genetic program. This study reveals that a single cell can be sufficient to generate innovative traits that have been central for a lineage to acquire new ecological opportunities and burst into diversification. One-sentence summaryA single giant cell orchestrates the developmental genetic program of a key innovation

evolutionary biology↗

bioRxiv2022

Carm1 regulates the speed of C/EBPa-induced transdifferentiation by a cofactor stealing mechanism

Cell fate decisions are driven by lineage-restricted transcription factors but how they are regulated is incompletely understood. The C/EBP-induced B cell to macrophage transdifferentiation (BMT) is a powerful system to address this question. Here we describe that C/EBP with a single arginine mutation (C/EBPR35A) induces a dramatically accelerated BMT in mouse and human cells. Changes in the expression of lineage-restricted genes occur as early as within 1 hour compared to 18 hours with the wild type. Mechanistically C/EBPR35A exhibits an increased affinity for PU.1, a bi-lineage transcription factor required for C/EBP-induced BMT. The complex induces more rapid chromatin accessibility changes and an enhanced relocation (stealing) of PU.1 from B cell to myeloid gene regulatory elements. Arginine 35 is methylated by Carm1 and inhibition of the enzyme accelerates BMT, similar to the mutant. Our data suggest that the relative proportions of methylated and unmethylated C/EBP in a bipotent progenitor can determine the velocity of cell fate choice and lineage directionality.

cell biology↗

bioRxiv2021

Real Age Prediction from the Transcriptome with RAPToR

Transcriptomic data is often affected by uncontrolled variation among samples that can obscure and confound the effects of interest. This is frequently due to unintended differences in developmental stages between samples. The transcriptome itself can be used to estimate developmental progression, but existing methods require many samples and do not estimate a real developmental time. Here we present RAPToR, a simple and precise computational method that estimates the real age of a sample from its transcriptome, exploiting existing time-series data as reference. RAPToR works with whole animal, dissected tissue and single-cell data, for the most common animal models, humans and even for nonmodel organisms lacking reference data. We show RAPToR estimated age improves differential expression analysis by recovering the signal of interest when confounded with age. RAPToR will be especially useful in large scale single organism profiling because it eliminates the need for accurate staging or synchronization before profiling.

bioinformatics↗

bioRxiv2020

Neuronal perception of the social environment intergenerationally controls germline development and generation time in C. elegans

An old and controversial question in biology is whether information perceived by the nervous system of an animal can cross the Weismann barrier to alter the phenotypes and fitness of their progeny. Here we show that such intergenerational transmission of sensory information occurs in the model organism, C. elegans, with a major effect on fitness. Specifically, that perception of social pheromones by chemosensory neurons controls the post-embryonic timing of development of one tissue - the germline - relative to others in an animals progeny. Neuronal perception of the social environment thus intergenerationally controls the generation time of this animal.

genetics↗

bioRxiv2019

Frataxin deficiency induces lipid accumulation and affects thermogenesis in brown adipose tissue

Decreased expression of the mitochondrial protein frataxin (FXN) causes Friedreichs ataxia (FRDA). FRDA is a neurodegenerative disease also characterized by systemic metabolic alterations that increase the risk of developing type 2 diabetes thus aggravating FRDA prognosis. Brown adipose tissue (BAT) is a mitochondria-enriched and anti-diabetic tissue that, in addition to its thermoregulatory role, turns excess energy into heat to maintain energy balance. Here we report that the FXN knock-in/knock-out (KIKO) mouse shows reduced energy expenditure and VO2, hyperlipidemia, decreased insulin sensitivity and enhanced circulating levels of leptin, recapitulating diabetes-like signatures. FXN deficiency leads to alteration of mitochondrial structure and oxygen consumption, decreased lipolysis and lipid accumulation in BAT. Transcriptomic data highlighted a blunted thermogenesis response, as several biological processes related to thermogenesis (e.g. response to temperature stimuli, mitochondrial gene transcription, triglyceride metabolism, adipogenesis) resulted affected in BAT of KIKO mice upon cold exposure. Decreased adaptation to cool temperature in association with limited PKA-mediated lipolysis and downregulation of the expression of the genes controlling mitochondrial metabolism and lipid catabolism were observed in KIKO mice. T37i brown adipocytes and primary adipocytes with FXN deficiency showed reduced thermogenesis and adipogenesis markers respectively recapitulating the molecular signatures detected in KIKO mice.\n\nCollectively our data point to BAT dysfunction in FRDA and suggest BAT as a promising target to overcome metabolic complications in FRDA.

pathology↗

bioRxiv2018

Single cell expression analysis uncouples transdifferentiation and reprogramming

Many somatic cell types are plastic, having the capacity to convert into other specialized cells (transdifferentiation)(1) or into induced pluripotent stem cells (iPSCs, reprogramming)(2) in response to transcription factor over-expression. To explore what makes a cell plastic and whether these different cell conversion processes are coupled, we exposed bone marrow derived pre-B cells to two different transcription factor overexpression protocols that efficiently convert them either into macrophages or iPSCs and monitored the two processes over time using single cell gene expression analysis. We found that even in these highly efficient cell fate conversion systems, cells differ in both their speed and path of transdifferentiation and reprogramming. This heterogeneity originatesin two starting pre-B cell subpopulations,large pre-BII and the small pre-BII cells they normally differentiate into. The large cells transdifferentiate slowly but exhibit a high efficiency of iPSC reprogramming. In contrast, the small cells transdifferentiate rapidly but are highly resistant to reprogramming. Moreover, the large B cells induce a stronger transient granulocyte/macrophage progenitor (GMP)-like state, while the small B cells undergo a more direct conversion to the macrophage fate. The large cells are cycling and exhibit high Myc activity whereas the small cells are Myc low and mostly quiescent. The observed heterogeneity of the two cell conversion processes can therefore be traced to two closely related cell types in the starting population that exhibit different types of plasticity. These data show that a somatic cells propensity for either transdifferentiation and reprogramming can be uncoupled.\n\nOne sentence summarySingle cell transcriptomics of cell conversions

developmental biology↗