Biology subjects

Langa, F.

Publications and source records attributed to Langa, F..

3 recordsLinked to original sources

bioRxiv2021

A fast Myh super enhancer dictates adult muscle fiber phenotype through competitive interactions with the fast Myh genes

The contractile properties of adult myofibers are shaped by their Myosin heavy chain (MYH) isoform content. We identify by snATAC-seq a 42kb super-enhancer (SE) at the locus regrouping the fast Myh (fMyh) genes. By 4C-seq we show that active fMyh promoters interact with the SE by DNA looping, leading to the activation of a single promoter per nucleus. A rainbow mouse transgenic model of the locus including the SE recapitulates the endogenous spatio-temporal expression of adult fMyh genes. In situ deletion of the SE by CRISPR/Cas9 editing demonstrates its major role in the control of associated fMyh genes, and deletion of two fMyh genes at the locus reveals an active competition of the promoters for the shared SE. Last, by disrupting the organization of fMyh, we uncover positional heterogeneity within limb skeletal muscles that may underlie selective muscle susceptibility to damage in certain myopathies.

cell biology↗

bioRxiv2020

Dynamics of myogenic differentiation using a novel Myogenin knock-in reporter mouse

BackgroundMyogenin is a transcription factor that is expressed during terminal myoblast differentiation in embryonic development and adult muscle regeneration. Investigation of this cell state transition has been hampered by the lack of a sensitive reporter to dynamically track cells during differentiation. ResultsHere, we report a knock-in mouse line expressing the tdTOMATO fluorescent protein from the endogenous Myogenin locus. Expression of tdTOMATO in MyogntdTom mice recapitulated endogenous Myogenin expression during embryonic muscle formation and adult regeneration and enabled the isolation of the Myogenin+ cell population. We also show that tdTOMATO fluorescence allows tracking of differentiating myoblasts in vitro and by intravital imaging in vivo. Lastly, we monitored by live imaging the cell division dynamics of differentiating myoblasts in vitro and showed that a fraction of the MYOGENIN+ population can undergo one round of cell division, albeit at a much lower frequency than MYOGENIN- myoblasts. ConclusionsWe expect that this reporter mouse will be a valuable resource for researchers investigating skeletal muscle biology in developmental and adult contexts.

cell biology↗

bioRxiv2019

The R2TP chaperone assembles cellular machineries in intestinal CBC stem cells and progenitors

The R2TP chaperone cooperates with HSP90 to integrate newly synthesized proteins into multi-subunit complexes, yet its role in tissue homeostasis is unknown. Here, we generated conditional, inducible knock-out mice for Rpap3 to inactivate this core component of R2TP in the intestinal epithelium. In adult mice, Rpap3 invalidation caused destruction of the small intestinal epithelium, and death within 10 days. Levels of R2TP substrates were decreased, with strong effects on mTOR, ATM and ATR. Rpap3-deficient CBC stem cells and progenitors also failed to import RNA polymerase II in the nucleus. This correlated with p53 activation, cell cycle arrest and apoptosis. Interestingly, post-mitotic, differentiated cells did not display any of those alterations, indicating that R2TP clients are built in actively proliferating cells. Analyses of tissues from colorectal cancer patients revealed that high RPAP3 levels correlate with bad cancer prognosis. Thus, in the intestine, the R2TP chaperone functions in physiologic and pathologic proliferation.

developmental biology↗