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Biology subjects

Egg, M.

Publications and source records attributed to Egg, M..

4 recordsLinked to original sources

In vitro approaches to study centriole and cilium function in early mouse embryogenesis

Although centrioles and primary cilia play an essential role in early mammalian development, their specific function during the interval between their initial formation and the subsequent arrest of embryogenesis in embryos deficient in centrioles or cilia remains largely unexplored. Here, we demonstrate that different 3D in vitro model systems recapitulate early centriole and cilium formation in mouse development. Centrioles and cilia are dispensable in 3D in vitro mouse rosettes, a model system that mimics key events of implantation, including polarization and lumenogenesis. In gastruloids, a model system that recapitulates developmental processes up to 8.5 days after fertilization, centriole loss results in early disassembly. In contrast, cells devoid of cilia continue to form elongated, differentiated and polarized gastruloids, with minor differences at 96 h. Finally, we show that in a mutant affecting the centriolar distal appendages, cilia are absent from 2D cultures but are capable of forming in 3D rosettes and gastruloids, highlighting the importance of multifactorial 3D environment setups in developmental studies. SummaryThis study presents the first in vitro analysis of centriole and cilium formation during early mouse embryonic development, using 3D models to mimic implantation, tissue patterning, and axis elongation, offering a controlled platform for investigating their roles in embryogenesis.

developmental biology↗

The central clock drives metabolic rhythms in muscle stem cells

Circadian rhythms are essential for organismal health. Satellite cells (SCs), the muscle resident stem cells, maintain a state of quiescence yet exhibit robust circadian oscillations at the transcriptional level. Although peripheral clocks have been extensively studied in various tissues, how the intrinsic clock of stem cells interacts with the central, distal clock is largely unknown. We used SC-specific reconstitution of the essential clock gene Bmal1 to elucidate the role of the local SC clock and its interplay with the central clock in the mouse brain and found that daily transcriptional control of metabolic processes in SCs depend on central clock input, independent of the SC clock. Central clock-driven genes were involved in lipid metabolism, functionally important for SC-mediated muscle repair, and autophagy was required for their oscillation. In summary, we provide the first evidence of circadian coordination of central and local clocks for control of rhythmic gene expression in quiescent stem cells. HighlightsO_LIBrain:satellite cell clock communication restores rhythms of core clock machinery in quiescent satellite cells C_LIO_LIBrain inputs are the dominant regulator of transcript rhythms in SCs, driving the oscillation of lipid metabolic genes. C_LIO_LIAutophagy in satellite cells is required for the oscillation of lipid metabolic genes. C_LIO_LIEarly phases of muscle regeneration depend on brain-driven circadian signals. C_LI

cell biology↗

Redirecting full-length FLT1 expression towards its soluble isoform promotes postischemic angiogenesis

Vascular endothelial growth factors and their tyrosine kinase receptors are key mediators of vasculogenesis and angiogenesis with FLT1 (VEGFR1) serving as a decoy receptor. A truncated mRNA transcript encoding soluble (s) FLT1 can be generated by premature cleavage and polyadenylation (APA). Although a shortening of transcripts is described in pathological settings, including heart diseases, the functional in vivo impact of FLT1 gene isoform generation and relevance for angiogenesis remain unknown. Here, we show that specific splice site mutations within Flt1 inhibit telescripting and activate APA in vivo to efficiently modulate gene isoform expression, inducing a complete loss of full-length (fl) Flt1 and a switch towards sFlt1 in mice. FLT1 is a high-affinity decoy receptor of VEGF limiting vessel overgrowth. We show that sFLT1 was sufficient for developmental vasculogenesis, whereas flFLT1 controlled ischemia-driven angiogenesis. Our results demonstrate that telescripting is essential in vivo for controlling Flt1 isoform expression and angiogenesis and can be harnessed to improve reparative revascularization. Furthermore, given the widespread abundance of APA signals, our approach may serve as a blueprint for studying telescripting and generating other truncated gene isoforms in vivo.

cell biology↗

U1 snRNP-dependent suppression of miRNA biogenesis by alternative intronic polyadenylation in melanoma

Activation of intronic polyadenylation signals results in premature cleavage and polyadenylation (PCPA). The majority of mammalian miRNAs are also located within intronic regions of protein-coding genes and are transcriptionally co-expressed with their host genes. Here we show that U1-dependent PCPA by telescripting dysregulates miRNA biogenesis. When U1 is reduced, miR-211 levels are decreased as a direct consequence of activation of a newly identified alternative intronic polyadenylation signal located upstream of miR-211 within its host gene TRPM1. Various melanoma cell lines revealed decreased U1 levels and a shift from full-length to truncated TRPM1 isoforms with concomitant decreased miR-211 expression. Modulation of TRPM1 alternative polyadenylation (APA) by morpholino oligonucleotides inhibits and potentially restores miR-211 expression to endogenous levels. This mechanism of intronic PCPA and its effects on miRNA biogenesis represents a previously unrecognized layer of gene expression regulation suitable for therapeutic modulation. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=88 SRC="FIGDIR/small/479622v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@169c2f1org.highwire.dtl.DTLVardef@7d8f34org.highwire.dtl.DTLVardef@144b9d8org.highwire.dtl.DTLVardef@10523f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗