Biology subjects

Goiame, R.

Publications and source records attributed to Goiame, R..

3 recordsLinked to original sources

bioRxiv2024

Uneven mitochondrial segregation during embryonic neurogenesis

Asymmetric divisions of vertebrate neural progenitors are critical for generating neurons while preserving the stem cell pool, ensuring proper central nervous system development. It was previously shown that the post-mitotic remodeling of mitochondrial activity in daughter cells influences neural fates. In this study, we demonstrate that unequal distribution of mitochondria during asymmetric mitosis plays a decisive role in triggering this differentiation process. Using live imaging to monitor mitochondrial segregation in individual progenitors and track their progenys fate within embryonic neural tissue, we show that daughter cells inheriting fewer mitochondria consistently differentiate into neurons, whereas their sibling receiving more mitochondria retains the progenitor status. Furthermore, experimental displacement of mitochondria during mitosis to force their unequal inheritance was sufficient to drive premature neuronal differentiation. Our findings establish a direct causal relationship between unequal mitochondrial inheritance and the asymmetric fate of sister cells in vivo, uncovering a key mechanism in neural development.

developmental biology↗

bioRxiv2024

CRISPR/Cas9-based somatic knock-in of reporters in the avian embryo in ovo

Gene editing and protein tagging are at the heart of modern developmental and cell biology. The advent of CRISPR/Cas9 based methods offers the possibility to develop customized approaches for genomic manipulations in non-classical experimental models. Here, we show that highly efficient somatic knock-ins of long DNA fragments can be achieved in the developing chick neural tube in ovo. We compare different types of repair matrices and different methods for the delivery of the CRISPR/Cas9 machinery, and find that an all plasmid-based approach and short arms of homology provide an easy and efficient method to achieve high frequencies of knock-in insertions with virtually no background signal. We use this method to target fluorescent reporters and dynamically monitor the subcellular distribution of endogenously expressed tagged proteins, as well as to insert the Gal4-VP16 transcription factor or the Cre recombinase at specific loci to label neural sub-populations in the chick embryonic spinal cord. Finally, we show that the method can also be applied to target the epiblast and somitic mesoderm.

developmental biology↗

bioRxiv2024

A low CDKN1c/p57kip2 expression in spinal progenitors drives the transition from proliferative to neurogenic modes of division

During vertebrate neurogenesis, a progressive transition from symmetric proliferative to asymmetric neurogenic divisions is critical to balance growth and differentiation. Using single-cell RNA-seq data from chick embryonic neural tube, we identify the cell cycle regulator Cdkn1c as a key regulator of this transition. While Cdkn1 is classically associated with neuronal cell cycle exit, we show that its expression initiates at low levels in neurogenic progenitors. Functionally targeting the onset of this expression impacts the course of neurogenesis: Cdkn1c knockdown impairs neuron production by favoring proliferative symmetric divisions. Conversely, inducing a low-level CDKN1c misexpression in self-expanding progenitors forces them to prematurely undergo neurogenic divisions. CDKN1c exerts this effect primarily by inhibiting the cyclin D-CDK complex and lengthening G1 phase duration. We propose that Cdkn1c acts as a dual driver of the neurogenic transition whose low level of expression first controls the progressive entry of progenitors into neurogenic modes of division before a higher expression mediates cell cycle exit in daughter cells. This highlights that the precise control of neurogenesis regulators expression levels sequentially imparts distinct functions, and is essential for proper neural development.

developmental biology↗