Biology subjects

Garcia-Marques, J.

Publications and source records attributed to Garcia-Marques, J..

6 recordsLinked to original sources

bioRxiv2025

Early Emergence of Projection-subtype fate-restricted Radial Glial Progenitors Orchestrates Neocortical Neurogenesis.

Radial glial progenitors (RGPs) generate all projection neurons (PNs) in the cerebral cortex through incompletely understood processes. Herein, we combine Mosaic Analysis with Double Markers (MADM)-based clonal analysis at embryonic days 12.5 and 13.5 with early postnatal callosal tracing to reveal a lineage progression that challenges the inside-outside model of cortical development and the conventional view of an invariable sequence of asymmetric neurogenic divisions. Our data demonstrate that early multipotent RGPs generate all extra-telencephalic (ET) and intra-telencephalic (IT) PNs across all layers through parallel sublineages and the random specification, during the earliest neurogenic divisions, of fate-restricted daughter RGPs. While the neuronal production of the parental multipotent RGPs consists of small ET-PN or IT-PN outputs, fate-restricted RGPs produce larger translaminar outputs spanning deep and upper layers of only IT-PNs, the predominant mammalian PN subtype. We further show that the emergence of IT-PN fate-restricted RGPs also leads to quantitatively and temporally stereotyped neurogenesis population-wise.

neuroscience↗

bioRxiv2021

TEMPO: A system to sequentially label and genetically manipulate vertebrate cell lineages

During development, regulatory factors appear in a precise order to determine cell fates over time. To investigate complex tissue development, one should not just label cell lineages but further visualize and manipulate cells with temporal control. Current strategies for tracing vertebrate cell lineages lack genetic access to sequentially produced cells. Here we present TEMPO (Temporal Encoding and Manipulation in a Predefined Order), an imaging-readable genetic tool allowing differential labelling and manipulation of consecutive cell generations in vertebrates. TEMPO is based on CRISPR and powered by a cascade of gRNAs that drive orderly activation/inactivation of reporters/effectors. Using TEMPO to visualize zebrafish and mouse neurogenesis, we recapitulated birth-order-dependent neuronal fates. Temporally manipulating cell-cycle regulators in mouse cortex progenitors altered the proportion and distribution of neurons and glia, revealing the effects of temporal gene perturbation on serial cell fates. Thus, TEMPO enables sequential manipulation of molecular factors, crucial to study cell-type specification. One-Sentence SummaryGaining sequential genetic access to vertebrate cell lineages.

developmental biology↗

bioRxiv2019

An efficient CRISPR-based strategy to insert small and large fragments of DNA using short homology arms

We previously reported a CRISPR-mediated knock-in strategy into introns of Drosophila genes, generating an attP-FRT-SA-T2A-GAL4-polyA-3XP3-EGFP-FRT-attP transgenic library for multiple uses (Lee et al., 2018b). The method relied on double stranded DNA (dsDNA) homology donors with [~]1 kb homology arms. Here, we describe three new simpler ways to edit genes in flies. We create single stranded DNA (ssDNA) donors using PCR and add 100 nt of homology on each side of an integration cassette, followed by enzymatic removal of one strand. Using this method, we generated GFP-tagged proteins that mark organelles in S2 cells. We then describe two dsDNA methods using cheap synthesized donors flanked by 100 nt homology arms and gRNA target sites cloned into a plasmid. Upon injection, donor DNA (1 to 5 kb) is released from the plasmid by Cas9. The cassette integrates efficiently and precisely in vivo. The approach is fast, cheap, and scalable.

genomics↗

bioRxiv2019

CAMIO for deletion analysis of endogenous DNA sequences in multicellular organisms

The genome is the blueprint for an organism. Interrogating the genome, especially locating critical cis-regulatory elements, requires deletion analysis. This is conventionally performed using synthetic constructs, making it cumbersome and non-physiological. Thus, we created Cas9-mediated Arrayed Mutagenesis of Individual Offspring (CAMIO) to achieve high-throughput analysis of native DNA. CAMIO utilizes CRISPR that is spatially restricted to generate independent deletions. Controlled by recombination, a single guide RNA is stochastically chosen from a set targeting a specific DNA region. Combining two sets increases variability, leading to either indels at 1-2 target sites or inter-target deletions. Cas9 restriction to male germ cells elicits autonomous double-strand-break repair, consequently creating offspring with diverse mutations. Thus, from a single population cross, we can obtain a deletion matrix covering a large expanse of DNA at both coarse and fine resolution. We demonstrate the ease and power of CAMIO by mapping 5UTR sequences crucial for chinmos post-transcriptional regulation.

genomics↗

bioRxiv2019

CLADES: a programmable sequence of reporters for lineage analysis

We present CLADES (Cell Lineage Access Driven by an Edition Sequence), a technology for cell lineage studies based on CRISPR/Cas9. CLADES relies on a system of genetic switches to activate and inactivate reporter genes in a pre-determined order. Targeting CLADES to progenitor cells allows the progeny to inherit a sequential cascade of reporters, coupling birth order with reporter expression. This gives us temporal resolution of lineage development that can be used to deconstruct an extended cell lineage by tracking the reporters expressed in the progeny. When targeted to the germ line, the same cascade progresses across animal generations, marking each generation with the corresponding combination of reporters. CLADES thus offers an innovative strategy for making programmable cascades of genes that can be used for genetic manipulation or to record serial biological events.\n\nOne Sentence SummaryA sequence of reporters for lineage analysis

developmental biology↗

bioRxiv2018

Unlimited genetic switches for cell-type specific manipulation

Gaining independent genetic access to discrete cell types is critical to interrogate their biological functions, as well as to deliver precise gene therapy. Transcriptome analyses have allowed us to profile cell populations with extraordinary precision, revealing that cell types are typically defined by a unique combination of genetic markers. Given the lack of adequate tools to target cell types based on multiple markers, most cell types have remained inaccessible to genetic manipulation. Here, we present CaSSA, a platform to create unlimited genetic switches based on CRISPR/Cas9 (Ca) and the DNA repair mechanism known as single-strand annealing (SSA). CaSSA allows engineering of independent genetic switches that each respond to a specific gRNA. Expressing multiple gRNAs in specific patterns enables multiplex cell type-specific manipulations and combinatorial genetic targeting. CaSSA is thus a new genetic tool that conceptually works as an unlimited number of recombinases and will facilitate genetic access to cell types in diverse organisms.

developmental biology↗