Biology subjects

Maugarny, A.

Publications and source records attributed to Maugarny, A..

3 recordsLinked to original sources

bioRxiv2026

The CUP-SHAPED COTYLEDON 2 - MIR164A regulatory feedback loop directs leaf morphogenesis

Gene regulatory networks (GRNs) establish the spatio-temporal gene expression patterns necessary for reproducible development of organisms. MicroRNAs have emerged as important regulators of gene expression controlling either target gene levels, spatial patterns or timing. These molecular functions may vary depending on how they are integrated into GRNs. Here we used the Arabidopsis leaf as a model to study the genetic and molecular interactions between the CUP-SHAPED COTYLEDON 2 (CUC2) transcription factor and its negative regulator, miR164A. Quantitative morphometric analyses showed that miR164A acts from early stages during leaf development regulating CUC2 expression dynamic rather than the spatial distribution of CUC2. At the molecular level, CUC2 directly activates MIR164A expression, forming a single negative feedback loop. Further, using a ratiometric approach, we identified a cis-regulatory element (CRE) sufficient to drive CUC2-dependent MIR164A expression at the leaf sinus. Ordinary differential equation (ODE) modelling suggests that CUC2-CRE may control the timely accumulation of CUC2. Accordingly, quantification of CUC2 protein accumulation dynamics using a spatio-temporal mean cartography strategy in CRISPR cis-regulatory variants at the MIR164A locus revealed that CUC2-dependent MIRA164A expression is required to maintain both the precise timing of CUC2 expression and CUC2 levels. Altogether, our work provides experimental evidence for a specific role of the CUC2-MIR164A module in shaping leaf development, highlighting the contribution of network topology to GRN functions.

plant biology↗

bioRxiv2024

Developmental rewiring of the NGAL/CUC/KLU network associated with pleiotropic roles of NGAL genes

Gene Regulatory Networks (GRNs) play prominent roles in regulating developmental processes, and their modulation across species is a major source for evolutionary innovation. However, it remains poorly understood how GRNs are rewired between different organs within a single species. This question is particularly relevant for pleiotropic genes, which may exhibit organ-specific GRN modulations potentially reflecting their diverse functions. To address this, we investigated the NGATHA-like (NGAL) genes, as a model for pleiotropic genes that regulate growth or patterning in multiple Arabidopsis organs via two distinct pathways involving the CUP-SHAPED COTYLEDON (CUC) and KLUH (KLU) genes. By combining genetic analysis with gene expression characterization, we uncovered significant organ-specific rewiring of the NGAL/CUC/KLU regulatory module. Our findings highlight that changes in gene expression patterns, potentially arising from developmental constraints, play a pivotal role in the organ-specific modulation of GRNs. Furthermore, GRNs at the molecular and functional levels do not always align perfectly, potentially due to the influence of additional regulatory mechanisms. Altogether, our findings reveal significant modulation of the GRNs associated with pleiotropic genes. We propose that this flexibility in GRNs facilitates gene pleiotropy.

plant biology↗

bioRxiv2023

Compensation of compromised PRC2 regulation by a miRNA ensures robustness of Arabidopsis leaf development

Robustness is pervasive throughout biological systems, enabling them to maintain persistent outputs despite perturbations in their components. Here, we reveal a novel mechanism contributing to leaf morphology robustness in the face of genetic perturbations. In Arabidopsis, leaf shape is established during early development through the quantitative action of the CUP-SHAPED COTYLEDON2 (CUC2) gene that is negatively regulated by the co-expressed MICRORNA164A (MIR164A) gene. Compromised epigenetic regulation due to defective Polycomb Repressive Complex 2 (PRC2) function results in the transcriptional derepression of CUC2 but has no impact on CUC2 protein dynamics or early morphogenesis. We solve this apparent paradox by showing that compromised PRC2 function simultaneously activates a compensatory mechanism involving another member of the MIR164 gene family, the MIR164B gene. This mechanism dampens CUC2 protein levels, thereby compensating for compromised PRC2 function and canalizing early leaf morphogenesis. Furthermore, we show that this compensation mechanism is active under different environmental conditions. Our findings shed light on how the interplay between different types of transcriptional regulation can contribute to developmental robustness.

plant biology↗