Biology subjects

Dittrich-Domergue, F.

Publications and source records attributed to Dittrich-Domergue, F..

5 recordsLinked to original sources

bioRxiv2025

The phytolongin AtPhyl2.1 is involved in cell plate formation and root development

SNAREs are critical elements of the membrane trafficking machinery with a wide variety of functionality across this family of proteins. Phytolongins are a recently identified subfamily of longins which possess the typical longin domain but lack a SNARE motif. Phytolongins have an ubiquitous tissue expression in Arabidopsis and are distributed throughout the secretory pathway. We focused on Phytolongin 2.1 (PHYL2.1) which localizes to the endoplasmic reticulum, and observed a strong root growth phenotype in the loss-of-function Atphyl2.1-1 mutant. We demonstrate that whilst cell elongation efficiency was not affected in the mutant, cell division was significantly reduced. The resulting decrease in root length in the Atphyl2.1-1 mutant is explained by a smaller number of cells which then elongate to enable root growth. Root apical meristem architecture of Atphyl2.1-1 and another mutant Atphyl2.1-2 was disturbed and distances from the root quiescent center to the transition zone and the first areas of mis-organized cells were affected in both mutants. Investigation of the SNARE AtKNOLLE revealed significant perturbation of Atphyl2.1-1 cell plate formation in the mis-organised areas. Our results provide a first characterization of the phytolongin AtPHYL2.1 which appears involved in root cell plate formation, root cell division and therefore root development. HighlightThe phytolongin AtPHYL2.1 significantly affects the efficiency of cell plate formation and root development in Arabidopsis thaliana.

plant biology↗

bioRxiv2025

Unveiling the molecular identity of plant autophagic compartments: A proteo-lipidomic study in Arabidopsis thaliana

Autophagy is an intracellular degradation and recycling pathway essential for cell quality control and plant tolerance to stress. The formation and maturation of autophagosomes, the cargo-packing vesicles, rely on extensive membrane remodeling, yet little is known about the nature, dynamics and functions of lipids in these events. Here, we established a method combing cell fractionation and immuno-isolation in native conditions to purify autophagic membranes from Arabidopsis thaliana. By integrating proteomic and lipidomic analyses, we defined their molecular footprint which, coupled to colocalization analyses, revealed potent actors involved in lipid metabolism, membrane trafficking and membrane remodeling, supporting a close interplay between lipid homeostasis and autophagosome biology. Characterization of the phagophore lipid composition showed low sterol and sphingolipid content, a predominance of glycerophospholipids, including phosphoinositides, and a particular enrichment in phosphatidylcholine and phosphatidylglycerol. Comparisons with other plant endomembranes and autophagic compartments from other organisms revealed the singularity of this lipid signature and notably identified phosphatidylglycerol as a plant-specific component of autophagic membranes. Analyses of inducible phosphatidylglycerol-deficient plants showed defects in autophagy activity thereby supporting the functional relevance of the phagophore lipid composition, particularly that of phosphatidylglycerol homeostasis. Together, our findings place lipids as fundamental components of the autophagy molecular landscape and provide a framework to further investigate their contribution to autophagosome biology and functions in plant acclimation to environmental changes. Significance StatementAutophagy is catabolic pathway critical for eukaryotic life and essential for plant acclimation to stress. It hinges on the remarkable plasticity of a specialized membrane, the phagophore, to orchestrate and support intense membrane remodeling events towards the formation of the autophagic vesicle containing cargo. To resolve their elusive molecular bases, we need to integrate inputs from both components of biological membranes: proteins and lipids, yet information regarding lipids is still very limited. Here, we isolated plant phagophores, established their protein and lipid molecular footprint, revealed its singularity and showed its physiological and functional relevance for autophagy activity. Our work highlights lipids as key regulators of plant autophagy and opens new doors for investigating how membrane dynamics shape cellular stress responses.

plant biology↗

bioRxiv2025

A dual component system instructs membrane hydrolysis during the final stages of plant autophagy

Autophagy is an intracellular catabolic process conserved across eukaryotes and critical for plant stress tolerance. Upon their delivery in the vacuole, how autophagic bodies containing cargo are hydrolyzed to warrant autophagy degradation remains poorly characterized. Here, we identify two Arabidopsis phospholipases as core components of the autophagy machinery. We find that LCAT3 and LCAT4 traffic to the vacuolar lumen and converge on autophagic bodies using differential pathways, placing them on the outer and inner side of the vesicle, respectively. Double knockouts lcat3,4 accumulate autophagic bodies and show reduced autophagy activity. In vivo reconstitution demonstrates that LCAT3 can hydrolyze the membrane of autophagic bodies, enabling the activity of LCAT4 to enhance this process. In sum, our work reveals that the concerted action of a multi-component system is required for the efficient and specific disruption of autophagic bodies as an obligatory step for the completion of the autophagy pathway.

plant biology↗

bioRxiv2024

Chaperone-Mediated Autophagy in Fish: A Key Function Amid a Changing Environment

Chaperone-Mediated Autophagy (CMA) is a major pathway of lysosomal proteolysis critical for cellular homeostasis and metabolism. While extensively studied in mammals, CMAs existence in fish has only been confirmed recently, offering exciting insights into its role in species facing environmental stress. Here, we shed light on the existence of 2 genes encoding the CMA-limiting factor Lamp2A (lysosomal associated membrane protein 2A) in rainbow trout (RT, Oncorhynchus mykiss), revealing distinct expression patterns across various tissues. Notably, RT lacking the most expressed Lamp2A exhibit profound hepatic proteome disturbances during acute nutritional stress, underscoring its pivotal role as a guardian of hepatic proteostasis. Building upon these findings, we introduce and validate the CMA activation score as a reliable indicator of CMA status, providing a valuable tool for detecting cellular stress in fish under environmental threats. Overall, our study offers new perspectives into understanding CMA from evolutionary and environmental contexts. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=70 SRC="FIGDIR/small/585855v1_ufig1.gif" ALT="Figure 1"> View larger version (10K): org.highwire.dtl.DTLVardef@de3c56org.highwire.dtl.DTLVardef@4b711forg.highwire.dtl.DTLVardef@efb4a1org.highwire.dtl.DTLVardef@13be9cc_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2021

Lyso-Phosphatidic Acid Acyl-Transferases: a link with intracellular protein transport in Arabidopsis root cells?

Phosphatidic acid (PA) and Lysophosphatidic acid acyltransferases (LPAATs) might be critical for the secretory pathway. Four extra-plastidial LPAATs (numbered 2,3,4 and 5) were identified in A. thaliana. These AtLPAATs, displaying an enzymatic activity specific for LPA to produce PA, are located in the endomembrane system. We focused on the putative role of the AtLPAATs 3, 4 and 5 in the secretory pathway of root cells through genetical (knock-out mutants), biochemical (activity inhibitor, lipid analyses) and imaging (live and immuno-confocal microscopies) approaches. Treating a lpaat4;lpaat5 double mutant with the LPAAT inhibitor CI976 showed a primary root growth decrease. The transport of the auxin transporter PIN2 was disturbed in this lpaat4;lpaat5 double mutant treated with CI976, but not that of H+-ATPases. The lpaat4;lpaat5 double mutant was sensitive to salt stress and the transport of the aquaporin PIP2;7 to the plasma membrane in the lpaat4;lpaat5 double mutant treated with CI976 was reduced. We measured the amounts of neo-synthesized PA in roots, and found a decrease in PA only in the lpaat4;lpaat5 double mutant treated with CI976, suggesting that the protein transport impairment was due to a critical PA concentration threshold. HighlightPhosphatidic acid produced by Lyso-Phosphatidic Acid Acyl-Transferases has an impact on the efficiency of the intracellular transport of some proteins in Arabidopsis thaliana root cells.

cell biology↗