Biology subjects

Dias, K.

Publications and source records attributed to Dias, K..

4 recordsLinked to original sources

bioRxiv2024

The zebrafish as a new model for studying chaperone-mediated autophagy unveils its role in spermatogenesis

Chaperone-Mediated Autophagy (CMA) is a major pathway of lysosomal proteolysis involved in numerous cellular processes, and whose dysfunction is associated to several pathologies. Initially studied in mammals and birds, recent findings have identified CMA in fish, reshaping our understanding of its evolution across metazoans. Given the exciting perspectives this finding offered, we have now developed the required tools to investigate and functionally asses that CMA function in a powerful fish genetic model: the zebrafish (Danio rerio). After adapting and validating a fluorescent reporter (KFERQ-Dendra2; previously used to track CMA in mammalian cells) in zebrafish primary embryonic cells, we first demonstrated CMA functionality in this fish species. Then, we developed a transgenic zebrafish line expressing the KFERQ-Dendra2 CMA reporter, enabling the real-time tracking of CMA activity in vivo. This model revealed heterogeneous CMA responses within tissues, highlighting the zebrafish as a valuable model for investigating tissue-specific and cell-scale variations in CMA. Moreover, a novel role for CMA has been uncovered, acting as a gatekeeper of sperm cell proteostasis, thereby playing a crucial role in the production of active and high-quality spermatozoa. Overall, these findings emphasize the zebrafish as a pivotal model for advancing our comprehension of the fundamental mechanisms underlying CMA.

cell 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

Single amino-acid mutation in the Drosophila melanogaster ribosomal protein uL11: an insight in its transcriptional activity

The ribosomal protein uL11 is located at the basis of the ribosome P-stalk and plays a paramount role in translational efficiency. In addition, no mutant for uL11 is available suggesting that this gene is haplo-insufficient as many other Ribosomal Protein Genes (RPGs). We have previously shown that overexpression of Drosophila melanogaster uL11 enhances the transcription of many RPGs and Ribosomal Biogenesis genes (RiBis) suggesting that uL11 might globally regulate the level of translation through its transcriptional activity. Moreover, uL11 trimethylated on lysine 3 (uL11K3me3) interacts with the chromodomain of the Enhancer of Polycomb and Trithorax Corto, and both proteins co- localize with RNA Polymerase II at many sites on polytene chromosomes. These data have led to the hypothesis that the N-terminal end of uL11, and more particularly the trimethylation of lysine 3, supports the extra-ribosomal activity of uL11 in transcription. To address this question, we mutated the lysine 3 codon using a CRISPR/Cas9 strategy and obtained several lysine 3 mutants. We describe here the first mutants of D. melanogaster uL11. Unexpectedly, the uL11K3A mutant, in which the lysine 3 codon is replaced by an alanine, displays a genuine Minute phenotype known to be characteristic of RPG deletions (longer development, low fertility, high lethality, thin and short bristles) whereas the uL11K3Y mutant, in which the lysine 3 codon is replaced by a tyrosine, is unaffected. In agreement, the rate of translation decreases in uL11K3A but not in uL11K3Y. Co-immunoprecipitation experiments show that the interaction between uL11 and the Corto chromodomain is impaired by both mutations. RNA- seq analysis from wing imaginal discs shows enrichment in the GO categories "glutathione metabolism" for up-regulated genes in both uL11K3A and uL11K3Y mutants and "regulation of transcription" for down-regulated genes in uL11K3A only. Analysis of the cis-regulatory sequences of these genes suggests that uL11 might regulate transcription of target genes in concert with the couple of transcription factors Mad/Med that mediate response to the Bone Morphogenetic Protein (BMP) signaling pathway.

developmental biology↗

bioRxiv2021

In mice and humans, the brain's blood vessels mature postnatally to acquire barrier and contractile properties

The brain dense vascular network is essential for distributing oxygen and nutrients to neural cells. The network develops during embryogenesis and leads to the formation of the endothelial blood-brain barrier (BBB). This barrier is surrounded by mural cells (pericytes and vascular smooth muscle cells (VSMCs)) and fibroblasts. Here, we compared the molecular and functional properties of brain vascular cells on postnatal day (P)5 vs. P15, via a transcriptomic analysis of purified mouse cortical microvessels (MVs) and the identification of vascular-cell-type-specific or -preferentially expressed transcripts. We found that endothelial cells (ECs), VSMCs and fibroblasts follow specific molecular maturation programs over this time period. In particular, ECs acquire P-glycoprotein (P-gP)-mediated efflux capacities. The arterial VSMC network expands, acquires contractile proteins (such as smooth muscle actin (SMA) and myosin heavy chain 11 (Myh11)) and becomes contractile. We also analyzed samples of human brain cortex from the early prenatal stage through to adulthood: the expression of endothelial P-gP increased at birth and Myh11 in VSMCs acts as a developmental switch (as in the mouse) at birth and up to the age of 2 of 5 years. Thus, in both mice and humans, the early postnatal phase is a critical period during which the essential properties of cerebral blood vessels (i.e. the endothelial efflux of xenobiotics and other molecules, and the VSMC contractility required for vessel tone and brain perfusion) are acquired and mature.

neuroscience↗