Biology subjects

Basso, V.

Publications and source records attributed to Basso, V..

4 recordsLinked to original sources

bioRxiv2023

Activation of Ca2+ phosphatase Calcineurin regulates Parkin translocation to mitochondria and mitophagy

Selective removal of dysfunctional mitochondria via autophagy is crucial for the maintenance of cellular homeostasis. This event is initiated by the translocation of the E3 ubiquitin ligase Parkin to damaged mitochondria, and it requires the Serine/Threonine-protein kinase PINK1. In a coordinated set of events, PINK1 operates upstream of Parkin in a linear pathway that leads to the phosphorylation of Parkin, Ubiquitin, and Parkin mitochondrial substrates, to promote ubiquitination of outer mitochondrial membrane proteins. Ubiquitin decorated mitochondria are selectively recruiting autophagy receptors,which are required to terminate the organelle via autophagy. In this work we show a previously uncharacterized molecular pathway that correlates the activation of the Ca2+-dependent phosphatase Calcineurin to Parkin-dependent mitophagy. Calcineurin downregulation or genetic inhibition prevents Parkin translocation to CCCP-treated mitochondria, and impairs stress-induced mitophagy, whereas Calcineurin activation promotes Parkin mitochondrial recruitment and basal mitophagy. Calcineurin interacts with Parkin, and promotes Parkin translocation in the absence of PINK1, but requires PINK1 expression to execute mitophagy in MEF cells. Genetic activation of Calcineurin in vivo boosts basal mitophagy in neurons, and corrects locomotor dysfunction and mitochondrial respiratory defects of a Drosophila model of impaired mitochondrial functions. Our study identifies Calcineurin as a novel key player in the regulation of Parkin translocation and mitophagy.

cell biology↗

bioRxiv2022

The establishment of Populus x Laccaria bicolor ectomycorrhiza requires the inactivation of MYC2 coordinated defense response with a key role for root terpene synthases

The jasmonic acid (JA) signaling pathway plays an important role in the establishment of the ectomycorrhizal symbiosis (ECM) between Laccaria bicolor and poplar. We previously showed that the L. bicolor effector MiSSP7 induces the stabilization of the poplar JAZ6, a JA co-repressor protein that binds to Populus MYC2.1 and MYC2.2, orthologs of the Arabidopsis MYC2 transcription factor (TF), blocking their activity. Here we showed that both TFs play a central role in root colonization by L. bicolor mycelium, since their overexpression decreased the formation of the Hartig net, the hyphal network involved in symbiotic nutrient exchanges. By combining RNA sequencing and DNA Affinity Purification sequencing (DAP-seq) analysis, we identified a core set of JA-responsive genes directly activated by poplar MYC2.1 and MYC2.2, that need to be bypassed by the fungi to colonize root apoplastic spaces. These genes encode for other TFs, receptor-like kinases and many defense-related proteins, including terpene synthases (TPS). Monoterpenes produced by some of these TPS impact L. bicolor growth and ECM formation, suggesting a role for poplar root monoterpenes as negative regulators of in planta fungal growth and ECM symbiosis. Significance statementThe ectomycorrhizal symbiosis is a predominant mutualistic plant-fungus interaction occurring in forests, sustaining tree health. Ectomycorrhizal fungi colonize the root intercellularly establishing the symbiotic interface required for bidirectional nutrients exchanges, the Hartig net. During root colonization, the fungus L. bicolor produces the effector protein MiSSP7 that binds to the jasmonate co-receptor PtJAZ6, maintaining the repression of MYC2-targeted genes. Here we showed that defensive genes are major targets of MYC2, suggesting that their strict control is required to allow fungal colonization, with special emphasis on the host root monoterpene synthesis. Future research will focus on how root terpene defenses mediate belowground mutualistic interactions and how they can be manipulated to engineer plants with enhanced disease resistance but stable mutualistic interactions.

plant biology↗

bioRxiv2022

The transcriptional regulator Sin3A balances IL-17A and Foxp3 expression in primary CD4 T cells

The Sin3 transcriptional regulator homolog A (Sin3A) is the core member of a multi-protein chromatin-modifying complex known to control gene transcription via epigenetic mechanisms. Its inactivation in developing thymocytes halts T cell maturation. We and others had previously shown that Sin3A controls STAT3 transcriptional activity. Given the role of STAT3 in the differentiation of T helper 17 cells critical in inflammatory disorders and against opportunistic infections, we asked whether Sin3A could also contribute to their differentiation. To this aim, we exploited CD4-Cre and CD4-CreERT2deleter strains for conditional and inducible Sin3A deletion in CD4 cell subsets. We report that Sin3A inactivation in vivo arrested thymocyte development at the double positive stage, hindering the characterization of mature T cells. At difference, tamoxifen-inducible Sin3A deletion proved permissive for in vitro proliferation of T cells in Th17 skewing conditions and the acquisition of memory markers. Transcriptional profiling indicated that while Sin3A inactivation imprinted T cells with a mTORC1 signaling gene signature, Sin3A deficient cells lacked the expression of IL-17A, the signature Th17 cytokine. This reflected a defective induction of Il17a, and also of the Il23R and Il22 genes, which occurred in spite of proper upregulation of the lineage defining transcription factor ROR{gamma}t. We found that Sin3A inactivation was paralleled by increased STAT3 phosphorylation and nuclear representation, and by higher fractions of IL-2 and FoxP3 expressing cells. Such events proved causally linked as inhibiting Foxp3 partially rescued IL-17A expression, and neutralizing IL-2 simultaneously lowered the representation of FoxP3+cells, while rescuing IL- 17A+ ones. Thus, together our data underline a previously unappreciated role for Sin3A in Th17 differentiation and the shaping of their immunoregulatory potential. StatementThis study identifies a new role for the transcriptional regulator Sin3A in the shaping of Th17 cell differentiation. Data indicate that by controlling IL-2 expression, and mTORC1 signaling, it balances IL-17A and Foxp3 levels, shaping Th17 inflammatory potentials.

immunology↗

bioRxiv2019

Duplicated KAI2 receptors with divergent ligand-binding specificities control distinct developmental traits in Lotus japonicus

Karrikins (KARs), smoke-derived butenolides, are perceived by the /{beta}-fold hydrolase KARRIKIN INSENSITIVE2 (KAI2) and are thought to mimic endogenous, yet elusive plant hormones tentatively called KAI2-ligands (KLs). The sensitivity to different karrikin types as well as the number of KAI2 paralogs varies among plant species, suggesting diversification and co-evolution of ligand-receptor relationships. In legumes, which comprise a number of important crops with protein-rich, nutritious seed, KAI2 has duplicated. We report sub-functionalization of KAI2a and KAI2b in the model legume Lotus japonicus and demonstrate that their ability to bind the synthetic ligand GR24ent-5DS differs in vitro as well as in genetic assays in Lotus japonicus and in the heterologous Arabidopsis thaliana background. These differences can be explained by the exchange of a widely conserved phenylalanine in the binding pocket of KAI2a with a tryptophan in KAI2b, which occured independently in KAI2 proteins of several unrelated angiosperms. Furthermore, two polymorphic residues in the binding pocket are conserved across a number of legumes and may contribute to ligand binding preferences. Unexpectedly, L. japonicus responds to diverse synthetic KAI2-ligands in an organ-specific manner. Hypocotyl development responds to KAR1, KAR2 and rac-GR24, while root system development responds only to KAR1. This organ-specificity cannot be explained by receptor-ligand preferences alone, because LjKAI2a is sufficient for karrikin responses in the hypocotyl, while LjKAI2a and LjKAI2b operate redundantly in roots. Our findings open novel research avenues into the evolution and diversity of butenolide ligand-receptor relationships, their ecological significance and the mechanisms controlling diverse developmental responses to different KAI2 ligands.

plant biology↗