Biology subjects

Puertollano, R.

Publications and source records attributed to Puertollano, R..

5 recordsLinked to original sources

bioRxiv2025

The lysosomal carrier SLC29A3 supports anti-bacterial signaling and promotes autophagy by activating TRPML1 in mouse dendritic cells

The solute carrier (SLC)29A3 exports nucleosides from lysosomes into the cytosol, maintaining solute homeostasis and providing metabolic intermediates for cellular processes. Loss-of-function mutations in SLC29A3 cause H syndrome, characterized by hyperinflammation and immunodeficiency. While dysfunctions in various cell types contribute to H syndrome and to SLC29A3 deficiency in mice, the mechanisms driving hyperinflammation and immunodeficiency are incompletely understood. Remarkably, the possible role played by dendritic cells (DCs), the most efficient antigen presenting cells and the main link between innate and adaptive immune responses, remains unknown. We show that, in murine DCs, SLC29A3 is recruited to phagosomes after bacterial capture, maintains phagosomal pH homeostasis, and ensures optimal phagosomal signaling to the production of IL-6, IL-12, and CCL-22. In addition, SLC29A3 promotes Ag presentation on MHC-II molecules to initiate adaptive immune responses. Notably, SLC29A3 supports the activity of the lysosomal calcium channel TRPML1, promoting transcription factor TFEB nuclear translocation and inducing autophagy, a major anti-inflammatory mechanism. Overexpression of human SLC29A3, but not the transport mutant G437R, in SLC29A3-deficient murine DCs restores cytokine production in response to bacteria phagocytosis, suggesting that SLC29A3 transport activity is required to drive anti-bacterial phagosomal signaling. Our data indicate that SLC29A3 plays a dual role in supporting immune function in DCs by promoting effective anti-microbial signaling and Ag presentation and inducing autophagy to control inflammation. Our findings also uncover a novel TRPML1-dependent mechanism by which SLC29A3 activates TFEB and suggest that defects in phagosomal signaling, TFEB activation and autophagy may contribute to immunodeficiency and hyperinflammation in SLC29A3 disorders.

cell biology↗

bioRxiv2023

The AKT2/SIRT5/TFEB pathway as a potential therapeutic target in atrophic AMD

Introductory paragraphAge-related macular degeneration (AMD), the leading cause of geriatric blindness, is a multi-factorial disease with retinal-pigmented epithelial (RPE) cell dysfunction as a central pathogenic driver. With RPE degeneration, lysosomal function is a core process that is disrupted. Transcription factors EB/E3 (TFEB/E3) tightly control lysosomal function; their disruption can cause aging disorders, such as AMD. Here, we show that induced pluripotent stem cells (iPSC)-derived RPE cells with the complement factor H variant [CFH (Y402H)] have increased AKT2, which impairs TFEB/TFE3 nuclear translocation and lysosomal function. Increased AKT2 can inhibit PGC1, which downregulates SIRT5, an AKT2 binding partner. SIRT5 and AKT2 co-regulate each other, thereby modulating TFEB-dependent lysosomal function in the RPE. Failure of the AKT2/SIRT5/TFEB pathway in the RPE induced abnormalities in the autophagy-lysosome cellular axis by upregulating secretory autophagy, thereby releasing a plethora of factors that likely contribute to drusen formation, a hallmark of AMD. Finally, overexpressing AKT2 in RPE cells in mice led to an AMD-like phenotype. Thus, targeting the AKT2/SIRT5/TFEB pathway could be a potential therapy for atrophic AMD.

cell biology↗

bioRxiv2022

Human variation impacting MCOLN2 restricts Salmonella Typhi replication by magnesium deprivation

Human genetic diversity can reveal critical factors in host-pathogen interactions. This is especially useful for human-restricted pathogens like Salmonella enterica serovar Typhi (S. Typhi), the cause of Typhoid fever. One key dynamic during infection is competition for nutrients: host cells attempt to restrict intracellular replication by depriving bacteria of key nutrients or delivering toxic metabolites in a process called nutritional immunity. Here, a cellular genome-wide association study of intracellular replication by S. Typhi in nearly a thousand cell lines from around the world--and extensive follow-up using intracellular S. Typhi transcriptomics and manipulation of magnesium concentrations--demonstrates that the divalent cation channel mucolipin-2 (MCOLN2) restricts S. Typhi intracellular replication through magnesium deprivation. Our results reveal natural diversity in Mg2+ limitation as a key component of nutritional immunity against S. Typhi. One-Sentence SummaryHuman immune cells genetically vary in their ability to use magnesium deprivation to restrict growth of the typhoid fever bacterium.

genetics↗

bioRxiv2018

The transcription factors TFEB and TFE3 link the FLCN-AMPK signaling axis to innate immune response and pathogen resistance

TFEB and TFE3 are transcriptional regulators of the innate immune response, but the mechanisms regulating their activation upon pathogen infection are poorly elucidated. Using C. elegans and mammalian models, we report that the master metabolic modulator 5-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN) act upstream of TFEB/TFE3 in the innate immune response, independently of the mTORC1 signaling pathway. In nematodes, loss of FLCN or overexpression of AMPK conferred pathogen resistance via activation of TFEB/TFE3-dependent antimicrobial genes, while ablation of total AMPK activity abolished this phenotype. Similarly, in mammalian cells, loss of FLCN or pharmacological activation of AMPK induced TFEB/TFE3-dependent pro-inflammatory cytokine expression. Importantly, a rapid reduction in cellular ATP levels in murine macrophages was observed upon lipopolysaccharide (LPS) treatment accompanied by an acute AMPK activation and TFEB nuclear localization. These results uncover an ancient, highly conserved and pharmacologically actionable mechanism coupling energy status with innate immunity.

immunology↗

bioRxiv2018

Lysosome enlargement during inhibition of the lipid kinase PIKfyve proceeds through lysosome coalescence

Lysosomes receive and degrade cargo from endocytosis, phagocytosis and autophagy. They also play an important role in sensing and instructing cells on their metabolic state. The lipid kinase PIKfyve generates phosphatidylinositol-3,5-bisphosphate to modulate lysosome function. PIKfyve inhibition leads to impaired degradative capacity, ion dysregulation, abated autophagic flux, and a massive enlargement of lysosomes. Collectively, this leads to various physiological defects including embryonic lethality, neurodegeneration and overt inflammation. While being the most dramatic phenotype, the reasons for lysosome enlargement remain unclear. Here, we examined whether biosynthesis and/or fusion-fission dynamics contribute to swelling. First, we show that PIKfyve inhibition activates TFEB, TFE3 and MITF enhancing lysosome gene expression. However, this did not augment lysosomal protein levels during acute PIKfyve inhibition and deletion of TFEB and/or related proteins did not impair lysosome swelling. Instead, PIKfyve inhibition led to fewer but enlarged lysosomes, suggesting that an imbalance favouring lysosome fusion over fission causes lysosome enlargement. Indeed, conditions that abated fusion curtailed lysosome swelling in PIKfyve-inhibited cells.\n\nSummary statementPIKfyve inhibition causes lysosomes to coalesce, resulting in fewer, enlarged lysosomes. We also show that TFEB-mediated lysosome biosynthesis does not contribute to swelling.

cell biology↗