Biology subjects

Amado, L.

Publications and source records attributed to Amado, L..

4 recordsLinked to original sources

bioRxiv2024

Pex3 promotes formation of peroxisome-peroxisome and peroxisome-lipid droplet contact sites

Peroxisomes are ubiquitous organelles that mediate central metabolic functions, such as fatty acid {beta}-oxidation, as well as diverse tissue- and organism-specific processes. Membrane contact sites, regions of close apposition with other organelles for direct communication, are central to several aspects of their life cycle. Pex3 is a conserved multifunctional peroxisomal transmembrane protein involved in the insertion of peroxisomal membrane proteins, in pexophagy, and in the formation of membrane contact sites. Here, we show that elevated Pex3 levels in Saccharomyces cerevisiae induce the formation of peroxisome clusters surrounded by lipid droplets, mediated by peroxisome-peroxisome and peroxisome-lipid droplet contact sites. This clustering occurs independently of Pex3 partners in other processes, Pex19, Inp1, and Atg36. The cytosolic domain of Pex3 binds peroxisomes, suggesting a direct role in homotypic contact site formation. Lipid droplet-peroxisome contact sites require the lipid droplet-localized triacylglycerol lipase Tgl4, which is enriched along with other lipases at this interface. Pex3 overexpression in Drosophila melanogaster similarly alters peroxisome and lipid droplet morphology and promotes contact site formation. Together, our results offer novel molecular insights into homotypic peroxisome contact sites and peroxisome-lipid droplet contact sites across species.

cell biology↗

bioRxiv2024

Type I TARPs regulate Kv7.2 potassium channels andsusceptibility to seizures

The M-current is a low-threshold potassium current that modulates neuronal excitability and suppresses repetitive firing. However, the mechanisms regulating M-channel function remain unclear. We identified type I Transmembrane AMPA receptor Regulatory Proteins (TARPs) as M-channel Kv7.2 subunit interactors in cortical neurons, with their interaction increasing upon neuronal depolarization. Co-expression of TARPs with Kv7.2 increased channel surface expression and Kv7.2-mediated currents, while disrupting TARP-{gamma}2 expression in neurons perturbed dendritic Kv7.2 nano-clusters and decreased M-currents. Knock-in mice with an intellectual disability-associated TARP-{gamma}2 variant showed reduced hippocampal M-currents and increased seizure susceptibility, indicating that disrupting TARP-{gamma}2 regulation of Kv7.2-M-channels is epileptogenic. These findings show that TARP-{gamma}2, a synaptic protein crucial for excitatory transmission, also controls intrinsic excitability via M-channels. This discovery provides a link between synaptic transmission and neuronal excitability, with implications for disease, as the interplay between synaptic and intrinsic plasticity is pivotal to how the brain adapts to varying input signals. HighlightsO_LIType I TARPs bind to Kv7.2-M-channels and enhance Kv7.2-mediated currents. C_LIO_LITARP-{gamma}2 governs the neuronal nano-organization and function of Kv7.2 channels. C_LIO_LIIntellectual disability-associated TARP-{gamma}2 variant impairs M-currents and facilitates seizures. C_LIO_LIType I TARPs can serve as molecular integrators of synaptic and intrinsic excitability. C_LI

neuroscience↗

bioRxiv2024

Cell-surface receptor-mediated regulation of synaptic organelle distribution controls dendritic spine maturation

The spine apparatus (SA), an endoplasmic reticulum-related organelle present in a subset of mature dendritic spines, plays a key role in postsynaptic development and has been implicated in various neurological disorders. However, the molecular mechanisms that dictate SA localization at selected synapses remain elusive. Here, we identify a postsynaptic signaling complex comprising the GPCR-like receptor GPR158 and a largely uncharacterized phospholipase C (PLC), PLCXD2, that controls SA abundance. Sparse genetic manipulations in vivo demonstrate that in the absence of GPR158, unrestrained PLCXD2 activity impedes postsynaptic SA incorporation and hampers dendritic spine maturation. Finally, we show that extracellular heparan sulfate proteoglycan (HSPG) binding modulates the GPR158-PLCXD2 interaction. Together, our findings reveal how a postsynaptic receptor signaling complex regulates the local lipid microenvironment to control SA abundance required for the proper maturation of dendritic spines.

neuroscience↗

bioRxiv2023

Yeast TLDc domain-containing proteins control assembly and subcellular localization of the V-ATPase

Yeast vacuoles, equivalent to lysosomes in other eukaryotes, are important acidic degradative organelles as well as storage compartments and signaling hubs. To perform these functions, they rely on important protein complexes, including the V-ATPase, responsible for organelle acidification. In this study, we used cross-linking mass spectrometry to characterize the protein complexes of isolated vacuoles. We were able to detect many known protein-protein interactions, including known protein complexes, as well as undescribed ones. Among these, we identified the uncharacterized TLDc domain-containing protein Rtc5 as a novel interactor of the V-ATPase. We show that Rtc5 localizes to the vacuole membrane depending on N-myristoylation and on its interactions with the V-ATPase. We further analyzed the influence of this protein, and the second yeast TLDc domain-containing protein, Oxr1, on V-ATPase function. We find that both Rtc5 and Oxr1 promote the disassembly of the vacuolar V-ATPase in vivo, counteracting the role of the assembly chaperone, the RAVE complex. Finally, Oxr1 is necessary for the retention in the late Golgi complex of an organelle-specific subunit of the V-ATPase. Collectively, our results shed light on the in vivo roles of yeast TLDc domain-containing proteins in relation to the V-ATPase, highlighting the multifaceted regulation of this crucial protein complex.

cell biology↗