Biology subjects

Vuchkovska, V.

Publications and source records attributed to Vuchkovska, V..

3 recordsLinked to original sources

bioRxiv2025

Polycystin-2 is cardioprotective against myocardial infarction by regulating the calcium-mediated ER stress response.

BackgroundPatients with autosomal polycystic kidney disease (ADPKD) have an increased risk and worsened outcomes for acute myocardial infarction (AMI), but the mechanism behind this is unknown. Polycystin 2 (PC2), the protein encoded by one of the two main genes mutated in ADPKD, is a calcium-permeant channel ubiquitously expressed; however, its role in cardiomyocytes remains poorly understood. One hallmark of AMI is ER stress, which PC2 is known to regulate adaptively; however, whether PC2 regulates ER stress in the ischemic heart is unknown. ObjectiveThis study investigates the mechanism by which PC2 regulates ER stress in myocardial ischemia. Methods and ResultsPC2 protein was increased in human ischemic heart failure samples and murine myocardial infarct samples, and it was enriched at ER-mitochondrial contact sites. Induction of myocardial infarction (MI) in cardiomyocyte-specific PC2-KO mice led to cardiac dysfunction and reduced PERK expression compared to control MI mice. ER stress induced by tunicamycin in vitro blunted PERK phosphorylation and subsequent CHOP upregulation in PC2 KO cells. Tunicamycin-induced ER stress resulted in a PC2-dependent ER calcium leak and mitochondrial calcium transients, along with increased mitochondrial function, all of which were decreased in PC2 KO cells. Moreover, PC2 KO cells after ER stress exhibited decreased mitochondrial membrane potential and increased apoptosis. Isolated WT cardiomyocytes exhibited increased diastolic calcium after acute ER stress induction and increased mitochondrial uptake, neither of which was seen in PC2 KO cells. Re-expression of full-length PC2 in vitro restored both the calcium leak and PERK phosphorylation in PC2 KO cells under ER stress, but not a pathological mutant PC2 D511V, which impairs ion channel activity. ConclusionsPC2 is upregulated during ER stress, where it localizes at ER-mitochondrial contact sites and acts as an ER calcium leak channel, thereby restoring cellular homeostasis during the adaptive phase of ER stress. PC2 provides cardioprotection during ischemic events by preventing maladaptive ER stress, which contributes to cardiac dysfunction. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=194 SRC="FIGDIR/small/668747v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@1e416d5org.highwire.dtl.DTLVardef@1971fd9org.highwire.dtl.DTLVardef@abeebcorg.highwire.dtl.DTLVardef@1c68f8d_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

Rbm45 Phylogenetics, Protein Domain Conservation, and Gene Architecture in Clade Metazoa

Mammalian Rbm45 is predominately expressed in neuronal tissue and is integral in brain development and neuronal differentiation under physiological conditions. Dysregulation of Rbm45 has been strongly associated with neurodegenerative disorders in humans and can drive hepatocellular carcinoma through reprogramming lipid metabolism. Intriguingly, Rbm45 is an ancient protein, evolutionarily conserved throughout metazoans, including in sponges which lack a nervous system. Curiously, the evolution of Rbm45 gene structure and protein domain conservation across kingdom Animalia is largely unknown. We performed phylogenetic analysis of Rbm45 nucleotide and amino acid sequences from 36 species representing 9 phyla: Porifera, Cnidaria, Priapulida, Mollusca, Brachiopoda, Arthropoda, Echinodermata, Hemichordata, and Chordata. While the tree from Rbm45 nucleotide sequence data resulted in clades Protostomia and Deuterostomia showing paraphyly, the phylogeny derived from Rbm45 amino acid sequence largely recapitulated known monophyletic relationships among metazoans. Human RBM45 protein structure includes three RNA-binding domains (RBD), a homo-oligomerization association (HOA) domain, a nuclear localization sequence (NLS), and a nuclear export sequence (NES). Multiple sequence alignment across the same 36 taxa used for phylogenetic analysis revealed conservation of all three RBDs, the HOA, and NLS; in contrast the NES was only detected in clade Craniata and not in clades Ambulacraria and Protostomia. Rbm45 gene structure analysis revealed increasing gene complexity concomitant with increasing evolutionary complexity. Rbm45 from non-bilaterian taxa had from 2 to 4 large exons, while bilaterian taxa had between 6 to17 small exons. These findings demonstrate that Rbm45 is an ancient, highly conserved gene among metazoans suggesting a function in a breadth of neural/sensory systems.

evolutionary biology↗

bioRxiv2023

TRiPPing the sensors: The osmosensing pathway of Polycystin 2

Mutations to polycystin-2 (PC2), a non-selective cation permeant transient receptor potential channel, results in polycystic kidney disease (PKD). Despite the disease relevance of PC2, the physiological agonist that activates PC2 has remained elusive. As one of the earliest symptoms in PKD is a urine concentrating deficiency, we hypothesized that shifts in osmolarity experienced by the collecting duct cells would activate PC2 and loss of PC2 would prevent osmosensing. We found that mice with inducible PC2 knocked out (KO) in renal tubules had dilute urine. Hyperosmotic stimuli induced a rise in endoplasmic reticulum (ER)-mediated cytosolic calcium which was absent in PC2 KO mice and PC2 KO cells. A pathologic point mutation that prevents ion flux through PC2 inhibited the calcium rise, pointing to the centrality of PC2 in the osmotic response. To understand how an extracellular stimulus activated ER-localized PC2, we examined microtubule-ER dynamics, and found that the osmotically induced calcium increase was preceded by microtubule destabilization. This was due to a novel interaction between PC2 and the microtubule binding protein MAP4 that tethers the microtubules to the ER. Finally, disruption of the MAP4-PC2 interaction prevented incorporation of the water channel aquaporin 2 following a hyperosmotic challenge, in part explaining the dilute urine. Our results demonstrate that MAP4-dependent microtubule stabilization of ER-resident PC2 is required for PC2 to participate in the osmosensing pathway. Moreover, osmolarity represents a bona fide physiological stimulus for ER-localized PC2 and loss of PC2 in renal epithelial cells impairs osmosensing ability and urine concentrating capacity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=92 SRC="FIGDIR/small/540007v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@1ddf689org.highwire.dtl.DTLVardef@164a89corg.highwire.dtl.DTLVardef@179d1dforg.highwire.dtl.DTLVardef@c1be99_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗