Biology subjects

Yarishkin, O.

Publications and source records attributed to Yarishkin, O..

5 recordsLinked to original sources

bioRxiv2025

PIEZO channels link mechanical forces to uterine contractions in parturition

AbstractMechanical forces are extensively involved in pregnancy and parturition, but their precise roles and mechanisms remain poorly understood. Here, we identify mechanically activated ion channels PIEZO1 and PIEZO2 as key mechanotransducers required for labor progression. Genetic deletion of Piezo1 and Piezo2 in mice resulted in weakened uterine contractions and severe parturition defects. Tissue-specific knockouts revealed that deletion in either the uterus or sensory neurons alone caused modest defects, whereas combined loss significantly impaired labor, demonstrating additive effects. Single-nuclei sequencing showed that loss of PIEZO reduced expression of connexin43 (Gja1), a gap junction protein in uterine smooth muscle cells, suggesting a mechanistic link to impaired contraction. These findings highlight the critical role of PIEZO channels in mechanotransduction during parturition and suggest therapeutic targets for labor dysfunction.

physiology↗

bioRxiv2025

Corticosteroids elevate intraocular pressure through suppression of TREK-1 signaling

Clinicians are often forced into the dilemma of whether to battle ocular inflammation or preserve vision imperiled by elevated intraocular pressure (IOP). Anti-inflammatory treatments utilizing glucocorticosteroid regimens may induce glaucoma by chronically elevating IOP via increased trabecular meshwork (TM) resistance to the flow of aqueous humor, but it is not known whether pressure transduction itself is impacted by steroids and how changes in TM mechanosignaling affect conventional outflow resistance and IOP. To address this, we investigated the role of TREK-1 (TWIK-related potassium channel-1), a mechanosensitive K+ channel, in regulation of outflow facility, transmembrane signaling and dexamethasone (DEX)-induced ocular hypertension (OHT). The expression of tandem-pore potassium channels in mouse TM cells was dominated by Trek-1 (Kcnk2) mRNA, with residual expression of Traak, Tresk2 and Twik3 and vanishingly low levels of Task1 and Trek2. DEX suppressed Trek1 transcription by [~]80% but did not affect expression of Trpv4 and Piezo1 genes. Chronic DEX administration depolarized the membrane potential of TM cells and elevated IOP in mice whereas the selective TREK-1 agonist ML-402 lowered IOP in rodent OHT models. ML-402 doubled the outflow facility in perfused mouse eyes at all applied pressures and hyperpolarized DEX-treated TM cells. These in vitro, ex vivo and in vivo results implicate TREK-1 channels in homeostatic regulation of TM mechanosignaling, conventional outflow regulation and IOP homeostasis. Suppression of TREK-1 signaling by corticosteroids underlies OHT and could contribute to steroid glaucoma but this can be obviated by pharmacological stimulation of the channel with cornea-permeant ML-402 eye drops.

physiology↗

bioRxiv2024

Osmosensing in trabecular meshwork cells

Aqueous humor drainage from the anterior eye constitutes a key determinant of intraocular pressure (IOP) under homeostatic and pathological conditions. Swelling of the trabecular meshwork (TM) increases its flow resistance but the mechanisms that sense and transduce osmotic gradients remain poorly understood. We used optical molecular analyses, optical imaging and electrophysiology to investigate TM osmotransduction and its role in calcium and chloride homeostasis. Anisosmotic conditions elicited proportional changes in TM cell volume. Swelling, but not shrinking, evoked increases in intracellular calcium concentration [Ca2+]TM. Hypotonicity-evoked calcium signals were sensitive to HC067047, a selective blocker of TRPV4 channels, whereas the agonist GSK1016790A promoted swelling under isotonic conditions. TRPV4 inhibition partially suppressed hypotonicity-induced volume increases and reduced the magnitude of the swelling-induced membrane current, with a substantial fraction of the swelling-evoked current abrogated by Cl- channel antagonists DIDS and niflumic acid. The volume-sensing transcriptome of primary human TM cells showed expression of TRPV4, TRPM4, AQP1, and TMEMC3B genes. Cl- channel expression was dominated by ANO6 transcripts, auxiliary levels of ANO3, ANO7 and ANO10 and modest expression of LTTRC genes that encode volume-activated anion channels. Thus, TRPV4-mediated cation influx works with Cl- efflux to sense and respond to osmotic stress, potentially contributing to pathological swelling, calcium overload and intracellular signaling that could exacerbate functional disturbances in inflammatory disease and glaucoma.

physiology↗

bioRxiv2021

TRPM4 is required for calcium oscillations downstream from the stretch-activated TRPV4 channel

Transduction of mechanical information is influenced by physical, chemical and thermal cues but the molecular mechanisms through which transducer activation shapes temporal signaling remain underexplored. In the present study, electrophysiology, histochemistry and functional imaging were combined with gene silencing and heterologous expression to gain insight into calcium signaling downstream from TRPV4 (Transient Receptor Potential Vanilloid 4), a stretch-activated nonselective cation channel. We show that trabecular meshwork (TM) cells, which employ mechanotransduction to actively regulate intraocular pressure, respond to the TRPV4 agonist GSK1016790A with fluctuations in intracellular Ca2+ concentration ([Ca2+]i) and an increase in [Na+]i. ([Ca2+]i oscillations coincided with a monovalent cation current that was suppressed by BAPTA, Ruthenium Red and 9-phenanthrol, an inhibitor of TRPM4 (Transient Receptor Potential Melastatin 4) channels. Accordingly, TM cells expressed TRPM4 mRNA, protein at the expected 130-150 kDa and showed punctate TRPM4 immunoreactivity at the membrane surface. Genetic silencing of TRPM4 antagonized TRPV4-evoked oscillatory signaling whereas TRPV4 and TRPM4 co-expression in HEK-293 cells reconstituted the oscillations. Membrane potential recordings indicated that TRPM4-dependent oscillations required release of Ca2+ from internal stores. 9-phenanthrol did not affect the outflow facility in mouse eyes. Collectively, our results show that TRPV4 activity initiates dynamic calcium signaling in TM cells by stimulating TRPM4 channels and intracellular Ca2+ release. These findings provide insight into the complexity of membrane-cytosolic interactions during TRPV4 signaling and may foster strategies to promote homeostatic regulation and counter pathological remodeling within the conventional outflow pathway of the mammalian eye.

cell biology↗

bioRxiv2020

Mechanotransduction and dynamic outflow regulation in trabecular meshwork requires Piezo1 channels

Mechanosensitivity of the trabecular meshwork (TM) is a key determinant of intraocular pressure (IOP) yet our understanding of the molecular mechanisms that subserve it remains in its infancy. Here, we show that mechanosensitive Piezo1 channels modulate the TM pressure response via calcium signaling and dynamics of the conventional outflow pathway. Pressure steps evoked fast, inactivating cation currents and calcium signals that were inhibited by Ruthenium Red, GsMTx4 and Piezo1 shRNA. Piezo1 expression was confirmed by transcript and protein analysis, and by visualizing Yoda1-mediated currents and [Ca2+]i elevations in primary human TM cells. Piezo1 activation was obligatory for transduction of physiological shear stress and was coupled to reorganization of F-actin cytoskeleton and focal adhesions. The importance of Piezo1 channels as pressure sensors was shown by the GsMTx4 -dependence of the pressure-evoked current and conventional outflow function. We also demonstrate that Piezo1 collaborates with the stretch-activated TRPV4 channel, which mediated slow, delayed currents to pressure steps. Collectively, these results suggest that TM mechanosensitivity utilizes kinetically, regulatory and functionally distinct pressure transducers to inform the cells about force-sensing contexts. Piezo1-dependent control of shear flow sensing, calcium homeostasis, cytoskeletal dynamics and pressure-dependent outflow suggests a novel potential therapeutic target for treating glaucoma. Significance StatementTrabecular meshwork (TM) is a highly mechanosensitive tissue in the eye that regulates intraocular pressure through the control of aqueous humor drainage. Its dysfunction underlies the progression of glaucoma but neither the mechanisms through which TM cells sense pressure nor their role in aqueous humor outflow are understood at the molecular level. We identified the Piezo1 channel as a key TM transducer of tensile stretch, shear flow and pressure. Its activation resulted in intracellular signals that altered organization of the cytoskeleton and cell-extracellular matrix contacts, and modulated the trabecular component of aqueous outflow whereas another channel, TRPV4, mediated a delayed mechanoresponse. These findings provide a new mechanistic framework for trabecular mechanotransduction and its role in the regulation of fast fluctuations in ocular pressure, as well as chronic remodeling of TM architecture that epitomizes glaucoma.

physiology↗