4 research outputs found
Sexual Dimorphism in Bidirectional Sr-Mitochondria Crosstalk in Ventricular Cardiomyocytes
Calcium transfer into the mitochondrial matrix during sarcoplasmic reticulum (SR) Ca2+ release is essential to boost energy production in ventricular cardiomyocytes (VCMs) and match increased metabolic demand. Mitochondria from female hearts exhibit lower mito-[Ca2+] and produce less reactive oxygen species (ROS) compared to males, without change in respiration capacity. We hypothesized that in female VCMs, more efficient electron transport chain (ETC) organization into supercomplexes offsets the deficit in mito-Ca2+ accumulation, thereby reducing ROS production and stress-induced intracellular Ca2+ mishandling. Experiments using mitochondria-targeted biosensors confirmed lower mito-ROS and mito-[Ca2+] in female rat VCMs challenged with β-adrenergic agonist isoproterenol compared to males. Biochemical studies revealed decreased mitochondria Ca2+ uniporter expression and increased supercomplex assembly in rat and human female ventricular tissues vs male. Importantly, western blot analysis showed higher expression levels of COX7RP, an estrogen-dependent supercomplex assembly factor in female heart tissues vs males. Furthermore, COX7RP was decreased in hearts from aged and ovariectomized female rats. COX7RP overexpression in male VCMs increased mitochondrial supercomplexes, reduced mito-ROS and spontaneous SR Ca2+ release in response to ISO. Conversely, shRNA-mediated knockdown of COX7RP in female VCMs reduced supercomplexes and increased mito-ROS, promoting intracellular Ca2+ mishandling. Compared to males, mitochondria in female VCMs exhibit higher ETC subunit incorporation into supercomplexes, supporting more efficient electron transport. Such organization coupled to lower levels of mito-[Ca2+] limits mito-ROS under stress conditions and lowers propensity to pro-arrhythmic spontaneous SR Ca2+ release. We conclude that sexual dimorphism in mito-Ca2+ handling and ETC organization may contribute to cardioprotection in healthy premenopausal females
A Keleti-Bodrog mentesĂtett Ă©s nem mentesĂtett rĂ©szĂ©nek összehasonlĂtĂł kĂ©miai elemzĂ©se
Mára a felszĂn alatti Ă©s a felszĂn feletti vizek minĹ‘sĂ©ge Ă©s mennyisĂ©ge globális problĂ©mává nĹ‘tte ki magát az emberi gondatlanság miatt. Fontosnak tartom vizeink vĂ©delmĂ©t, hiszen a Föld Ă©desvĂzkĂ©szlete korlátozott mennyisĂ©gben áll rendelkezĂ©sĂĽnkre. A Bodrogközben találhatĂł a Keleti-Bodrog elnevezĂ©sű holtmeder, ahol a vizsgálataimat vĂ©geztem. A meder kĂĽlönlegessĂ©ge abban rejlik, hogy az 1970-es Ă©vekben vĂ©grehajtott töltĂ©skorrekciĂł keretĂ©ben kettĂ©vágták, ezáltal az egyik rĂ©szĂ©t teljesen elvágták a BodrogtĂłl. Ezt az oldalt neveztĂĽk el a Keleti-Bodrog mentesĂtett rĂ©szĂ©nek, mĂg a másikat, ahol a folyĂłval valĂł kapcsolat a mai napig fennáll, nem mentesĂtettnek. Ez a dolgozat azzal a cĂ©llal kĂ©szĂĽlt, hogy összehasonlĂtsam a Keleti-Bodrog mentesĂtett Ă©s nem mentesĂtett rĂ©szĂ©t.BSc/BABiolĂłgiag
Koleszterin hatása a Kv1.2 feszültségfüggő kálium csatornára
Jelen tanulmányban azt vizsgáltuk, hogy hogyan mĂłdosĂtja a feszĂĽltsĂ©gfĂĽggĹ‘ Kv1.2 ioncsatornák működĂ©sĂ©t a membrán koleszterintartalmának növelĂ©se. A sejtmembrán koleszterin tartalmát genetikai faktorok, az Ă©trend, kĂĽlönbözĹ‘ betegsĂ©gek Ă©s gyĂłgyszerek szabályozzák, a Kv csatornák pedig szĂ©les körben elterjedtek gyakorlatilag az összes szövettĂpusban. Ezen ismeretek tekintetĂ©ben nyilvánvalĂł, hogy a közöttĂĽk lĂ©vĹ‘ interakciĂł rĂ©szletes feltĂ©rkĂ©pezĂ©se rendkĂvĂĽl fontos: hogy milyen tĂpusĂş csatornák Ă©rintettek Ă©s milyen mĂ©rtĂ©kben befolyásolja működĂ©sĂĽket a membrán koleszterin tartalmának változása, egyes betegsĂ©gek tĂĽneteinek vagy gyĂłgyszerek mellĂ©khatásainak jobb megĂ©rtĂ©sĂ©hez vezethet.MSc/MABiolĂłgusG
MCU overexpression evokes disparate dose-dependent effects on mito-ROS and spontaneous Ca\u3csup\u3e2 Ăľ\u3c/sup\u3e release in hypertrophic rat cardiomyocytes
Cardiac dysfunction in heart failure (HF) and diabetic cardiomyopathy (DCM) is associated with aberrant intracellular Ca2 Ăľ handling and impaired mitochondrial function accompanied with reduced mitochondrial calcium concentration (mito-[Ca2 Ăľ ]). Pharmacological or genetic facilitation of mito-Ca2 Ăľ uptake was shown to restore Ca2 Ăľ transient amplitude in DCM and HF, improving contractility. However, recent reports suggest that pharmacological enhancement of mito-Ca2 Ăľ uptake can exacerbate ryanodine receptor-mediated spontaneous sarcoplasmic reticulum (SR) Ca2 Ăľ release in ventricular myocytes (VMs) from diseased animals, increasing propensity to stress-induced ventricular tachyarrhythmia. To test whether chronic recovery of mito-[Ca2 Ăľ ] restores systolic Ca2 Ăľ release without adverse effects in diastole, we overexpressed mitochondrial Ca2 Ăľ uniporter (MCU) in VMs from male rat hearts with hypertrophy induced by thoracic aortic banding (TAB). Measurement of mito-[Ca2 Ăľ ] using genetic probe mtRCamp1h revealed that mito-[Ca2 Ăľ ] in TAB VMs paced at 2 Hz under b-adrenergic stimulation is lower compared with shams. Adenoviral 2.5-fold MCU overexpression in TAB VMs fully restored mito-[Ca2 Ăľ ]. However, it failed to improve cytosolic Ca2 Ăľ handling and reduce proarrhythmic spontaneous Ca2 Ăľ waves. Furthermore, mitochondrial-targeted genetic probes MLS-HyPer7 and OMM-HyPer revealed a significant increase in emission of reactive oxygen species (ROS) in TAB VMs with 2.5-fold MCU overexpression. Conversely, 1.5-fold MCU overexpression in TABs, that led to partial restoration of mito-[Ca2 Ăľ ], reduced mitochondria-derived reactive oxygen species (mito-ROS) and spontaneous Ca2 Ăľ waves. Our findings emphasize the key role of elevated mito-ROS in disease-related proarrhythmic Ca2 Ăľ mishandling. These data establish nonlinear mito-[Ca2 Ăľ ]/mito-ROS relationship, whereby partial restoration of mito-[Ca2 Ăľ ] in diseased VMs is protective, whereas further enhancement of MCU-mediated Ca2 Ăľ uptake exacerbates damaging mito-ROS emission