Biology subjects

Ranek, M.

Publications and source records attributed to Ranek, M..

3 recordsLinked to original sources

bioRxiv2024

VERICIGUAT RESCUES cGMP PRODUCTION IN HUMAN AORTIC VASCULAR SMOOTH MUSCLE CELLS AND AUGMENTS VASORELAXATION IN AORTIC RINGS EXPOSED TO HIGH GLUCOSE

BackgroundNormal endothelial cell dependent vascular smooth muscle cell function is mediated by nitric oxide (NO), which stimulates soluble guanylyl cyclase (sGC) production of the second messenger, cyclic guanosine monophosphate (cGMP) leading to increased protein kinase G (PKG) activity and vascular smooth muscle relaxation. NO bioavailability is impaired in inflammatory settings, such as high glucose (HG). We examined whether the direct sGC sensitizer/stimulator vericiguat, augments cGMP production in human vascular smooth muscle cells (HVSMC) exposed to high glucose and explored its effect on vasorelaxation. MethodsAortic HVSMCs were exposed to HG for 24h. In the treatment group, cells also received 1uM vericiguat for 24h. After incubation, cGMP and PKG activity were measured. Additionally, thoracic murine aortas were exposed to HG or to normal glucose (NG) control. The rings were then placed in an organ chamber bath and dose response curves to increasing doses of acetylcholine (Ach) and sodium nitroprusside were constructed for three groups: control (normal glucose), HG alone, and HG + vericiguat. ResultsHVSMCs exposed to HG produced significantly less cGMP than those exposed to NG. cGMP production in the presence of HG was rescued when treated with 1uM vericiguat. Additionally, PKG activity was impaired in the presence of HG and enzyme activity was restored with vericiguat. In isolated mouse aortic rings, ACh mediated relaxation was impaired following treatment with HG, but was improved when a HG group was treated with vericiguat. ConclusionsThe sGC sensitizer/stimulator vericiguat restored cGMP production and PKG activity in the setting of HG. Vericiguat enhanced ACh-mediated vasorelaxation in the setting of HG. The findings suggest clinical studies are warranted to investigate the potential of sGC sensitization/stimulation as a therapeutic intervention to improve vascular endothelial-dependent function that is impaired in pro-inflammatory settings that are associated with the development of atherosclerotic disease.

molecular biology↗

bioRxiv2023

Protective concentric cardiac proteostasis adaptations to chronic cAMP-stress at young ages wanes in advanced age leading to accelerated cardiac aging

Dysregulated proteostasis, leading to accumulation of misfolded proteins, electron-dense aggregates (lipofuscin, LF), preamyloid oligomers (PAOs), and proteotoxic stress is a hallmark of aging. We investigated how efficiently proteostatic adaptations to chronic cardiac cyclic adenosine monophosphate (cAMP)-dependent stress change with aging in mice harboring marked, cardiac-specific over-expression of adenylyl cyclase VIII (TGAC8). We assessed protein quality control (PQC) mechanisms: ubiquitin proteasome system (UPS), autophagic flux via macroautophagy, and mitophagy in left ventricles (LVs) of TGAC8 and wild type littermates (WT) at 3-4 months and at 17-21 months of age. At 3-4 months of age TGAC8 mice exhibited markers of increased autophagic flux, measured by levels of microtubule-associated protein 1 light chain 3 (LC3), p62, and their phospho-forms in TGAC8 LV; cathepsin L1 activity was also significantly increased. In addition, canonical mitophagy signaling was enhanced, as receptors PARKIN, p62S405 and p62S351 were all upregulated, confirming a more efficient proteostasis in TGAC8 at 3-4 months vs WT. In advanced age, however, the PQC mechanisms were overwhelmed by proteotoxic stress, manifested in insufficient proteasome activity and an unbalanced autophagic flux (accelerated for markers such as LC3A in the context of a slower overall flux), leading to an increase in the accumulation of protein aggregates (increased ratio of insoluble/soluble protein fractions). Although both canonical (PARKIN, p62S405 and p62S351 receptors) and non-canonical (FKBP8 receptor) mitophagy signaling were upregulated in advanced age in TGAC8, mitophagy was markedly impaired and mitochondrial dysfunction increased. Accumulation of LF bodies, of brownish-to-black pigments, and of LC3+ and p62+-inclusions of aberrant sizes, of desmin cardiac preamyloid oligomers (PAOs) and of cleaved desmin, tagged for ubiquitination, were all increased in TGAC8 compared to young TGAC8. In contrast, the rate of protein synthesis and levels of soluble aggregates were reduced in aged vs young TGAC8, a sign of "normal" aging. Thus, increased proteostatic mechanisms maintain cardiac health in TGAC8 in youth (3-4 months), but long-term exposure to chronic cardiac stress, imposed by sustained activation of the AC/cAMP/PKA/Ca2+ signaling axis, results in severely dysregulated proteostasis in TGAC8 vs WT mice, associated with proteostatic insufficiency and increased cardiomyopathy that leads to accelerated cardiac aging. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC="FIGDIR/small/553128v3_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@73ff64org.highwire.dtl.DTLVardef@1842158org.highwire.dtl.DTLVardef@1a92684org.highwire.dtl.DTLVardef@1fe596_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

A Remarkable Adaptive Paradigm Of Heart Performance And Protection Emerges In Response To The Constitutive Challenge Of Marked Cardiac-Specific Overexpression Of Adenylyl Cyclase Type 8

Adult mice with cardiac-specific overexpression of adenylyl cyclase (AC) type VIII (TGAC8) adapt to an incessantly increased cAMP-induced cardiac workload ([~]30% increases in heart rate, ejection fraction and cardiac output) for up to a year without signs of heart failure or excessive mortality. Here we show that despite markedly increased cardiac work, classical cardiac hypertrophy markers were absent in TGAC8, total left ventricular (LV) mass was not increased: a reduced LV cavity volume in TGAC8 was encased by thicker LV walls harboring an increased number of small cardiac myocytes and a network of small interstitial non-cardiac myocytes, manifesting increased proliferation markers and compared to WT. Protein synthesis, proteosome activity, autophagy, and Nrf-2, Hsp90, ACC2 protein levels were increased in TGAC8, but LV ATP and phosphocreatine levels in vivo did not differ by genotype. 2,323 transcripts and 2,184 proteins identified in unbiased omics analyses, spanning a wide array of biological processes and molecular functions in numerous cellular compartments differed in TGAC8 vs WT; and over 250 canonical signaling pathways characteristic of adaptive survival circuitry of cancers, including PI3K and growth factor signaling, cytokine and T cell receptor signaling, immune responses, ROS scavenging, proliferation, protection from apoptosis, and nutrient sensing, were activated in TGAC8; and compared to WT there was a shift from fatty acid oxidation to increased aerobic glycolysis in the context of increased utilization of the pentose phosphate shunt and nucleotide synthesis. Thus, the adaptive paradigm, that becomes activated in the LV of TGAC8 in response to severe chronic, intense AC/PKA/Ca2+ signaling embodies many hallmarks of cancer.

physiology↗