Biology subjects

Paolocci, N.

Publications and source records attributed to Paolocci, N..

8 recordsLinked to original sources

bioRxiv2024

ATP Citrate Lyase Supports Cardiac Function and NAD+/NADH Balance And Is Depressed in Human Heart Failure

BackgroundATP-citrate lyase (ACLY) converts citrate into acetyl-CoA and oxaloacetate in the cytosol. It plays a prominent role in lipogenesis and fat accumulation coupled to excess glucose, and its inhibition is approved for treating hyperlipidemia. In RNAseq analysis of human failing myocardium, we found ACLY gene expression is reduced; however the impact this might have on cardiac function and/or metabolism has not been previously studied. As new ACLY inhibitors are in development for cancer and other disorders, such understanding has added importance. MethodsCardiomyocytes, ex-vivo beating hearts, and in vivo hearts with ACLY inhibited by selective pharmacologic (BMS303141, ACLYi) or genetic suppression, were studied. Regulation of ACLY gene/protein expression, and effects of ACLYi on function, cytotoxicity, tricarboxylic acid (TCA)-cycle metabolism, and redox and NAD+/NADH balance were assessed. Mice with cardiac ACLY knockdown induced by AAV9-acly-shRNA or cardiomyocyte tamoxifen-inducible Acly knockdown were studied. ResultsAcly gene expression was reduced more in obese patients with heart failure and preserved EF (HFpEF) than HF with reduced EF. In vivo pressure-overload and in vitro hormonal stress increased ACLY protein expression, whereas it declined upon fatty-acid exposure. Acute ACLYi (1-hr) dose-dependently induced cytotoxicity in adult and neonatal cardiomyocytes, and caused substantial reduction of systolic and diastolic function in myocytes and ex-vivo beating hearts. In the latter, ATP/ADP ratio also fell and lactate increased. U13C-glucose tracing revealed an ACLY-dependent TCA-bypass circuit in myocytes, where citrate generated in mitochondria is transported to the cytosol, metabolized by ACLY and then converted to malate to re-enter mitochondria, bypassing several NADH-generating steps. ACLYi lowered NAD+/NADH ratio and restoring this balance ameliorated cardiomyocyte toxicity. Oxidative stress was undetected with ACLYi. Adult hearts following 8-weeks of reduced cardiac and/or cardiomyocyte ACLY downregulation exhibited ventricular dilation and reduced function that was prevented by NAD augmentation. Cardiac dysfunction from ACLY knockdown was worse in hearts subjected to sustained pressure-overload, supporting a role in stress responses. ConclusionsACLY supports normal cardiac function through maintenance of the NAD+/NADH balance and is upregulated by hemodynamic and hormonal stress, but depressed by lipid excess. ACLY levels are most reduced in human HFpEF with obesity potentially worsening cardio-metabolic reserve.

molecular biology↗

bioRxiv2023

Spatial analysis of NOS2 and COX2 interaction with T-effector cells reveals immunosuppressive landscapes associated with poor outcome in ER- breast cancer patients

Multiple immunosuppressive mechanisms exist in the tumor microenvironment that drive poor outcomes and decrease treatment efficacy. The co-expression of NOS2 and COX2 is a strong predictor of poor prognosis in ER- breast cancer and other malignancies. Together, they generate pro-oncogenic signals that drive metastasis, drug resistance, cancer stemness, and immune suppression. Using an ER- breast cancer patient cohort, we found that the spatial expression patterns of NOS2 and COX2 with CD3+CD8+PD1- T effector (Teff) cells formed a tumor immune landscape that correlated with poor outcome. NOS2 was primarily associated with the tumor-immune interface, whereas COX2 was associated with immune desert regions of the tumor lacking Teff cells. A higher ratio of NOS2 or COX2 to Teff was highly correlated with poor outcomes. Spatial analysis revealed that regional clustering of NOS2 and COX2 was associated with stromal-restricted Teff, while only COX2 was predominant in immune deserts. Examination of other immunosuppressive elements, such as PDL1/PD1, Treg, B7H4, and IDO1, revealed that PDL1/PD1, Treg, and IDO1 were primarily associated with restricted Teff, whereas B7H4 and COX2 were found in tumor immune deserts. Regardless of the survival outcome, other leukocytes, such as CD4 T cells and macrophages, were primarily in stromal lymphoid aggregates. Finally, in a 4T1 model, COX2 inhibition led to a massive cell infiltration, thus validating the hypothesis that COX2 is an essential component of the Teff exclusion process and, thus, tumor evasion. Our study indicates that NOS2/COX2 expression plays a central role in tumor immunosuppression. Our findings indicate that new strategies combining clinically available NOS2/COX2 inhibitors with various forms of immune therapy may open a new avenue for the treatment of aggressive ER- breast cancers.

cancer biology↗

bioRxiv2023

Male violence disrupts estrogen receptor β signaling in the female hippocampus

Women are the main target of intimate partner violence (IPV), which is escalating worldwide. Mechanisms subtending IPV-related disorders, such as anxiety, depression and PTSD, remain unclear. We employed a mouse model molded on an IPV scenario (male vs. female prolonged violent interaction) to unearth the neuroendocrine alterations triggered by an aggressive male mouse on the female murine brain. Experimental IPV (EIPV) prompted marked anxiety-like behavior in young female mice, coincident with high circulating/cerebral corticosterone levels. The hippocampus of EIPV-inflicted female animals displayed neuronal loss, reduced BrdU-DCX-positive nuclei, decreased mature DCX-positive cells, and diminished dendritic arborization level in the dentate gyrus (DG), features denoting impaired neurogenesis and neuronal differentiation. These hallmarks were associated with marked down-regulation of estrogen receptor {beta} (ER{beta}) density in the hippocampus, especially in the DG and dependent prosurvival ERK signaling. Conversely, ER expression was unchanged. After EIPV, the DG harbored lowered local BDNF pools, diminished TrkB phosphorylation, and elevated glucocorticoid receptor phosphorylation. In unison, ER{beta} KO mice had heightened anxiety-like behavior and curtailed BDNF levels at baseline, despite enhanced circulating estradiol levels, while dying prematurely during EIPV. Thus, reiterated male-to-female violence jeopardizes hippocampal homeostasis in the female brain, perturbing ER{beta}/BDNF signaling, thus instigating anxiety and chronic stress.

neuroscience↗

bioRxiv2023

Ischemia/Reperfusion Injury and Oxidative Stress Impair Cardiac Desmin Proteostasis

BackgroundThough acute mortality by myocardial infarction (MI) has declined in past decades, MI still represents one of the leading causes of heart failure (HF) development. We recently demonstrated the accumulation of toxic desmin aggregates in patients with HF of ischemic origin. Since desmin aggregates are toxic for the heart we aimed to test whether their formation can be induced by oxidative stress as a proxy for reperfusion injury, as well as addressing the effects of therapeutic strategies aimed at reducing desmin aggregation with cardiac oxidative stress. Methods and ResultsWe demonstrate here that oxidative stress is able to induce desmin aggregation, acutely, in a cell-specific and dose-dependent fashion. We also show that elevation of O-linked {beta}-N-acetylglucosamine (O-GlcNAc) prior to or after oxidative stress reduces the formation of toxic desmin aggregates and its pro-aggregating desmin post-translational modifications (PTM). In addition, we show for the first time a role for the transmembrane protease serine 13 (TMPRSS13) with desmin cleavage in response to oxidative stress while desmins single cysteine plays a protective role from I/R injury, which is independent of gain or loss of desmin function. ConclusionsThe proliferation of desmin PTM-forms (i.e., proteoforms) and its aggregation hallmark acute and chronic cardiac stress and result in both loss of and gain of desmin function. We report here two novel mechanisms that could be targeted for therapy to preserve desmin homeostasis and cardiac function in the acute settings of oxidative stress and reperfusion injury.

biochemistry↗

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↗

bioRxiv2021

Cardiac-generated sympathetic stress alters heart-brain communication, reduces EEG-theta activity, and increases locomotor behavior

The central nervous system modulates heart function on a beat-to-beat basis via increasingly understood mechanisms. Conversely, whether and how humoral/functional cardiac variations shape brain activity and adaptive behavior remains unclear. This study shows that mice overexpressing adenylyl cyclase type 8 in myocytes (TGAC8), characterized by persistently elevated heart rate/contractility, also display increased locomotion. This effect is sustained by enhanced gamma rhythms, as evidenced by simultaneous behavioral and EEG/ECG monitoring. These changes are specific because they are not paralleled by other modifications, such as heightened anxiety-like behavior. In unison, TGAC8 mice hippocampus exhibits upregulated GABA-A receptors, whose activation chiefly accounts for gamma activity generation. Moreover, the Granger causality analysis between ECG and EEG attests to the causal involvement of the autonomic component of the heartbeat in shaping EEG gamma oscillations in a bottom-up modality. Mechanistically, TGAC8 harbors elevated circulating dopamine/DOPA levels of cardiac origin and upregulated hippocampal D5 dopamine receptor levels. In synergy with the GABA-A receptor, D5 activation favors hippocampal inhibitory currents that drive EEG gamma oscillations. These studies, therefore, inform how heart-initiated functional and/or humoral modifications reverberate back to the brain to modulate specific primary adaptive responses, such as locomotion. SignificanceThe brain is continuously aware of the functional status of many bodily organs, modulating, for instance, the hearts activity beat-by-beat. Conversely, how cardiac activity modifications impact brain function and behavior is less understood. We disclose that augmenting myocyte adenyl cyclase 8 (AC8) activity in mice increases their locomotion. Elevated cardiac AC8 levels lead to higher circulating dopamine and DOPA, hormones crucially involved in movement control, and increased expression of the hippocampuss GABA-A and D5 receptors; the activation of the latter modifies hippocampal gamma oscillations shaping locomotor activity. Thus, the brain interprets changes in myocardial AC8 activity as a "sustained exercise-like" situation and responds by activating areas commanding to increase locomotion.

physiology↗

bioRxiv2021

Myocardial BDNF regulates cardiac bioenergetics through the transcription factor Yin Yang 1

Circulating Brain-derived Neurotrophic Factor (BDNF) is markedly decreased in heart failure patients. Both BDNF and its receptor, Tropomyosin Related Kinase Receptor (TrkB), are expressed in cardiomyocytes, however the role of myocardial BDNF signaling in cardiac pathophysiology is poorly understood. We found that cardiac-specific TrkB knockout (cTrkB KO) mice displayed a blunted adaptive cardiac response to exercise, with attenuated upregulation of transcription factor networks controlling mitochondrial biogenesis/metabolism, including Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1). The cTrkB KO mice developed an exacerbated heart failure progression with transaortic constriction. The downregulation of PGC-1 in cTrkB KO mice exposed to exercise or TAC resulted in decreased cardiac energetics. We further unraveled that BDNF induces PGC-1 upregulation and bioenergetics through a novel signaling pathway, the pleiotropic transcription factor Yin Yang 1 (YY1). Taken together, our findings suggest that myocardial BDNF plays a critical role in regulating cellular energetics in the cardiac stress response.

molecular biology↗

bioRxiv2020

UPREGULATION OF SUPEROXIDE DISMUTASE 2 BY ASTROCYTES IN THE SIV/MACAQUE MODEL OF HIV-ASSOCIATED NEUROLOGIC DISEASE

HIV-associated neurocognitive disorders (HAND) remain prevalent despite implementation of antiretroviral therapy (ART). Development of HAND is linked to mitochondrial dysfunction and oxidative stress in the brain; therefore, upregulation of antioxidant defenses is critical to curtail neuronal damage. Superoxide dismutase 2 (SOD2) is a mitochondrial antioxidant enzyme essential for maintaining cellular viability. We hypothesized that SOD2 was upregulated during retroviral infection. Using a simian immunodeficiency virus (SIV)-infected macaque model of HIV, quantitative PCR showed elevated SOD2 mRNA in cortical gray (GM, 7.6-fold for SIV vs. uninfected) and white matter (WM, 77-fold for SIV vs. uninfected) during SIV infection. Further, SOD2 immunostaining was enhanced in GM and WM from SIV-infected animals. Double immunofluorescence labeling illustrated that SOD2 primarily co-localized with astrocyte marker glial fibrillary acidic protein (GFAP) in SIV-infected animals. Interestingly, in ART-treated SIV-infected animals, brain SOD2 RNA levels were similar to uninfected animals. Additionally, using principal component analysis in a transcriptomic approach, SOD2 and GFAP expression separated SIV-infected from uninfected brain tissue. Projection of these data into a HIV dataset revealed similar expression changes, thereby validating the clinical relevance. Together, our findings suggest that novel SOD2-enhancing therapies may delay the onset or reduce severity of HAND seen in ART-treated HIV-infected patients.

neuroscience↗