Biology subjects

Zorzano, A.

Publications and source records attributed to Zorzano, A..

9 recordsLinked to original sources

bioRxiv2025

Altered endothelial mitochondrial Opa1-related fusion in mouse amplifies age-associated vascular and kidney damages

BackgroundCardiovascular diseases are the major cause of death worldwide and their frequency increases with age in association with progressive kidney damages. Endothelial cells (ECs) are early affected in cardiovascular diseases. Although energy production in ECs involves glycolysis, endothelial mitochondria play a role in modulating cellular signalling. A reduction in fusion protein Opa1 level in ECs decreases the vascular response to flow and increased oxidative stress in perfused kidneys. Thus, we hypothesized that reduced Opa1 expression contributes to vascular aging. MethodsWe used male and female mice with ECs specific Opa1 knock-out (EC-Opa1), and littermate wild-type (EC-WT) mice aged 6 (young) and 20 months (old). Mesenteric resistance arteries (MRA) and kidneys were collected for vascular reactivity and Western-blot analysis. ResultsIn old EC-Opa1 mice blood urea was greater than in age-matched EC-WT mice and MRA showed hypercontractilty and reduced endothelium-dependent relaxation. In kidneys, the mitochondria fission protein Fis-1 and the peroxisome proliferator-activated receptor gamma coactivator-1 alpha (Pgc-1) were increase in old EC-Opa1 mice. The level of eNOS expression was greater in young EC-Opa1 mice and caveolin-1 expression greater in old EC-Opa1 mice. Moreover, in kidneys from EC-Opa1 old mice, NADPH-oxidase subunits gp91, p47 and p67 expression was greater than in age-matched EC-WT mice. No difference was observed between old and young EC-WT mice. ConclusionReduced mitochondrial fusion in mouse ECs altered mesenteric vascular reactivity and increased oxidative stress in aging kidneys. Thus, Opa1 might protect the vascular tree in target organs such as the kidney during aging.

physiology↗

bioRxiv2025

Fasting-induced hepatic gluconeogenesis is compromised in Anxa6-/- mice

Maintaining constant blood glucose levels is essential for energizing glucose-dependent tissues. During the fed state, insulin lowers elevated blood glucose, while in the fasted state, glucagon maintains blood glucose levels through hepatic stimulation of fatty acid oxidation, glycogenolysis, and gluconeogenesis (GNG). The liver plays a crucial role in these metabolic adaptations. Deregulation of GNG is a hallmark of type 2 diabetes mellitus (T2DM), driven by hepatic insulin resistance, elevated glucagon levels, and excess circulating free fatty acids. Despite normal insulin-sensitive control of glucose levels and effective glycogen mobilization, Anxa6 knockout (Anxa6-/-) mice display rapid hypoglycaemia during fasting. This metabolic disarrangement, in particular during the early stages of fasting is characterized by a low respiratory exchange ratio (RER) and increased lipid oxidation during the diurnal period, indicating a reliance on lipid oxidation due to hypoglycaemia. Elevated glucagon levels during fasting suggest deficiencies in GNG. Further analysis reveals that Anxa6-/- mice are unable to utilize alanine for hepatic GNG, highlighting a specific impairment in the glucose-alanine cycle in fasted Anxa6-/- mice, underscoring the critical role of ANXA6 in maintaining glucose homeostasis under metabolic stress. During fasting, slightly reduced expression levels of alanine aminotransferase 2 (Gpt2) and lactate dehydrogenase (Ldha2), enzymes converting alanine to pyruvate, and the hepatic alanine transporter SNAT4 might contribute to these observations in the Anxa6-/- mice. These findings identify that ANXA6 deficiency causes an inability to maintain glycolytic metabolism under fasting conditions due to impaired alanine-dependent GNG.

physiology↗

bioRxiv2024

Trajectory analysis of hepatic stellate cell differentiation reveals metabolic regulation of cell commitment and fibrosis

Defining the trajectory of cells during differentiation and disease offers the possibility to understand the mechanisms driving cell fate and identity. However, trajectories of human cells are largely unexplored. By investigating the proteome trajectory of iPSCs differentiation to hepatic stellate cells (dHSCs), we identified RORA as a key transcription factor governing the metabolic reprogramming of HSCs necessary for HSCs commitment, identity, and activation. Using RORA deficient iPSCs and pharmacologic interventions, we showed that RORA is required for mesoderm differentiation and prevents dHSCs activation by reducing the high energetic state of the cells. While RORA knockout mice had enhanced fibrosis, RORA agonists rescued multi- organ fibrosis in in vivo models. RORA expression was consistently found to be negatively correlated with liver fibrosis and HSCs activation markers in patients with liver disease. This study reveals that RORA regulates cell metabolic plasticity, crucial for mesoderm differentiation, pericyte quiescence, and fibrosis, influencing cell commitment and disease mechanisms. SummaryThis study describes the trajectory of induced pluripotent stem cells (iPSCs) differentiation to hepatic stellate cells (dHSCs). We identify RAR-related orphan receptor alpha (RORA) as a transcription factor essential for mesoderm commitment and dHSCs identity and fibrogenic activation by regulating metabolic plasticity.

cell biology↗

bioRxiv2023

The new signaling pathway ERK5/TP53INP2 sensitizes cancer cells to death-receptor agonists and Natural Killer cells

Death receptor ligand TRAIL is a promising cancer therapy due to its ability to selectively trigger extrinsic apoptosis in cancer cells. However, TRAIL-based therapies in humans have shown limitations, mainly due inherent or acquired resistance of tumor cells. To address this issue, current efforts are focussed on dissecting the intracellular signaling pathways involved in resistance to TRAIL, to identify strategies that sensitize cancer cells to TRAIL-induced cytotoxicity. In this work, we describe the oncogenic MEK5-ERK5 pathway as a critical regulator of cancer cell resistance to the apoptosis induced by death receptor ligands. Using 2D and 3D cell cultures and transcriptomic analyses, we show that ERK5 controls the proteostasis of TP53INP2, a protein necessary for full activation of caspase-8 activation in response to TNF, FasL or TRAIL. Mechanistically, ERK5 phosphorylates and induces ubiquitylation and proteasomal degradation of TP53INP2, resulting in cancer cell resistance to TRAIL. Concordantly, ERK5 inhibition or genetic deletion, by stabilizing TP53INP2, sensitizes cancer cells to the apoptosis induced by recombinant TRAIL and TRAIL/FasL expressed by Natural Killer cells. The MEK5-ERK5 pathway regulates cancer cell proliferation and survival, and ERK5 inhibitors have shown anticancer activity in preclinical models of solid tumors. Using endometrial cancer patient-derived xenograft organoids, we propose ERK5 inhibition as an effective strategy to sensitize cancer cells to TRAIL-based therapies and Natural Killer cells.

cancer biology↗

bioRxiv2022

Mitofusin-2 in nucleus accumbens D2-MSNs regulates social dominance and neuronal function

The nucleus accumbens (NAc) is a brain hub regulating motivated behaviors, including social competitiveness. Mitochondrial function in the NAc is critically implicated in the association between anxiety and social competitiveness, and the mitochondrial fusion protein mitofusin 2 (Mfn2) in NAc neurons has been shown to regulate anxiety-related behaviors. However, it remains unexplored whether accumbal Mfn2 levels also affect social behavior and whether Mfn2 actions in the emotional and social domain are driven by distinct cell types. Here, we found that subordinate-prone highly anxious rats show reduced accumbal Mfn2 levels and that Mfn2 overexpression promotes dominant behavior. In mice, selective Mfn2 downregulation in NAc dopamine D2 receptor-expressing medium spiny neurons (D2-MSNs) induced social subordination, accompanied by reduced mitochondrial function and decreased neuronal excitability. Instead, D1-MSN-targeted Mfn2 downregulation affected competitive ability only transiently mainly by increases in anxiety-like behaviors. Our results assign dissociable cell-type specific roles to Mfn2 in the NAc in modulating social dominance and anxiety.

neuroscience↗

bioRxiv2021

Defective Slc7a7 transport reduces systemic arginine availability compromising erythropoiesis and iron homeostasis

AbstractLysinuric Protein Intolerance (LPI) is an inborn error of metabolism resulting from SLC7A7 deficiency that causes diminished plasma concentration of cationic amino acids. The clinical picture is highly heterogeneous among patients, who commonly present intolerance to protein intake and more severe complications such as hematological abnormalities and kidney failure. Although current treatments aim to address the metabolic defects of LPI, they have been unsatisfactory when treating the most severe symptoms. Here we show that the absence of Slc7a7 in mice causes iron overload as a result of erythropoiesis failure. Regarding iron metabolism, we demonstrate that reduced plasma erythropoietin triggers a strong iron overload, as erythropoietin administration restores normal iron levels and mitigate hematological alterations. Interestingly, we found that human LPI is associated with hyperferritinemia but not iron overload, a trait that might be influenced by the citrulline treatment. Furthermore, we show that erythropoietin is a key factor in the hematological abnormalities in LPI. Our study reveals a mechanism leading to LPI-induced hematological complications and identifies erythropoietin supplementation as a promising therapeutic strategy for human LPI. Significance StatementThe systemic metabolic environment derived from Slc7a7-ablation in epithelial cells from kidney and intestine causes erythropoiesis failure prompting therefore iron overload. Here, we identify erythropoietin as the main driver of erythropoiesis failure as exogenous erythropoietin administration restores normal erythroblast population. In addition, we have also analyzed human data and found that patients with LPI have abnormal ferritin levels. Finally, as human LPI, citrulline treatment in mice restores normal iron homeostasis, highlighting the relevance of the systemic environment in LPI. Erythropoietin supplementation emerges as a promising therapeutic strategy for human LPI without the inflammatory effect associated with citrulline supplementation.

molecular biology↗

bioRxiv2021

Disrupted circadian core-clock oscillations in Type 2 Diabetes are linked to altered rhythmic mitochondrial metabolism

Circadian rhythms are generated by an auto-regulatory feedback loop composed of transcriptional activators and repressors. Disruption of circadian rhythms contributes to Type 2 diabetes (T2D) pathogenesis. We elucidated whether altered circadian rhythmicity of clock genes is associated with metabolic dysfunction in T2D. Transcriptional cycling of core clock genes ARNTL, CLOCK, CRY1 and NR1D1 was altered in skeletal muscle from individuals with T2D and this was coupled with reduced number and amplitude of cycling genes and disturbed circadian oxygen consumption. Mitochondrial associated genes were enriched for differential circadian amplitudes in T2D, and positively correlated with insulin sensitivity. ChIP- sequencing identified CLOCK and BMAL1 binding to circadian mitochondrial genes associated with insulin sensitivity, implicating regulation by the core clock. Mitochondria disruption altered core-clock gene expression and free-radical production, phenomena that were restored by resveratrol treatment. We identify bi-directional communication between mitochondrial function and rhythmic gene expression, processes which are disturbed in diabetes.

physiology↗

bioRxiv2020

Increased glycolysis is an early outcome of palmitate-mediated lipotoxicity

Palmitic acid is the most abundant saturated fatty acid in human serum. In cell culture systems, palmitate overload is considered a toxic stimulus, and promotes lipid accumulation, insulin resistance, endoplasmic reticulum stress, oxidative stress, as well as cell death. An increased supply of fatty acids has also been shown to change the predominant form of the mitochondrial network, although the metabolic effects of this change are still unclear. Here, we aimed to uncover the early bioenergetic outcomes of lipotoxicity. We incubated hepatic PLC/PRF/5 cells with palmitate conjugated to BSA and followed real-time oxygen consumption and extracellular acidification for 6 hours. Palmitate increased glycolysis as soon as 1 hour after the stimulus, while oxygen consumption was not disturbed, despite overt mitochondrial fragmentation and cellular reductive imbalance. Palmitate only induced mitochondrial fragmentation if glucose and glutamine were available, while glycolytic enhancement did not require glutamine, showing it is not dependent on morphological changes. NAD(P)H levels were significantly abrogated in palmitate-treated cells. Knockdown of the mitochondrial NAD(P) transhydrogenase or addition of the mitochondrial oxidant-generator menadione in control cells modulated ATP production from glycolysis. Indeed, using selective inhibitors, we found that the production of superoxide/hydrogen peroxide at the IQ site of electron transport chain complex I is associated with the metabolic rewiring promoted by palmitate, while not changing mitochondrial oxygen consumption. In conclusion, we demonstrate that increased glycolytic flux linked to mitochondrially-generated redox imbalance is an early bioenergetic result of palmitate overload and lipotoxicity.

biochemistry↗

bioRxiv2017

A Comprehensive Reanalysis Of Publicly Available GWAS Datasets Reveals An X Chromosome Rare Regulatory Variant Associated With High Risk For Type 2 Diabetes.

The reanalysis of publicly available GWAS data represents a powerful and cost-effective opportunity to gain insights into the genetics and pathophysiology of complex diseases. We demonstrate this by gathering and reanalyzing public type 2 diabetes (T2D) GWAS data for 70,127 subjects, using an innovative imputation and association strategy based on multiple reference panels (1000G and UK10K). This approach led us replicate and fine map 50 known T2D loci, and identify seven novel associated regions: five driven by common variants in or near LYPLAL1, NEUROG3, CAMKK2, ABO and GIP genes; one by a low frequency variant near EHMT2; and one driven by a rare variant in chromosome Xq23, associated with a 2.7-fold increased risk for T2D in males, and located within an active enhancer associated with the expression of Angiotensin II Receptor type 2 gene (AGTR2), a known modulator of insulin sensitivity. We further show that the risk T allele reduces binding of a nuclear protein, resulting in increased enhancer activity in muscle cells. Beyond providing novel insights into the genetics and pathophysiology of T2D, these results also underscore the value of reanalyzing publicly available data using novel analytical approaches.

genetics↗