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The Liver Regulates Ectopic Calcification in Pseudoxanthoma Elasticum

ABSTRACT: Pseudoxanthoma Elasticum (PXE) is a rare disease caused by loss of function of the gene Abcc6 and characterized by ectopic calcification of multiple tissues including the heart and vasculature. The physiological reasons underlying ectopic calcification in PXE remain unclear. We created a robust model of ectopic cardiac calcification where animals globally deficient in the gene Abcc6 developed extensive mineralization of the heart within 3 days of cardiac injury. To obtain insight into the underlying mechanisms of ectopic cardiac calcification in PXE, we generated animals with cardiomyocyte specific deletion of Abcc6 but did not observe any calcification, suggesting that Abcc6 was acting in a myocyte non-autonomous manner to cause calcification. Inflammation is known to play a key role in mediating ectopic calcification of the cardiovascular system but bone marrow transplantation experiments from wild type animals into Abcc6 deficient animals did not rescue the calcific phenotype. However, tissue specific deletion of Abcc6 in the liver was sufficient to cause post injury cardiac calcification, suggesting a role of the liver in driving ectopic calcification of distant tissues. Metabolomics and gene expression analysis of animals globally deficient or with liver specific deletion of Abcc6 demonstrated deficiencies in nucleotide metabolism and pathways regulating cellular energetics. We show that such metabolic abnormalities are associated with profound abnormalities in cellular respiration in the injured cardiac tissue. Functional abnormalities in cellular respiration in the injured heart were similar in animals globally deficient in Abcc6 or with liver specific deletion demonstrating that hepatic Abcc6 expression regulates cellular respiration in the injured heart. Calcification of the heart in Abcc6 deficient states was not secondary to induction of an osteogenic gene expression program but occurred rapidly secondary to dystrophic calcification with initial mineralization deposits noted within dead cardiac muscle. Treatment with clodronate or etidronate, bisphosphonates that prevent the growth of mineralization, was sufficient to rescue the phenotype of ectopic cardiac calcification in Abcc6 deficient states. Taken together, these observations highlight the role of the liver in regulating target tissue metabolic and mitochondrial function in causing ectopic calcification in Abcc6 deficient states.

ORGANISM(S): Mus musculus

PROVIDER: GSE312469 | GEO | 2026/02/12

REPOSITORIES: GEO

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Project description:Pseudoxanthoma Elasticum (PXE) is a rare disease caused by loss of function of the gene Abcc6 and characterized by ectopic calcification of multiple tissues including the heart and vasculature. The physiological reasons underlying ectopic calcification in PXE remain unclear. We created a robust model of ectopic cardiac calcification where animals globally deficient in the gene Abcc6 developed extensive mineralization of the heart within 3 days of cardiac injury. To obtain insight into the underlying mechanisms of ectopic cardiac calcification in PXE, we generated animals with cardiomyocyte specific deletion of Abcc6 but did not observe any calcification, suggesting that Abcc6 was acting in a myocyte non-autonomous manner to cause calcification. Inflammation is known to play a key role in ectopic calcification of the cardiovascular system but bone marrow transplantation experiments from wild type animals into Abcc6 deficient animals did not rescue the calcific phenotype. However, tissue specific deletion of Abcc6 in the liver was sufficient to cause post injury cardiac calcification, suggesting a role of the liver in driving ectopic calcification of distant tissues. Metabolomics and gene expression analysis of animals globally deficient or with liver specific deletion of Abcc6 demonstrated deficiencies in nucleotide metabolism and pathways regulating cellular energetics. We show that such metabolic abnormalities are associated with profound abnormalities in cellular respiration in the injured cardiac tissue. Functional abnormalities in cellular respiration in the injured heart were similar in animals globally deficient in Abcc6 or with liver specific deletion demonstrating that abcc6 regulates cellular respiration in the heart in a liver cell autonomous manner. Notably calcification of the heart in Abcc6 deficient states was not secondary to induction of an osteogenic gene expression program in the heart but occurred rapidly secondary to dystrophic calcification with initial mineralization deposits noted with the cardiac muscle. Treatment with clodronate, a clinically approved bisphosphonate that prevents growth of mineralization was sufficient to rescue the phenotype of ectopic cardiac calcification in Abcc6 deficient states. Taken together, these observations highlight the role of the liver in regulating cardiac metabolic and mitochondrial function and causing ectopic calcification in Abcc6 deficient states.

Project description:Background: The in vivo gene response associated with hyperthermia and subsequent return to homeostasis or development of heat illness is poorly understood. Early activation of gene networks in the heat stress response is likely to lead to the systemic inflammation, multi-organ functional impairment, and other pathophysiological states characteristic of heat illness. Here, we perform an unbiased global characterization of the multi-organ gene response using an in vivo model of heat stress in the conscious rat. Results: Rats were subjected to elevated temperatures until implanted thermal probes indicated a maximal core temperature of 41.8 M-BM-0C (Tc,Max). Liver, lung, kidney, and heart were harvested at Tc,Max, 24 hours, and 48 hours after heat stress in groups of experimental animals and time-matched controls kept at ambient temperature. Clinical chemistries suggested abnormal function in liver, kidney, and lung at Tc,Max, and cardiac histopathology at 48 hours supported persistent cardiac damage in 3 out of 6 animals. Microarray analysis identified 78 differentially expressed genes common to all 4 organs at Tc,Max (i.e., the consensus heat stress response). Gene set enrichment analysis of gene ontology terms identified 25 biological processes in 4 general gene ontology categories: protein folding, regulation of apoptosis, response to cytokines, and transcriptional responses. Functional analysis clustering of the 78 differentially expressed genes in the consensus heat stress response also identified functional categories of protein folding and regulation of apoptosis. Self-organizing maps identified gene-specific signatures corresponding to protein folding disorders specific to only heat-stressed rats with histopathologic evidence of cardiac injury at 48 hours. Enrichment analysis of differentially expressed proteins in heat-injured hearts at 48 hours corroborated gene enrichment analysis results. Quantitative proteomics analysis by iTRAQ demonstrated that differential protein expression was not comparable to transcript expression at Tc,Max and 24 hours. However, the profile of differentially expressed proteins closely matched the transcriptomic profile in heat-injured animals at 48 hours. Pathway analysis at both the transcript and protein levels supported catastrophic deficits in energetics and cellular metabolism, chronic proteotoxic response, and activation of the unfolded protein response. Calculation of protein super-saturation scores demonstrated an increased propensity of proteins to aggregate in the hearts of heat-injured animals at 48 hours, consistent with accumulation of misfolded proteins. Conclusions: Global transcriptomic and proteomic analysis identified networks of genes and proteins initiating an unfolded protein response, metabolic dysfunction, and mitochondrial energy crisis in animals with histopathologic evidence of persistent heat injury, providing the basis for a systems-level physiological model of heat illness and recovery. To induce the pathophysiological effects of heat stress, conscious rats were placed in an incubator at 37M-BM-:C and their core temperature was monitored. Animals were sacrificed when their core temperature reached 41.8M-BM-:C (Tc,Max), or they were returned to their normal housing environment and were allowed to recover for up to 24 or 48 hours prior to sacrifice. Time-matched controls were euthanized at times corresponding to Tc,Max, 24 hours, and 48 hours. For each condition n=6 for a total of 36 animals. Four tissues (liver, lung, kidney and heart) were analyzed from each animal for a total of 144 arrays; however a few arrays did not pass QC therefore only 140 are reported here: 34 liver, 35 lung, 36 kidney, or 35 heart.

Project description:<p>Cardiac fibrosis, characterized by excessive extracellular matrix (ECM) deposition in the myocardium, is a critical target for heart disease treatments. Pw1 (paternally expressed gene 3) is an imprinted gene expressed from the paternally allele, and de novo purine biosynthesis (DNPB) is a crucial pathway for nucleotide synthesis. However, the roles of PW1 and DNPB in ECM production by cardiac fibroblasts during myocardial ischemia are not yet understood. To induce myocardial damage, we performed left anterior descending coronary artery ligation. We generated Pw1CreER-2A-eGFP and Pw12A-CreER knock-in mouse lines to evaluate the expression of the two Pw1 alleles in normal and injured hearts. Bisulfite sequencing was employed to analyze the DNA methylation of the Pw1 imprinting control region. We identified the phosphoribosylformylglycinamidine synthase (Pfas) gene, encoding the DNPB enzyme PFAS, as a direct target of PW1 using chromatin immunoprecipitation sequencing and real-time quantitative polymerase chain reaction. The role of DNPB in ECM production and cardiac fibrosis post-injury was examined in vitro using cultured cardiac fibroblasts and in vivo with Pfas-deficient mice. Our study demonstrates that myocardial infarction reduces DNA methylation at the imprinting control region of the maternally imprinted gene Pw1, triggering a switch from monoallelic imprinting to biallelic expression of Pw1 in cardiac fibroblasts. In activated cardiac fibroblasts, increased Pw1 expression promotes purine biosynthesis and induces ECM production by transcriptionally activating the DNPB factor Pfas. Notably, we identified that DNPB is essential for ECM production in activated fibroblasts and that loss of Pfas in fibroblasts limits cardiac fibrosis and improves heart function after heart injury. This study reveals that post-injury, the imprinting of Pw1 is disrupted, highlighting a novel role for the downstream DNPB pathway in cardiac fibrogenesis. Targeting DNPB presents a promising therapeutic strategy for improving cardiac repair following injury.</p>

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The Liver Regulates Ectopic Calcification in Pseudoxanthoma Elasticum

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