RARE DISEASE
Pyruvate carboxylase deficiency, infantile type
Pyruvate carboxylase deficiency, infantile type
Pyruvate carboxylase deficiency, infantile type
Synonyms: Pyruvate carboxylase deficiency type A
Synonyms: Pyruvate carboxylase deficiency type A
Synonyms: Pyruvate carboxylase deficiency type A
Drug discovery
0
drugs
With orphan designations
Overview
Pyruvate carboxylase deficiency, infantile type (Type A), is a rare autosomal recessive mitochondrial disorder caused by PC gene mutations, leading to deficient pyruvate carboxylase activity. It manifests in infancy (2-5 months) with lactic acidosis, failure to thrive, hypotonia, seizures, and developmental delay. Biochemical hallmarks include hypoglycemia, ketosis, hyperalaninemia, and elevated lactate (2–10 mmol/L). Prognosis is poor, with mortality in infancy/early childhood despite supportive care [1][5][6][9].
Categories: rare genetic diseases, rare inborn errors of metabolism, rare neurological diseases
Research Papers
30 drug discovery papers about Pyruvate carboxylase deficiency, infantile type, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
30 drug discovery papers about Pyruvate carboxylase deficiency, infantile type, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2023-12-28 | Pyruvate carboxylase deficiency type C; variable presentation and beneficial effect of triheptanoin
Abstract Pyruvate carboxylase is a mitochondrial enzyme essential for the tricarboxylic acid cycle (TCA), gluconeogenesis and fatty‐acid synthesis. Pyruvate carboxylase deficiency (PCD) mostly presents with life‐limiting encephalopathy (types A/B). A milder type C presentation is rare, with a comparatively favourable prognosis. Therapies remain essentially supportive. Triheptanoin is an odd‐chain triglyceride, with the potential to replenish TCA intermediates (anaplerosis), and its metabolites cross the blood–brain‐barrier. Outcomes of triheptanoin treatment in PCD types A/B have been disappointing, but have not been reported in type C. Here, we present two new patients with PCD type C, and report the response to treatment with triheptanoin in one. Patient 1 (P1) presented with neonatal‐onset lactic acidosis and recurrent symptomatic lactic acidosis following exercise and during illnesses, with frequent hospitalisations. Speech development was delayed. MRI‐brain showed delayed cerebral myelination. Patient 2 (P2) presented with episodic ketoacidosis, hyperlactataemia and hypoglycaemia at 2 years of age, with gross motor delay and mild global volume loss on MRI brain. Treatment with triheptanoin was commenced in P1 at 3 years of age with up‐titration to 35 mL/day (25% of daily energy intake) over 6 months, due to transient diarrhoea. Dietary long‐chain triglycerides were restricted, with fat‐soluble vitamin supplementation. Subsequently, hospitalisations during intercurrent illnesses decreased, post‐exertional hyperlactataemia resolved and exercise tolerance improved. Continued developmental progress was observed, and repeat MRI 18 months after initiation showed improved myelination. Triheptanoin was well‐tolerated and appeared efficacious during 2 years' follow‐up, and has potential to restore energy homeostasis and myelin synthesis in PCD type C.
2023-06-30 | The Presence of Pyruvate Carboxylase in the Human Brain and its Role in the Survival of Cultured Human Astrocytes
Pyruvate carboxylase (PC) is a mitochondrial, biotin-containing enzyme catalyzing the ATP-dependent synthesis of oxaloacetate from pyruvate and bicarbonate, with a critical anaplerotic role in sustaining the brain metabolism. Based on the studies performed on animal models, PC expression was assigned to be glia-specific. To study PC distribution among human neural cells, we probed the cultured human astrocytes and brain sections with antibodies against PC. Additionally, we tested the importance of PC for the viability of cultured human astrocytes by applying the PC inhibitor 3-chloropropane-1,2-diol (CPD). Our results establish the expression of PC in mitochondria of human astrocytes in culture and brain tissue and also into a subpopulation of the neurons in situ. CPD negatively affected the viability of astrocytes in culture, which could be partially reversed by supplementing media with malate, 2-oxoglutarate, citrate, or pyruvate. The provided data estimates PC expression in human astrocytes and neurons in human brain parenchyma. Furthermore, the enzymatic activity of PC is vital for sustaining the viability of cultured astrocytes.
2023-06-19 | Clinical, biochemical and molecular characterization of 12 patients with pyruvate carboxylase deficiency treated with triheptanoin.
Pyruvate carboxylase (PC) deficiency is a rare autosomal recessive mitochondrial neurometabolic disorder of energy deficit resulting in high morbidity and mortality, with limited therapeutic options. The PC homotetramer has a critical role in gluconeogenesis, anaplerosis, neurotransmitter synthesis, and lipogenesis. The main biochemical and clinical findings in PC deficiency (PCD) include lactic acidosis, ketonuria, failure to thrive, and neurological dysfunction. Use of the anaplerotic agent triheptanoin on a limited number of individuals with PCD has had mixed results. We expand on the potential utility of triheptanoin in PCD by examining the clinical, biochemical, molecular, and health-related quality-of-life (HRQoL) findings in a cohort of 12 individuals with PCD (eight with Type A and two each with Types B and C) treated with triheptanoin ranging for 6 days to about 7 years. The main endpoints were changes in blood lactate and HRQoL scores, but collection of useful data was limited to about half of subjects. An overall trend of lactate reduction with time on triheptanoin was noted, but with significant variability among subjects and only one subject reaching close to statistical significance for this endpoint. Parent reported HRQoL assessments with treatment showed mixed results, with some subjects showing no change, some improvement, and some worsening of overall scores. Subjects with buried amino acids in the pyruvate carboxyltransferase domain of PC that undergo destabilizing replacements may be more likely to respond (with lactate reduction or HRQoL improvement) to triheptanoin compared to those with replacements that disrupt tetramerization or subunit-subunit interface contacts. The reason for this difference is unclear and requires further validation. We observed significant variability but an overall trend of lactate reduction with time on triheptanoin and mixed parent reported outcome changes by HRQoL assessments for subjects with PCD on long-term triheptanoin. The mixed results noted with triheptanoin therapy in this study could be due to endpoint data limitation, variability of disease severity between subjects, limitation of the parent reported HRQoL tool, or subject genotype variability. Alternative designed trials and more study subjects with PCD will be needed to validate important observations from this work.
2021-05-20 | Excess exogenous pyruvate inhibits lactate dehydrogenase activity in live cells in an MCT1-dependent manner
Cellular pyruvate is an essential metabolite at the crossroads of glycolysis and oxidative phosphorylation, capable of supporting fermentative glycolysis by reduction to lactate mediated by lactate dehydrogenase (LDH) among other functions. Several inherited diseases of mitochondrial metabolism impact extracellular (plasma) pyruvate concentrations, and [1-13C]pyruvate infusion is used in isotope-labeled metabolic tracing studies, including hyperpolarized magnetic resonance spectroscopic imaging. However, how these extracellular pyruvate sources impact intracellular metabolism is not clear. Herein, we examined the effects of excess exogenous pyruvate on intracellular LDH activity, extracellular acidification rates (ECARs) as a measure of lactate production, and hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates across a panel of tumor and normal cells. Combined LDH activity and LDHB/LDHA expression analysis intimated various heterotetrameric isoforms comprising LDHA and LDHB in tumor cells, not only canonical LDHA. Millimolar concentrations of exogenous pyruvate induced substrate inhibition of LDH activity in both enzymatic assays ex vivo and in live cells, abrogated glycolytic ECAR, and inhibited hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates in cellulo. Of importance, the extent of exogenous pyruvate-induced inhibition of LDH and glycolytic ECAR in live cells was highly dependent on pyruvate influx, functionally mediated by monocarboxylate transporter-1 localized to the plasma membrane. These data provided evidence that highly concentrated bolus injections of pyruvate in vivo may transiently inhibit LDH activity in a tissue type- and monocarboxylate transporter-1-dependent manner. Maintaining plasma pyruvate at submillimolar concentrations could potentially minimize transient metabolic perturbations, improve pyruvate therapy, and enhance quantification of metabolic studies, including hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging and stable isotope tracer experiments.
2019-03-19 | Triheptanoin alters [U-13C6]-glucose incorporation into glycolytic intermediates and increases TCA cycling by normalizing the activities of pyruvate dehydrogenase and oxoglutarate dehydrogenase in a chronic epilepsy mouse model.
Triheptanoin is anticonvulsant in several seizure models. Here, we investigated changes in glucose metabolism by triheptanoin interictally in the chronic stage of the pilocarpine mouse epilepsy model. After injection of [U- 13 C 6 ]-glucose (i.p.), enrichments of 13 C in intermediates of glycolysis and the tricarboxylic acid (TCA) cycle were quantified in hippocampal extracts and maximal activities of enzymes in each pathway were measured. The enrichment of 13 C glucose in plasma was similar across all groups. Despite this, we observed reductions in incorporation of 13 C in several glycolytic intermediates compared to control mice suggesting glucose utilization may be impaired and/or glycogenolysis increased in the untreated interictal hippocampus. Triheptanoin prevented the interictal reductions of 13 C incorporation in most glycolytic intermediates, suggesting it increased glucose utilization or – as an additional astrocytic fuel – it decreased glycogen breakdown. In the TCA cycle metabolites, the incorporation of 13 C was reduced in the interictal state. Triheptanoin restored the correlation between 13 C enrichments of pyruvate relative to most of the TCA cycle intermediates in “epileptic” mice. Triheptanoin also prevented the reductions of hippocampal pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase activities. Decreased glycogen breakdown and increased glucose utilization and metabolism via the TCA cycle in epileptogenic brain areas may contribute to triheptanoin's anticonvulsant effects.
small molecules
2023-12-28 | Pyruvate carboxylase deficiency type C; variable presentation and beneficial effect of triheptanoin
Abstract Pyruvate carboxylase is a mitochondrial enzyme essential for the tricarboxylic acid cycle (TCA), gluconeogenesis and fatty‐acid synthesis. Pyruvate carboxylase deficiency (PCD) mostly presents with life‐limiting encephalopathy (types A/B). A milder type C presentation is rare, with a comparatively favourable prognosis. Therapies remain essentially supportive. Triheptanoin is an odd‐chain triglyceride, with the potential to replenish TCA intermediates (anaplerosis), and its metabolites cross the blood–brain‐barrier. Outcomes of triheptanoin treatment in PCD types A/B have been disappointing, but have not been reported in type C. Here, we present two new patients with PCD type C, and report the response to treatment with triheptanoin in one. Patient 1 (P1) presented with neonatal‐onset lactic acidosis and recurrent symptomatic lactic acidosis following exercise and during illnesses, with frequent hospitalisations. Speech development was delayed. MRI‐brain showed delayed cerebral myelination. Patient 2 (P2) presented with episodic ketoacidosis, hyperlactataemia and hypoglycaemia at 2 years of age, with gross motor delay and mild global volume loss on MRI brain. Treatment with triheptanoin was commenced in P1 at 3 years of age with up‐titration to 35 mL/day (25% of daily energy intake) over 6 months, due to transient diarrhoea. Dietary long‐chain triglycerides were restricted, with fat‐soluble vitamin supplementation. Subsequently, hospitalisations during intercurrent illnesses decreased, post‐exertional hyperlactataemia resolved and exercise tolerance improved. Continued developmental progress was observed, and repeat MRI 18 months after initiation showed improved myelination. Triheptanoin was well‐tolerated and appeared efficacious during 2 years' follow‐up, and has potential to restore energy homeostasis and myelin synthesis in PCD type C.
2023-06-30 | The Presence of Pyruvate Carboxylase in the Human Brain and its Role in the Survival of Cultured Human Astrocytes
Pyruvate carboxylase (PC) is a mitochondrial, biotin-containing enzyme catalyzing the ATP-dependent synthesis of oxaloacetate from pyruvate and bicarbonate, with a critical anaplerotic role in sustaining the brain metabolism. Based on the studies performed on animal models, PC expression was assigned to be glia-specific. To study PC distribution among human neural cells, we probed the cultured human astrocytes and brain sections with antibodies against PC. Additionally, we tested the importance of PC for the viability of cultured human astrocytes by applying the PC inhibitor 3-chloropropane-1,2-diol (CPD). Our results establish the expression of PC in mitochondria of human astrocytes in culture and brain tissue and also into a subpopulation of the neurons in situ. CPD negatively affected the viability of astrocytes in culture, which could be partially reversed by supplementing media with malate, 2-oxoglutarate, citrate, or pyruvate. The provided data estimates PC expression in human astrocytes and neurons in human brain parenchyma. Furthermore, the enzymatic activity of PC is vital for sustaining the viability of cultured astrocytes.
2023-06-19 | Clinical, biochemical and molecular characterization of 12 patients with pyruvate carboxylase deficiency treated with triheptanoin.
Pyruvate carboxylase (PC) deficiency is a rare autosomal recessive mitochondrial neurometabolic disorder of energy deficit resulting in high morbidity and mortality, with limited therapeutic options. The PC homotetramer has a critical role in gluconeogenesis, anaplerosis, neurotransmitter synthesis, and lipogenesis. The main biochemical and clinical findings in PC deficiency (PCD) include lactic acidosis, ketonuria, failure to thrive, and neurological dysfunction. Use of the anaplerotic agent triheptanoin on a limited number of individuals with PCD has had mixed results. We expand on the potential utility of triheptanoin in PCD by examining the clinical, biochemical, molecular, and health-related quality-of-life (HRQoL) findings in a cohort of 12 individuals with PCD (eight with Type A and two each with Types B and C) treated with triheptanoin ranging for 6 days to about 7 years. The main endpoints were changes in blood lactate and HRQoL scores, but collection of useful data was limited to about half of subjects. An overall trend of lactate reduction with time on triheptanoin was noted, but with significant variability among subjects and only one subject reaching close to statistical significance for this endpoint. Parent reported HRQoL assessments with treatment showed mixed results, with some subjects showing no change, some improvement, and some worsening of overall scores. Subjects with buried amino acids in the pyruvate carboxyltransferase domain of PC that undergo destabilizing replacements may be more likely to respond (with lactate reduction or HRQoL improvement) to triheptanoin compared to those with replacements that disrupt tetramerization or subunit-subunit interface contacts. The reason for this difference is unclear and requires further validation. We observed significant variability but an overall trend of lactate reduction with time on triheptanoin and mixed parent reported outcome changes by HRQoL assessments for subjects with PCD on long-term triheptanoin. The mixed results noted with triheptanoin therapy in this study could be due to endpoint data limitation, variability of disease severity between subjects, limitation of the parent reported HRQoL tool, or subject genotype variability. Alternative designed trials and more study subjects with PCD will be needed to validate important observations from this work.
2021-05-20 | Excess exogenous pyruvate inhibits lactate dehydrogenase activity in live cells in an MCT1-dependent manner
Cellular pyruvate is an essential metabolite at the crossroads of glycolysis and oxidative phosphorylation, capable of supporting fermentative glycolysis by reduction to lactate mediated by lactate dehydrogenase (LDH) among other functions. Several inherited diseases of mitochondrial metabolism impact extracellular (plasma) pyruvate concentrations, and [1-13C]pyruvate infusion is used in isotope-labeled metabolic tracing studies, including hyperpolarized magnetic resonance spectroscopic imaging. However, how these extracellular pyruvate sources impact intracellular metabolism is not clear. Herein, we examined the effects of excess exogenous pyruvate on intracellular LDH activity, extracellular acidification rates (ECARs) as a measure of lactate production, and hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates across a panel of tumor and normal cells. Combined LDH activity and LDHB/LDHA expression analysis intimated various heterotetrameric isoforms comprising LDHA and LDHB in tumor cells, not only canonical LDHA. Millimolar concentrations of exogenous pyruvate induced substrate inhibition of LDH activity in both enzymatic assays ex vivo and in live cells, abrogated glycolytic ECAR, and inhibited hyperpolarized [1-13C]pyruvate-to-[1-13C]lactate conversion rates in cellulo. Of importance, the extent of exogenous pyruvate-induced inhibition of LDH and glycolytic ECAR in live cells was highly dependent on pyruvate influx, functionally mediated by monocarboxylate transporter-1 localized to the plasma membrane. These data provided evidence that highly concentrated bolus injections of pyruvate in vivo may transiently inhibit LDH activity in a tissue type- and monocarboxylate transporter-1-dependent manner. Maintaining plasma pyruvate at submillimolar concentrations could potentially minimize transient metabolic perturbations, improve pyruvate therapy, and enhance quantification of metabolic studies, including hyperpolarized [1-13C]pyruvate magnetic resonance spectroscopic imaging and stable isotope tracer experiments.
2019-03-19 | Triheptanoin alters [U-13C6]-glucose incorporation into glycolytic intermediates and increases TCA cycling by normalizing the activities of pyruvate dehydrogenase and oxoglutarate dehydrogenase in a chronic epilepsy mouse model.
Triheptanoin is anticonvulsant in several seizure models. Here, we investigated changes in glucose metabolism by triheptanoin interictally in the chronic stage of the pilocarpine mouse epilepsy model. After injection of [U- 13 C 6 ]-glucose (i.p.), enrichments of 13 C in intermediates of glycolysis and the tricarboxylic acid (TCA) cycle were quantified in hippocampal extracts and maximal activities of enzymes in each pathway were measured. The enrichment of 13 C glucose in plasma was similar across all groups. Despite this, we observed reductions in incorporation of 13 C in several glycolytic intermediates compared to control mice suggesting glucose utilization may be impaired and/or glycogenolysis increased in the untreated interictal hippocampus. Triheptanoin prevented the interictal reductions of 13 C incorporation in most glycolytic intermediates, suggesting it increased glucose utilization or – as an additional astrocytic fuel – it decreased glycogen breakdown. In the TCA cycle metabolites, the incorporation of 13 C was reduced in the interictal state. Triheptanoin restored the correlation between 13 C enrichments of pyruvate relative to most of the TCA cycle intermediates in “epileptic” mice. Triheptanoin also prevented the reductions of hippocampal pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase activities. Decreased glycogen breakdown and increased glucose utilization and metabolism via the TCA cycle in epileptogenic brain areas may contribute to triheptanoin's anticonvulsant effects.
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