👤 A Makris

Carbamoyl phosphate synthetase 1 (CPS1) deficiency is a rare metabolic disorder that, in neonatal onset, is typically characterized by severe life-threatening and neurologically injuring hyperammonemic episodes with high unmet patient need. Patients that retain limited enzyme activity may present later in life with less severe hyperammonemia. CPS1 drives the first step in the urea cycle, the pathway terrestrial mammals utilize to metabolize nitrogen. In order to probe the effect of hyperammonemia on the developing nervous system and explore new therapies, a murine Cps1 exon 3-4 mutant was previously generated. However, these mice die within 24 h of birth, limiting study capabilities. Herein, we developed a novel Cps1 hypomorphic murine model with residual enzyme activity that maintains survival, but with dysfunction of Cps1 that could be detected biochemically. Characterization, based on the orthologous human variant Asn674Ile, revealed that the variant is reproducible, 100% penetrant and biochemically phenocopies the human disorder. The hypomorph presents with elevated ammonia and glutamate, and reduced citrulline, and with an impaired rate of ureagenesis, providing a novel platform to study and develop therapies for CPS1 deficiency. Show less

Carbamoyl phosphate synthetase 1 (CPS1) deficiency, a urea-cycle disorder, results in hyperammonemia initiating a sequence of adverse events that can lead to coma and death if not treated rapidly. There is a high unmet need for an effective therapeutic for this disorder, especially in early neonatal patients where mortality is excessive. However, development of an adeno-associated virus (AAV)-based approach is hampered by large cDNA size and high protein requirement. We developed an oversized AAV vector as a gene therapy to treat Show less

Psoriasis is a chronic inflammatory condition related to an increased atherosclerotic cardiovascular disease (ASCVD) risk. To investigate whether lipoprotein (a) [Lp(a)] levels are increased in patients with psoriasis. A comprehensive literature search up to January 30, 2025 was conducted utilizing PubMed and Cochrane Library databases. A qualitative synthesis and a meta-analysis on Lp(a) mean differences (MD) between psoriasis cases and healthy controls (HC) was performed. The protocol of this meta-analysis has been registered to PROSPERO (No. CRD420250652465). Eighteen studies with 1650 psoriasis patients and 1621 HC were eligible for qualitative synthesis. Pooled analysis from 16 studies (1401 psoriasis patients and 1320 HC) demonstrated that psoriasis patients had significantly higher Lp(a) levels compared with the HC group (MD: 6.72 mg/dL, 95%CI: 4.32-9.12, Our findings suggest that Lp(a) levels are significantly elevated in psoriasis patients, further adding to their ASCVD risk. Show less

The development of single-molecule co-agonists for the glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) and glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) is considered a breakthrough in the treatment of obesity and type 2 diabetes. But although GIPR-GLP-1R co-agonism decreases body weight with superior efficacy relative to GLP-1R agonism alone in preclinical Show less

Futibatinib is a covalently binding FGFR1-4 inhibitor that received US Food and Drug Administration approval for the treatment of patients with previously treated, advanced intrahepatic cholangiocarcinoma harboring FGFR2 gene fusions/rearrangements. This phase I trial evaluated the pharmacokinetics (PKs), safety, and tolerability of futibatinib in subjects with impaired hepatic function and matched healthy volunteers. Twenty-two subjects with hepatic impairment (8 mild [Child-Pugh 5-6], 8 moderate [7-9], and 6 severe [10-15]) and 16 matched healthy control subjects received a single oral dose of futibatinib 20 mg. Futibatinib PKs were compared between subjects with mild/moderate/severe hepatic impairment and each corresponding control cohort and the overall control cohort. Relationships between futibatinib PKs and Child-Pugh scores and liver function tests were examined via scatter/regression plots. Compared with matched controls, the area under the plasma concentration-time curve from time zero to infinity increased by 21%/20%/18% and the maximum plasma concentration (C Show less

Life-threatening hyperammonemia occurs in both inherited and acquired liver diseases affecting ureagenesis, the main pathway for detoxification of neurotoxic ammonia in mammals. Protein O-GlcNAcylation is a reversible and nutrient-sensitive post-translational modification using as substrate UDP-GlcNAc, the end-product of hexosamine biosynthesis pathway. Here we show that increased liver UDP-GlcNAc during hyperammonemia increases protein O-GlcNAcylation and enhances ureagenesis. Mechanistically, O-GlcNAcylation on specific threonine residues increased the catalytic efficiency for ammonia of carbamoyl phosphate synthetase 1 (CPS1), the rate-limiting enzyme in ureagenesis. Pharmacological inhibition of O-GlcNAcase, the enzyme removing O-GlcNAc from proteins, resulted in clinically relevant reductions of systemic ammonia in both genetic (hypomorphic mouse model of propionic acidemia) and acquired (thioacetamide-induced acute liver failure) mouse models of liver diseases. In conclusion, by fine-tuned control of ammonia entry into ureagenesis, hepatic O-GlcNAcylation of CPS1 increases ammonia detoxification and is a novel target for therapy of hyperammonemia in both genetic and acquired diseases. Show less

Despite biochemical and genetic testing being the golden standards for identification of proximal urea cycle disorders (UCDs), genotype-phenotype correlations are often unclear. Co-occurring partial defects affecting more than one gene have not been demonstrated so far in proximal UCDs. Here, we analyzed the mutational spectrum of 557 suspected proximal UCD individuals. We probed oligomerizing forms of NAGS, CPS1 and OTC, and evaluated the surface exposure of residues mutated in heterozygously affected individuals. BN-PAGE and gel-filtration chromatography were employed to discover protein-protein interactions within recombinant enzymes. From a total of 281 confirmed patients, only 15 were identified as "heterozygous-only" candidates (i.e. single defective allele). Within these cases, the only missense variants to potentially qualify as dominant negative triggers were CPS1 p.Gly401Arg and NAGS p.Thr181Ala and p.Tyr512Cys, as assessed by residue oligomerization capacity and surface exposure. However, all three candidates seem to participate in critical intramolecular functions, thus, unlikely to facilitate protein-protein interactions. This interpretation is further supported by BN-PAGE and gel-filtration analyses revealing no multiprotein proximal urea cycle complex formation. Collectively, genetic analysis, structural considerations and in vitro experiments point against a prominent role of dominant negative effects in human proximal UCDs. Show less

The urea cycle enzyme carbamoyl phosphate synthetase 1 (CPS1) catalyzes the initial step of the urea cycle; bi-allelic mutations typically present with hyperammonemia, vomiting, ataxia, lethargy progressing into coma, and death due to brain edema if ineffectively treated. The enzyme deficiency is particularly difficult to treat; early recognition is essential to minimize injury to the brain. Even under optimal conditions, therapeutic interventions are of limited scope and efficacy, with most patients developing long-term neurologic sequelae. One significant encumberment to gene therapeutic development is the size of the CPS1 cDNA, which, at 4.5 kb, nears the packaging capacity of adeno-associated virus (AAV). Herein we developed a split AAV (sAAV)-based approach, packaging the large transgene and its regulatory cassette into two separate vectors, thereby delivering therapeutic CPS1 by a dual vector system with testing in a murine model of the disorder. Cps1-deficient mice treated with sAAVs survive long-term with markedly improved ammonia levels, diminished dysregulation of circulating amino acids, and increased hepatic CPS1 expression and activity. In response to acute ammonia challenging, sAAV-treated female mice rapidly incorporated nitrogen into urea. This study demonstrates the first proof-of-principle that sAAV-mediated therapy is a viable, potentially clinically translatable approach to CPS1 deficiency, a devastating urea cycle disorder. Show less