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6 recordsLinked to original sources
PubMed2025

Cysteinyl leukotrienes stimulate gut absorption of food allergens to promote anaphylaxis in mice.

Food-specific immunoglobulin E (IgE) triggers life-threatening anaphylaxis; however, for unclear reasons, some people with food-specific IgE are asymptomatic upon allergen consumption. We studied strains of mice with different sensitivities to anaphylaxis when orally challenged with allergen to identify possible causes. In resistant C57BL/6 mice, intestinal goblet cells transported less food allergen than did anaphylaxis-susceptible strains, even before allergic sensitization. In a forward genetic screen, resistance was correlated with dipeptidase 1 (Dpep1) variants. DPEP1 is expressed in intestinal epithelium and catabolizes leukotriene D4 (LTD4). Blocking DPEP1 with cilastatin, deleting Dpep1, or administering LTD4 orally enhanced allergen transport in resistant mice. Conversely, pretreatment of susceptible mice with a synthesis inhibitor, zileuton, abrogated allergen absorption and oral anaphylaxis, indicating that this could be an approach to treating food allergy.

Animals↗
PubMed2025

The Biosynthetic Pathway to the Pyrroloiminoquinone Marine Natural Product Ammosamide C.

Ammosamide C is a marine natural product containing a highly decorated pyrroloiminoquinone core. Studies on the biosynthetic gene cluster (BGC) that produces ammosamides previously revealed that they are made by a series of posttranslational modifications (PTMs). The BGC includes genes encoding a precursor peptide AmmA and four enzymes known as PEptide Aminoacyl-tRNA Ligases (PEARLs). Initial studies into the ammosamide biosynthetic pathway demonstrated Trp addition to a precursor peptide by the PEARL AmmB2. Thereafter, sequential modifications by several enzymes, including two other PEARLs lead to the formation of a peptide intermediate bearing a C-terminal diaminoquinone. In the present work, we present the biosynthetic steps that convert this intermediate to ammosamide C. The PEARL AmmB4 unexpectedly appends an arginine to the C-terminus of the aforementioned intermediate. Then, C-terminal proteolysis by the heterodimeric TldD/E-like protease Amm12/13 releases a dipeptide, which is subsequently cleaved by the dipeptidase Amm19 to produce a Trp-derived diaminoquinone. Amm3 next catalyzes the conversion of this Trp derivative to the corresponding chlorinated ammosamaic acid. Finally, a putative aminotransferase Amm20 performs an amidation, and Amm23 methylates this intermediate to arrive at ammosamide C; the order of these last two steps could not be determined definitively. This study reveals an unexpectedly lengthy route to ammosamide that illustrates the opportunistic nature of natural product biosynthesis, demonstrates a role for a PEARL that is unlike previous roles, identifies steps that are not PTMs, and adds Arg-tRNA to the growing repertoire of aminoacyl tRNAs that are used by PEARLs.

Biological Products↗
PubMed2026

ACE2 and Parkinsonism‑related bone metabolic alterations: signaling pathways and hub gene analysis.

Clinical co-occurrence of Parkinson's disease (PD) and age-related bone loss in elderly patients has garnered increasing attention, yet its molecular mechanisms remain incompletely elucidated. This study used an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model in Ace2-/y mice to investigate the regulatory mechanisms of bone-brain axis-related genes and signaling pathways. Behavioral tests assessed motor and non-motor symptoms. Immunohistochemistry, Western blot, and histopathological staining analyzed dopaminergic neuron activity, microglial activation, and bone metabolic abnormalities. GEO dataset transcriptomics and weighted gene co-expression network analysis (WGCNA) identified key hub genes, with receiver operating characteristic (ROC) curves evaluating their diagnostic value in public single-disease transcriptome data. MPTP significantly exacerbated motor dysfunction and depression-like behaviors; Ace2 deletion lowered total Wnt, β-catenin, BMP and IGF-1 protein abundance alongside reduced phosphorylation ratios of their downstream kinases in brain and bone, while upregulating RANKL/RANK/OPG-associated inflammatory mediators, accompanied by elevated total α-synuclein, Casp3 and Bax protein levels. The parallel reduction of these signaling proteins only suggests potential perturbation of related cascades; WGCNA identified 10 hub genes (e.g., DNM1, OCRL, OPA1), whose dysregulation was linked to synaptic dysfunction and inflammation. ROC analysis based on single-disease datasets showed high diagnostic accuracy for PD and `osteoporosis (OP) (AUC: 0.683-0.981), with core genes influencing synaptic, MAPK, Rap1, and Ras pathways. These preclinical findings indicate that Ace2 deficiency is associated with concurrent pathological abnormalities in the brain and transient bone metabolic disturbance under short-term MPTP treatment in growing young male mice; coordinated dysregulation of shared signaling pathways was observed in the two tissues, consistent with a potential bone-brain axis pathological phenotype, though causal bidirectional tissue cross-talk cannot be confirmed in the current experimental design, providing candidate targets that warrant further validation.

Animals↗
PubMed2026

Investigation of ACE gene polymorphism and serum ACE activity in relation to alopecia areata among Iraqi patients.

BACKGROUND: Alopecia areata (AA) is a multifactorial disorder with immune dysregulation and genetic susceptibility, affecting 0.5-2% globally. OBJECTIVE: This study investigated angiotensin converting enzyme (ACE) gene insertion /deletion (I/D) polymorphism and serum ACE activity in Iraqi AA patients and their association with inflammatory cytokines (interleukin [IL]-17) and nutritional markers to understand disease progression. METHODS: This case-control study included 50 AA patients (Male and Female) and 35 healthy controls. ACE gene polymorphism (rs1799752) was analyzed using real-time polymerase chain reaction (qPCR) with high-resolution melting (HRM) analysis. Serum IL-17 levels were determined by enzyme-linked immunosorbent assay (ELISA), and biochemical markers were measured using an automated analyzer. RESULTS: ACE gene polymorphism (rs1799752) showed non-significant genotype distribution between patient and control groups (p&#xa0;>&#xa0;0.05), though a trend toward DD genotype enrichment was observed in patients. Serum ACE levels were significantly higher in patients versus controls (p&#xa0;<&#xa0;0.0001) with high diagnostic performance. ACE correlated positively with IL-17 (P&#xa0;<&#xa0;0.0001) and negatively with vitamin D3 and zinc (P&#xa0;<&#xa0;0.0001). Female patients had significantly higher ACE levels than males (P&#xa0;<&#xa0;0.01). CONCLUSIONS: ACE emerges as an immunometabolic hub in AA pathogenesis, integrating inflammation with nutritional deficits, suggesting its potential as a biomarker and therapeutic target.

Humans↗
PubMed2026

Establishment of human induced pluripotent stem cell lines and isogenic gene-corrected controls from three patients with prolidase deficiency.

Prolidase deficiency is an autosomal recessive inborn error of metabolism caused by pathogenic variants in the PEPD gene. To date, close to 200 patients have been reported worldwide with a poorly understood pathomechanism. The PEPD gene encodes an enzyme that is involved in the final steps of collagen degradation. Urine amino acid analysis or specific dipeptide analysis can establish the biochemical diagnosis. In this study, we reprogrammed peripheral blood mononuclear cells (PBMCs) from three prolidase deficient patients into induced pluripotent stem cell (iPSC) lines and additionally generated isogenic controls using CRISPR-Cas9 genome editing. The pathogenic PEPD variants identified in our patients were NP_000276.2:p.? (NIHTVBi032-A), NP_000276.2:p.(Ile415Asn)/NP_000276.2:p.(Trp326Ter) (NIHTVBi033-A), and NP_000276.2:p.(Arg265Ter) (NIHTVBi034-A). These iPSC lines are valuable models to help investigate the pathomechanism of prolidase deficiency.

Humans↗
PubMed2026

Revisiting endothelial tropism of SARS-CoV-2 using a cell-specific hACE2 mouse model.

UNLABELLED: Severe COVID-19 is frequently associated with vascular complications, raising ongoing debate about whether SARS-CoV-2 can directly infect endothelial cells and thereby contribute to disease pathogenesis. Although endothelial cells express angiotensin-converting enzyme 2 (ACE2), the in vivo relevance of endothelial-restricted viral tropism remains unclear. To directly assess the consequences of endothelial-restricted SARS-CoV-2 tropism in vivo, we generated a transgenic mouse model expressing human ACE2 under control of the endothelial-specific Cdh5 promoter (Cdh5-hACE2). Despite confirmed pulmonary endothelial expression and protein presence of hACE2, SARS-CoV-2 infection of Cdh5-hACE2 mice did not induce clinical illness, detectable viral replication, immune cell influx in the lung, or histopathological abnormalities in the lung or brain. These findings indicate that endothelial-restricted SARS-CoV-2 tropism alone is insufficient to drive productive infection and clinical disease in vivo, suggesting that endothelial involvement in COVID-19 likely arises in the context of broader cellular infection or systemic host responses rather than from primary endothelial infection. IMPORTANCE: Although SARS-CoV-2 primarily infects the upper and lower airways, COVID-19 was quickly recognized as a multi-organ disease, in which vascular complications are a recurring feature. This has raised the possibility that direct infection of endothelial cells contributes to disease pathogenesis. However, whether vascular injury arises from productive endothelial infection or instead represents a secondary consequence of systemic inflammation remains unresolved. To directly disentangle these possibilities and define the in vivo consequences of endothelial-restricted viral tropism, we generated a transgenic mouse model expressing human ACE2 under the control of the endothelial-specific Cdh5 promoter (Cdh5-hACE2).

Animals↗