Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 10-month-old boy presented with a history of a generalized cutaneous bullous eruption since 3 months of age. Emesis, flush, pruritus, and fatigue had accompanied relapsing episodes of sometimes extensive blistering. Histopathology showed dense dermal infiltrates of mast cells on hematoxylin and eosin and corroborating immunohistochemical staining. Laboratory examination revealed a markedly high level of serum tryptase. Based on these results and after consecutive staging, the patient was diagnosed with diffuse cutaneous bullous mastocytosis (BM). Mutation analysis detected a deletion mutation (del419) in C-Kit by direct exon sequencing. This rare entity must be considered in the differential diagnosis whenever a child presents with bullae and erosions. A crucial diagnostic hint is that rubbing of affected skin areas results in whealing (Darier's sign). A comprehensive diagnostic approach, advanced therapeutic strategies, regular follow-ups, and instruction of patients and relatives on prevention and prophylaxis are highly indicated.
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PMID:Diffuse cutaneous mastocytosis masquerading as epidermolysis bullosa. 2185 15

Coagulation factor XII (FXII) drives production of the inflammatory peptide bradykinin. Pathological mutations in the F12 gene, which encodes FXII, provoke acute tissue swelling in hereditary angioedema (HAE). Interestingly, a recently identified F12 mutation, causing a W268R substitution, is not associated with HAE. Instead, FXII-W268R carriers experience cold-inducible urticarial rash, arthralgia, fever, and fatigue. Here, we aimed to investigate the molecular characteristics of the FXII-W268R variant. We expressed wild type FXII (FXII-WT), FXII-W268R, and FXII-T309R (which causes HAE), as well as other FXII variants in HEK293 freestyle cells. Using chromogenic substrate assays, immunoblotting, and ELISA, we analyzed expression media, cell lysates, and purified proteins for FXII activation. Recombinant FXII-W268R forms increased amounts of intracellular cleavage products that are also present in expression medium and display enzymatic activity. The active site-incapacitated variant FXII-W268R/S544A reveals that intracellular fragmentation is largely dependent on autoactivation. Purified FXII-W268R is highly sensitive to activation by plasma kallikrein and plasmin, compared with FXII-WT or FXII-T309R. Furthermore, binding studies indicated that the FXII-W268R variant leads to the exposure of a plasminogen-binding site that is cryptic in FXII-WT. In plasma, recombinant FXII-W268R spontaneously triggers high-molecular-weight kininogen cleavage. Our findings suggest that the W268R substitution influences FXII protein conformation and exposure of the activation loop, which is concealed in FXII-WT. This results in intracellular autoactivation and constitutive low-grade secretion of activated FXII. These findings help to explain the chronically increased contact activation in carriers of the FXII-W268R variant.
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PMID:A mutation in the kringle domain of human factor XII that causes autoinflammation, disturbs zymogen quiescence, and accelerates activation. 3177 82