Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162316 (iron deficiency anemia)
 3,806 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Matriptase-2 is a transmembrane serine protease that negatively regulates hepcidin expression by cleaving membrane-bound hemojuvelin. Matriptase-2 has a complex ectodomain, including a C-terminal serine protease domain and its activation requires an autocatalytic cleavage. Matriptase-2 mutations have been reported in several patients with iron-refractory iron deficiency anemia. Here we describe a patient with 2 missense mutations in the second class A low-density lipoprotein receptor (LDLRA) domain. Functional studies of these 2 mutations and of a previously reported mutation in the second C1r/C1s, urchin embryonic growth factor and bone morphogenetic protein 1 (CUB) domain were performed. Transfection of mutant cDNAs showed that membrane targeting of the 2 LDLRA mutants was impaired, with Golgi retention of the variants. The activating cleavage was absent for the LDLRA mutants and reduced for the CUB mutant. All 3 mutated proteins were still able to physically interact with hemojuvelin but only partially repressed hepcidin expression compared with wild-type matriptase-2. Our results underline the importance of LDLRA and CUB domains of matriptase-2.
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PMID:Molecular mechanisms of the defective hepcidin inhibition in TMPRSS6 mutations associated with iron-refractory iron deficiency anemia. 1935 98

Mutations leading to abrogation of matriptase-2 proteolytic activity in humans are associated with an iron-refractory iron deficiency anemia (IRIDA) due to elevated hepcidin levels. In this paper we describe 12 IRIDA patients belonging to 7 unrelated families and identify 10 (9 novel) TMPRSS6 mutations spread along the gene sequence: 5 missense, 1 non sense and 4 frameshift. The frameshift and non sense mutations are predict to result in truncated protein lacking the catalytic domain. The causal role of missense mutations (Y141C, I212T, R271Q, S304L and C510S) is demonstrated by in silico analysis, their absence in 100 control chromosomes and the high conservation of the involved residues. The C510S mutation in the LDLRA domain in silico model causes an intra-molecular structural imbalance that impairs matriptase-2 activation. We also assessed the in vitro effect on hepcidin promoter and the proteolytic activity of I212T and R271Q variants demonstrating a reduced inhibitory effect for the former mutation, but surprisingly a normal function for R271Q which appears a silent mutation in vitro. Based on mRNA expression studies I212T could also decrease the total amount of protein produced, likely interfering with mRNA stability. Collectively, our results extend the pattern of TMPRSS6 mutations associated with IRIDA and propose a model of causality for some of the novel missense mutation.
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PMID:Novel TMPRSS6 mutations associated with iron-refractory iron deficiency anemia (IRIDA). 2023 50