Skip to Main content Skip to Navigation
Journal articles

Inactive matriptase-2 mutants found in IRIDA patients still repress hepcidin in a transfection assay despite having lost their serine protease activity.

Abstract : Mutations of the TMPRSS6 gene, which encodes Matriptase-2, are responsible for iron-refractory iron-deficiency anemia. Matriptase-2 is a transmembrane protease that downregulates hepcidin expression. We report one frameshift (p.Ala605ProfsX8) and four novel missense mutations (p.Glu114Lys, p.Leu235Pro, p.Tyr418Cys, p.Pro765Ala) found in IRIDA patients. These mutations lead to changes in both the catalytic and noncatalytic domains of Matriptase-2. Analyses of the mutant proteins revealed a reduction of autoactivating cleavage and the loss of N-Boc-Gln-Ala-Arg-p-nitroanilide hydrolysis. This resulted either from a direct modification of the active site or from the lack of the autocatalytic cleavage that transforms the zymogen into an active protease. In a previously described transfection assay measuring the ability of Matriptase-2 to repress the hepcidin gene (HAMP) promoter, all mutants retained some, if not all, of their transcriptional repression activity. This suggests that caution is called for in interpreting the repression assay in assessing the functional relevance of Matriptase-2 substitutions. We propose that Matriptase-2 activity should be measured directly in the cell medium of transfected cells using the chromogenic substrate. This simple test can be used to determine whether a sequence variation leading to an amino acid substitution is functionally relevant or not.
Complete list of metadatas

Cited literature [27 references]  Display  Hide  Download

https://www.hal.inserm.fr/inserm-00748562
Contributor : Gaël Nicolas <>
Submitted on : Friday, October 3, 2014 - 12:01:05 PM
Last modification on : Wednesday, August 19, 2020 - 11:17:01 AM
Long-term archiving on: : Sunday, January 4, 2015 - 10:11:19 AM

Identifiers

Citation

Flavia Guillem, Caroline Kannengiesser, Claire Oudin, Anne Lenoir, Pavle Matak, et al.. Inactive matriptase-2 mutants found in IRIDA patients still repress hepcidin in a transfection assay despite having lost their serine protease activity.. Human Mutation, Wiley, 2012, 33 (9), pp.1388-96. ⟨10.1002/humu.22116⟩. ⟨inserm-00748562⟩

Share

Metrics

Record views

1284

Files downloads

1044