title: Novel Splice Site Mutation in MAMLD1 in a Patient with Hypospadias.
abstract: MAMLD1 is a causative gene for disorders of sex development. Several MAMLD1 mutations have been shown to cause hypospadias by generating dysfunctional proteins and/or unstable mRNAs. Here, we identified an intronic mutation of MAMLD1 (g.IVS4-2A>G) in 1 of 180 hypospadias patients. RT-PCR of the patient's skin sample showed normal expression of full-length MAMLD1 and markedly reduced expression of a known splice variant lacking exon 4. A hitherto unreported splice variant that lacks exon 5 was similarly identified in samples of the patient and control individuals. The full-length transcript of the patient contained mutant mRNA lacking the first 10 nucleotides of exon 5 (c.1822_1831delACTCATGTAG, p.K609fsX1070). In vitro assays using cells expressing the full-length wild-type and mutant proteins revealed reduced expression of the mutant. The expression of the wild-type and mutant MAMLD1 showed parallel changes upon treatment with a proteasome inhibitor and a translation inhibitor. The mutant-expressing cells exerted low transactivation activity for the Hes3 promoter, which reflected limited expression of the mutant protein. These results imply that the pathogenic events resulting from MAMLD1 mutations include splice errors. Furthermore, this study raises the possibility of translation failure of MAMLD1 mutants, which deserves further investigation.
authors.affiliation: Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Igarashi
authors.forename: Yuka
authors.initials: Y
authors.lastname: Wada
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kojima
authors.forename: Mami
authors.initials: M
authors.lastname: Miyado
authors.forename: Michiko
authors.initials: M
authors.lastname: Nakamura
authors.forename: Koji
authors.initials: K
authors.lastname: Muroya
authors.forename: Kentaro
authors.initials: K
authors.lastname: Mizuno
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Nonomura
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kohri
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ogata
authors.forename: Maki
authors.initials: M
authors.lastname: Fukami
mesh_terms: D001483:Base Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005837:Genitalia, Male / Q000473:pathology; D057809:HEK293 Cells; D006801:Humans; D007021:Hypospadias / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D022821:RNA Splice Sites / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012867:Skin / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation
chemical_list: D004268:DNA-Binding Proteins; C528016:MAMLD1 protein, human; D009687:Nuclear Proteins; D022821:RNA Splice Sites; D012333:RNA, Messenger; D014157:Transcription Factors