Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria

Malcolm A. Leissring, Wesley Farris, Xining Wu, Danos C. Christodoulou, Marcia C. Haigis, Leonard Guarente, Dennis J. Selkoe

Research output: Contribution to journalArticle

118 Citations (Scopus)

Abstract

IDE (insulin-degrading enzyme) is a widely expressed zinc-metallopeptidase that has been shown to regulate both cerebral amyloid β-peptide and plasma insulin levels in vivo. Genetic linkage and allelic association have been reported between the IDE gene locus and both late-onset Alzheimer's disease and Type II diabetes mellitus, suggesting that altered IDE function may contribute to some cases of these highly prevalent disorders. Despite the potentially great importance of this peptidase to health and disease, many fundamental aspects of IDE biology remain unresolved. Here we identify a previously undescribed mitochondrial isoform of IDE generated by translation at an in-frame initiation codon 123 nucleotides upstream of the canonical translation start site, which results in the addition of a 41-amino-acid N-terminal mitochondrial targeting sequence. Fusion of this sequence to the N-terminus of green fluorescent protein directed this normally cytosolic protein to mitochondria, and full-length IDE constructs containing this sequence were also directed to mitochondria, as revealed by immuno-electron microscopy. Endogenous IDE protein was detected in purified mitochondria, where it was protected from digestion by trypsin and migrated at a size consistent with the predicted removal of the N-terminal targeting sequence upon transport into the mitochondrion. Functionally, we provide evidence that IDE can degrade cleaved mitochondrial targeting sequences. Our results identify new mechanisms regulating the subcellular localization of IDE and suggest previously unrecognized roles for IDE within mitochondria.

Original languageEnglish (US)
Pages (from-to)439-446
Number of pages8
JournalBiochemical Journal
Volume383
Issue number3
DOIs
StatePublished - Nov 1 2004
Externally publishedYes

Fingerprint

Insulysin
Mitochondria
Protein Isoforms
Genetic Linkage
Initiator Codon
Immunoelectron Microscopy
Metalloproteases
Medical problems
Green Fluorescent Proteins
Amyloid
Trypsin
Type 2 Diabetes Mellitus
Electron microscopy
Zinc
Digestion
Alzheimer Disease
Proteins
Peptide Hydrolases
Fusion reactions
Nucleotides

Keywords

  • Alzheimer's disease
  • Diabetes mellitus
  • Insulin-degrading enzyme
  • Metallopeptidase
  • Mitochondrion

ASJC Scopus subject areas

  • Biochemistry

Cite this

Leissring, M. A., Farris, W., Wu, X., Christodoulou, D. C., Haigis, M. C., Guarente, L., & Selkoe, D. J. (2004). Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria. Biochemical Journal, 383(3), 439-446. https://doi.org/10.1042/BJ20041081

Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria. / Leissring, Malcolm A.; Farris, Wesley; Wu, Xining; Christodoulou, Danos C.; Haigis, Marcia C.; Guarente, Leonard; Selkoe, Dennis J.

In: Biochemical Journal, Vol. 383, No. 3, 01.11.2004, p. 439-446.

Research output: Contribution to journalArticle

Leissring, MA, Farris, W, Wu, X, Christodoulou, DC, Haigis, MC, Guarente, L & Selkoe, DJ 2004, 'Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria', Biochemical Journal, vol. 383, no. 3, pp. 439-446. https://doi.org/10.1042/BJ20041081
Leissring, Malcolm A. ; Farris, Wesley ; Wu, Xining ; Christodoulou, Danos C. ; Haigis, Marcia C. ; Guarente, Leonard ; Selkoe, Dennis J. / Alternative translation initiation generates a novel isoform of insulin-degrading enzyme targeted to mitochondria. In: Biochemical Journal. 2004 ; Vol. 383, No. 3. pp. 439-446.
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