title: LC-MS/MS identification of doublecortin as abundant beta cell-selective protein discharged by damaged beta cells in vitro.
abstract: There is a clinical need for plasma tests that can directly detect injury to pancreatic beta cells in type 1 diabetes. Such tests require biomarkers that are abundantly and selectively released into plasma by damaged beta cells. We combined LC-MS/MS proteomics and tissue-comparative transcriptomics of FACS-purified beta cells for bottom-up identification of candidate markers. Less than 10% of 467 proteins detected in beta cells showed endocrine-enriched expression. One surprising candidate was the neuronal migration marker doublecortin: in situ analysis revealed uniform doublecortin expression in the cytoplasm of all beta cells. Western blotting and real-time PCR confirmed its strong beta cell-selectivity outside the brain and its high molar abundance, indicating promising biomarker properties in comparison to GAD65, a more established marker of beta cell injury. DCX potential was validated in vitro: chemically-induced necrosis of rat and human beta cells led to a discharge of intracellular doublecortin into the extracellular space, proportionate to the amount of injured cells, and similar to GAD65. In vivo, recombinant DCX showed favorable pharmacokinetic properties, with a half-life in plasma of around 3h. Combined, our findings provide first proof-of-principle for doublecortin as biomarker for beta cell injury in vitro, advocating its further validation as biomarker in vivo.
authors: Diabetes Research Center, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
authors: L
authors: L
authors: Jiang
authors: B
authors: B
authors: Brackeva
authors: G
authors: G
authors: Stangé
authors: K
authors: K
authors: Verhaeghen
authors: O
authors: O
authors: Costa
authors: S
authors: S
authors: Couillard-Després
authors: P
authors: P
authors: Rotheneichner
authors: L
authors: L
authors: Aigner
authors: C
authors: C
authors: Van Schravendijk
authors: D
authors: D
authors: Pipeleers
authors: Z
authors: Z
authors: Ling
authors: F
authors: F
authors: Gorus
authors: G A
authors: GA
authors: Martens
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis*; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D005968:Glutamate Decarboxylase / Q000097:blood; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology*; D008869:Microtubule-Associated Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D009479:Neuropeptides / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D040901:Proteomics; D051381:Rats; D059467:Transcriptome
chemical_list: D015415:Biomarkers; C000714328:DCX protein, human; C000714848:Dcx protein, rat; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2