Forschungsdatenbank PMU-SQQUID

PMU-Autor/inn/en

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.

Useful keywords (using NLM MeSH Indexing)

Animals

Biological Markers/analysis*

Glutamate Decarboxylase/blood

Humans

Insulin-Secreting Cells/metabolism

Insulin-Secreting Cells/pathology*

Microtubule-Associated Proteins/immunology

Microtubule-Associated Proteins/isolation*

purification

Microtubule-Associated Proteins/metabolism*

Neuropeptides/immunology

Neuropeptides/isolation*

purification

Neuropeptides/metabolism*

Proteomics

Rats

Transcriptome

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