Unbiased Profiling of the Human Proinsulin Biosynthetic Interaction Network Reveals a Role for Peroxiredoxin 4 in Proinsulin Folding.
Duc T TranAnita PottekatSaiful A MirSalvatore LoguercioInsook JangAlexandre Rosa CamposKathleen M ScullyReyhaneh LahmyMing LiuPeter ArvanWilliam E BalchRandal J KaufmanPamela Itkin-AnsariPublished in: Diabetes (2020)
The β-cell protein synthetic machinery is dedicated to the production of mature insulin, which requires the proper folding and trafficking of its precursor, proinsulin. The complete network of proteins that mediate proinsulin folding and advancement through the secretory pathway, however, remains poorly defined. Here we used affinity purification and mass spectrometry to identify, for the first time, the proinsulin biosynthetic interaction network in human islets. Stringent analysis established a central node of proinsulin interactions with endoplasmic reticulum (ER) folding factors, including chaperones and oxidoreductases, that is remarkably conserved in both sexes and across three ethnicities. The ER-localized peroxiredoxin PRDX4 was identified as a prominent proinsulin-interacting protein. In β-cells, gene silencing of PRDX4 rendered proinsulin susceptible to misfolding, particularly in response to oxidative stress, while exogenous PRDX4 improved proinsulin folding. Moreover, proinsulin misfolding induced by oxidative stress or high glucose was accompanied by sulfonylation of PRDX4, a modification known to inactivate peroxiredoxins. Notably, islets from patients with type 2 diabetes (T2D) exhibited significantly higher levels of sulfonylated PRDX4 than islets from healthy individuals. In conclusion, we have generated the first reference map of the human proinsulin interactome to identify critical factors controlling insulin biosynthesis, β-cell function, and T2D.
Keyphrases
- endothelial cells
- oxidative stress
- endoplasmic reticulum
- mass spectrometry
- high glucose
- type diabetes
- molecular dynamics simulations
- induced apoptosis
- dna damage
- induced pluripotent stem cells
- pluripotent stem cells
- single cell
- transcription factor
- adipose tissue
- cell death
- binding protein
- ischemia reperfusion injury
- endoplasmic reticulum stress
- lymph node
- cell proliferation
- mesenchymal stem cells
- liquid chromatography
- signaling pathway
- diabetic rats
- bone marrow
- heat shock protein