Hypothesis

PERK-mediated translational attenuation protects beta cell identity by limiting IAPP synthesis during aging-induced ER stress.

Rationale

• Aging beta cells show chronic ER stress, elevated HSPA5, and heterogeneous UPR marker distribution 1.
• PERK activation reduces global protein synthesis while allowing selective translation of ATF4 and stress‑response genes 2.
• In beta cells, PERK signaling is protective against diabetes, whereas IRE1α/XBP1s expansion correlates with secretory demand 3.
• IAPP aggregation is triggered when ER load exceeds folding capacity, linking translational load to amyloid formation 4.
• Loss of PDX1 and NKX6.1 coincides with ER stress, but the direction of causality remains unclear 1.

Mechanistic Insight

We propose that sustained PERK-eIF2α phosphorylation in aging beta cells reduces the influx of nascent IAPP peptides into the ER lumen, thereby decreasing the propensity for misfolding and amyloid nucleation. Simultaneously, PERK-dependent ATF4 upregulates chaperones and autophagy components that restore proteostasis. When PERK signaling wanes or becomes maladaptive, translational restraint is lost, IAPP synthesis overwhelms the compromised ER, and amyloid deposits accelerate beta-cell dedifferentiation.

Testable Predictions

1. In aged human islets, beta cells with high p-eIF2α (active PERK) will exhibit lower intracellular IAPP levels and reduced amyloid staining compared to neighboring cells with low p-eIF2α.
2. Pharmacological enhancement of PERK signaling (e.g., with low-dose CCT020312) in aged mouse islets will decrease IAPP oligomer formation and preserve PDX1/NKX6.1 expression.
3. Conversely, beta-cell-specific PERK knockout in aged mice will exacerbate IAPP aggregation, increase lipofuscin, and hasten loss of insulin secretory capacity.
4. Single-cell transcriptomics will reveal an inverse correlation between PERK-target gene signatures (ATF4, CHOP, GADD34) and IAPP mRNA translation rates across individual beta cells.

Experimental Approach

• Obtain pancreatic donors stratified by age and diabetic status; perform multiplex immunofluorescence for p-eIF2α, IAPP, PDX1, and amyloid-specific dye (e.g., Thioflavin-S). Quantify co-localization at single-cell resolution.
• Treat aged mouse islets ex vivo with PERK activator or inhibitor; measure IAPP secretion, Thioflavin-T fluorescence, and insulin glucose-stimulated secretion.
• Generate inducible beta-cell-specific PERK KO mice; monitor aging cohorts for IAPP deposition via PET-compatible amyloid tracer and glucose tolerance.
• Apply scRNA-seq with ribosome profiling (Ribo-Seq) on isolated islets to assess translation efficiency of IAPP versus chaperone mRNAs in relation to PERK activity.

If predictions hold, the hypothesis positions PERK-mediated translational attenuation as a safeguard that couples ER load to amyloidogenic risk, offering a node where boosting PERK function could delay age-related beta-cell failure. Failure to observe the predicted inverse relationship between PERK activity and IAPP amyloidosis would falsify the model.