Acute glucose stimulation drives coordinated translational reprogramming in primary pancreatic islets: from global...

Pancreatic beta cells must rapidly escalate protein synthesis to maintain systemic glucose homeostasis. While the transcriptional responses are well characterized, the immediate translational dynamics governing this adaptive phase remain poorly defined.

We performed high-resolution ribosome profiling (Ribo-seq) on primary mouse islets under acute low-glucose (2.5 mM) and high-glucose (25 mM) conditions and integrated analysis of the differential translation, functional enrichment, translational efficiency (TE), and ribosome kinetics. The protein levels and mRNA expression were validated using Western blot and quantitative PCR (qPCR), respectively.

We identified extensive translational reprogramming involving 1, 680 differentially translated genes. High glucose triggered a significant upregulation of immediate early genes (e.g., Fos and Nr4a1) and a concurrent inhibition of stress-related genes (e.g., Ddit3 and Trib3). On the other hand, beta cells prioritized the synthesis of cytosolic ribosomal proteins and elongation factors to expand the biosynthetic machinery. This was coordinated with a scale-up of the downstream secretory pathway (e.g., Sec61a1) and a metabolic realignment, characterized by the translational upregulation of mitochondrial enzymes (e.g., Cs and Fh1) despite the relative suppression of mitochondrial biogenesis genes. Furthermore, TE analysis revealed that several genes were regulated independent of their mRNA levels, such as Rpl3 and Atf4. Finally, kinetic analysis suggested that high glucose affected the ribosome occupancy density and distribution on specific transcripts, such as Ins1.

Our research characterizes the translatome as a dynamic regulator of the glucose response. By revealing these rapid translational nodes, we provide potential targets to restore the insulin synthetic capacity and secretory function in T2DM, offering a mechanistic framework for the development of therapies centered on preserving β-cell proteostasis.