Pancreatic β-cell dysfunction is partially ameliorated by absence of AMPK signaling

Type 2 diabetes results when pancreatic β-cells fail to secrete insulin sufficient to maintain glucose homeostasis. Cellular O-GlcNAcylation by O-GlcNAc transferase (OGT) is a key regulator of β-cell function, with reduced OGT activity resulting in β-cell failure (PMID: 26673325). Excessive autophagy may contribute to this failure, as the absence of OGT in β-cells also results in elevated autophagy (PMID: 39388284). AMP-activated protein kinase (AMPK), a primary driver of autophagy, cross-talks with OGT via reciprocal phosphorylation and O-GlcNAcylation (PMID: 24563466), leading us to hypothesize that a reduction in AMPK-driven autophagy would prevent β-cell dysfunction and resultant hyperglycemia in an OGT-deficient mouse model. To test this, we crossed mice expressing rat insulin 2 promoter (RIP)-Cre with mice expressing loxP-flanked OGT, AMPK, or both, thereby generating mice with β-cell-specific genetic deletions of OGT (βOGTKO), AMPK (βAMPKKO), or both (βOGT/AMPKKO). Floxed Cre-negative littermates were pooled as control, with all mice on a C57BL/6 background. Statistical analyses were performed by one- or two-way ANOVA, with multiple comparisons p-value-corrected by Bonferroni. In the β-cells of βOGTKO mice, we first observed increased AMPK phosphorylation at Thr172, indicating elevated AMPK activity. In assessing overall glucose homeostasis in females, non-fasting hyperglycemia was evident in βOGTKO by 12 weeks of age, with blood glucose >400 mg/dL by 16 weeks. In βOGT/AMPKKO, hyperglycemia was blunted, with no difference from control observed until 14 weeks, and not surpassing 200 mg/dL by 16 weeks. βAMPKKO exhibited normoglycemia until at least 16 weeks of age. At 7-9 weeks, prior to the onset of apparent hyperglycemia, we performed in one subset (n=4-10) an IPGTT, and in another subset (n=3) collected pancreatic islets to test in vitro GSIS. In contrast to what was observed with glycemia, both βOGTKO and βAMPKKO mice exhibited decreased glucose clearance following the IPGTT compared to controls, with βOGT/AMPKKO mice showing exacerbated glucose intolerance beyond that of the control and single deletion groups. Compared to islets from control mice, total insulin content did not differ for βAMPKKO, but decreased to a similar degree for both βOGTKO and βOGT/AMPKKO. There was no effect on stimulation index by GSIS for any genotype. Overall, loss of β-cell AMPK signaling in βOGTKO mice offers some protection against hyperglycemia, but this is not explained by an improvement in β-cell insulin content or secretion. Further experiments targeting the downstream effects of AMPK, OGT, and their roles on autophagy are necessary to understand the mechanisms at play. This work was supported by the NIH funding grants: T32 Postdoctoral Fellowship (T32DK083250) to VP; F31 Predoctoral Fellowship (F31DK131860) to SJ; R56 (R56DK136293) to EA. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.