ß-cell dedifferentiation in HOMA-ßlow and HOMA-ßhigh subjects.

CONTEXT: ß-cell dedifferentiation ratio is increased in type 2 diabetes; but its direct link to in vivo ß-cell function in human remains unclear. OBJECTIVE: The present study was designed to investigate whether ß-cell dedifferentiation in situ was closely associated with ß-cell function in vivo and to identify targets crucial for ß-cell dedifferentiation/function in human. METHODS: We acquired HOMA-ß values, calculated the number of hormone-negative endocrine cells and evaluated important markers and novel candidates for ß-cell dedifferentiation/function on paraneoplastic pancreatic tissues from 13 patients with benign pancreatic cystic neoplasm (PCN) or intrapancreatic accessory spleen. RESULTS: Both ß-cell dedifferentiation ratio and dedifferentiation marker (Aldh1a3) were inversely related with in vivo ß-cell function (HOMA-ß) and in situ ß-cell functional markers Glut2 and Ucn3 in human. Moreover, the islets from HOMA-ßlow subjects were manifested as 1) increased ß-cell dedifferentiation ratio, 2) enriched dedifferentiation maker Aldh1a3, and 3) lower expression of Glut2 and Ucn3, compared to those from HOMA-ßhigh subjects. We found that basic leucine zipper transcription factor 2 (Bach2) expression was significantly induced in islets from HOMA-ßlow patients and was positively correlated with the ratio of ß-cell dedifferentiation in human. CONCLUSIONS: Our findings emphasize the contribution of ß-cell dedifferentiation to ß-cell dysfunction in human. The Bach2 induction in ß-cells with higher frequency of dedifferentiation observed in HOMA-ßlow subjects reinforce its distinctive role as a pharmaceutical target of ß-cell dedifferentiation for the treatment of human diabetes.

Simultaneous Interface Engineering and Phase Tuning of CeO2-Decorated Catalysts for Boosted Oxygen Evolution Reaction.

Heterogeneous catalysts have attracted extensive attention among various emerging catalysts for their exceptional oxygen evolution reaction (OER) capabilities, outperforming their single-component counterparts. Nonetheless, the synthesis of heterogeneous materials with predictable, precise, and facile control remains a formidable challenge. Herein, a novel strategy involving the decoration of catalysts with CeO2 is introduced to concurrently engineer heterogeneous interfaces and adjust phase composition, thereby enhancing OER performance. Theoretical calculations suggest that the presence of ceria reduces the free energy barrier for the conversion of nitrides into metals. Supporting this, the experimental findings reveal that the incorporation of rare earth oxides enables the controlled phase transition from nitride into metal, with the proportion adjustable by varying the amount of added rare earth. Thanks to the role of CeO2 decoration in promoting the reaction kinetics and fostering the formation of the genuine active phase, the optimized Ni3FeN/Ni3Fe/CeO2-5% nanoparticles heterostructure catalyst exhibits outstanding OER activity, achieving an overpotential of just 249 mV at 10 mA cm-2. This approach offers fresh perspectives for the conception of highly efficient heterogeneous OER catalysts, contributing a strategic avenue for advanced catalytic design in the field of energy conversion.

Mettl3-Mediated m6A Methylation Controls Pancreatic Bipotent Progenitor Fate and Islet Formation.

The important role of m6A RNA modification in ß-cell function has been established; however, how it regulates pancreatic development and endocrine differentiation remains unknown. Here, we generated transgenic mice lacking RNA methyltransferase-like 3 (Mettl3) specifically in Pdx1+ pancreatic progenitor cells and found the mice with the mutation developed hyperglycemia and hypoinsulinemia at age 2 weeks, along with an atrophic pancreas, reduced islet mass, and abnormal increase in ductal formation. At embryonic day 15.5, Mettl3 deletion had caused a significant loss of Ngn3+ endocrine progenitor cells, which was accompanied by increased Sox9+ ductal precursor cells. We identified histone deacetylase 1 (Hdac1) as the critical direct m6A target in bipotent progenitors, the degeneration of which caused abnormal activation of the Wnt/Notch signaling pathway and blocked endocrine differentiation. This transformation could be manipulated in embryonic pancreatic culture in vitro through regulation of the Mettl3-Hdac1-Wnt/Notch signaling axis. Our finding that Mettl3 determines endocrine lineage by modulating Hdac1 activity during the transition of bipotent progenitors might help in the development of targeted endocrine cell protocols for diabetes treatment.

Fabrication of Ce-doped Hollow NiCo2 O4 Nanoprisms with Heterointerface from MOF-Engaged Strategy for Oxygen Evolution Reaction.

The reasonable design and controlled synthesis of efficient and hollow nanocatalysts with plentiful heterointerface and fully exposed active sites to accelerate the electron transfer and mass transfer process for oxygen evolution reaction (OER) is highly desirable for water splitting by electrolysis. Herein, a metal-organic framework (MOF)-engaged strategy is developed to prepare Ce-doped hollow mesoporous NiCo2 O4 nanoprisms (NiCo2 O4 /CeO2 HNPs) for enhanced OER. Due to the advanced synthesis strategy generating a large number of interfaces between NiCo2 O4 and CeO2 , as well as modulated electrons of the active center by the synergistic action of multi-metals, the obtained catalyst exhibits excellent OER performance with a small overpotential of 290 mV at current density (J) of 10 mA cm-2 . Spinel/Perovskite hollow nanoprisms synthesized by a similar way demonstrates the versatility of our strategy. This work may provide new insights into the development of rare earth-doped hollow polymetallic spinel oxide catalysts.

ß-Cell glucokinase expression was increased in type 2 diabetes subjects with better glycemic control.

BACKGROUND: Type 2 diabetes (T2D) is characterized by a progressive deterioration of ß-cell function with a continuous decline in insulin secretion. Glucokinase (GCK) facilitates the rate-limiting step of glycolysis in pancreatic ß-cells, to acquire the proper glucose-stimulated insulin secretion. Multiple glucokinase activators (GKAs) have been developed and clinically tested. However, the dynamic change of human pancreatic GCK expression during T2D progression has not been investigated. METHODS: We evaluated GCK expression by measuring the average immunoreactivity of GCK in insulin+ or glucagon+ cells from pancreatic sections of 11 nondiabetic subjects (ND), 10 subjects with impaired fasting glucose (IFG), 9 with well-controlled T2D (wT2D), and 5 individuals with poorly controlled T2D (uT2D). We also assessed the relationship between GCK expression and adaptive unfolded protein response (UPR) in human diabetic ß-cells. RESULTS: We did not detect changes of GCK expression in IFG islets. However, we found ß-cell GCK levels were significantly increased in T2D with adequate glucose control (wT2D) but not in T2D with poor glucose control (uT2D). Furthermore, there was a strong positive correlation between GCK expression and adaptive UPR (spliced X-box binding protein 1 [XBP1s] and activating transcription factor 4 [ATF4]), as well as functional maturity marker (urocortin-3 [UCN3]) in human diabetic ß-cells. CONCLUSIONS: Our study demonstrates that inductions of GCK enhanced adaptive UPR and UCN3 in human ß-cells, which might be an adaptive mechanism during T2D progression. This finding provides a rationale for exploring novel molecules that activate ß-cell GCK and thereby improve pharmacological treatment of T2D.