Martens G A, Motté E, Kramer G, Stangé G, Gaarn L W, Hellemans K, Nielsen J H, Aerts J M, Ling Z, Pipeleers D
Diabetes Research Center, Brussels Free University (VUB), Laarbeeklaan 103, B1090 Brussel, Belgium Department of Clinical Chemistry and Radioimmunology, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, B1090 Brussels, Belgium Department of Medical Biochemistry, Academisch Medisch Centrum, Amsterdam, The Netherlands Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
J Mol Endocrinol. 2013 Dec 19;52(1):11-28. doi: 10.1530/JME-13-0106. Print 2014 Feb.
Neonatal β cells are considered developmentally immature and hence less glucose responsive. To study the acquisition of mature glucose responsiveness, we compared glucose-regulated redox state, insulin synthesis, and secretion of β cells purified from neonatal or 10-week-old rats with their transcriptomes and proteomes measured by oligonucleotide and LC-MS/MS profiling. Lower glucose responsiveness of neonatal β cells was explained by two distinct properties: higher activity at low glucose and lower activity at high glucose. Basal hyperactivity was associated with higher NAD(P)H, a higher fraction of neonatal β cells actively incorporating (3)H-tyrosine, and persistently increased insulin secretion below 5 mM glucose. Neonatal β cells lacked the steep glucose-responsive NAD(P)H rise between 5 and 10 mM glucose characteristic for adult β cells and accumulated less NAD(P)H at high glucose. They had twofold lower expression of malate/aspartate-NADH shuttle and most glycolytic enzymes. Genome-wide profiling situated neonatal β cells at a developmental crossroad: they showed advanced endocrine differentiation when specifically analyzed for their mRNA/protein level of classical neuroendocrine markers. On the other hand, discrete neonatal β cell subpopulations still expressed mRNAs/proteins typical for developing/proliferating tissues. One example, delta-like 1 homolog (DLK1) was used to investigate whether neonatal β cells with basal hyperactivity corresponded to a more immature subset with high DLK1, but no association was found. In conclusion, the current study supports the importance of glycolytic NADH-shuttling in stimulus function coupling, presents basal hyperactivity as novel property of neonatal β cells, and provides potential markers to recognize intercellular developmental differences in the endocrine pancreas.
新生β细胞在发育上被认为是不成熟的，因此对葡萄糖的反应性较低。为了研究成熟葡萄糖反应性的获得过程，我们比较了从新生大鼠或10周龄大鼠中纯化的β细胞的葡萄糖调节氧化还原状态、胰岛素合成及分泌，并通过寡核苷酸和液相色谱-串联质谱分析对其转录组和蛋白质组进行了测定。新生β细胞较低的葡萄糖反应性可由两种不同特性来解释：低葡萄糖水平时活性较高，高葡萄糖水平时活性较低。基础高活性与较高的烟酰胺腺嘌呤二核苷酸（磷酸）（NAD(P)H）水平、更高比例的新生β细胞主动掺入3H-酪氨酸以及在5 mM葡萄糖以下胰岛素分泌持续增加有关。新生β细胞在5至10 mM葡萄糖之间缺乏成年β细胞特有的陡峭的葡萄糖反应性NAD(P)H升高，并且在高葡萄糖水平下积累的NAD(P)H较少。它们苹果酸/天冬氨酸-NADH穿梭体和大多数糖酵解酶的表达降低了两倍。全基因组分析表明新生β细胞处于发育的十字路口：当专门分析其经典神经内分泌标志物的mRNA/蛋白质水平时，它们显示出先进的内分泌分化。另一方面，离散的新生β细胞亚群仍表达发育中/增殖组织特有的mRNA/蛋白质。例如，δ样1同源物（DLK1）被用于研究具有基础高活性的新生β细胞是否对应于具有高DLK1的更不成熟亚群，但未发现相关性。总之，本研究支持糖酵解NADH穿梭在刺激-功能偶联中的重要性，将基础高活性作为新生β细胞的新特性，并提供了潜在标志物以识别内分泌胰腺中的细胞间发育差异。
