当前位置: X-MOL 学术Diabetol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
The lack of functional nicotinamide nucleotide transhydrogenase only moderately contributes to the impairment of glucose tolerance and glucose-stimulated insulin secretion in C57BL/6J vs C57BL/6N mice
Diabetologia ( IF 8.2 ) Pub Date : 2021-08-27 , DOI: 10.1007/s00125-021-05548-7
Anne-Françoise Close 1 , Heeyoung Chae 1 , Jean-Christophe Jonas 1
Affiliation  

Aims/hypothesis

Nicotinamide nucleotide transhydrogenase (NNT) is involved in mitochondrial NADPH production and its spontaneous inactivating mutation (NntTr [Tr, truncated]) is usually considered to be the main cause of the lower glucose tolerance of C57BL/6J vs C57BL/6N mice. However, the impact of this mutation on glucose tolerance remains disputed. Here, we singled out the impact of NntTr from that of other genetic variants between C57BL/6J and C57BL/6N mice on mitochondrial glutathione redox state (EGSH), glucose-stimulated insulin secretion (GSIS) and glucose tolerance.

Methods

Male and female N5BL/6J mice that express wild-type Nnt (NntWT) or NntTr (N5-WT and N5-Tr mice) on the C57BL/6J genetic background were obtained by crossing N5BL/6J NntWT/Tr heterozygous mice. C57BL/6J and C57BL/6N mice were from Janvier Labs. The Nnt genotype was confirmed by PCR and the genetic background by whole genome sequencing of one mouse of each type. Glucose tolerance was assessed by IPGTT, ITT and fasting/refeeding tests. Stimulus–secretion coupling events and GSIS were measured in isolated pancreatic islets. Cytosolic and mitochondrial EGSH were measured using the fluorescent redox probe GRX1–roGFP2 (glutaredoxin 1 fused to redox-sensitive enhanced GFP).

Results

The Nnt genotype and genetic background of each type of mouse were confirmed. As reported previously in C57BL/6N vs C57BL/6J islets, the glucose regulation of mitochondrial (but not cytosolic) EGSH and of NAD(P)H autofluorescence was markedly improved in N5-WT vs N5-Tr islets, confirming the role of NNT in mitochondrial redox regulation. However, ex vivo GSIS was only 1.2–1.4-times higher in N5-WT vs N5-Tr islets, while it was 2.4-times larger in C57BL/6N vs N5-WT islets, questioning the role of NNT in GSIS. In vivo, the ITT results did not differ between N5-WT and N5-Tr or C57BL/6N mice. However, the glucose excursion during an IPGTT was only 15–20% lower in female N5-WT mice than in N5-Tr and C57BL/6J mice and remained 3.5-times larger than in female C57BL/6N mice. Similar observations were made during a fasting/refeeding test. A slightly larger (~30%) impact of NNT on glucose tolerance was found in males.

Conclusions/interpretation

Although our results confirm the importance of NNT in the regulation of mitochondrial redox state by glucose, they markedly downsize the role of NNT in the alteration of GSIS and glucose tolerance in C57BL/6J vs C57BL/6N mice. Therefore, documenting an NntWT genotype in C57BL/6 mice does not provide proof that their glucose tolerance is as good as in C57BL/6N mice.

Graphical abstract



中文翻译:

在 C57BL/6J 与 C57BL/6N 小鼠中,功能性烟酰胺核苷酸转氢酶的缺乏仅对葡萄糖耐量和葡萄糖刺激的胰岛素分泌造成中度损害

目标/假设

烟酰胺核苷酸转氢酶 (NNT) 参与线粒体 NADPH 的产生,其自发失活突变 ( Nnt Tr [Tr, truncated]) 通常被认为是 C57BL/6J 与 C57BL/6N 小鼠相比葡萄糖耐量降低的主要原因。然而,这种突变对葡萄糖耐量的影响仍然存在争议。在这里,我们将Nnt Tr与 C57BL/6J 和 C57BL/6N 小鼠之间的其他遗传变异对线粒体谷胱甘肽氧化还原状态 (E GSH )、葡萄糖刺激的胰岛素分泌 (GSIS) 和葡萄糖耐量的影响区分开来。

方法

通过杂交 N5BL/6J Nnt WT/Tr杂合子小鼠获得在 C57BL/6J 遗传背景上表达野生型Nnt ( Nnt WT ) 或Nnt Tr (N5-WT 和 N5-Tr 小鼠) 的雄性和雌性 N5BL/6J 小鼠. C57BL/6J 和 C57BL/6N 小鼠来自 Janvier Labs。Nnt基因型通过PCR确认,遗传背景通过每种类型的一只小鼠的全基因组测序确认通过 IPGTT、ITT 和禁食/再喂食测试评估葡萄糖耐量。在孤立的胰岛中测量刺激 - 分泌耦合事件和 GSIS。细胞溶质和线粒体 E GSH使用荧光氧化还原探针 GRX1-roGFP2(与氧化还原敏感的增强型 GFP 融合的谷氧还蛋白 1)测量。

结果

确认了每种小鼠的Nnt基因型和遗传背景。正如之前在 C57BL/6N 与 C57BL/6J 胰岛中报道的那样,线粒体(但不是细胞溶质)E GSH的葡萄糖调节N5-WT 与 N5-Tr 胰岛的 NAD(P)H 自发荧光显着改善,证实了 NNT 在线粒体氧化还原调节中的作用。然而,N5-WT 与 N5-Tr 胰岛的离体 GSIS 仅高 1.2-1.4 倍,而 C57BL/6N 与 N5-WT 胰岛的 2.4 倍大,质疑 NNT 在 GSIS 中的作用。在体内,ITT 结果在 N5-WT 和 N5-Tr 或 C57BL/6N 小鼠之间没有差异。然而,在 IPGTT 期间,雌性 N5-WT 小鼠的葡萄糖偏移仅比 N5-Tr 和 C57BL/6J 小鼠低 15-20%,并且仍然是雌性 C57BL/6N 小鼠的 3.5 倍。在禁食/再喂食测试期间进行了类似的观察。在男性中发现 NNT 对葡萄糖耐量的影响略大(~30%)。

结论/解释

尽管我们的结果证实了 NNT 在葡萄糖调节线粒体氧化还原状态中的重要性,但它们显着降低了 NNT 在 C57BL/6J 与 C57BL/6N 小鼠中 GSIS 和葡萄糖耐量改变中的作用。因此,在 C57BL/6 小鼠中记录Nnt WT基因型并不能证明它们的葡萄糖耐量与 C57BL/6N 小鼠一样好。

图形概要

更新日期:2021-10-07
down
wechat
bug