cNPAS2 induced β cell dysfunction by regulating KANK1 expression in type 2 diabetes

Figure 1 Changes of the glucose tolerance test, glucose-stimulated insulin secretion test in diabetes mellitus type 2 mice. A: In the control group and diabetes mellitus type 2 (T2DM) groups, the glucose tolerance test curve and the area under the curve were assessed after orally gavage with glucose; B: After stimulation of glucose, plasma insulin concentrations were measured in different phases during glucose-stimulated insulin secretion test in control group and T2DM group. ^aP < 0.0001. T2DM: Diabetes mellitus type 2; OGTT: Glucose tolerance test; GSIS: Glucose-stimulated insulin secretion test.

Figure 2 NPAS2 is highly expressed in diabetes mellitus type 2 samples. A: NPAS2 levels in islet tissues of control group and diabetes mellitus type 2 (T2DM) group were detected by reverse transcription-PCR; B: Western blotting showed the overexpression of NPAS2 in T2DM. ^aP < 0.0001. T2DM: Diabetes mellitus type 2.

Figure 3 KANK1 was the potential target gene of NPAS2. A: Scatter plot revealed the favorable connection between KANK1 and NPAS2 in diabetes mellitus type 2 (T2DM); B and C: The expression of KANK1 in T2DM group was higher than that in control group. ^aP < 0.0001. T2DM: Diabetes mellitus type 2.

Figure 4 NPAS2 regulates KANK1expression. A: Quantitative reverse transcriptase PCR (qRT-PCR) showed that NPAS2 overexpression increased the mRNA level of KANK1; B: Western blotting showed that NPAS2 overexpression enhanced the protein of KANK1; C: qRT-PCR showed knocking down NPAS2 with shRNA decreased the mRNA level of KANK1; D: Western blotting showed knocking down NPAS2 with shRNA decreased the protein of KANK1. ^aP < 0.01, ^bP < 0.001, ^cP < 0.0001. T2DM: Diabetes mellitus type 2.

Figure 5 NPAS2 and KANK1 deceased β-cell survival. A and B: CCK-8 tests showed that knocking down NPAS2 and KANK1 increased the proliferation of MIN6 cells. ^aP < 0.01.

Figure 6 NPAS2 deceased β-cell survival by regulating KANK1 expression. The cell proliferation rate in sh-Control + Empty vector, sh-NPAS2 + Empty vector, sh-Control + OE-KANK1 and sh-NPAS2 + OE-KANK1, MIN6 cell injury model and the Empty vector + sh-Control model by CCK8 test. ^aP < 0.01, ^bP < 0.001.

Figure 7 Gastric bypass may treat type 2 diabetes by down-regulating NPAS2 and KANK1. A: Quantitative reverse transcriptase PCR showed the mRNA content of KANK1 and NPAS2 in the β-cell of mice; B: Western blotting indicated the protein of KANK1 and NPAS2 in the β-cell of mice. ^aP < 0.0001.