| 1. |
- Tyka, K., et al.
(författare)
-
MCPIP1 is a novel link between diabetogenic conditions and impaired insulin secretory capacity
- 2021
-
Ingår i: Biochimica Et Biophysica Acta-Molecular Basis of Disease. - : Elsevier BV. - 0925-4439. ; 1867:10
-
Tidskriftsartikel (refereegranskat)abstract
- During diabetes development insulin production and glucose-stimulated insulin secretion (GSIS) are defective due to inflammation-related, yet not fully understood mechanisms. MCPIP1 (monocyte chemotactic protein-induced protein-1) is a strong regulator of inflammation, and acts predominantly as a specific RNase. The impact of MCPIP1 on insulin secretory capacity is unknown. We show that the expression of the ZC3H12A gene, which encodes MCPIP1, was induced by T1DM- and by T2DM-simulating conditions, with a stronger effect of cytokines. The number of MCPIP1-positive pancreatic islet-cells, including beta-cells, was significantly higher in diabetic compared to nondiabetic individuals. In the 3' UTR regions of mRNAs coding for Pdx1 (pancreatic and duodenal homeobox 1), FoxO1 (forkhead box protein O1), and of a novel regulator of insulin handling, Grp94 (glucose-regulated protein 94), MCPIP1-target structures were detected. Overexpression of the wild type MCPIP1(wt), but not of the mutant MCPIP1(D141N) (lacking the RNase activity), decreased the expression of genes involved in insulin production and GSIS. Additionally INS1-E-MCPIP1(wt) cells exhibited a higher Ire1 (inositol-requiring enzyme 1) expression. MCPIP1(wt) overexpression blunted GSIS and glucose-mediated calcium influx with no deleterious effects on glucose uptake or glucokinase activity. We identify MCPIP1 as a new common link between diabetogenic conditions and beta-cell failure. MCPIP1 may serve as an interesting target for novel beta-cell protective approaches.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Karlsson, Cecilia, 1968, et al.
(författare)
-
Identification of Proteins Associated with the Early Restoration of Insulin Sensitivity After Biliopancreatic Diversion
- 2020
-
Ingår i: Journal of Clinical Endocrinology & Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 105:11
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Insulin resistance (IR) is a risk factor for type 2 diabetes, diabetic kidney disease, cardiovascular disease and nonalcoholic steatohepatitis. Biliopancreatic diversion (BPD) is the most effective form of bariatric surgery for improving insulin sensitivity. Objective: To identify plasma proteins correlating with the early restoration of insulin sensitivity after BPD. Design: Prospective single-center study including 20 insulin-resistant men with morbid obesity scheduled for BPD. Patient characteristics and blood samples were repeatedly collected from baseline up to 4 weeks postsurgery. IR was assessed by homeostatic model assessment for insulin resistance (HOMA-IR), Matsuda Index, and by studying metabolic profiles during meal tolerance tests. Unbiased proteomic analysis was performed to identify plasma proteins altered by BPD. Detailed plasma profiles were made on a selected set of proteins by targeted multiple reaction monitoring mass spectrometry (MRM/MS). Changes in plasma proteome were evaluated in relation to metabolic and inflammatory changes. Results: BPD resulted in improved insulin sensitivity and reduced body weight. Proteomic analysis identified 29 proteins that changed following BPD. Changes in plasma levels of afamin, apolipoprotein A-IV (ApoA4), and apolipoprotein A-II (ApoA2) correlated significantly with changes in IR. Conclusion: Circulating levels of afamin, ApoA4, and ApoA2 were associated with and may contribute to the rapid improvement in insulin sensitivity after BPD.
|
|
| 7. |
- Khilji, M. S., et al.
(författare)
-
The inducible β5i proteasome subunit contributes to proinsulin degradation in GRP94-deficient β-cells and is overexpressed in type 2 diabetes pancreatic islets
- 2020
-
Ingår i: American Journal of Physiology - Endocrinology and Metabolism. - 0193-1849. ; 318:6
-
Tidskriftsartikel (refereegranskat)abstract
- Proinsulin is a misfolding-prone protein, and its efficient breakdown is critical when β-cells are confronted with high-insulin biosynthetic demands, to prevent endoplasmic reticulum stress, a key trigger of secretory dysfunction and, if uncompensated, apoptosis. Proinsulin degradation is thought to be performed by the constitutively expressed standard proteasome, while the roles of other proteasomes are unknown. We recently demonstrated that deficiency of the proinsulin chaperone glucoseregulated protein 94 (GRP94) causes impaired proinsulin handling and defective insulin secretion associated with a compensated endoplasmic reticulum stress response. Taking advantage of this model of restricted folding capacity, we investigated the role of different proteasomes in proinsulin degradation, reasoning that insulin secretory dynamics require an inducible protein degradation system. We show that the expression of only one enzymatically active proteasome subunit, namely, the inducible β5i-subunit, was increased in GRP94 CRISPR/Cas9 knockout (KO) cells. Additionally, the level of β5i-containing intermediate proteasomes was significantly increased in these cells, as was β5i-related chymotrypsin-like activity. Moreover, proinsulin levels were restored in GRP94 KO upon β5i small interfering RNA-mediated knockdown. Finally, the fraction of β-cells expressing the β5i subunit is increased in human islets from type 2 diabetes patients. We conclude that β5i is an inducible proteasome subunit dedicated to the degradation of mishandled proinsulin. Copyright © 2020 the American Physiological Society.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
