| 1. |
- Balboa, Diego, et al.
(författare)
-
Functional, metabolic and transcriptional maturation of human pancreatic islets derived from stem cells.
- 2022
-
Ingår i: Nature Biotechnology. - : Springer Nature. - 1087-0156 .- 1546-1696. ; 40:7, s. 1042-1055
-
Tidskriftsartikel (refereegranskat)abstract
- Transplantation of pancreatic islet cells derived from human pluripotent stem cells is a promising treatment for diabetes. Despite progress in the generation of stem-cell-derived islets (SC-islets), no detailed characterization of their functional properties has been conducted. Here, we generated functionally mature SC-islets using an optimized protocol and benchmarked them comprehensively against primary adult islets. Biphasic glucose-stimulated insulin secretion developed during in vitro maturation, associated with cytoarchitectural reorganization and the increasing presence of alpha cells. Electrophysiology, signaling and exocytosis of SC-islets were similar to those of adult islets. Glucose-responsive insulin secretion was achieved despite differences in glycolytic and mitochondrial glucose metabolism. Single-cell transcriptomics of SC-islets in vitro and throughout 6 months of engraftment in mice revealed a continuous maturation trajectory culminating in a transcriptional landscape closely resembling that of primary islets. Our thorough evaluation of SC-islet maturation highlights their advanced degree of functionality and supports their use in further efforts to understand and combat diabetes.
|
|
| 2. |
- Kooner, Jaspal S, et al.
(författare)
-
Genome-wide association study in individuals of South Asian ancestry identifies six new type 2 diabetes susceptibility loci.
- 2011
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 43:10
-
Tidskriftsartikel (refereegranskat)abstract
- We carried out a genome-wide association study of type-2 diabetes (T2D) in individuals of South Asian ancestry. Our discovery set included 5,561 individuals with T2D (cases) and 14,458 controls drawn from studies in London, Pakistan and Singapore. We identified 20 independent SNPs associated with T2D at P < 10(-4) for testing in a replication sample of 13,170 cases and 25,398 controls, also all of South Asian ancestry. In the combined analysis, we identified common genetic variants at six loci (GRB14, ST6GAL1, VPS26A, HMG20A, AP3S2 and HNF4A) newly associated with T2D (P = 4.1 × 10(-8) to P = 1.9 × 10(-11)). SNPs at GRB14 were also associated with insulin sensitivity (P = 5.0 × 10(-4)), and SNPs at ST6GAL1 and HNF4A were also associated with pancreatic beta-cell function (P = 0.02 and P = 0.001, respectively). Our findings provide additional insight into mechanisms underlying T2D and show the potential for new discovery from genetic association studies in South Asians, a population with increased susceptibility to T2D.
|
|
| 3. |
- Mojtaba Ghiasi, Seyed, et al.
(författare)
-
The Endoplasmic Reticulum Chaperone Glucose-Regulated Protein 94 is Essential for Proinsulin Handling
- 2019
-
Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 68:4, s. 747-760
-
Tidskriftsartikel (refereegranskat)abstract
- Although endoplasmic reticulum (ER) chaperone binding to mutant proinsulin has been reported, the role of protein chaperones in the handling of wild-type proinsulin is under-investigated. Here, we have explored the importance of glucose regulated protein 94 (GRP94), a prominent ER chaperone known to fold insulin-like growth factors, in proinsulin handling within β-cells. We found that GRP94 co-immunoprecipitated with proinsulin and that inhibition of GRP94 function and/or expression reduced glucose-dependent insulin secretion, shortened proinsulin half-life and lowered intracellular proinsulin and insulin levels. This phenotype was accompanied by post-ER proinsulin misprocessing and higher numbers of enlarged insulin granules that contained amorphic material with reduced immunogold staining for mature insulin. Insulin granule exocytosis was two-fold accelerated but the secreted insulin had diminished bioactivity. Moreover, GRP94 knockdown or knockout in β-cells selectively activated Protein Kinase R-like Endoplasmic Reticulum Kinase (PERK), without increasing apoptosis levels. Finally, GRP94 mRNA was overexpressed in islets from T2D patients. We conclude that GRP94 is a chaperone crucial for proinsulin handling and insulin secretion.
|
|
| 4. |
- Ren, Weicheng, et al.
(författare)
-
Genetic and transcriptomic analyses of diffuse large B-cell lymphoma patients with poor outcomes within two years of diagnosis
- 2024
-
Ingår i: Leukemia. - : Springer Nature. - 0887-6924 .- 1476-5551. ; 38:2, s. 438-441
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the improvements in clinical outcomes for DLBCL, a significant proportion of patients still face challenges with refractory/relapsed (R/R) disease after receiving first-line R-CHOP treatment. To further elucidate the underlying mechanism of R/R disease and to develop methods for identifying patients at risk of early disease progression, we integrated clinical, genetic and transcriptomic data derived from 2805 R-CHOP-treated patients from seven independent cohorts. Among these, 887 patients exhibited R/R disease within two years (poor outcome), and 1918 patients remained in remission at two years (good outcome). Our analysis identified four preferentially mutated genes (TP53, MYD88, SPEN, MYC) in the untreated (diagnostic) tumor samples from patients with poor outcomes. Furthermore, transcriptomic analysis revealed a distinct gene expression pattern linked to poor outcomes, affecting pathways involved in cell adhesion/migration, T-cell activation/regulation, PI3K, and NF-kappa B signaling. Moreover, we developed and validated a 24-gene expression score as an independent prognostic predictor for treatment outcomes. This score also demonstrated efficacy in further stratifying high-risk patients when integrated with existing genetic or cell-of-origin subtypes, including the unclassified cases in these models. Finally, based on these findings, we developed an online analysis tool (https://lymphprog.serve.scilifelab.se/app/lymphprog) that can be used for prognostic prediction for DLBCL patients.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Yang, Mingyu, et al.
(författare)
-
Indicator-dependent differences in detection of local intracellular Ca2+release events evoked by voltage-gated Ca2+entry in pancreatic & beta;-cells
- 2023
-
Ingår i: Cellular Signalling. - : Elsevier BV. - 0898-6568 .- 1873-3913. ; 109
-
Tidskriftsartikel (refereegranskat)abstract
- Genetically encoded Ca2+ indicators have become widely used in cell signalling studies as they offer advantages over cell-loaded dye indicators in enabling specific cellular or subcellular targeting. Comparing responses from dye and protein-based indicators may provide information about indicator properties and cell physiology, but side-by-side recordings in cells are scarce. In this study, we compared cytoplasmic Ca2+ concentration ([Ca2+]i) changes in insulin-secreting & beta;-cells recorded with commonly used dyes and indicators based on circularly permuted fluorescent proteins. Total internal reflection fluorescence (TIRF) imaging of K+ depolarizationtriggered submembrane [Ca2+]i increases showed that the dyes Fluo-4 and Fluo-5F mainly reported stable [Ca2+]i elevations, whereas the proteins R-GECO1 and GCaMP5G more often reported distinct [Ca2+]i spikes from an elevated level. [Ca2+]i spiking occurred also in glucose-stimulated cells. The spikes reflected Ca2+ release from the endoplasmic reticulum, triggered by autocrine activation of purinergic receptors after exocytotic release of ATP and/or ADP, and the spikes were consequently prevented by SERCA inhibition or P2Y1-receptor antagonism. Widefield imaging, which monitors the entire cytoplasm, increased the spike detection by the Ca2+ dyes. The indicator-dependent response patterns were unrelated to Ca2+ binding affinity, buffering and mobility, and probably reflects the much slower dissociation kinetics of protein compared to dye indicators. Ca2+ dyes thus report signalling within the submembrane space excited by TIRF illumination, whereas the protein indicators also catch Ca2+ events originating outside this volume. The study highlights that voltage-dependent Ca2+ entry in & beta;-cells is tightly linked to local intracellular Ca2+ release mediated via an autocrine route that may be more important than previously reported direct Ca2+ effects on phospholipase C or on intracellular channels mediating calcium-induced calcium release.
|
|
| 8. |
- Yang, Mingyu
(författare)
-
Pitfalls in β-cell ion imaging with fluorescent indicators and their use for real-time detection of somatostatin secretion
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fluorescent ion indicators have become indispensable tools in cell physiology. Dye indicators can easily be loaded into most types of cells, while genetically encoded indicators are advantageous in allowing specific cellular or subcellular targeting. Comparing responses of dye and protein-based indicators may provide useful insights into indicator properties and cellular processes. Here, a few genetically encoded Ca2+ indicators and fluorescent Ca2+ dyes were compared in insulin-secreting β-cells. Recordings of depolarization-triggered changes of the cytoplasmic Ca2+ concentration ([Ca2+]i) beneath the plasma membrane with total internal reflection fluorescence microscopy demonstrated distinct [Ca2+]i spikes with protein-based indicators, while the dyes mainly reported stable [Ca2+]i elevations. The spikes reflected Ca2+ release from the endoplasmic reticulum, triggered by autocrine purinergic receptor activation from exocytotic release of ATP. The indicator-dependent differences were unrelated to Ca2+ binding affinity and buffering and probably reflected slower Ca2+ dissociation kinetics of the protein indicators. In glucose-stimulated mouse islets, the dye Fura-2 reported the characteristic [Ca2+]i response with an initial lowing followed by rapid increase, which was abolished by hyperpolarization with the K+-channel opener diazoxide. The simultaneously present genetically encoded indicator R-GECO1 failed to detect the lowering and reported a spurious [Ca2+]i elevation also in the presence of diazoxide, responses that could be ascribed to pH sensitivity of the indicator. Recordings with fluorescent H+ indicators demonstrated that glucose increases cytoplasmic pH in β-cells. Elevations of [Ca2+]i counteracted the alkalinization and [Ca2+]i oscillations in glucose-stimulated islets were associated with anti-phasic oscillations of [Ca2+]i and pH. A [Ca2+]i imaging-based reporter cell assay for real-time detection of the islet hormone somatostatin was generated by transfecting HeLa cells with somatostatin receptor 2, the G-protein Gα15 and R-GECO1. The reporter cells detected somatostatin secretion from islets imaged in the same view-field as dose-dependent [Ca2+]i elevations. Mouse and human islets released somatostatin in response to high K+, glucose, and the hormones GLP-1 and ghrelin. In glucose-stimulated mouse islets, bursts of somatostatin release were synchronized with islet [Ca2+]i oscillations. Analyses of islets from human donors indicated that type 2 diabetes is associated with hypersecretion of somatostatin. In conclusion, this thesis highlights potential pitfalls with fluorescent ion indicators in β-cell signalling studies and provides new insights into β-cell regulation of [Ca2+]i and pH. Moreover, it introduces an assay for real-time detection of somatostatin secretion from islets that holds promise for studies of the role of this hormone under normal conditions and in diabetes.
|
|
| 9. |
|
|
