Objective: Pancreatic ductal cells will be differentiated into islet-like cell with the activation of PRL-PRLR signaling pathway in vitro.
Methods: Primary mouse and human pancreatic ductal cells ...were obtained by CK-19 labelling and MACS sorting of digested pancreatic tissue, and selected cells were cultured with recombinant mouse prolactin and recombinant human prolactin. Subsequently, the cell clusters formed by the pancreatic ductal cells were stained by anti-insulin, anti-GCK, anti-GLUT2, anti-PC1/3 Abs. In vitro, glucose stimulated insulin secretion (GSIS) was quantified. Prolactin related signaling pathway, glucose transportation and insulin secretion related proteins were assessed by immunoblotting. Lastly, the in vitro formed islet-like cells were transplanted under the kidney capsule of diabetic mice. To assess the role for blood glucose regulation of transplanted islet-like cells, blood glucose, c-peptide and intravenous glucose tolerance tests were performed and immunofluorescence staining for insulin and glucagon was performed on the grafts.
Results: At day 7, the pancreatic ductal cells, also called progenitor cells, expressed CK-19; at day 14, the ductal cells were aggregated and formed sphere-shaped cell clusters. At day 21, the cell clusters stained positive for insulin and etc. By in vitro GSIS test, we measured a 2.58±0.32-fold increase of insulin secretion in response to a 16.7 mM glucose stimulation. Immunoblotting demonstrated that PDX-1, MafA and other genes were expressed. At day 21, the cell clusters expressed PDX-1, insulin and glucagon. In vivo studies showed that diabetic mice transplanted with islet-like cells, maintained blood glucose levels below 300 mg/dL with c-peptide detected in the serum. Further tissue staining indicated that the transplanted islet-like cells contained both β-cells and α-cells.
Conclusion: Out study shows that in vitro stimulation by prolactin might differentiate pancreatic ductal cells into islet-like cells.
Disclosure
Y. Wang: None.
Funding
National Natural Science Foundation of China (81802504); Sichuan Science and Technology Bureau (2022YFH0005, 2023YFH0010)
Abnormal accumulation of saturated fatty acids in the heart results in insulin resistance, stress kinase activation, and increased cardiovascular risk in humans. The viability of human cardiac ...progenitor cells (CPC) is essential for myocardium homeostasis. This study investigates the ability of palmitate, a saturated fatty acid, to induce apoptosis, autophagy, and stress kinase activation in human CPC isolated from right auricle biopsies of nondiabetic, non-obese subjects, and the potential protective effects of insulin on palmitate-induced abnormalities. Human CPC expressed both IR-A and IR-B, and IR-A was more expressed than IR-B, as assessed by quantitative RT-PCR and immunoblotting. Exposure of human CPC to 100 nM insulin for 15 minutes resulted in increased Akt (S473) and p44/p42 MAPK (T202/Y204) phosphorylation (p<0.05), as evidenced by immunoblotting. Treatment of human CPC with palmitate 0.25 mM for 16 h induced apoptosis (p<0.05), as assessed by caspase-3 cleavage and ELISA assay, and increased S63-phosphorylation of c-Jun (p<0.05), a downstream transcription factor of JNK 1/2, as assessed by immunoblotting. Exposure of human CPC to 0.25 mM palmitate for 16 h resulted also in increased autophagy, evidenced by light chain 3-II immunoblotting (p<0.05). Pretreatment with 20 µM SP600125, a JNK inhibitor, for 1 h inhibited palmitate-induced apoptosis (p<0.05), but not autophagy. Similarly, pretreatment with 10 mM 3-methyladenine, an autophagy inhibitor, for 1 h decreased palmitate-induced apoptosis (p<0.05). Interestingly, palmitate effects on apoptosis, autophagy, and on stress kinase activation, were prevented when human CPC were pretreated with 100 nM insulin for 1 h (p<0.05). In conclusion, insulin prevents palmitate-induced apoptosis by inhibition of JNK signaling and autophagy in human CPC. Hence, preserving insulin signaling in human CPC might protect from lipotoxicity-induced metabolic alterations in the heart.
Disclosure
I. Calderoni: None. R. Doria: None. C. Caccioppoli: None. V. Genchi: None. G. Palma: None. G. Santarpino: None. A.D. Milano: None. A. Leonardini: None. A. Natalicchio: Other Relationship; AstraZeneca, Novo Nordisk, Sanofi, Boehringer-Ingelheim, Lilly. S. Perrini: None. A. Cignarelli: Speaker's Bureau; Eli Lilly and Company, Novo Nordisk, Sanofi. F. Giorgino: Research Support; Lilly, Roche Diabetes Care. Consultant; Novo Nordisk, Lilly. Speaker's Bureau; Abbott, Boehringer-Ingelheim, Lilly. Advisory Panel; Boehringer-Ingelheim, Amarin Corporation, Medtronic, Roche Diabetes Care, Sanofi. Speaker's Bureau; Sanofi. Advisory Panel; Bayer Inc., Novo Nordisk. Research Support; AlfaSigma. Speaker's Bureau; Medscape. L. Laviola: Speaker's Bureau; Abbott. Advisory Panel; A. Menarini Diagnostics, Boehringer Ingelheim Inc., Eli Lilly and Company, Novo Nordisk, Roche Diabetes Care. Speaker's Bureau; Terumo Corporation. Other Relationship; Medtronic. Advisory Panel; Sanofi.
Background: Increased adiposity has long been associated with insulin resistance and adipose tissue plays a crucial role in regulating metabolic homeostasis, as its dysfunction in obesity leads to ...insulin resistance and type 2 diabetes (T2D). The primary function of white adipose tissue (WAT) is to store energy as lipids while brown adipose tissue (BAT) regulates thermogenesis by dissipating energy in a form of heat. The process of browning involves transdifferention of WAT into brown-like or beige adipocytes, which exhibit the same functional properties as BAT. Browning of WAT is an attractive approach against obesity and insulin resistance. In addition, evidence indicate that activation of the energy sensor AMP-activated protein kinase (AMPK) could counteract insulin resistance. The aim of this study is to examine if carnosic acid (CA), induces browning via activation of AMPK in 3T3-L1 white adipocytes.
Material and methods: Cell morphology, lipid accumulation, mitochondrial density, and browning markers such as uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) levels were assessed using Cytation5 microscope, Oil-O-Red (ORO), MitoTracker Red, immunoblotting and immunocytochemistry.
Results: Microscopic investigation revealed that CA reduced the size and number of lipid droplets in the cells, giving a rise to a brown-like phenotype. The reduction of lipid accumulation was also confirmed by ORO stain. Next, CA increased mitochondrial density and protein expression of UCP-1 and PGC-1-α in 3T3-L1 adipocytes. Most importantly, pre-treatment with compound C, prevented the CA-induced reduction in lipid accumulation, and mitochondrial density and blocked the CA-induced increase in UCP-1 and PGC-1 expression.
Conclusion: This study demonstrates that CA has a pronounced potential in stimulating browning of adipocytes via AMPK-dependent mechanism. Future in vivo studies are required to fully examine the effects of CA.
Disclosure
F.Vlavcheski: None. N.Tsakiridis: None. A.Giacca: None. E.Tsiani: None.
Funding
Natural Science and Engineering Research Council of Canada (RGPIN-2018-06666)
Irisin is a hormone secreted by skeletal muscle, able to improve metabolic homeostasis and promote energy expenditure. We have previously demonstrated that irisin protects human and rodent β-cells ...and pancreatic islets from lipotoxicity-induced apoptosis, increases insulin biosynthesis and glucose-stimulated insulin secretion (GSIS), and promotes β-cell proliferation, both in vitro and in vivo in mice. Irisin may also restore the defects that are characteristic of islets from T2D patients. Although it has been demonstrated that irisin mediates its effects on bone and fat via αV integrin receptors, the presence of an irisin receptor in β-cells has not been reported. In INS-1E cells, we found that irisin activates its intracellular signalling and enhances GSIS in the presence of a specific αV integrin knockdown or a chemical inhibitor of cellular integrins (RGDS), thus excluding the involvement of integrin receptors in irisin effects. Through a pull-down assay/mass spectrometry approach, we identified 102 irisin interactors in human pancreatic islets, mostly belonging to intracellular compartments (i.e., vesicles and membrane rafts), and not including canonical membrane receptors. We therefore hypothesized that irisin could be endocytosed in pancreatic β-cells and confirmed this by immunoblotting and immunofluorescence techniques. In addition, nystatin, an inhibitor of lipid-raft dependent endocytosis, reduced irisin entry into β-cells. These results suggest for the first time that irisin effects on pancreatic β-cells are independent of engaging the αV integrin receptor and may instead depend on its endocytosis. These results are important beyond irisin, as they propose a potential new mechanism of action for peptide hormones. In addition, we highlight the possibility that the same hormone, i.e. irisin, may signal through different receptors in different target tissues.
Disclosure
N.Marrano: None. A.Borrelli: None. G.Biondi: None. M.Rella: None. A.Cignarelli: Speaker's Bureau; Eli Lilly and Company, Novo Nordisk, Sanofi. S.Perrini: None. L.Laviola: Advisory Panel; A. Menarini Diagnostics, Boehringer Ingelheim Inc., Eli Lilly and Company, Novo Nordisk, Roche Diabetes Care, Sanofi, Other Relationship; Medtronic, Speaker's Bureau; Abbott, Terumo Corporation. F.Giorgino: Advisory Panel; Boehringer-Ingelheim, Amarin Corporation, Medtronic, Roche Diabetes Care, Sanofi, Bayer Inc., Novo Nordisk, Consultant; Novo Nordisk, Lilly, Research Support; Lilly, Roche Diabetes Care, AlfaSigma, Speaker's Bureau; Abbott, Boehringer-Ingelheim, Lilly, Sanofi, Medscape. A.Natalicchio: Other Relationship; AstraZeneca, Novo Nordisk, Sanofi, Boehringer-Ingelheim, Lilly.
Type 1 diabetes is a disease characterized by hyperglycemia resulting from defects in insulin secretion. Streptozotocin (STZ)-induced pancreatic β-cell damage is commonly used as causing ...hyperglycemia of type 1 diabetes model. It has been established that the carboxyl terminus of heat shock protein 70-interacting protein (CHIP) contributes to the pathogeneses of diabetic complications. However, the mechanisms linking type 1 diabetes and CHIP-dependent antidiabetic signaling pathway remain to be addressed. Here we utilized STZ-induced murine model of type 1 diabetes to examine DNA damage responses (DDR) during pancreatic β-cell apoptosis. This study was undertaken to explore the mechanism whereby CHIP instigates pancreatic β-cell apoptosis via DDR-dependent signaling pathway. Wild type and CHIP haplodeficient mice were i.p. injected with 50 or 100 mg/kg STZ in order to induce experimental mouse model of type I diabetes. STZ-induced hyperglycemia, glucose intolerance, and inflammatory responses were exacerbated in CHIP haplodeficient mice compared to Wild type. In addition, immunoblotting data revealed that depletion of CHIP with siRNA against rat stub1 enhanced STZ-induced apoptosis and DDR pathway in INS-1 cells, a rat insulinoma cell line. Notably, CHIP inhibition deteriorates STZ-induced cell cycle arrest and oxidative stress in INS-1 cells. In addition to in vitro study, immunohistochemical and immunoblotting study showed that CHIP haplodeficiency exacerbates DDR in pancreas from an experimental mouse model of type I diabetes. These results suggest that CHIP protects against STZ-induced pancreatic β-cell apoptosis and hyperglycemia by interrupting the DDR-mediated apoptotic pathway. Key words: diabetes, CHIP, DNA damage response, apoptosis, β-cell
Disclosure
A. Hwang: None.
Endoplasmic reticulum calcium (ER Ca2+) levels are primarily maintained through the sarco-ER Ca2+ ATPase (SERCA) pump. We have demonstrated reduced SERCA2 expression in islets from human cadaveric ...donors with Type 2 Diabetes (T2D) compared to normoglycemic controls and linked β-cell specific deletion of SERCA2 with impaired proinsulin processing. To test mechanisms of how reduced ER Ca2+ and SERCA2 deficiency regulate proinsulin processing, a SNAP-tagged human proinsulin adenovirus (SNAP-proinsulin) was overexpressed in rat insulinoma β-cells where SERCA2 had been deleted (S2KO INS-1) using CRISPR/Cas9 and in islets from C57BL/6 mice with SERCA2 haploinsufficiency fed a high fat diet or treated ex vivo with glucolipotoxicity (GLT). Immunoblotting SNAP-tagged cleavage products showed reduced proinsulin processing in SERCA2 deficient models compared to wildtype (WT), these defects were exacerbated by GLT treatment. To determine whether reduced processing could be related to impaired trafficking of proinsulin within the β-cell secretory pathway, SNAP-proinsulin was fluorescently labelled in C57BL/6 mouse islets treated with GLT. The colocalization of SNAP-proinsulin with Golgi immuno-marker, Giantin, suggested an accumulation in this compartment. The ER is the main site of lipid synthesis and lipid remodeling is known to regulate β-cell function. Preliminary mass spectrometry data revealed that loss of SERCA2 increases ER levels of phosphatidylcholine and decreases ceramide and sphingomyelin in S2KO INS-1 cells compared to WT cells. Taken together, these results demonstrate that ER Ca2+ deficiency changes ER lipid composition, which may affect proinsulin processing and trafficking. Characterizing this novel mechanism could provide valuable insight into β-cell dysfunction in T2D.
Disclosure
M.Hartley: Employee; Eli Lilly and Company. M.J.Pearson: None. F.Syed: None. H.Bui: None. T.Kono: None. K.D.Roth: Employee; Eli Lilly and Company. C.Evans-molina: Advisory Panel; Provention Bio, Inc., DiogenX, Avotres Inc., Neurodon, MaiCell Therapeutics, Other Relationship; Isla Technology, Bristol-Myers Squibb Company, Nimbus Therapeutics, Research Support; Lilly, Astellas Pharma Inc.
Funding
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK093954, R01DK127308, R01DK127236)
Centrosomes play an important role in various cellular processes, including spindle formation and chromosome segregation. They are composed of two orthogonally arranged centrioles, whose duplication ...occurs only once per cell cycle. Accurate control of centriole numbers is essential for the maintenance of genomic integrity. Although it is well appreciated that polo-like kinase 4 (Plk4) plays a central role in centriole biogenesis, how it is recruited to centrosomes and whether this step is necessary for centriole biogenesis remain largely elusive. Here we showed that Plk4 localizes to distinct subcentrosomal regions in a temporally and spatially regulated manner, and that Cep192 and Cep152 serve as two distinct scaffolds that recruit Plk4 to centrosomes in a hierarchical order. Interestingly, Cep192 and Cep152 competitively interacted with the cryptic polo box of Plk4 through their homologous N-terminal sequences containing acidic-α-helix and N/Q-rich motifs. Consistent with these observations, the expression of either one of these N-terminal fragments was sufficient to delocalize Plk4 from centrosomes. Furthermore, loss of the Cep192- or Cep152-dependent interaction with Plk4 resulted in impaired centriole duplication that led to delayed cell proliferation. Thus, the spatiotemporal regulation of Plk4 localization by two hierarchical scaffolds, Cep192 and Cep152, is critical for centriole biogenesis.
Recent studies have shown that anti-Ro52 antibody is associated with both interstitial lung disease (ILD) and the degree of disease severity in juvenile patients with dermatomyositis (DM). We found ...that more than half of adult patients with DM were positive for anti-Ro52 antibody. In this study, we analysed the correlation between anti-Ro52 antibody and ILD in adult patients with DM.
Serum samples were collected from 153 adult inpatients with DM, at the First Medical Centre of PLA General Hospital, Beijing, China, who met the classification criteria of idiopathic inflammatory myopathies from March 1, 2016 to September 30, 2019. The patients were followed up to May 31, 2020. Immunoblotting was used to detect 16 types of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) from serum samples. High-resolution computed tomography (HRCT) was used to calculate the ILD score, and tumours were screened. Clinical data and HRCT scores were evaluated and analysed retrospectively.
Our results showed that anti-Ro52 antibodies were the most commonly found antibodies in patients with DM, with a positive rate of 52.9%. Anti-Ro52, anti-aminoacyl-tRNA synthetase (anti-ARS), and anti-melanoma differentiation-related gene 5 (anti-MDA5) antibodies were found to be risk factors for ILD development. Anti-Ro52 antibodies had a strong predictive effect on ILD in patients with DM.
The occurrence of ILD is highly likely in patients with DM who are positive for the anti-Ro52 antibodies. Thus, anti-Ro52 antibodies is an independent risk factor for ILD in patients with DM.
•Anti-Ro52 antibodies were the most commonly found antibodies and an independent risk factor for ILD in patients with DM.•Anti-Ro52, anti-ARS and anti-MDA5 antibodies were found to be risk factors for ILD development in DM.•Anti-Ro52 antibodies had a predictive effect on ILD development and are an independent risk factor for ILD in patients with DM.•When both anti-Ro52 and anti-MDA5 antibodies were present, the HRCT scores of ILD increased.
The antigen-presenting molecule MR1 presents vitamin B-related antigens (VitB antigens) to mucosal-associated invariant T (MAIT) cells through an uncharacterized pathway. We show that MR1, unlike ...other antigen-presenting molecules, does not constitutively present self-ligands. In the steady state it accumulates in a ligand-receptive conformation within the endoplasmic reticulum. VitB antigens reach this location and form a Schiff base with MR1, triggering a 'molecular switch' that allows MR1-VitB antigen complexes to traffic to the plasma membrane. These complexes are endocytosed with kinetics independent of the affinity of the MR1-ligand interaction and are degraded intracellularly, although some MR1 molecules acquire new ligands during passage through endosomes and recycle back to the surface. MR1 antigen presentation is characterized by a rapid 'off-on-off' mechanism that is strictly dependent on antigen availability.
Constitutive activation of the NF-κB pathway is associated with diffuse large B-cell lymphoma (DLBCL) pathogenesis, but whether microRNA dysfunction can contribute to these events remains unclear. ...Starting from an integrative screening strategy, we uncovered that the negative NF-κB regulator TNFAIP3 is a direct target of miR-125a and miR-125b, which are commonly gained and/or overexpressed in DLBCL. Ectopic expression of these microRNAs in multiple cell models enhanced K63-linked ubiquitination of proximal signaling complexes and elevated NF-κB activity, leading to aberrant expression of its transcriptional targets and the development of a proproliferative and antiapoptotic phenotype in malignant B cells. Concordantly, genetic inhibition of miR-125a/miR-125b blunted NF-κB signals, whereas rescue assays and genetic modulation of a TNFAIP3-null model defined the essential role of the TNFAIP3 targeting on miR-125a/miR-125b-mediated lymphomagenesis. Importantly, miR-125a/mir-125b effects on TNFAIP3 expression and NF-κB activity were confirmed in a well-characterized cohort of primary DLBCLs. Our data delineate a unique epigenetic model for aberrant activation of the NF-κB pathway in cancer and provide a coherent mechanism for the role of these miRNAs in immune cell activation and hematopoiesis. Further, as miR-125b is a direct NF-κB transcriptional target, our results suggest the presence of a positive self-regulatory loop whereby termination of TNFAIP3 function by miR-125 could strengthen and prolong NF-κB activity.
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