1
|
Kimani CN, Reuter H, Kotzé SH, Muller CJF. Regeneration of Pancreatic Beta Cells by Modulation of Molecular Targets Using Plant-Derived Compounds: Pharmacological Mechanisms and Clinical Potential. Curr Issues Mol Biol 2023; 45:6216-6245. [PMID: 37623211 PMCID: PMC10453321 DOI: 10.3390/cimb45080392] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 08/26/2023] Open
Abstract
Type 2 diabetes (T2D) is characterized by pancreatic beta-cell dysfunction, increased cell death and loss of beta-cell mass despite chronic treatment. Consequently, there has been growing interest in developing beta cell-centered therapies. Beta-cell regeneration is mediated by augmented beta-cell proliferation, transdifferentiation of other islet cell types to functional beta-like cells or the reprograming of beta-cell progenitors into fully differentiated beta cells. This mediation is orchestrated by beta-cell differentiation transcription factors and the regulation of the cell cycle machinery. This review investigates the beta-cell regenerative potential of antidiabetic plant extracts and phytochemicals. Various preclinical studies, including in vitro, in vivo and ex vivo studies, are highlighted. Further, the potential regenerative mechanisms and the intra and extracellular mediators that are of significance are discussed. Also, the potential of phytochemicals to translate into regenerative therapies for T2D patients is highlighted, and some suggestions regarding future perspectives are made.
Collapse
Affiliation(s)
- Clare Njoki Kimani
- Biomedical Research and Innovation Platform (BRIP), South African Medical Research Council (SAMRC), Cape Town 7505, South Africa;
- Division of Clinical Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7505, South Africa
| | - Helmuth Reuter
- Division of Clinical Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7505, South Africa
| | - Sanet Henriët Kotzé
- Division of Clinical Anatomy, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town 7505, South Africa
- Division of Anatomy, Department of Biomedical Sciences, School of Veterinary Medicine, Ross University, Basseterre P.O. Box 334, Saint Kitts and Nevis
| | - Christo John Fredrick Muller
- Biomedical Research and Innovation Platform (BRIP), South African Medical Research Council (SAMRC), Cape Town 7505, South Africa;
- Centre for Cardio-Metabolic Research in Africa, Division of Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Stellenbosch 7600, South Africa
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa
| |
Collapse
|
2
|
Murray HE, Zafar A, Qureshi KM, Paget MB, Bailey CJ, Downing R. The potential role of multifunctional human amniotic epithelial cells in pancreatic islet transplantation. J Tissue Eng Regen Med 2021; 15:599-611. [PMID: 34216434 DOI: 10.1002/term.3214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/23/2021] [Indexed: 11/08/2022]
Abstract
Pancreatic islet cell transplantation has proven efficacy as a treatment for type 1 diabetes mellitus, chiefly in individuals who are refractory to conventional insulin replacement therapy. At present its clinical use is restricted, firstly by the limited access to suitable donor organs but also due to factors associated with the current clinical transplant procedure which inadvertently impair the long-term functionality of the islet graft. Of note, the physical, biochemical, inflammatory, and immunological stresses to which islets are subjected, either during pretransplant processing or following implantation are detrimental to their sustained viability, necessitating repeated islet infusions to attain adequate glucose control. Progressive decline in functional beta (β)-cell mass leads to graft failure and the eventual re-instatement of exogenous insulin treatment. Strategies which protect and/or preserve optimal islet function in the peri-transplant period would improve clinical outcomes. Human amniotic epithelial cells (HAEC) exhibit both pluripotency and immune-privilege and are ideally suited for use in replacement and regenerative therapies. The HAEC secretome exhibits trophic, anti-inflammatory, and immunomodulatory properties of relevance to islet graft survival. Facilitated by β-cell supportive 3D cell culture systems, HAEC may be integrated with islets bringing them into close spatial arrangement where they may exert paracrine influences that support β-cell function, reduce hypoxia-induced islet injury, and alter islet alloreactivity. The present review details the potential of multifunctional HAEC in the context of islet transplantation, with a focus on the innate capabilities that may counter adverse events associated with the current clinical transplant protocol to achieve long-term islet graft function.
Collapse
Affiliation(s)
- Hilary E Murray
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Ali Zafar
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK.,Queen Elizabeth Hospital Birmingham, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Khalid M Qureshi
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK.,Bradford Royal Infirmary, Bradford Teaching Hospitals NHS Foundation Trust, Bradford, UK
| | - Michelle B Paget
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Clifford J Bailey
- Diabetes Research, School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Richard Downing
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| |
Collapse
|
3
|
Abstract
Pancreatic islet beta cells (β-cells) synthesize and secrete insulin in response to rising glucose levels and thus are a prime target in both major forms of diabetes. Type 1 diabetes ensues due to autoimmune destruction of β-cells. On the other hand, the prevailing insulin resistance and hyperglycemia in type 2 diabetes (T2D) elicits a compensatory response from β-cells that involves increases in β-cell mass and function. However, the sustained metabolic stress results in β-cell failure, characterized by severe β-cell dysfunction and loss of β-cell mass. Dynamic changes to β-cell mass also occur during pancreatic development that involves extensive growth and morphogenesis. These orchestrated events are triggered by multiple signaling pathways, including those representing the transforming growth factor β (TGF-β) superfamily. TGF-β pathway ligands play important roles during endocrine pancreas development, β-cell proliferation, differentiation, and apoptosis. Furthermore, new findings are suggestive of TGF-β's role in regulation of adult β-cell mass and function. Collectively, these findings support the therapeutic utility of targeting TGF-β in diabetes. Summarizing the role of the various TGF-β pathway ligands in β-cell development, growth and function in normal physiology, and during diabetes pathogenesis is the topic of this mini-review.
Collapse
Affiliation(s)
- Ji-Hyun Lee
- Cell Growth and Metabolism Section, Diabetes, Endocrinology & Obesity Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bethesda, MD, USA
| | - Ji-Hyeon Lee
- Cell Growth and Metabolism Section, Diabetes, Endocrinology & Obesity Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bethesda, MD, USA
| | - Sushil G Rane
- Cell Growth and Metabolism Section, Diabetes, Endocrinology & Obesity Branch, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Bethesda, MD, USA
- Correspondence: Sushil G. Rane, PhD, Cell Growth and Metabolism Section, Diabetes, Endocrinology and Obesity Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Clinical Research Center, Building 10, CRC-West 5-5940, 10 Center Drive, Bethesda, MD 20892, USA.
| |
Collapse
|
4
|
Gilloteaux J. Primary cilia in the Syrian hamster biliary tract: Bile flow antennae and outlooks about signaling on the hepato-biliary-pancreatic stem cells. TRANSLATIONAL RESEARCH IN ANATOMY 2020. [DOI: 10.1016/j.tria.2020.100063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
|
5
|
Kwon MJ, Lee YJ, Jung HS, Shin HM, Kim TN, Lee SH, Rhee BD, Kim MK, Park JH. The direct effect of lobeglitazone, a new thiazolidinedione, on pancreatic beta cells: A comparison with other thiazolidinediones. Diabetes Res Clin Pract 2019; 151:209-223. [PMID: 30954516 DOI: 10.1016/j.diabres.2019.04.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 03/14/2019] [Accepted: 04/01/2019] [Indexed: 12/11/2022]
Abstract
AIMS The direct effects of thiazolidinediones (TZDs) on pancreatic beta cells have been controversial. The aim of this study was to find out whether a novel TZD, lobeglitazone, has beneficial effects on pancreatic beta cells and db/db mice compared to those of other TZDs. METHODS INS-1 cells were incubated at a high-glucose concentration with various concentrations of troglitazone, rosiglitazone, pioglitazone, and lobeglitazone. Apoptosis and proliferation of beta cells, markers for ER stress and glucose-stimulated insulin secretion (GSIS) were assessed. In addition, C57BL/6 db/db mice were treated with pioglitazone or lobeglitazone for 4 weeks, and metabolic parameters and the configuration of pancreatic islets were also examined. RESULTS Lobeglitazone and other TZDs decreased INS-1 cell apoptosis in high-glucose conditions. Lobeglitazone and other TZDs significantly decreased hyperglycemia-induced increases in ER stress markers and increased GSIS. Metabolic parameters showed greater improvement in db/db mice treated with pioglitazone and lobeglitazone than in control mice. Islet size, cell proliferation, and beta cell mass were increased, and collagen surrounding the islets was decreased in treated mice. CONCLUSIONS Lobeglitazone showed beneficial effects on beta cell survival and function against hyperglycemia. The prosurvival and profunction effects of lobeglitazone were comparable to those of other TZDs.
Collapse
Affiliation(s)
- Min Jeong Kwon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, Republic of Korea
| | - Yong Jae Lee
- CKD Research Institute, Yongin, Gyeonggi-do, Republic of Korea
| | - Hye Sook Jung
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, Republic of Korea
| | - Hyun Mi Shin
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, Republic of Korea
| | - Tae Nyun Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea
| | - Soon Hee Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea
| | - Byoung Doo Rhee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea
| | - Mi-Kyung Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, Republic of Korea.
| | - Jeong Hyun Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, Republic of Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, Republic of Korea.
| |
Collapse
|
6
|
Zafar A, Lee J, Yesmin S, Paget MB, Bailey CJ, Murray HE, Downing R. Rotational culture and integration with amniotic stem cells reduce porcine islet immunoreactivity in vitro and slow xeno-rejection in a murine model of islet transplantation. Xenotransplantation 2019; 26:e12508. [PMID: 30963627 DOI: 10.1111/xen.12508] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 02/04/2019] [Accepted: 03/07/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND Pre-transplant modification of porcine islets may improve their suitability for clinical use in diabetes management by supporting graft function and reducing the potential for xeno-rejection. The present study investigates intra-graft incorporation of stem cells that secrete beta (β)-cell trophic and immunomodulatory factors to preserve function and alter immune cell responsiveness to porcine islets. METHODS Isolated porcine islets were maintained in a three-dimensional rotational cell culture system (RCCS) to facilitate aggregation with human amniotic epithelial cells (AECs). Assembled islet constructs were assessed for functional integrity and ability to avoid xeno-recognition by CD4+ T-cells using mixed islet:lymphocyte reaction assays. To determine whether stem cell-mediated modification of porcine islets provided a survival advantage over native islets, structural integrity was examined in a pig-to-mouse islet transplant model. RESULTS Rotational cell culture system supported the formation of porcine islet:AEC aggregates with improved insulin-secretory capacity compared to unmodified islets, whilst the xeno-response of purified CD4+ T-cells to AEC-bearing grafts was significantly (P < 0.05) attenuated. Transplanted AEC-bearing grafts demonstrated slower rejection in immune-competent recipients compared to unmodified islets. CONCLUSIONS/INTERPRETATION Rotational culture enables pre-transplant modification of porcine islets by integration with immunomodulatory stem cells capable of subduing xeno-reactivity to CD4+ T-cells. This reduces islet rejection and offers translational potential to widen availability and improve the clinical effectiveness of islet transplantation.
Collapse
Affiliation(s)
- Ali Zafar
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Jou Lee
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Shameema Yesmin
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Michelle B Paget
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Clifford J Bailey
- Diabetes Research, School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Hilary E Murray
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| | - Richard Downing
- The Islet Research Laboratory, Worcestershire Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK
| |
Collapse
|
7
|
TGF-β Family Signaling in Ductal Differentiation and Branching Morphogenesis. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a031997. [PMID: 28289061 DOI: 10.1101/cshperspect.a031997] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Epithelial cells contribute to the development of various vital organs by generating tubular and/or glandular architectures. The fully developed forms of ductal organs depend on processes of branching morphogenesis, whereby frequency, total number, and complexity of the branching tissue define the final architecture in the organ. Some ductal tissues, like the mammary gland during pregnancy and lactation, disintegrate and regenerate through periodic cycles. Differentiation of branched epithelia is driven by antagonistic actions of parallel growth factor systems that mediate epithelial-mesenchymal communication. Transforming growth factor-β (TGF-β) family members and their extracellular antagonists are prominently involved in both normal and disease-associated (e.g., malignant or fibrotic) ductal tissue patterning. Here, we discuss collective knowledge that permeates the roles of TGF-β family members in the control of the ductal tissues in the vertebrate body.
Collapse
|
8
|
Pei H, Zhai C, Li H, Yan F, Qin J, Yuan H, Zhang R, Wang S, Zhang W, Chang M, Wang Y, Pei X. Connexin 32 and connexin 43 are involved in lineage restriction of hepatic progenitor cells to hepatocytes. Stem Cell Res Ther 2017; 8:252. [PMID: 29116012 PMCID: PMC5678556 DOI: 10.1186/s13287-017-0703-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 09/06/2017] [Accepted: 10/19/2017] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Bi-potential hepatic progenitor cells can give rise to both hepatocytes and cholangiocytes, which is the last phase and critical juncture in terms of sequentially hepatic lineage restriction from any kind of stem cells. If their differentiation can be controlled, it might access to functional hepatocytes to develop pharmaceutical and biotechnology industries as well as cell therapies for end-stage liver diseases. METHODS In this study, we investigated the influence of Cx32 and Cx43 on hepatocyte differentiation of WB-F344 cells by in vitro gain and loss of function analyses. An inhibitor of Cx32 was also used to make further clarification. To reveal p38 MAPK pathway is closely related to Cxs, rats with 70% partial hepatectomy were injected intraperitoneally with a p38 inhibitor, SB203580. Besides, the effects of p38 MAPK pathway on differentiation of hepatoblasts isolated from fetal rat livers were evaluated by addition of SB203580 in culture medium. RESULTS In vitro gain and loss of function analyses showed overexpression of Connexin 32 and knockdown of Connexin 43 promoted hepatocytes differentiation from hepatic progenitor cells. In addition, in vitro and ex vivo research revealed inhibition of p38 mitogen-activated protein kinase pathway can improve hepatocytes differentiation correlating with upregulation of Connexin 32 expression and downregulation of Connexin 43 expression. CONCLUSIONS Here we demonstrate that Connexins play crucial roles in facilitating differentiation of hepatic progenitors. Our work further implicates that regulators of Connexins and their related pathways might provide new insights to improve lineage restriction of stem cells to mature hepatocytes.
Collapse
Affiliation(s)
- Haiyun Pei
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- South China Institute of Biomedicine, Guangzhou, 510005 China
| | - Chao Zhai
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Huilin Li
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Fang Yan
- Tissue Engineering Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Jinhua Qin
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- Tissue Engineering Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- South China Institute of Biomedicine, Guangzhou, 510005 China
| | - Hongfeng Yuan
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Rui Zhang
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Shuyong Wang
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- Tissue Engineering Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- South China Institute of Biomedicine, Guangzhou, 510005 China
| | - Wencheng Zhang
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Mingyang Chang
- Tissue Engineering Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Yunfang Wang
- Tissue Engineering Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
| | - Xuetao Pei
- Stem Cell and Regenerative Medicine Lab, Beijing Institute of Transfusion Medicine, Beijing, 100850 China
- South China Institute of Biomedicine, Guangzhou, 510005 China
| |
Collapse
|
9
|
Qureshi KM, Lee J, Paget MB, Bailey CJ, Curnow SJ, Murray HE, Downing R. Low gravity rotational culture and the integration of immunomodulatory stem cells reduce human islet allo-reactivity. Clin Transplant 2014; 29:90-8. [DOI: 10.1111/ctr.12488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/05/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Khalid M. Qureshi
- The Islet Research Laboratory; Worcester Clinical Research Unit; Worcestershire Acute Hospitals NHS Trust; Worcester UK
| | - Jou Lee
- The Islet Research Laboratory; Worcester Clinical Research Unit; Worcestershire Acute Hospitals NHS Trust; Worcester UK
| | - Michelle B. Paget
- The Islet Research Laboratory; Worcester Clinical Research Unit; Worcestershire Acute Hospitals NHS Trust; Worcester UK
| | - Clifford J. Bailey
- Diabetes Research; Aston Pharmacy School; School of Life and Health Sciences; Aston University; Aston Triangle Birmingham UK
| | - S. John Curnow
- Centre for Translational Inflammation Research; College of Medical and Dental Sciences; University of Birmingham Research Laboratories; Queen Elizabeth Hospital Birmingham; Edgbaston Birmingham UK
| | - Hilary E. Murray
- The Islet Research Laboratory; Worcester Clinical Research Unit; Worcestershire Acute Hospitals NHS Trust; Worcester UK
| | - Richard Downing
- The Islet Research Laboratory; Worcester Clinical Research Unit; Worcestershire Acute Hospitals NHS Trust; Worcester UK
| |
Collapse
|
10
|
Amsterdam A, Shpigner L, Raanan C, Schreiber L, Melzer E, Seger R. Dynamic distribution of ERK, p38 and JNK during the development of pancreatic ductal adenocarcinoma. Acta Histochem 2014; 116:1434-42. [PMID: 25440531 DOI: 10.1016/j.acthis.2014.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Revised: 09/21/2014] [Accepted: 09/22/2014] [Indexed: 12/12/2022]
Abstract
We recently discovered that oncogenic c-kit is highly expressed concomitantly with the development of pancreatic ductal adenocarcinoma (PDAC). Since oncogenic c-kit may activate major pathways of protein tyrosine phosphorylation, we decided to investigate this issue in the major protein phosphorylation cascades. In normal pancreas labeling with antiphosphorylated ERK1/2 (pERK1/2) antibody was mainly confined to islets of Langerhans in close overlapping with insulin containing cells. Phosphorylated p38 (pp38) showed a similar pattern of distribution, while only weak labeling was evident for pJNK and no labeling of pMEK was observed. As expected, general ERK1/2 (gERK1/2), general p38 (gp38), general JNK (gJNK) as well as general MEK (gMEK) were all evident in islets of Langerhans and in the exocrine tissue. In early development of PDAC, pERK1/2 and pp38 retained their localization in islets of Langerhans. Intensive staining of pERK1/2 was also evident in the cancerous ducts, while the labeling with antibodies to pp38 was more moderate. While pJNK staining in islets of Langerhans was weak, with no labeling in the cancerous ducts, antibodies to gJNK revealed intensive staining suggesting the weak staining of pJNK is not due to the lack of the enzyme. In a more advanced stage of PDAC the carcinomas were clearly stained with pERK1/2 and pp38, while moderate staining with pJNK was also evident. In liver metastases, the cancer cells were heavily labeled with all three phospho-MAPKs. It should be noted that the localization of all three kinases was mainly in the cell nuclei. In the more advanced stage of PDAC, heavy labeling was evident using antibodies to gERK1/2, gp38, gJNK and gMEK. However, no labeling to pMEK was evident in parallel sections. Our data suggest that both in normal and cancerous pancreas, most of the MAPK activities are located in islets of Langerhans and cancerous ducts. It is suggested that using inhibitors to protein kinases may attenuate the progression of the disease.
Collapse
Affiliation(s)
- Abraham Amsterdam
- Department of Molecular Cell Biology, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel.
| | - Lotem Shpigner
- Department of Molecular Cell Biology, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel
| | - Calanit Raanan
- Department of Veterinary Resources, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel
| | | | - Ehud Melzer
- Department of Gastroentrology, Kaplan Medical Center, Rehovot 76100, Israel
| | - Rony Seger
- Department of Biological Regulation, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 76100, Israel
| |
Collapse
|
11
|
Boerner BP, George NM, Targy NM, Sarvetnick NE. TGF-β superfamily member Nodal stimulates human β-cell proliferation while maintaining cellular viability. Endocrinology 2013; 154:4099-112. [PMID: 23970788 PMCID: PMC3800770 DOI: 10.1210/en.2013-1197] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In an effort to expand human islets and enhance allogeneic islet transplant for the treatment of type 1 diabetes, identifying signaling pathways that stimulate human β-cell proliferation is paramount. TGF-β superfamily members, in particular activin-A, are likely involved in islet development and may contribute to β-cell proliferation. Nodal, another TGF-β member, is present in both embryonic and adult rodent islets. Nodal, along with its coreceptor, Cripto, are pro-proliferative factors in certain cell types. Although Nodal stimulates apoptosis of rat insulinoma cells (INS-1), Nodal and Cripto signaling have not been studied in the context of human islets. The current study investigated the effects of Nodal and Cripto on human β-cell proliferation, differentiation, and viability. In the human pancreas and isolated human islets, we observed Nodal mRNA and protein expression, with protein expression observed in β and α-cells. Cripto expression was absent from human islets. Furthermore, in cultured human islets, exogenous Nodal stimulated modest β-cell proliferation and inhibited α-cell proliferation with no effect on cellular viability, apoptosis, or differentiation. Nodal stimulated the phosphorylation of mothers against decapentaplegic (SMAD)-2, with no effect on AKT or MAPK signaling, suggesting phosphorylated SMAD signaling was involved in β-cell proliferation. Cripto had no effect on human islet cell proliferation, differentiation, or viability. In conclusion, Nodal stimulates human β-cell proliferation while maintaining cellular viability. Nodal signaling warrants further exploration to better understand and enhance human β-cell proliferative capacity.
Collapse
Affiliation(s)
- Brian P Boerner
- MD, and Nora E. Sarvetnick, PhD, University of Nebraska Medical Center, 985965 Nebraska Medical Center, Omaha, Nebraska 68198-5965. ; or
| | | | | | | |
Collapse
|
12
|
Xiao X, Wiersch J, El-Gohary Y, Guo P, Prasadan K, Paredes J, Welsh C, Shiota C, Gittes GK. TGFβ receptor signaling is essential for inflammation-induced but not β-cell workload-induced β-cell proliferation. Diabetes 2013; 62:1217-26. [PMID: 23248173 PMCID: PMC3609557 DOI: 10.2337/db12-1428] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Protection and restoration of a functional β-cell mass are fundamental strategies for prevention and treatment of diabetes. Consequently, knowledge of signals that determine the functional β-cell mass is of immense clinical relevance. Transforming growth factor β (TGFβ) superfamily signaling pathways play a critical role in development and tissue specification. Nevertheless, the role of these pathways in adult β-cell homeostasis is not well defined. Here, we ablated TGFβ receptor I and II genes in mice undergoing two surgical β-cell replication models (partial pancreatectomy or partial duct ligation), representing two triggers for β-cell proliferation, increased β-cell workload and local inflammation, respectively. Our data suggest that TGFβ receptor signaling is necessary for baseline β-cell proliferation. By either provision of excess glucose or treatment with exogenous insulin, we further demonstrated that inflammation and increased β-cell workload are both stimulants for β-cell proliferation but are TGFβ receptor signaling dependent and independent, respectively. Collectively, by using a pancreas-specific TGFβ receptor-deleted mouse model, we have identified two distinct pathways that regulate adult β-cell proliferation. Our study thus provides important information for understanding β-cell proliferation during normal growth and in pancreatic diseases.
Collapse
Affiliation(s)
- Xiangwei Xiao
- Division of Pediatric Surgery, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Choi JH, Lim KH, Park E, Kim JY, Choi YK, Baek KH. Glutamate-ammonia ligase and reduction of G0 population in PANC-1 cells. J Cell Biochem 2012; 114:303-13. [DOI: 10.1002/jcb.24370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 08/13/2012] [Indexed: 12/18/2022]
|
14
|
The many faces of p38 mitogen-activated protein kinase in progenitor/stem cell differentiation. Biochem J 2012; 445:1-10. [DOI: 10.1042/bj20120401] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regulation of stem cells is essential for development and adult tissue homoeostasis. The proper control of stem cell self-renewal and differentiation maintains organ physiology, and disruption of such a balance results in disease. There are many mechanisms that have been established as stem cell regulators, such as Wnt or Notch signals. However, the intracellular mechanisms that mediate and integrate these signals are not well understood. A new intracellular pathway that has been reported to be involved in the regulation of many stem cell types is that of p38 MAPK (mitogen-activated protein kinase). In particular, p38α is essential for the proper differentiation of many haematopoietic, mesenchymal and epithelial stem/progenitor cells. Many reports have shown that disruption of this kinase pathway has pathological consequences in many organs. Understanding the extracellular cues and downstream targets of p38α in stem cell regulation may help to tackle some of the pathologies associated with improper differentiation and regulation of stem cell function. In the present review we present a vision of the current knowledge on the roles of the p38α signal as a regulator of stem/progenitor cells in different tissues in physiology and disease.
Collapse
|
15
|
Li G, Yang X, Zhang Y, Liu H, Zhang W, Shen Y, Fan W, Lu Z, Lu D. Comparative proteomics study of freshly isolated, in vitro cultured, and proliferating islet preparation cells. J Endocrinol Invest 2011; 34:816-23. [PMID: 20926920 DOI: 10.3275/7275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND In vitro islet expansion has recently drawn interest for its potential application in diabetes therapy, while how islet cells adapt to in vitro circumstances is not quite clear. AIM Proteomics changes of cultivated islet cells under different conditions were examined in this study. MATERIAL/SUBJECTS AND METHODS A comparative proteomics study was performed on fresh isolated islet cells, cultured cells and in vitro proliferating islet cells stimulated by basic fibroblast growth factor via electrophoresis and liquid chromatography in tandem with mass spectrometry. RESULTS In total, 1897 proteins were identified in this study. Hierarchical analysis revealed substantial changes in the proteome during cultivation but relatively less difference between different culture conditions. Over 100 proteins showed significantly different expression levels between groups, most of which are involved in metabolism or cell process pathways. Overall, the detected proteins were involved in 152 known pathways. Furthermore, in-depth investigation suggested that some proteins, such as extracellular signal-regulated protein kinases and Rac, might play key roles in the proliferation, apoptosis, and differentiation of in vitro cultured islet cells. CONCLUSION We established comparative proteome references of fresh and cultured islet cells, which could provide useful information for future islet transplantation strategy.
Collapse
Affiliation(s)
- G Li
- The State Key Laboratory of Genetic Engineering and The MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, China
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Hanley SC, Assouline-Thomas B, Makhlin J, Rosenberg L. Epidermal growth factor induces adult human islet cell dedifferentiation. J Endocrinol 2011; 211:231-9. [PMID: 21933872 DOI: 10.1530/joe-11-0213] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Given the inherent therapeutic potential of the morphogenetic plasticity of adult human islets, the identification of factors controlling their cellular differentiation is of interest. The epidermal growth factor (EGF) family has been identified previously in the context of pancreatic organogenesis. We examined the role of EGF in an in vitro model whereby adult human islets are embedded in a collagen gel and dedifferentiated into duct-like epithelial structures (DLS). We demonstrated that DLS formation was EGF dependent, while residual DLS formation in the absence of added EGF was abrogated by EGF receptor inhibitor treatment. With respect to signaling, EGF administration led to an increase in c-Jun NH2-terminal kinase (JNK) phosphorylation early in DLS formation and in AKT and extracellular signal-regulated kinase (ERK) phosphorylation late in the process of DLS formation, concomitant with the increased proliferation of dedifferentiated cells. In the absence of EGF, these phosphorylation changes are not seen and the typical increase in DLS epithelial cell proliferation seen after 10 days in culture is attenuated. Thus, in our model, EGF is necessary for islet cell dedifferentiation, playing an important role in both the onset of DLS formation (through JNK) and in the proliferation of these dedifferentiated cells (through AKT and ERK).
Collapse
Affiliation(s)
- Stephen C Hanley
- Department of Surgery, McGill University, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
17
|
Qureshi KM, Oliver RJ, Paget MB, Murray HE, Bailey CJ, Downing R. Human amniotic epithelial cells induce localized cell-mediated immune privilege in vitro: implications for pancreatic islet transplantation. Cell Transplant 2010; 20:523-34. [PMID: 20887662 DOI: 10.3727/096368910x528111] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chronic systemic immunosuppression in cell replacement therapy restricts its clinical application. This study sought to explore the potential of cell-based immune modulation as an alternative to immunosuppressive drug therapy in the context of pancreatic islet transplantation. Human amniotic epithelial cells (AEC) possess innate anti-inflammatory and immunosuppressive properties that were utilized to create localized immune privilege in an in vitro islet cell culture system. Cellular constructs composed of human islets and AEC (islet/AEC) were bioengineered under defined rotational cell culture conditions. Insulin secretory capacity was validated by glucose challenge and immunomodulatory potential characterized using a peripheral blood lymphocyte (PBL) proliferation assay. Results were compared to control constructs composed of islets or AEC cultured alone. Studies employing AEC-conditioned medium examined the role of soluble factors, and fluorescence immunocytochemistry was used to identify putative mediators of the immunosuppressive response in isolated AEC monocultures. Sustained, physiologically appropriate insulin secretion was observed in both islets and islet/AEC constructs. Activation of resting PBL proliferation occurred on exposure to human islets alone but this response was significantly (p < 0.05) attenuated by the presence of AEC and AEC-conditioned medium. Mitogen (phytohaemagglutinin, 5 μg/ml)-induced PBL proliferation was sustained on contact with isolated islets but abrogated by AEC, conditioned medium, and the islet/AEC constructs. Immunocytochemical analysis of AEC monocultures identified a subpopulation of cells that expressed the proapoptosis protein Fas ligand. This study demonstrates that human islet/AEC constructs exhibit localized immunosuppressive properties with no impairment of β-cell function. The data suggest that transplanted islets may benefit from the immune privilege status conferred on them as a consequence of their close proximity to human AEC. Such an approach may reduce the need for chronic systemic immunosuppression, thus making islet transplantation a more attractive treatment option for the management of insulin-dependent diabetes.
Collapse
Affiliation(s)
- Khalid M Qureshi
- The Islet Research Laboratory, Worcester Clinical Research Unit, Worcestershire Acute Hospitals NHS Trust, Worcester, UK.
| | | | | | | | | | | |
Collapse
|
18
|
Hanley SC, Austin E, Assouline-Thomas B, Kapeluto J, Blaichman J, Moosavi M, Petropavlovskaia M, Rosenberg L. {beta}-Cell mass dynamics and islet cell plasticity in human type 2 diabetes. Endocrinology 2010; 151:1462-72. [PMID: 20176718 DOI: 10.1210/en.2009-1277] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Studies of long-standing type 2 diabetes (T2D) report a deficit in beta-cell mass due to increased apoptosis, whereas neogenesis and replication are unaffected. It is unclear whether these changes are a cause or a consequence of T2D. Moreover, whereas islet morphogenetic plasticity has been demonstrated in vitro, the in situ plasticity of islets, as well as the effect of T2D on endocrine differentiation, is unknown. We compared beta-cell volume, neogenesis, replication, and apoptosis in pancreata from lean and obese (body mass index > or = 27 kg/m(2)) diabetic (5 +/- 2 yr since diagnosis) and nondiabetic cadaveric donors. We also subjected isolated islets from diabetic (3 +/- 1 yr since diagnosis) and nondiabetic donors to an established in vitro model of islet plasticity. Differences in beta-cell volume between diabetic and nondiabetic donors were consistently less pronounced than those reported in long-standing T2D. A compensatory increase in beta-cell neogenesis appeared to mediate this effect. Studies of induced plasticity indicated that islets from diabetic donors were capable of epithelial dedifferentiation but did not demonstrate regenerative potential, as was seen in islets from nondiabetic donors. This deficiency was associated with the overexpression of Notch signaling molecules and a decreased neurogenin-3(+) cell frequency. One interpretation of these results would be that decreased beta-cell volume is a consequence, not a cause, of T2D, mediated by increased apoptosis and attenuated beta-cell (re)generation. However, other explanations are also possible. It remains to be seen whether the morphogenetic plasticity of human islets, deficient in vitro in islets from diabetic donors, is a component of normal beta-cell mass dynamics.
Collapse
Affiliation(s)
- Stephen C Hanley
- M.Eng., Montréal General Hospital C9-128, 1650 Cedar Avenue, Montréal, Québec, Canada H3G 1A4
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Park KS, Kim YS, Kim JH, Choi BK, Kim SH, Oh SH, Ahn YR, Lee MS, Lee MK, Park JB, Kwon CH, Joh JW, Kim KW, Kim SJ. Influence of human allogenic bone marrow and cord blood-derived mesenchymal stem cell secreting trophic factors on ATP (adenosine-5'-triphosphate)/ADP (adenosine-5'-diphosphate) ratio and insulin secretory function of isolated human islets from cadaveric donor. Transplant Proc 2010; 41:3813-8. [PMID: 19917393 DOI: 10.1016/j.transproceed.2009.06.193] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 06/15/2009] [Indexed: 10/20/2022]
Abstract
Successful islet transplantation (ITx) is not only dependent on the number of islets, but also their quality, including viability, metabolic activity, and function. Islet quality decreases during cultivation after the isolation procedure. To overcome this obstacle, we established the practice of islet and mesenchymal stem cells (MSCs) coculture. This coculture condition improved the ATP (adenosine-5'-triphosphate)/ADP (adenosine-5'-diphosphate) ratio and insulin secretory function in vitro. It is believed that the enhancement of islet quality in islet-MSCs cocultures may be caused by the secretion of active agents by MSCs. Herein we have shown that interleukin-6 (IL-6), vascular endothelial growth factor-A (VEGF-A), hepatocyte growth factor (HGF), and transforming growth factor-beta (TGF-beta) were significantly increased as measured by enzyme-linked immunosorbent assay (ELISA) in MSCs-cultured medium, factors that have been shown to improve the survival, function, and angiogenesis/revascularization of islets. These results indicated that the quality of human islets was enhanced by trophic molecules secreted by MSCs, which influence the intracellular islet ATP content and insulin secretory function.
Collapse
Affiliation(s)
- K S Park
- Department of Molecular Medicine, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
Pancreatic islets are highly vascularized micro-organs. Approximately 10% of an islet consists of blood vessels. The induction and maintenance of the islet vascular system depend on VEGF secreted from β-cells. VEGF is also critical for the phenotype of the islet vasculature by induction of a vast number of fenestrae. The islet vasculature serves the role of supplying the endocrine cells with oxygen and nutrients, but may also be important for proper glucose sensing of the cells, for paracrine support of endocrine function and growth, and for drainage of metabolites and secreted islet hormones into the systemic circulation. Emerging evidence suggests an important role of islet endothelial cells to maintain β-cell function and growth by secretion of molecules such as hepatocyte growth factor, thrombospondin-1 and laminins, thereby forming a vascular niche for the endocrine cells.
Collapse
Affiliation(s)
- Johan Olerud
- a Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Åsa Johansson
- a Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Per-Ola Carlsson
- b Department of Medical Sciences, Section for Endocrinology and Diabetology, Uppsala University Hospital, Uppsala, Sweden and Department of Medical Cell Biology, Husargatan 3, Box 571, SE-75123, Uppsala, Sweden.
| |
Collapse
|
21
|
Altirriba J, Barbera A, Del Zotto H, Nadal B, Piquer S, Sánchez-Pla A, Gagliardino JJ, Gomis R. Molecular mechanisms of tungstate-induced pancreatic plasticity: a transcriptomics approach. BMC Genomics 2009; 10:406. [PMID: 19715561 PMCID: PMC2741493 DOI: 10.1186/1471-2164-10-406] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 08/28/2009] [Indexed: 01/15/2023] Open
Abstract
Background Sodium tungstate is known to be an effective anti-diabetic agent, able to increase beta cell mass in animal models of diabetes, although the molecular mechanisms of this treatment and the genes that control pancreas plasticity are yet to be identified. Using a transcriptomics approach, the aim of the study is to unravel the molecular mechanisms which participate in the recovery of exocrine and endocrine function of streptozotocin (STZ) diabetic rats treated with tungstate, determining the hyperglycemia contribution and the direct effect of tungstate. Results Streptozotocin (STZ)-diabetic rats were treated orally with tungstate for five weeks. Treated (STZ)-diabetic rats showed a partial recovery of exocrine and endocrine function, with lower glycemia, increased insulinemia and amylasemia, and increased beta cell mass achieved by reducing beta cell apoptosis and raising beta cell proliferation. The microarray analysis of the pancreases led to the identification of three groups of differentially expressed genes: genes altered due to diabetes, genes restored by the treatment, and genes specifically induced by tungstate in the diabetic animals. The results were corroborated by quantitative PCR. A detailed description of the pathways involved in the pancreatic effects of tungstate is provided in this paper. Hyperglycemia contribution was studied in STZ-diabetic rats treated with phloridzin, and the direct effect of tungstate was determined in INS-1E cells treated with tungstate or serum from untreated or treated STZ-rats, observing that tungstate action in the pancreas takes places via hyperglycemia-independent pathways and via a combination of tungstate direct and indirect (through the serum profile modification) effects. Finally, the MAPK pathway was evaluated, observing that it has a key role in the tungstate-induced increase of beta cell proliferation as tungstate activates the mitogen-activated protein kinase (MAPK) pathway directly by increasing p42/p44 phosphorylation and indirectly by decreasing the expression of raf kinase inhibitor protein (Rkip), a negative modulator of the pathway. Conclusion In conclusion, tungstate improves pancreatic function through a combination of hyperglycemia-independent pathways and through its own direct and indirect effects, whereas the MAPK pathway has a key role in the tungstate-induced increase of beta cell proliferation.
Collapse
Affiliation(s)
- Jordi Altirriba
- Diabetes and Obesity Laboratory, Endocrinology and Nutrition Unit, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clinic de Barcelona, Barcelona, Spain.
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Hanley SC, Pilotte A, Massie B, Rosenberg L. Cellular origins of adult human islet in vitro dedifferentiation. J Transl Med 2008; 88:761-72. [PMID: 18490899 DOI: 10.1038/labinvest.2008.41] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cultured human islets can be dedifferentiated to duct-like structures composed mainly of cytokeratin+ and nestin+ cells. Given that these structures possess the potential to redifferentiate into islet-like structures, we sought to elucidate their specific cellular origins. Adenoviral vectors were engineered for beta-, alpha-, delta- or PP-cell-specific GFP expression. A double-stranded system was designed whereby cultures were infected with two vectors: one expressed GFP behind the cumate-inducible promoter sequence, and the other expressed the requisite transactivator behind the human insulin, glucagon, somatostatin or pancreatic polypeptide promoter. This system labels hormone+ cells in the islet in a cell-specific manner, allowing these cells to be tracked during the course of transformation from islet to duct-like structure. Post-infection, islets were cultured to induce dedifferentiation. Fluorescence microscopy demonstrated that alpha-, delta- and PP-cells contributed equally to the cytokeratin+ population, with minimal beta-cell contribution, whereas the converse was true for nestin+ cells. Complementary targeted cell ablation studies, using streptozotocin or similar adenoviral expression of the Bax (Bcl2-associated X protein) toxigene, validated these findings and suggested a redundancy between alpha-, delta- and PP-cells with respect to cytokeratin+ cell derivation. These results call into question the traditional understanding of islet cells as being terminally differentiated and provide support for the concept of adult islet morphogenetic plasticity.
Collapse
|