Conditional β1‐integrin‐deficient mice display impaired pancreatic β cell function

Riopel, Matthew; Krishnamurthy, Mansa; Li, J; Liu, S; Leask, Andrew; Wang, R

doi:10.1002/path.2849

Cited by 58 publications

(73 citation statements)

References 75 publications

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“…16 We found that mice with b1 integrin deficiency controlled by the collagen I promoter had a primary defect in PSCs and islets in the pancreas, which led to a significant decrease in ECM products in the exocrine compartment. b1 integrin-deficient mice displayed significantly decreased food intake with a loss of body weight, which was associated with reduced pancreatic amylase, carboxypeptidase A and regenerating islet-derived protein II expression.…”

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confidence: 83%

“…17 Progeny mice with positive genotype, as analyzed by polymerase chain reaction (PCR), 17 were induced by intraperitoneal injection of 1 mg tamoxifen (4-hydroxytamoxifen; Sigma, St Louis, MO, USA) per mouse per day for 5 days at 3 weeks of age. 16 Corn oil-injected Crepositive and tamoxifen-injected Cre-negative mouse groups were merged as controls (Ctrl) and experiments were carried out on male mice at 4 and 7 weeks post-injection. Deletion of b1 integrin was confirmed by quantitative RT-PCR, western blot and immunofluorescence as described previously.…”

Section: Materials and Methods Conditional B1 Integrin-deficient Micementioning

confidence: 99%

“…Deletion of b1 integrin was confirmed by quantitative RT-PCR, western blot and immunofluorescence as described previously. 16 A Rosa26loxP-STOP-lacZ mouse (Jackson Laboratories), which does not express the b-galactosidase reporter gene unless cre recombinase is expressed in the nucleus, was crossed with Col1a2-Cre-ER T to identify the cells within the pancreas that expressed cre under control of the Col1a2 promoter. 17 All protocols were approved by the Animal Use Subcommittee at the University of Western Ontario in accordance with the guidelines of the Canadian Council of Animal Care.…”

Section: Materials and Methods Conditional B1 Integrin-deficient Micementioning

confidence: 99%

“…Furthermore, these b1 integrin-deficient mice displayed a significant decrease in pancreatic focal adhesion kinase and extracellular signalregulated kinase 1/2 activation, along with increased caspase-3 cleavage and decreased cyclin D1 expression. 16 However, the effects of b1 integrin deficiency on pancreatic exocrine morphology and function in conditional b1 integrindeficient mice have still to be determined.…”

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confidence: 99%

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β1 integrin–extracellular matrix interactions are essential for maintaining exocrine pancreas architecture and function

Riopel

Liu

et al. 2013

Laboratory Investigation

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Integrin receptors are responsible for integrating extracellular matrix signals inside the cell. The most prominent integrin receptor, b1 integrin, has a role in cell function, survival and differentiation. Recently, we demonstrated a profound in vivo role of b1 integrin expression in the pancreas on glucose homeostasis and islet function. Here, we extend these results by examining the role of b1 integrin in exocrine pancreatic structure and function. Adult C57Bl/6 mice hemizygous for a collagen type Ia2 (Col1a2) promoter-controlled tamoxifen-inducible Cre recombinase gene and homozygous for loxP-b1 integrin were injected with tamoxifen or corn oil to generate mice deleted or not for b1 integrin. Pancreata derived from these male mice were analyzed by quantitative reverse transcriptase-polymerase chain reaction, western blot and immunofluorescence. Our results showed that b1 integrin-deficient mice displayed a significant decrease in pancreas weight with a significant reduction of amylase, regenerating islet-derived protein II and carboxypeptidase-A expression (Po0.05-0.01). Compared with control pancreata, b1 integrin-deficient pancreata showed reduced mRNA expression of extracellular matrix (collagen type Ia2, fibronectin and laminin) genes (Po0.05), detached acini clusters and lost focal adhesion structure. Moreover, b1 integrin-deficient pancreatic acinar cells displayed decreased proliferation (Po0.05) and increased apoptosis (Po0.001). Apoptosis was reduced to that of controls when isolated exocrine clusters were cultured in media supplemented with extracellular matrix proteins. Taken together, these results implicate b1 integrin as an essential component for maintaining exocrine pancreatic structure and function. Integrin receptors have a significant role in cell-cell and cellextracellular matrix (ECM) contacts in many different tissue types. There are 18 a and 8 b receptors capable of forming 24 heterodimeric interactions; yet, half these interactions are made up by b1 integrin receptors. 1 This b1 integrin receptor group is largely responsible for attachment to the ECM. 2 Upon stimulation, b1 integrin has been shown to mediate cell motility, survival, proliferation and differentiation. [2][3][4][5] Pancreatic acini are enclosed round structures that produce digestive enzymes. 6 Basal lamina covers the acini at the basal surface, stimulating acini integrin receptors. 6 Pancreatic stellate cells (PSCs) are identified as periacinar fibroblast-like cells of the pancreas that express glial fibrillary acidic protein (GFAP) and produce ECM proteins in support of surrounding tissue. 7 PSCs are also, in part, responsible for the fibrosis observed in chronic pancreatitis. 8,9 Previous studies have shown that a3b1 integrin is essential for proper apical/ basolateral cell surface receptor organization and basement membrane formation in the submandibular gland. 10 As well, b1 integrin deficiency has shown to interfere with laminin-1 expression and basement membrane synthesis and assembly in embryoid bodies 11 and te...

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confidence: 83%

Section: Materials and Methods Conditional B1 Integrin-deficient Micementioning

confidence: 99%

Section: Materials and Methods Conditional B1 Integrin-deficient Micementioning

confidence: 99%

mentioning

confidence: 99%

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β1 integrin–extracellular matrix interactions are essential for maintaining exocrine pancreas architecture and function

Riopel

Liu

et al. 2013

Laboratory Investigation

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“…10 Integrins modulate multiple cellular processes in a variety of tissues. In the mouse pancreas, the conditional removal of β1 integrin leads to dysfunction of the endocrine 11 and exocrine 12 compartments. Removal of β1 integrin in developing pancreatic β cells leads to a massive reduction in insulin-positive cells and cell-cycle progression genes, suggesting that β cell expansion relies upon β1 integrin and ECM interactions.…”

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confidence: 99%

Fibrin supports human fetal islet-epithelial cell differentiation via p70s6k and promotes vascular formation during transplantation

Riopel

Trinder

et al. 2015

Laboratory Investigation

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The human fetal pancreas expresses a variety of extracellular matrix (ECM) binding receptors known as integrins. A provisional ECM protein found in blood clots that can bind to integrin receptors and promote β cell function and survival is fibrin. However, its role in support of human fetal pancreatic cells is unknown. We investigated how fibrin promotes human fetal pancreatic cell differentiation in vitro and in vivo. Human fetal pancreata were collected from 15 to 21 weeks of gestation and collagenase digested. Cells were then plated on tissue-culture polystyrene, or with 2D or 3D fibrin gels up to 2 weeks, or subcutaneously transplanted in 3D fibrin gels. The human fetal pancreas contained rich ECM proteins and expressed integrin αVβ3. Fibrin-cultured human fetal pancreatic cells had significantly increased expression of PDX-1, glucagon, insulin, and VEGF-A, along with increased integrin αVβ3 and phosphorylated FAK and p70 s6k . Fibrin-cultured cells treated with rapamycin, the mTOR pathway inhibitor, had significantly decreased phospho-p70 s6k and PDX-1 expression. Transplanting fibrin-mixed cells into nude mice improved vascularization compared with collagen controls. These results suggest that fibrin supports islet cell differentiation via p70 s6k and promotes vascularization in human fetal islet-epithelial clusters in vivo. Islet transplantation for the treatment of diabetes is currently limited by a shortage of available donor pancreata. 1 To surpass this problem, generating β cells from progenitor cell sources is a viable option. 2 However, this procedure and others like it produce low numbers of effective, functional β cells. 2 A greater understanding of the factors, especially those in the microenvironment, that regulate pancreatic development and islet cell differentiation is required to significantly increase the yield of β cells that these procedures generate for islet transplantation.Human pancreatic development begins at day 26 post conception, with tubular structures protruding from the ventral and dorsal side of the foregut endoderm. Two transcription factors that are required for the initiation of pancreatic development are PTF-1A and PDX-1, 3 in which the latter also promotes β cell maturation and function. 4 By 8 weeks of age, SOX9 is expressed in the pool of pancreatic progenitors 5 and is essential to support their proliferation and survival as well as maintain a transcriptional network with other factors. 6 SOX9 is also an important regulator of pancreatic endocrine cell differentiation. 5 Insulin positivity emerges around 7.5 weeks post conception, followed by glucagon and somatostatin 1 week later. 7 Islet-like structures eventually form where cells commonly express more than one hormone. 7 Subsequently, clustering occurs leading to construction of the islet of Langerhans. 8,9 Cell receptors in the human fetal pancreas that allow interactions with the extracellular environment (ECM) are integrins. Integrins are a family of highly expressed heterodimeric α and β receptors that bind to mo...

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Critical role of c-Kit in beta cell function: increased insulin secretion and protection against diabetes in a mouse model

Feng

Turco

et al. 2012

Diabetologia

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Aims/hypothesis The receptor tyrosine kinase, c-Kit, and its ligand, stem cell factor, control a variety of cellular processes, including pancreatic beta cell survival and differentiation as revealed in c-Kit Wv mice, which have a point mutation in the c-Kit allele leading to loss of kinase activity and develop diabetes. The present study further investigated the intrinsic role of c-Kit in beta cells, especially the underlying mechanisms that influence beta cell function. Methods We generated a novel transgenic mouse model with c-KIT overexpression specifically in beta cells (c-KitβTg) to further examine the physiological and functional roles of c-Kit in beta cells. Isolated islets from these mice were used to investigate the underlying molecular pathway of c-Kit in beta cells. We also characterised the ability of c-Kit to protect animals from high-fat-diet-induced diabetes, as well as to rescue c-Kit Wv mice from early onset of diabetes. Results c-KitβTg mice exhibited improved beta cell function, with significantly improved insulin secretion, and increased beta cell mass and proliferation in response to high-fat-dietinduced diabetes. c-KitβTg islets exhibited upregulation of: (1) insulin receptor and IRSs; (2) Akt and glycogen synthase kinase 3β phosphorylation; and (3) transcription factors important for islet function. c-KIT overexpression in beta cells also rescued diabetes observed in c-Kit Wv mice. Conclusions/interpretation These findings demonstrate that c-Kit plays a direct protective role in beta cells, by regulating glucose metabolism and beta cell function. c-Kit may therefore represent a novel target for treating diabetes.

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Conditional β1‐integrin‐deficient mice display impaired pancreatic β cell function

Cited by 58 publications

References 75 publications

β1 integrin–extracellular matrix interactions are essential for maintaining exocrine pancreas architecture and function

β1 integrin–extracellular matrix interactions are essential for maintaining exocrine pancreas architecture and function

Fibrin supports human fetal islet-epithelial cell differentiation via p70s6k and promotes vascular formation during transplantation

Critical role of c-Kit in beta cell function: increased insulin secretion and protection against diabetes in a mouse model

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