Islet beta-cell regeneration and reg genes

NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

NF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

Fibroblasts accelerate islet revascularization and improve long-term graft survival in a mouse model of subcutaneous islet transplantation

Pancreatic islet transplantation has been considered for many years a promising therapy for beta-cell replacement in patients with type-1 diabetes despite that long-term clinical results are not as satisfactory. This fact points to the necessity of designing strategies to improve and accelerate islets engraftment, paying special attention to events assuring their revascularization. Fibroblasts constitute a cell population that collaborates on tissue homeostasis, keeping the equilibrium between production and degradation of structural components as well as maintaining the required amount of survival factors. Our group has developed a model for subcutaneous islet transplantation using a plasma-based scaffold containing fibroblasts as accessory cells that allowed achieving glycemic control in diabetic mice. Transplanted tissue engraftment is critical during the first days after transplantation, thus we have gone in depth into the graft-supporting role of fibroblasts during the first ten days after islet transplantation. All mice transplanted with islets embedded in the plasma-based scaffold reversed hyperglycemia, although long-term glycemic control was maintained only in the group transplanted with the fibroblasts-containing scaffold. By gene expression analysis and histology examination during the first days we could conclude that these differences might be explained by overexpression of genes involved in vessel development as well as in β-cell regeneration that were detected when fibroblasts were present in the graft. Furthermore, fibroblasts presence correlated with a faster graft re-vascularization, a higher insulin-positive area and a lower cell death. Therefore, this work underlines the importance of fibroblasts as accessory cells in islet transplantation, and suggests its possible use in other graft-supporting strategies.

Proteomic analysis reveals downregulation of housekeeping proteins in the diabetic vascular proteome

AIMS

Type 2 diabetes (T2D) increases the risk of death associated with cardiovascular complications. However, a complete understanding of protein changes within the diabetic vasculature is still lacking.

METHODS

Herein, we utilized mass spectrometry to perform vascular and urinary proteome analysis using a rat model of high-fat feeding and low-dose streptozotocin to simulate late-stage T2D. The purpose of this study was to identify aortic and urine proteins that are differentially expressed in normal and T2D rats.

RESULTS

High-fat feeding and low-dose streptozotocin resulted in hyperglycemia, hypoinsulinemia and high levels of circulating free fatty acids. Using a shotgun proteomic approach, high-mobility-group protein B1 and spondin-1 were significantly increased in T2D aorta compared to control aorta, suggesting vascular inflammation and smooth muscle proliferation, respectively. However, the majority of differentially expressed aortic proteins were downregulated in T2D, including proteins associated with coagulation, cell differentiation and redox homeostasis. Strikingly, we report a significant downregulation of commonly used cytoskeletal housekeeping proteins in T2D aorta. Urine from T2D rats displayed increased expression of proteins involved in inflammation and oxidative stress and decreased expression of proteins associated with lipid metabolism and cell adhesion. A number of differentially expressed proteins in urine of T2D rats have previously been reported in human T2D, thereby supporting this animal model as a good representation of human T2D.

CONCLUSIONS

Our data offer new information regarding key pathways that could be therapeutically targeted to combat the cardiovascular complications of T2D.

The pancreatic cancer secreted REG4 promotes macrophage polarization to M2 through EGFR/AKT/CREB pathway

In the periphery of pancreatic ductal adenocarcinoma (PDAC), high accumulation of tumor-associated macrophages (TAMs), which exhibit M2 phenotype, has been shown to be correlated with extra-pancreatic invasion, lymph vessel invasion, lymph node involvement and shortened survival time. However, mechanisms by which tumor cells educate and reprogram TAMs remain largely unclear. The phenotype of TAMs in PDAC tissues was confirmed by immunofluoresence and confocal microscopy. Human CD14+ monocytes were incubated with recombinant human REG4 (rREG4) before being stimulated with LPS and IL-10 and IL-6 were measured with ELISA. A panel of M1 and M2 genes were measured by quantitative real-time PCR. Panc1, AsPC1 and BxPC3 cells were cultured in the conditioned medium (CM) and treated with REG4. The macrophages were infected with CREB shRNA or cultured by the CM of Panc1 cells infected with REG4 shRNA. The expression of CD163, CD206 and REG4 and the phosphorylation levels of epidermal growth factor receptor (EGFR), AKT and cAMP response element-binding protein (CREB) in cells were assessed with western blotting. Cell proliferation and invasiveness were also assessed. The rREG4 or the conditioned medium of Panc1 cells which secreted REG4 induced the polarization macrophages to M2 phenotype. Treatment of human macrophages with REG4 resulted in phosphorylation of EGFR, AKT and CREB. The latter was responsible for REG4-mediated macrophage polarization to M2. The conditioned medium of macrophages treated with rREG4 promoted the proliferation and invasion of pancreatic cancer cell lines. REG4, overexpressed in PDAC and secreted by cancer cells, promoted macrophage polarization to M2, through at least in part, activation of ERK1/2 and CREB and changed the microenvironment to facilitate cancer growth and metastasis.

REG Iα activates c-Jun through MAPK pathways to enhance the radiosensitivity of squamous esophageal cancer cells

Identification of the key molecules that mediate susceptibility to anticancer treatments would be highly desirable. Based on clinical and cell biological studies, we recently proposed that regenerating gene (REG) Iα may be such a molecule. In the present study, we hypothesized that REG Iα increases radiosensitivity through activation of mitogen-activated protein kinase (MAPK) pathways. To test that idea, we transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Iα and examined its involvement in MAPK signaling and its effect on susceptibility to radiotherapy. We found that REG Iα-expressing cells showed increased expression of c-Jun messenger RNA (mRNA) and phospho-c-Jun protein mediated via the c-Jun N-terminal kinase (JNK) pathway and extracellular signal-regulated kinase (ERK) pathway, as well as increased radiosensitivity. Immunohistochemical analysis confirmed the activation of c-Jun in tumors expressing REG Iα. Collectively, these findings suggest that REG Iα activates c-Jun via the JNK and ERK pathway, thereby enhancing radiosensitivity.

Epigenetic modulation of type-1 diabetes via a dual effect on pancreatic macrophages and β cells

Epigenetic modifiers are an emerging class of anti-tumor drugs, potent in multiple cancer contexts. Their effect on spontaneously developing autoimmune diseases has been little explored. We report that a short treatment with I-BET151, a small-molecule inhibitor of a family of bromodomain-containing transcriptional regulators, irreversibly suppressed development of type-1 diabetes in NOD mice. The inhibitor could prevent or clear insulitis, but had minimal influence on the transcriptomes of infiltrating and circulating T cells. Rather, it induced pancreatic macrophages to adopt an anti-inflammatory phenotype, impacting the NF-κB pathway in particular. I-BET151 also elicited regeneration of islet β-cells, inducing proliferation and expression of genes encoding transcription factors key to β-cell differentiation/function. The effect on β cells did not require T cell infiltration of the islets. Thus, treatment with I-BET151 achieves a 'combination therapy' currently advocated by many diabetes investigators, operating by a novel mechanism that coincidentally dampens islet inflammation and enhances β-cell regeneration.

Epigenetic regulation of REG1A and chemosensitivity of cutaneous melanoma

Regenerating gene 1A (REG1A) plays an important role in tissue regeneration and in cell proliferation in epithelium origin tumors; however, its role in melanoma has not been explored in details. The objective of this study was to identify whether REG1A is expressed in cutaneous melanoma and if REG1A expression status can predict prognosis in cutaneous melanoma patients with metastasis. We also determined whether epigenetic regulation of the promoter region regulates REG1A expression. AJCC stage III cutaneous melanoma specimens with clinically well annotated stage III lymph node melanoma metastasis tissue microarray were assessed by IHC. MALDI-TOF-mass spectrometry and HM450K array were used to identify REG1A promoter region CpG site methylation. Chemotherapeutic agent response by melanoma cells as related to REG1A protein expression was assessed. Post-surgery melanoma patients followed by adjuvant chemotherapy with high REG1A expression had a significantly better prognosis (disease-specific survival) compared with patients with low REG1A expression (log rank test; p = 0.0013). The demethylating reagent 5-Aza-2'-deoxycytidine activated REG1A promoter region resulting in enhanced REG1A mRNA and protein expression in melanoma cell lines. Promoter region CpG methylation was shown to regulate REG1A expression in melanoma cells. Moreover, melanoma lines with high REG1A mRNA expression were more susceptible to Dacarbazine and Cisplatin, as compared with those with low REG1A mRNA expression. In conclusion, REG1A expression status may be useful as a biomarker in melanoma patients for sensitivity to these chemotherapeutic agents. The epigenetic regulation of the REG1A promoter region may offer a potential therapeutic approach to improve chemotherapy for metastatic melanoma patients.

REG1A expression status suggests chemosensitivity among advanced thoracic esophageal squamous cell carcinoma patients treated with esophagectomy followed by adjuvant chemotherapy

BACKGROUND

Regenerating gene 1A (REG1A) plays an important role in tissue regeneration and in cell proliferation in the mucous membrane of the gastrointestinal tract. We previously reported that the positive expression status of REG1A was predictive of chemoradiosensitivity in patients treated with preoperative chemoradiotherapy before esophagectomy or with definitive chemoradiotherapy. To further confirm the utility of REG1A as a chemosensitivity marker, we carried out an additional retrospective clinical study aimed at determining whether REG1A is a reliable chemosensitivity marker in patients treated with esophagectomy followed by adjuvant chemotherapy.

METHOD

A total of 177 patients with T2-4 thoracic esophageal squamous cell carcinoma received curative surgery without preoperative treatment at Akita University Hospital between 2001 and 2011. A tissue microarray was constructed, and REG1A expression status was analyzed immunohistochemically. We then statistically analyzed the relationships between REG1A expression status and 5-year overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS).

RESULTS

In the adjuvant group (n=105), REG1A-positive patients showed significantly better prognoses than REG1A-negative patients. (5-year OS, p=.0022; DSS, p=.0004; and DFS, p=.0040). However, there were no significant differences between REG1A-positive and REG1A-negative patients in the surgery group (n=72). Univariate and multivariate analyses showed REG1A expression status to be a significant prognostic factor affecting 5-year DSS, comparable to lymph node metastatic status.

CONCLUSION

The present study suggests REG1A expression status has the potential to be a highly reliable and clinically useful chemosensitivity marker in patients treated with advanced thoracic esophageal squamous cell carcinoma. REG1A expression status will provide a good indication of treatment strategy and enable more individualized treatment for patients.

Urinary levels of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein as a diagnostic biomarker in patients with bladder cancer

Background

To assess the possibility of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP) as a biological marker for detecting Bladder cancer (BCa), we examined the expression of HIP/PAP in both BCa specimens and BCa cell lines and measured HIP/PAP levels in urine from patients with BCa.

Methods

HIP/PAP expression in BCa samples was evaluated by western blot analysis, and urinary levels of HIP/PAP in patients with BCa were measured by enzyme-linked immunosorbent assay. Urine samples were collected from 10 healthy volunteers and 109 with benign urological disorders as controls, and from 101 patients who were diagnosed with BCa.

Results

HIP/PAP was highly expressed in BCa samples as compared with control bladder. Urinary HIP/PAP concentrations were significantly higher in BCa patients than in controls (median value; 3.184 pg/mL vs. 55.200 pg/mL, P <0.0001, by Mann–Whitney U test). Urinary HIP/PAP levels in BCa patients correlated positively with pathological T stages and progression-risk groups among non-muscle invasive BCa (P = 0.0008, by Kruskal-Wallis test). Regarding the recurrence-risk classifications of non-muscle invasive BCa, the urinary levels of HIP/PAP were significantly higher in the intermediate than in the low risk group (P = 0.0002, by Mann–Whitney U test). Based on a cut-off of 8.5 pg/mL, the ability of urinary HIP/PAP levels to detect BCa had a sensitivity of 80.2%, specificity of 78.2%, positive predictive value (PPV) of 75.7%, and negative predictive value (NPV) of 82.3%.

Conclusions

HIP/PAP was abundantly expressed in BCa, and the urinary levels of HIP/PAP could be a novel and potent biomarker for detection of BCa, and also for predicting the risks of recurrence- and progression-risk of non-muscle invasive BCa. A large scale study will be needed to establish the usefulness of this biomarker.

Evaluation of REG4 for early diagnosis and prognosis of gastric cancer

We explored the correlation between the development of gastric cancer and the concentration of REG4 and hence the suitability of REG4 as an indicator of the prognosis of patients with GC. Real-time polymerase chain reaction was conducted to detect REG4 messenger RNA expression. The amount of the REG4 protein was measured by immunohistochemistry staining of tissue and enzyme-linked immunosorbent assay of serum. Serum carcinoembryonic antigen and carbohydrate antigen 19-9 concentrations were measured using a commercial automated immunoassay. Real-time polymerase chain reaction results confirmed that REG4 was significantly up-regulated in gastric cancer compared with paired normal mucosa (P < .001). Immunohistochemistry staining revealed that high expression of REG4 correlated with diffuse type, poor differentiation, lymph node metastasis, distant metastasis, and TNM stage III or IV. The mean survival time for patients in the REG4-positive group was significantly less than that in the REG4-negative group (P = .013). The percentage of serum samples that were REG4 positive was 44.0%, which was higher than that for serum carcinoembryonic antigen (P = .039) or carbohydrate antigen 19-9 (P = .012) in TNM stage I and was significantly higher (P = .031) than that in TNM stage II. Thus, REG4 may be not only a prognostic indicator but also a better serum marker than carcinoembryonic antigen and carbohydrate antigen 19-9 for early diagnosis of gastric cancer.

Serum tumor antigen REG4 as a diagnostic biomarker in pancreatic ductal adenocarcinoma

BACKGROUND AND AIMS

Serum biomarkers for the early detection of pancreatic cancer are not currently available. We evaluated the usefulness of a novel serum marker, REG4, in the diagnosis of pancreatic cancer, as compared to carbohydrate antigen (CA) 19-9.

METHODS

We collected pretherapeutic sera from 92 patients with pancreatic cancer, as well as sera from 28 patients with other pancreatic tumors, 11 patients with pancreatitis, and 69 healthy controls. Serum levels of REG4 were measured using a standard sandwich enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with healthy controls, serum levels of REG4 were higher in pancreatic cancer patients (P < 0.001), and in patients with pancreatitis (P < 0.001). Receiver operating characteristic (ROC) analysis indicated that serum REG4 performed better than serum CA19-9 for distinguishing patients with pancreatic cancer from healthy controls [areas under the curve (AUC) for REG4 and CA19-9 were 0.922 and 0.884, respectively]. When we validated the study, the sensitivity of REG4 for pancreatic cancer was 94.9%, specificity was 64.0%, and accuracy was 77.5% for the REG4 cutoff value of 3.49 ng/ml. No correlation was seen between serum REG4 and CA19-9 levels, with the sensitivity, specificity, and accuracy of the combined markers reaching 100.0, 60.0, and 77.5%, respectively. No significant differences were seen among any stages of pancreatic cancer. In surgical specimens, immunohistochemical analysis found a correlation between serum REG4 levels and REG4 expression in pancreatic cancers.

CONCLUSIONS

REG4 is expressed in pancreatic cancer, and serum levels of REG4 offer a useful indicator for distinguishing between patients with pancreatic cancer and healthy subjects. Serum REG4 has potential for use as a screening serum marker for pancreatic cancers, including early-stage cancers.

Regenerating gene I regulates interleukin-6 production in squamous esophageal cancer cells

Regenerating gene (REG) I plays important roles in cancer cell biology. The purpose of this study was to determine whether REG I affects cytokine production in cancer cells. We transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Ialpha and Ibeta and examined its effects on cytokine expression. We found that transfecting TE-5 and TE-9 cells with REG I Ialpha and Ibeta led to significantly increased expression of interleukin (IL)-6 mRNA and protein, but it had little or no effect on expression of IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17A, interferon-gamma, tumor necrosis factor-alpha, granulocyte-colony stimulating factor or transforming growth factor-beta1. The elevated IL-6 expression seen in REG Ialpha transfectants was silenced by small interfering RNA-mediated knockdown. These finding suggest that REG I may act through IL-6 to exert effects on squamous esophageal cancer cell biology.

Pancreatic regenerating protein I in chronic pancreatitis and aging: implications for new therapeutic approaches to diabetes

OBJECTIVES

We investigated the relationship of pancreatic regenerating protein (reg) in models of acinar cell atrophy and aging, and the effect of reg I protein replacement on glucose tolerance.

METHODS

Rats underwent pancreatic duct ligation (PDL) and were followed through 12 months. Aging rats were studied at 12 and 20 months. Intraperitoneal glucose tolerance tests (IPGTTs) were performed, pancreatic reg I, reg I receptor, insulin gene expression, and reg I protein levels were measured. Pancreatic duct ligation and aged animals were treated with exogenous reg I protein and assessed for glucose metabolism.

RESULTS

After PDL, chronic atrophic pancreatitis developed, with a progressive loss of acinar cells and pancreatic reg I. During aging, a similar depression of reg I gene expression was also noted. The reg I levels correlated with pancreatic insulin levels. Twelve months after PDL, IPGTT results were abnormal, which were significantly improved by administration of reg I protein. Aged animals demonstrated depressed IPGTT, which marginally improved after reg I administration. Anti-reg antibody administration to young rats depressed IPGTT to elderly levels.

CONCLUSIONS

Depletion of the acinar product reg I is associated with the pathogenesis of impaired glucose tolerance of pancreatitis-associated diabetes and aging, and replacement therapy could be useful in these patients. Reg I is an acinar cell product, which affects islet function.

Stem/Progenitor cell sources of insulin-producing cells for the treatment of diabetes

Patients with diabetes experience decreased insulin secretion that is linked to a significant reduction in the number of islet cells. Reversal of diabetes can be achieved through islet transplantation, but the scarcity of donor islets severely hinders wide application of this therapeutic modality. Toward that end, embryonic stem cells, adult tissue-residing progenitor cells, and regenerating native beta-cells may serve as sources of islet cell surrogates. Insulin-producing cells generated from stem or progenitor cells display subsets of native beta-cell attributes, indicating the need for further development of methods for differentiation to completely functional beta-cells. Pharmacological approaches aiming at stimulating the in vivo/ex vivo regeneration of beta-cells have also been proposed as a way of augmenting islet cell mass. We review the current state of the generation of insulin-producing cells from different sources with emphasis on embryonic stem cells and adult progenitor cells. Challenges for the clinical use of these sources are also discussed.

Novel tumor marker REG4 detected in serum of patients with resectable pancreatic cancer and feasibility for antibody therapy targeting REG4

Pancreatic ductal adenocarcinoma (PDAC) shows the worst mortality rate among common malignancies, with a 5-year survival rate of only 4%, and the majority of PDAC patients are diagnosed at an advanced stage in which no effective therapy is available at present. Although the proportion of curable cases is still not so high, surgical resection of early stage PDAC is the only way to cure the disease. Hence, establishment of a screening strategy to detect early stage PDAC by novel serological markers is required urgently, and development of novel molecular therapies for PDAC treatment is also eagerly expected. We here report overexpression of REG4, a new member of the regenerating islet-derived (REG) family, in PDAC cells on the basis of genome-wide cDNA microarray analysis as well as reverse transcription-polymerase chain reaction and immunohistochemical analysis. We also detected significant elevation of REG4 in the serum of some patients with early-stage PDAC using our enzyme-linked immunosorbent assay system, indicating the possibility of REG4 as a new serological marker of PDAC. Furthermore, we found that knockdown of endogenous REG4 expression in PDAC cell lines with small interfering RNA caused a decrease in cell viability. Concordantly, addition of recombinant REG4 to the culture medium enhanced growth of a PDAC cell line in a dose-dependent manner. A monoclonal antibody against REG4 neutralized its growth-promoting effects and attenuated significantly the growth of PDAC cells. These findings indicate that REG4 is a promising tumor marker to screen early-stage PDAC, and also that neutralization of REG4 by the antibody may offer novel potential tools for the treatment of PDAC.

Gene therapy for type 1 diabetes

The most intensively studied autoimmune disorder, type 1 diabetes mellitus (DM1), has attracted perhaps the greatest interest for gene-based therapeutic and prophylactic interventions. The final clinical manifestation of this immunologically and genetically complex disease, the absence of insulin, is the major starting point for almost all the gene therapy modalities attempted to date. Insulin replacement by transplantation of islets of Langerhans or surrogate beta cells is the obvious choice, but the allogeneic nature of the transplants activates potent antidonor immunoreactivity necessitating gene and cell-based immunosuppressive strategies as an alternative to the toxic pharmacologic immunosuppressives indicated for classic solid organ transplants. Accumulating knowledge of the cellular mechanisms involved in onset, however, have yielded promising tolerance induction prophylactic approaches using genes and cells. Despite the early successes in a number of animal models, the true test of efficacy in humans remains to be demonstrated.

Conditional expression demonstrates the role of the homeodomain transcription factor Pdx1 in maintenance and regeneration of beta-cells in the adult pancreas

The homeodomain transcription factor Pdx1 is essential for pancreas development. To investigate the role of Pdx1 in the adult pancreas, we employed a mouse model in which transcription of Pdx1 could be reversibly repressed by administration of doxycycline. Repression of Pdx1 in adult mice impaired expression of insulin and glucagon, leading to diabetes within 14 days. Pdx1 repression was associated with increased cell proliferation predominantly in the exocrine pancreas and upregulation of genes implicated in pancreas regeneration. Following withdrawal of doxycycline and derepression of Pdx1, normoglycemia was restored within 28 days; during this period, Pdx1(+)/Ins(+) and Pdx(+)/Ins(-) cells were observed in association with the duct epithelia. These findings confirm that Pdx1 is required for beta-cell function in the adult pancreas and indicate that in the absence of Pdx1 expression, a regenerative program is initiated with the potential for Pdx1-dependent beta-cell neogenesis.

Gene- and cell-based therapeutics for type I diabetes mellitus

Type 1 diabetes mellitus, an autoimmune disorder is an attractive candidate for gene and cell-based therapy. From the use of gene-engineered immune cells to induce hyporesponsiveness to autoantigens to islet and beta cell surrogate transplants expressing immunoregulatory genes to provide a local pocket of immune privilege, these strategies have demonstrated proof of concept to the point where translational studies can be initiated. Nonetheless, along with the proof of concept, a number of important issues have been raised by the choice of vector and expression system as well as the point of intervention; prophylactic or therapeutic. An assessment of the current state of the science and potential leads to the conclusion that some strategies are ready for safety trials while others require varying degrees of technical and conceptual refinement.

Gene and cell therapies for diabetes mellitus: strategies and clinical potential

The last 5 years have witnessed an explosion in the use of genes and cells as biomedicines. While primarily aimed at cancer, gene engineering and cell therapy strategies have additionally been used for Mendelian, neurodegenerative and metabolic disorders. The main focus of gene and cell therapy strategies in metabolism has been diabetes mellitus. This disease is a disorder of glucose homeostasis, either due to the immune-mediated eradication of pancreatic beta cells in the islets of Langerhans (type 1 diabetes) or resulting from insulin resistance and obesity syndromes where the insulin-producing capability of the beta cell is ultimately exhausted in the face of insensitivity to the effects of insulin in the peripheral glucose-utilising tissues (type 2 diabetes). A significant number of animal studies have demonstrated the potential in restoring normoglycaemia by islet transplantation in the context of immunoregulation achieved by gene transfer of immunoregulatory genes to allo- and xenogeneic islets ex vivo. Additionally, gene and cell therapy has also been used to induce tolerance to auto- and alloantigens and to generate the tolerant state in autoimmune rodent animal models of type 1 diabetes or rodent recipients of allogeneic/xenogeneic islet transplants. The achievements of gene and cell therapy in type 2 diabetes are less evident, but seminal studies promise that this modality can be relevant to treat and perhaps prevent the underlying causes of the disease. Here we present an overview of the current status of gene and cell therapy for type 1 and 2 diabetes and we propose potential therapeutic options that could be clinically useful. For type 1 diabetes, transplantation of islets engineered to evade or suppress the recipient immune response is the most readily-available technology today. A number of gene delivery vectors encoding proteins that impair a variety of immune cells have already been examined and proven versatile. More challenging but, nonetheless, just over the horizon are attempts to promote tolerance to islet allografts. Type 2 diabetes will likely require a better understanding of the processes that determine insulin sensitivity in the periphery. Targeting tissues such as muscle and fat with vectors encoding genes whose products promote insulin sensitivity and glucose uptake is an approach that does not carry with it the side-effects often associated with pharmacologic agents currently in use. In the end, progress in vector design, elucidation of antigen-specific immunity and insulin sensitivity will provide the framework for gene drug use in the treatment of type 1 and type 2 diabetes.

A family of 16-kDa pancreatic secretory stress proteins form highly organized fibrillar structures upon tryptic activation

A group of 16-kDa proteins, synthesized and secreted by rat pancreatic acinar cells and composed of pancreatic stone protein (PSP/reg) and isoforms of pancreatitis-associated protein (PAP), show structural homologies, including conserved amino acid sequences, cysteine residues, and highly sensitive N-terminal trypsin cleavage sites, as well as conserved functional responses in conditions of pancreatic stress. Trypsin activation of recombinant stress proteins or counterparts contained in rat pancreatic juice (PSP/reg, PAP I and PAP III) resulted in conversion of 16-kDa soluble proteins into 14-kDa soluble isoforms (pancreatic thread protein and pancreatitis-associated thread protein, respectively) that rapidly polymerize into insoluble sedimenting structures. Activated thread proteins show long lived resistance to a wide spectrum of proteases contained in pancreatic juice, including serine proteases and metalloproteinases. In contrast, PAP II, following activation with trypsin or pancreatic juice, does not form insoluble structures and is rapidly digested by pancreatic proteases. Scanning and transmission electron microscopy indicate that activated thread proteins polymerize into highly organized fibrillar structures with helical configurations. Through bundling, branching, and extension processes, these fibrillar structures form dense matrices that span large topological surfaces. These findings suggest that PSP/reg and PAP I and III isoforms consist of a family of highly regulated soluble secretory stress proteins, which, upon trypsin activation, convert into a family of insoluble helical thread proteins. Dense extracellular matrices, composed of helical thread proteins organized into higher ordered matrix structures, may serve physiological functions within luminal compartments in the exocrine pancreas.

Human REG family genes are tandemly ordered in a 95-kilobase region of chromosome 2p12

Reg, first isolated from a rat regenerating islet cDNA library, is expressed in regenerating islet beta-cells. Recently, it has been revealed that Reg and Reg-related genes constitute a multigene family, the Reg family. In human, the four REG family genes, i.e., REG 1 alpha, REG 1 beta, REG-related sequence (RS) and HIP/PAP, have so far been isolated. In this study, we analyzed YAC clones containing the four genes and performed two-color FISH to determine the map order of the genes. The human REG family genes are tandemly ordered in the 95-kbp DNA region of chromosome 2p12 as follows: 2cen-HIP/PAP-RS-REG I alpha-REG I beta-ptel.