Role of microRNA-21 in the formation of insulin-producing cells from pancreatic progenitor cells

The Potential of miR-21 in Stem Cell Differentiation and its Application in Tissue Engineering and Regenerative Medicine

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two important types of non-coding RNAs that are not translated into protein. These molecules can regulate various biological processes, including stem cell differentiation and self-renewal. One of the first known miRNAs in mammals is miR-21. Cancer-related studies have shown that this miRNA has proto-oncogene activity and is elevated in cancers. However, it is confirmed that miR-21 inhibits stem cell pluripotency and self-renewal and induces differentiation by targeting various genes. Regenerative medicine is a field of medical science that tries to regenerate and repair damaged tissues. Various studies have shown that miR-21 plays an essential role in regenerative medicine by affecting stem cell proliferation and differentiation. In this review, we will discuss the function of miR-21 in regenerative medicine of the liver, nerve, spinal cord, wound, bone, and dental tissues. In addition, the function of natural compounds and lncRNAs will be analyzed as potential regulators of miR-21 expression in regenerative medicine.

iPSC-Derived Pancreatic Progenitors Lacking FOXA2 Reveal Alterations in miRNA Expression Targeting Key Pancreatic Genes

Recently, we reported that forkhead box A2 (FOXA2) is required for the development of human pancreatic α- and β-cells. However, whether miRNAs play a role in regulating pancreatic genes during pancreatic development in the absence of FOXA2 expression is largely unknown. Here, we aimed to capture the dysregulated miRNAs and to identify their pancreatic-specific gene targets in pancreatic progenitors (PPs) derived from wild-type induced pluripotent stem cells (WT-iPSCs) and from iPSCs lacking FOXA2 (FOXA2^-/-iPSCs). To identify differentially expressed miRNAs (DEmiRs), and genes (DEGs), two different FOXA2^-/-iPSC lines were differentiated into PPs. FOXA2^-/- PPs showed a significant reduction in the expression of the main PP transcription factors (TFs) in comparison to WT-PPs. RNA sequencing analysis demonstrated significant reduction in the mRNA expression of genes involved in the development and function of exocrine and endocrine pancreas. Furthermore, miRNA profiling identified 107 downregulated and 111 upregulated DEmiRs in FOXA2^-/- PPs compared to WT-PPs. Target prediction analysis between DEmiRs and DEGs identified 92 upregulated miRNAs, predicted to target 1498 downregulated genes in FOXA2^-/- PPs. Several important pancreatic TFs essential for pancreatic development were targeted by multiple DEmiRs. Selected DEmiRs and DEGs were further validated using RT-qPCR. Our findings revealed that FOXA2 expression is crucial for pancreatic development through regulating the expression of pancreatic endocrine and exocrine genes targeted by a set of miRNAs at the pancreatic progenitor stage. These data provide novel insights of the effect of FOXA2 deficiency on miRNA-mRNA regulatory networks controlling pancreatic development and differentiation.

Therapeutic Potential of miRNAs for Type 2 Diabetes Mellitus: An Overview

MicroRNA(miRNA)s have been identified as an emerging class for therapeutic interventions mainly due to their extracellularly stable presence in humans and animals and their potential for horizontal transmission and action. However, treating Type 2 diabetes mellitus using this technology has yet been in a nascent state. MiRNAs play a significant role in the pathogenesis of Type 2 diabetes mellitus establishing the potential for utilizing miRNA-based therapeutic interventions to treat the disease. Recently, the administration of miRNA mimics or antimiRs in-vivo has resulted in positive modulation of glucose and lipid metabolism. Further, several cell culture-based interventions have suggested beta cell regeneration potential in miRNAs. Nevertheless, few such miRNA-based therapeutic approaches have reached the clinical phase. Therefore, future research contributions would identify the possibility of miRNA therapeutics for tackling T2DM. This article briefly reported recent developments on miRNA-based therapeutics for treating Type 2 Diabetes mellitus, associated implications, gaps, and recommendations for future studies.

Sox6, A Potential Target for MicroRNAs in Cardiometabolic Disease

PURPOSE OF REVIEW

The study aims to review recent advances in knowledge on the interplay between miRNAs and the sex-determining Region Y (SRY)-related high-mobility-group box 6 (Sox6) in physiology and pathophysiology, highlighting an important role in autoimmune and cardiometabolic conditions.

RECENT FINDINGS

The transcription factor Sox6 is an important member of the SoxD family and plays an indispensable role in adult tissue homeostasis, regeneration, and physiology. Abnormal expression of the Sox6 gene has been implicated in several disease conditions including diabetes, cardiomyopathy, autoimmune diseases, and hypertension. Expression of Sox6 is regulated by miRNAs, which are RNAs of about 22 nucleotides, and have also been implicated in several pathophysiological conditions where Sox6 plays a role. Regulation of Sox6 by miRNAs is important in diverse physiological tissues and organs. Dysregulation of the interplay between miRNAs and Sox6 is an important determinant of various disease conditions and may be actionable for therapeutic purposes.

The Predominant microRNAs in β-cell Clusters for Insulin Regulation and Diabetic Control

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic β-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in β-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of β-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into β-cells, resulting in enhanced β-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of β-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived β-cells to therapeutically relevant outputs will be discussed as well.

The Role of MicroRNAs in the Induction of Pancreatic Differentiation

Stem cell-based therapy is one of the therapeutic options with promising results in the treatment of diabetes. Stem cells from various sources are expanded and induced to generate the cells capable of secreting insulin. These insulin-producing cells [IPCs] could be used as an alternative to islets in the treatment of patients with diabetes. Soluble growth factors, small molecules, geneencoding transcription factors, and microRNAs [miRNAs] are commonly used for the induction of stem cell differentiation. MiRNAs are small non-coding RNAs with 21-23 nucleotides that are involved in the regulation of gene expression by targeting multiple mRNA targets. Studies have shown the dynamic expression of miRNAs during pancreatic development and stem cell differentiation. MiR- 7 and miR-375 are the most abundant miRNAs in pancreatic islet cells and play key roles in pancreatic development as well as islet cell functions. Some studies have tried to use these small RNAs for the induction of pancreatic differentiation. This review focuses on the miRNAs used in the induction of stem cells into IPCs and discusses their functions in pancreatic β-cells.

Emerging roles of Sox6 in the renal and cardiovascular system

The function of Sex-determining Region Y (SRY)-related high-mobility-group box (Sox) family of transcription factors in cell fate decisions during embryonic development are well-established. Accumulating evidence indicates that the Sox family of transcription factors are fundamental in adult tissue homeostasis, regeneration, and physiology. The SoxD subfamily of genes are expressed in various cell types of different organs during embryogenesis and adulthood and have been involved in cell-fate determination, cellular proliferation and survival, differentiation, and terminal maturation in a number of cell lineages. The dysregulation in the function of SoxD proteins (i.e. Sox5, Sox6, Sox13, and Sox23) have been implicated in different disease conditions such as chondrodysplasia, cancer, diabetes, hypertension, autoimmune diseases, osteoarthritis among others. In this minireview, we present recent developments related to the transcription factor Sox6, which is involved in a number of diseases such as diabetic nephropathy, adipogenesis, cardiomyopathy, inflammatory bowel disease, and cancer. Sox6 has been implicated in the regulation of renin expression and JG cell recruitment in mice during sodium depletion and dehydration. We provide a current perspective of Sox6 research developments in last five years, and the implications of Sox6 functions in cardiovascular physiology and disease conditions.

Multi-omics profiling reveals microRNA-mediated insulin signaling networks

Background

MicroRNAs (miRNAs) play a key role in mediating the action of insulin on cell growth and the development of diabetes. However, few studies have been conducted to provide a comprehensive overview of the miRNA-mediated signaling network in response to glucose in pancreatic beta cells. In our study, we established a computational framework integrating multi-omics profiles analyses, including RNA sequencing (RNA-seq) and small RNA sequencing (sRNA-seq) data analysis, inverse expression pattern analysis, public data integration, and miRNA targets prediction to illustrate the miRNA-mediated regulatory network at different glucose concentrations in INS-1 pancreatic beta cells (INS-1), which display important characteristics of the pancreatic beta cells.

Results

We applied our computational framework to the expression profiles of miRNA/mRNA of INS-1, at different glucose concentrations. A total of 1437 differentially expressed genes (DEGs) and 153 differentially expressed miRNAs (DEmiRs) were identified from multi-omics profiles. In particular, 121 DEmiRs putatively regulated a total of 237 DEGs involved in glucose metabolism, fatty acid oxidation, ion channels, exocytosis, homeostasis, and insulin gene regulation. Moreover, Argonaute 2 immunoprecipitation sequencing, qRT-PCR, and luciferase assay identified Crem, Fn1, and Stc1 are direct targets of miR-146b and elucidated that miR-146b acted as a potential regulator and promising target to understand the insulin signaling network.

Conclusions

In this study, the integration of experimentally verified data with system biology framework extracts the miRNA network for exploring potential insulin-associated miRNA and their target genes. The findings offer a potentially significant effect on the understanding of miRNA-mediated insulin signaling network in the development and progression of pancreatic diabetes.

Curcumin Suppresses Cell Proliferation, Migration, and Invasion Through Modulating miR-21-5p/SOX6 Axis in Hepatocellular Carcinoma

Background: Curcumin is the major component of turmeric, which has an anticancer property in multiple cancers, including hepatocellular carcinoma (HCC). However, the mechanisms are still largely unclear. This research aims to assess the pharmacological function of curcumin and explore the potential microRNA (miRNA)-mRNA regulatory mechanism in curcumin-mediated HCC progression. Materials and Methods: Hep3B and Huh-7 cells were used for in vitro experiments. Cells were exposed to various doses of curcumin, and transfection was conducted using Lipofectamine 2000. Cell proliferation, migration, and invasion were examined using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide or transwell assay. The abundances of miR-21-5p and gender-determining region Y-related high-mobility group box 6 (SOX6) were examined using quantitative real-time polymerase chain reaction or Western blot. The relationship between miR-21-5p and SOX6 was analyzed through luciferase reporter analysis. Results: Curcumin repressed HCC cell proliferation, migration, and invasion. miR-21-5p level was decreased in curcumin-treated cells, and miR-21-5p overexpression reversed curcumin-mediated inhibition of HCC progression. SOX6 was targeted through miR-21-5p, and SOX6 restoration attenuated miR-21-5p-induced promotion of HCC progression. Moreover, curcumin exposure increased SOX6 expression through regulating miR-21-5p, and knockdown of SOX6 overturned curcumin-modulated suppression of HCC progression. Conclusions: Curcumin repressed proliferation, migration, and invasion of HCC cells by regulating miR-21-5p and SOX6, indicating the promisingly pharmacological effect of curcumin in HCC.

microRNA-181c-5p promotes the formation of insulin-producing cells from human induced pluripotent stem cells by targeting smad7 and TGIF2

Generating insulin-producing cells (IPCs) from human pluripotent stem cells is a promising method for studying the molecular mechanism underlying pancreas development and a potential treatment source for type 1 diabetes. Previous studies have shown that miR-181c-5p is highly enriched in adult islets; however, its role in pancreatic β cell differentiation is poorly understood. In this study, we differentiated human induced pluripotent stem cells (hiPSCs) into IPCs in a stepwise process that recapitulated pancreas organogenesis and observed that miR-181c-5p continuously accumulated throughout the entire differentiation process. hiPSCs were transduced with lentiviral vectors containing human miR-181c-5p precursor, which significantly increased the endodermal markers SOX17, FOXA2, CXCR4 and GATA4 and pancreatic endocrine-specific gene expression, including PDX1, NKX6.1, MAFA and Insulin. miR-181c-5p overexpression exerted little effect on the efficiency of definitive endoderm, whereas it promoted the differentiation of pancreatic progenitors and IPCs, especially for NKX6.1-positive and insulin-positive cells differentiation. Transplanted these cells exhibit glucose-stimulated C-peptide secretion in vivo and protect mice from chemically induced diabetes. It was found that miR-181c-5p directly targets the 3'UTR of smad7 and TGIF2 mRNA, which are known to be endogenous repressors of TGF-β-smad2/3 signaling, to decrease their mRNA and protein levels. Furthermore, overexpressed miR-181c-5p led to an elevation of the smad2/3 phosphorylation levels in hiPSC-derived cells, while treatment with smad2/3 inhibitors following miR-181c-5p overexpression had opposite effects on IPC formation. These results suggest that miR-181c-5p is critically involved in pancreatic lineage commitment through direct repression of smad7 and TGIF2 and that it modulates TGF-β-smad2/3 signaling activation and increases the feasibility of using patient-specific hiPSCs for β cell replacement therapy for type 1 diabetes.

Expression study of candidate miRNAs and evaluation of their potential use as biomarkers of diabetic neuropathy

Aim: To evaluate the expression of candidate miRNAs in relation to diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN). Materials & methods: The expression of six candidate miRNAs has been evaluated in 49 Type 2 diabetes patients with neurological evaluation. Results: A higher expression of miR-128a was seen in patients with DPN compared with those without DPN (p = 0.015). miR-155 and miR-499a seemed to be down-expressed in patients with DPN (p = 0.04 and p = 0.05, respectively). A lower expression of miR-155 (p = 0.05) was observed even in patients with CAN with respect to CAN-negative. A higher expression of miR-155 was associated with the rs767649 polymorphism variant allele compared with the wild-type allele (p = 0.03). Conclusion: miR-128a, miR-155 and miR-499a might be involved in diabetic neuropathies development.

Role of TGF-β/Smad Pathway in the Transcription of Pancreas-Specific Genes During Beta Cell Differentiation

Autoimmune destruction of pancreatic beta cells causes absolute insulin deficiency and results in type 1 diabetes mellitus (T1DM). The substitution of healthy pancreatic beta cells for damaged cells would be the ideal treatment for T1DM; thus, the generation of pancreatic beta cells from adult stem cells represents an attractive avenue for research. In this study, a cocktail of factors was used to induce the differentiation of pancreatic beta cells from mesenchymal stem cells (MSCs). The differentiation program was divided into five stages, and the roles of the cocktail factors used during each stage were systematically elucidated. Activin A was found to phosphorylate Smad2 and Smad3 in stage III, thereby activating the TGF-β/Smad pathway. Meanwhile, the endocrine-specific transcription factor, Ngn3, and the pancreas-specific miRNAs, miR-375 and miR-26a, were dramatically elevated in stage III. We next demonstrated that Smad4, an important transcription factor in the TGF-β/Smad pathway, could bind to the promoter sequences of target genes and enhance their transcription to initiate the differentiation of beta cells. Use of SB-431542, an inhibitor of the TGF-β/Smad pathway, demonstrated in vivo and in vitro that this pathway plays a critical role in the production of pancreatic beta cells and in modulating insulin secretion. Thus, the TGF-β/Smad pathway is involved in the production of beta cells from adult stem cells by enhancing the transcription of Ngn3, miR-375, and miR-26a. These findings further underline the significant promise of cell transplant therapies for type 1 diabetes mellitus.

Insight into miRNAs related with glucometabolic disorder

A microRNA (miRNA) is a single-stranded, small and non-coding RNA molecule that contains 20-25 nucleotides. More than 2000 miRNAs have been identified in human genes since the first miRNA was discovered in Caenorhabditis elegans in the early 1990s. miRNAs play a crucial role in various biological processes by regulating gene expression through post-transcriptional mechanisms. The alterations of their levels are associated with various diseases, such as glucometabolic disorder and lipid metabolism disorder. In recent years, miRNAs have been proved to be involved in regulating the functions of pancreatic β-cells, insulin resistance and other biological behaviors related to glucometabolic disorder and the pathogenesis of diabetes mellitus (DM). This review summarized specific miRNAs, including miRNA-375 (miR-375), miRNA-155 (miR-155), miRNA-21 (miR-21), miRNA-33 (miR-33), the let-7 family and some other miRNAs related to glucometabolic regulation, introduced the obstacles and challenges in miRNA therapy, and discussed the prospect of new treatment methods for glucometabolic disorder.

MicroRNA-432 is downregulated in osteosarcoma and inhibits cell proliferation and invasion by directly targeting metastasis-associated in colon cancer-1

The aberrant expression of microRNAs (miRNAs/miRs) in osteosarcoma (OS) has been demonstrated in previous studies, and deregulation of miRNA expression has been associated with several types of cancer, including OS development and progression. Therefore, identifying the functional role of miRNAs in OS onset and development may facilitate the identification of novel and effective therapeutic targets for the treatment of patients with OS. Previous studies have demonstrated that miR-432 is involved in tumor formation and progression in several types of cancer. However, the expression pattern, functional role and underlying mechanism of miR-432 in OS remain unknown. In the current study, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to measure miR-432 expression levels in OS tissue samples and cell lines. The effect of miR-432 overexpression on OS cell proliferation and invasion was detected using Cell Counting Kit-8 and Transwell invasion assays, respectively. Bioinformatics analysis was used to predict metastasis-associated in colon cancer 1 (MACC1) as a putative target of miR-432 and this was confirmed using a dual-luciferase reporter assay, RT-qPCR and western blot analysis. The current study demonstrated that miR-432 expression levels were significantly reduced in OS tissue samples and cell lines. In addition, functional assays revealed that overexpression of miR-432 significantly decreased OS cell proliferation and invasion. Furthermore, MACC1 was identified as a direct target gene of miR-432 in OS. MACC1 expression levels were significantly increased in OS tissue samples and an inverse correlation was observed between miR-432 and MACC1 expression in OS tissue samples. In addition, rescue experiments demonstrated that overexpression of MACC1 partially reversed the anti-proliferative and anti-invasive effects of miR-432 in OS cells. In conclusion, the present study demonstrated that miR-432 inhibited OS cell proliferation and invasion in vitro through direct targeting of MACC1, and miR-432 may be a potential therapeutic target for the treatment of OS.

Isolation and biological characteristic evaluation of a novel type of cartilage stem/progenitor cell derived from Small‑tailed Han sheep embryos

Cartilage stem/progenitor cells (CSPCs) are a novel stem cell population and function as promising therapeutic candidates for cell‑based cartilage repair. Until now, numerous existing research materials have been obtained from humans, horses, cows and other mammals, but rarely from sheep. In the present study, CSPCs with potential applications in repairing tissue damage and cell‑based therapy were isolated from 45‑day‑old Small‑tailed Han Sheep embryos, and examined at the cellular and molecular level. The expression level of characteristic surface markers of the fetal sheep CSPCs were also evaluated by immunofluorescence, reverse transcription‑polymerase chain reaction analysis and flow cytometric assays. Biological growth curves were drawn in accordance with cell numbers. Additionally, karyotype analysis showed no marked differences in the in vitro cultured CSPCs and they were genetically stable among different passages. The CSPCs were also capable of adipogenic, osteogenic and chondrogenic lineage progression under the appropriate induction medium in vitro. Together, these findings provide a theoretical basis and experimental evidence for cellular transplant therapy in tissue engineering.

Induction of hepatocytes-derived insulin-producing cells using small molecules and identification of microRNA profiles during this procedure

The transplantation of insulin-producing cells (IPCs) or pancreatic progenitor cells is a theoretical therapy for diabetes with insulin insufficiency. Isolated hepatocytes from newborn rats (within 24 h after birth) were progressively induced into IPCs using 5-aza-2'-deoxycytidine, Trichostatin A, retinoic acid, insulin-transferrin-selenium, and nicotinamide. We transplanted Pdx1+ pancreatic progenitors into STZ-induced diabetic mice and found the decreased blood glucose and increased insulin level in comparison with diabetic model. The dynamic expression profiles of microRNAs (miRNAs) were identified using microarray. We found 67 miRNAs were decreasingly expressed; 52 miRNAs were increasingly expressed; 27 miRNAs were specially inhibited in Stage 1 cells (multipotent progenitor cells); and 58 miRNAs were specially inhibited in Pdx1+ cells (Stage 2). Further analysis showed these miRNAs' targets were associated with genetic recombination, stem cell pluripotency maintenance, cellular structure reorganization and insulin secretion. Enrichment analysis using KEGG pathway showed the differentiation of IPCs from hepatocytes was massively more likely not mediated by canonical Wnt/β-catenin signaling. In addition, the BMP/Smad signaling was involved in this progression. We found the dysregulated miRNAs profiles were inconsistent with cell phenotypes and might be responsible for small molecule-mediated cell differentiation during IPCs induction.

Melatonin promotes self-renewal of nestin-positive pancreatic stem cells through activation of the MT2/ERK/SMAD/nestin axis

Although melatonin has been shown to exhibit a wide variety of biological functions, its effects on promotion of self-renewal in pancreatic stem cells remain unknown. In this study, we incubated murine pancreatic stem cells (PSCs) with various concentrations of melatonin (0.01, 0.1, 1, 10 or 100 μM) to screen for the optimum culture medium for increasing cell proliferation. We found that 10 μM melatonin can significantly increase proliferation and enhance expression of a stem cell marker, nestin, in PSCs via melatonin receptor 2 (MT2). Thus, we used 10 μM melatonin to study the melatonin-mediated molecular mechanisms of cell proliferation in PSCs. We applied extracellular signal-regulated kinase (ERK) pathway inhibitor SCH772984 and transforming growth factor beta (TGF-β) pathway inhibitor SB431542, along with interfering RNAs siERK1, siERK2, siSmad2, siSmad3, siSmad4 and siNestin, to melatonin-treated PSCs to research the roles of these genes in self-renewal. The results revealed a novel molecular mechanism by which melatonin promotes self-renewal of PSCs: a chain reaction in the MT2/ERK/SMAD/nestin axis promoted the aforementioned self-renewal as well as inhibited differentiation. In addition, upregulation of nestin created a positive feedback loop in the regulation of the transforming growth factor beta 1 (TGF-β1)/SMADs pathway by promoting expression of Smad4. Conversely, knockdown of nestin significantly suppressed the proliferative effect in melatonin-treated PSCs. These are all novel mechanisms through which the ERK pathway cooperatively crosstalks with the SMAD pathway to regulate nestin expression, thereby enhancing self-renewal in PSCs.

MicroRNA-34c acts as a bidirectional switch in the maturation of insulin-producing cells derived from mesenchymal stem cells

miRNAs regulate insulin secretion, pancreatic development, and beta-cell differentiation. However, their function in the differentiation of IPCs from MSCs is poorly understood. In this study, to screen for miRNAs and their targets that function during the formation of IPCs from MSCs, we examined the miRNA expression profiles of MSCs and IPCs using RNA-seq and qPCR to confirm the above results. We found that miR-34c exhibited transient upregulation at an early stage of the formation of IPCs derived from MSCs. Next, we analyzed the biological function of miR-34c by predicting its targets using bioinformatic tools. Combining our data with those from previous reports, we found that miR-34c and its targets play an important role in the formation of IPCs. Therefore, we overexpressed miR-34c and expressed small interfering RNAs of its targets in MSCs to investigate their functions in IPC formation. We found that miR-34c acts as a bidirectional switch in the formation of IPCs derived from MSCs by regulating the expression of targets to affect insulin synthesis and secretion. miR-34c was shown to downregulate its targets, including PDE7B, PDGFRA, and MAP2K1, to increase proinsulin synthesis, but when miR-34c continually dysregulated such expression, it suppressed the expression of other targets, namely ACSL4 and SAR1A, weakening insulin secretion in IPCs. These results suggest that endogenous miRNAs involved in the formation of IPCs from stem cells should be considered in the development of effective cell transplant therapy for diabetes.

Mesenchymal cells are required for epithelial duct cell-to-beta cell maturation and function in an injured adult pancreas in the rat

The islet, the endocrine portion of the pancreas - develops from an invagination of the pancreatic duct epithelial cells (PDECs) into the surrounding tissue. The contact of the PDECs with mesenchymal cells (MSCs) may be an essential drive for endocrine cell fate. During pancreatic development, cells that express Neurogenin-3 (Ngn3) biomarker are precursors of insulin- producing beta cells. These precursors have been reported in the neogenesis of islets from adult tissues following the surgical ligation of the main pancreatic duct (PDL). But the capacity of these precursors to induce the appropriate signals to complete the entire neogenesis program has been questioned. We studied the fate of co-culture of PDECs and MSCs from the ligated adult pancreas and established the exact location of adult stem- or progenitor-like cells that give rise to beta cells. PDECs were cultured in direct contact with or without MSCs in serum-containing culture media. The cytomorphology of the cells in co-cultures was determined and the immunocytochemical study of the cells was carried out using anti-Ngn3, anti-insulin and anti-cytokeratin-7 (CK7) antibodies. Both the PDEC/MSC- and PDEC/MSC+ cultures showed out- pocketing from duct epithelium by the end of the second week, which are distinct as cell clusters only in PDEC/MSC+ cells later in week four, exhibiting numerous branching ducts. Co-expression of Ngn3 with insulin was observed in both cultures from the second week. However, characterizations of these Ngn3+ cells in the PDEC/MSC+ culture revealed that these cells also co-expressed a CK7 biomarker. This study provides new evidence of the ductal epithelial nature of beta cells in injured adult pancreata; and that the mesenchymal stromal cells are required to sustain Ngn3 expression for beta cell maturation and function.

Culturing and transcriptome profiling of progenitor-like colonies derived from adult mouse pancreas

Background

Transplantation of insulin-producing cells is considered an important diabetes therapy. Many research studies have shown that insulin-producing cells can be derived from the in-vitro cultured pancreatic colonies with self-renewal ability and multilineage potential. Even though these progenitor-like colonies have been prepared from adult pancreas cells, the efficient culture method is hardly established and regulation of the colonies is rarely known. We confirmed previously that single cells acquired from adult mouse pancreas could form cyst-like colonies in a 3D semi-solid system containing Matrigel and methylcellulose. These colonies could be passaged continuously without losing progenitor-like capacity. In the previous culturing system, however, conditioned medium from murine embryonic-stem-cell-derived pancreatic-like cells was used. This unregulated ingredient may reduce repeatability and affect following study. Thus, a new culturing system with certain components needs to be developed.

Methods

Single cell suspension was acquired from adult mouse pancreas and cultured in a Matrigel-based 3D system with epidermal growth factor, Nicotinamide, B27, and Noggin to form ring colonies. Serial-passage assay was performed to evaluate self-renewal ability. Real-time polymerase chain reaction and immunostaining were used to detect the expression of progenitor-related genes. A 2D differentiation method was used to testify the multilineage potency of the colonies. High-throughput sequencing (HTS) of the colonies was performed to profile the differentially expressed genes.

Results

We developed a 3D culturing system deprived of conditioned medium to propagate those colonies with high proliferative efficiency. HTS of the transcriptome of mRNAs, microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) showed differentially expressed genes compared to the whole pancreas (as control). In mRNAs, several surface marker genes were identified in the colonies. Moreover in noncoding RNAs, miR-21a, miR-31 and miR-155 were upregulated and miR-217, miR-802 and miR-375 were downregulated in colonies along with a number of other miRNAs and lncRNAs.

Conclusions

Our results offer an efficient culture system for pancreatic progenitor-like colonies and HTS of the colonies serves as a target resource for following study of in-vitro cultured pancreatic progenitors. These findings should also contribute to our understanding of the transcriptional regulation of these progenitor-like colonies and the mechanisms behind their functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0626-y) contains supplementary material, which is available to authorized users.

Milk's Role as an Epigenetic Regulator in Health and Disease

It is the intention of this review to characterize milk's role as an epigenetic regulator in health and disease. Based on translational research, we identify milk as a major epigenetic modulator of gene expression of the milk recipient. Milk is presented as an epigenetic "doping system" of mammalian development. Milk exosome-derived micro-ribonucleic acids (miRNAs) that target DNA methyltransferases are implicated to play the key role in the upregulation of developmental genes such as FTO, INS, and IGF1. In contrast to miRNA-deficient infant formula, breastfeeding via physiological miRNA transfer provides the appropriate signals for adequate epigenetic programming of the newborn infant. Whereas breastfeeding is restricted to the lactation period, continued consumption of cow's milk results in persistent epigenetic upregulation of genes critically involved in the development of diseases of civilization such as diabesity, neurodegeneration, and cancer. We hypothesize that the same miRNAs that epigenetically increase lactation, upregulate gene expression of the milk recipient via milk-derived miRNAs. It is of critical concern that persistent consumption of pasteurized cow's milk contaminates the human food chain with bovine miRNAs, that are identical to their human analogs. Commercial interest to enhance dairy lactation performance may further increase the epigenetic miRNA burden for the milk consumer.

The role of microRNAs in islet β-cell development

Cell-based therapies suggest novel treatments to overcome the complication of the current therapeutic approaches in diabetes mellitus type 1. Replacement of the destroyed pancreatic islet β-cells by appropriate alternative cells needs an efficient approach to differentiate the cells into viable and functional insulin producing cells. Small non-coding RNA molecules, microRNAs (miRNA), have critical roles in post-transcriptional regulation of gene expression. Therefore, they can direct the cells toward β-cell like cells and control islet β-cell development. Previous reports showed the manipulation of the miRNA expression on islet β-cell differentiation and regeneration. Likewise, the regulation of epithelial to mesenchymal transi-tion by the miR-30 family and the miR-200 family may be a useful approach to conduct islet β-cell development. Investigation of stem cells differentiation showed that the dynamic expression patterns of miR-375 and miR-7 are similar to developing human fetal pancreas while dynamic expression of miR-146a and miR-34a occurred during the differentiation. Moreover, miR-342 and its both targets, FOXA2 and MAFB, are found in β-cell differentiation and maturation. Because miRNAs can target specific transcription factors during islet β-cell development and differentiation, they could be offerred as alternative regenerative treatment for diabetes mellitus. Considering that the application of these non-coding RNAs remains limited in the literature, in this review article, we present an overview of the roles of miRNAs in the islet β-cell development, focusing on the application of different miRNAs in the experimental protocols.

Regulatory Roles of MicroRNAs in Diabetes

MicroRNAs (miRNAs), a class of endogenous small noncoding RNAs in eukaryotes, have been recognized as significant regulators of gene expression through post-transcriptional mechanisms. To date, >2000 miRNAs have been identified in the human genome, and they orchestrate a variety of biological and pathological processes. Disruption of miRNA levels correlates with many diseases, including diabetes mellitus, a complex multifactorial metabolic disorder affecting >400 million people worldwide. miRNAs are involved in the pathogenesis of diabetes mellitus by affecting pancreatic β-cell functions, insulin resistance, or both. In this review, we summarize the investigations of the regulatory roles of important miRNAs in diabetes, as well as the potential of circulating miRNAs as diagnostic markers for diabetes mellitus.

Melatonin improves reprogramming efficiency and proliferation of bovine-induced pluripotent stem cells

Melatonin can modulate neural stem cell (NSC) functions such as proliferation and differentiation into NSC-derived pluripotent stem cells (N-iPS) in brain tissue, but the effect and mechanism underlying this are unclear. Thus, we studied how primary cultured bovine NSCs isolated from the retinal neural layer could transform into N-iPS cell. NSCs were exposed to 0.01, 0.1, 1, 10, or 100 μm melatonin, and cell viability studies indicated that 10 μm melatonin can significantly increase cell viability and promote cell proliferation in NSCs in vitro. Thus, 10 μm melatonin was used to study miR-302/367-mediated cell reprogramming of NSCs. We noted that this concentration of melatonin increased reprogramming efficiency of N-iPS cell generation from primary cultured bovine NSCs and that this was mediated by downregulation of apoptosis-related genes p53 and p21. Then, N-iPS cells were treated with 1, 10, 100, or 500 μm melatonin, and N-iPS (M-N-iPS) cell proliferation was measured. We noted that 100 μm melatonin increased proliferation of N-iPS cells via increased phosphorylation of intracellular ERK1/2 via activation of its pathway in M-N-iPS via melatonin receptors 1 (MT1). Finally, we verified that N-iPS cells and M-N-iPS cells are similar to typical embryonic stem cells including the expression of pluripotency markers (Oct4 and Nanog), the ability to form teratomas in vivo, and the capacity to differentiate into all three embryonic germ layers.

Role of microRNA 21 in diabetes and associated/related diseases

Diabetes mellitus (DM) is a disease related to metabolic disorder and becoming an epidemic in developing countries. Current treatments for DM include modified lifestyle practice, obesity treatment, oral hypoglycemic agents, and insulin sensitizers, yet no cure is available in sight for the disease, despite it requires new insight into the molecular and pathophysiology. MicroRNAs (miRNAs) are small noncoding RNAs considered as of greater biological importance and controls molecular signaling pathways in diabetic pathogenesis. The microRNA 21 is an important microRNA frequently upregulated in all types of diseases suggesting that it plays an important role in cell proliferation, and apoptosis. The present mini review highlights the recent investigations related to the importance of miR-21 in different types of DM based on the up-to-date reports.

Comparative Transcriptomic Analyses of Differentially Expressed Genes in Transgenic Melatonin Biosynthesis Ovine HIOMT Gene in Switchgrass

Melatonin serves pleiotropic functions in prompting plant growth and resistance to various stresses. The accurate biosynthetic pathway of melatonin remains elusive in plant species, while the N-acetyltransferase and O-methyltransferase were considered to be the last two key enzymes during its biosynthesis. To investigate the biosynthesis and metabolic pathway of melatonin in plants, the RNA-seq profile of overexpression of the ovine HIOMT was analyzed and compared with the previous transcriptome of transgenic oAANAT gene in switchgrass, a model plant for cellulosic ethanol production. A total of 946, 405, and 807 differentially expressed unigenes were observed in AANAT vs. control, HIOMT vs. control, and AANAT vs. HIOMT, respectively. Two hundred and seventy-five upregulated and 130 downregulated unigenes were detected in transgenic oHIOMT line comparing with control, including the significantly upregulated (F-box/kelch-repeat protein, zinc finger BED domain-containing protein-3) genes, which were potentially correlated with enhanced phenotypes of shoot, stem and root growth in transgenic oHIOMT switchgrass. Several stress resistant related genes (SPX domain-containing membrane protein, copper transporter 1, late blight resistance protein homolog R1A-6 OS etc.) were specifically and significantly upregulated in transgenic oHIOMT only, while metabolism-related genes (phenylalanine-4-hydroxylase, tyrosine decarboxylase 1, protein disulfide-isomerase and galactinol synthase 2 etc.) were significantly upregulated in transgenic oAANAT only. These results provide new sights into the biosynthetic and physiological functional networks of melatonin in plants.