Genetic variants that are associated with susceptibility to type 2 diabetes (T2D) are important f... more Genetic variants that are associated with susceptibility to type 2 diabetes (T2D) are important for identification of individuals at risk and can provide insights into the molecular basis of disease. Analysis of T2D in domestic animals provides both the opportunity to improve veterinary management and breeding programs as well as to identify novel T2D risk genes. Australian-bred Burmese (ABB) cats have a 4-fold increased incidence of type 2 diabetes (T2D) compared to Burmese cats bred in the United States. This is likely attributable to a genetic founder effect. We investigated this by performing a genome-wide association scan on ABB cats. Four SNPs were associated with the ABB T2D phenotype with p values <0.005. All exons and splice junctions of candidate genes near significant single-nucleotide polymorphisms (SNPs) were sequenced, including the genes DGKG, IFG2BP2, SLC8A1, E2F6, ETV5, TRA2B and LIPH. Six candidate polymorphisms were followed up in a larger cohort of ABB cats wi...
Immunoglobulin G (IgG) glycosylation is essential for function of the immune system, but the gene... more Immunoglobulin G (IgG) glycosylation is essential for function of the immune system, but the genetic and environmental factors that underlie its inter-individual variability are not well defined. The Collaborative Cross (CC) genetic resource harnesses over 90% of the common genetic variation of the mouse. By analyzing the IgG glycome composition of 95 CC strains, we made several important observations: (i) glycome variation between mouse strains was higher than between individual humans, despite all mice having the same environmental influences; (ii) five genetic loci were found to be associated with murine IgG glycosylation; (iii) variants outside traditional glycosylation site motifs affected glycome variation; (iv) bisecting N-acetylglucosamine (GlcNAc) was produced by several strains although most previous studies have reported the absence of glycans containing the bisecting GlcNAc on murine IgGs; and (v) common laboratory mouse strains are not optimal animal models for studying...
The Journal of investigative dermatology, Jan 11, 2017
Giant congenital nevi are associated with clinical complications such as neurocutaneous melanosis... more Giant congenital nevi are associated with clinical complications such as neurocutaneous melanosis and melanoma. Virtually nothing is known about why some individuals develop these lesions. We previously identified the sonic hedgehog (Shh) pathway regulator Cdon as a candidate nevus modifier gene. Here we validate this by studying Cdon knockout mice, and go on to establishment the mechanism by which Shh exacerbates nevogenesis. Cdon knockout mice develop blue nevi without the need for somatic melanocyte oncogenic mutation. In a mouse model carrying melanocyte NRASQ61K we found that strain backgrounds that carry genetic variants that cause increased keratinocyte Shh pathway activity, as measured by Gli1 and Gli2 expression, develop giant congenital nevi. Shh components are also active adjacent to human congenital nevi. Mechanistically, this exacerbation of nevogenesis is driven via the release of the melanocyte mitogen endothelin-1 from keratinocytes. We then suppressed nevus developm...
In previous studies, we developed a new technique (ionic gelation vibrational jet flow; IGVJF) in... more In previous studies, we developed a new technique (ionic gelation vibrational jet flow; IGVJF) in order to encapsulate pancreatic β-cells, for insulin in vivo delivery, and diabetes treatment. The fabricated microcapsules showed good morphology but limited cell functions. Thus, this study aimed to optimize the IGVJF technique, by utilizing integrated electrode tension, coupled with high internal vibration, jet-flow polymer stream rate, ionic bath-gelation concentrations, and gelation time stay. The study also utilized double inner/outer nozzle segmented-ingredient flow of microencapsulating dispersion, in order to form β-cell microcapsules. Furthermore, a microcapsule-stabilizing bile acid was added, and microcapsule's stability and cell functions measured. Buchi-based built-in system utilizing IGVJF technology was screened to produce best microcapsule-containing β-cells with or without a stabilizing-enhancing bile acid. Formed microcapsules were examined, for physical character...
Aim: A semisynthetic primary bile acid (PBA) has exerted hypoglycemic effects in Type 1 diabetic ... more Aim: A semisynthetic primary bile acid (PBA) has exerted hypoglycemic effects in Type 1 diabetic animals, which were hypothesized to be due to its anti-inflammatory and cellular glucose-regulatory effects. Thus, the research purpose aimed to examine antidiabetic effects of a PBA, in terms of cellular inflammation and survival and insulin release, in the context of supporting β-cell delivery and Type 1 diabetic treatment. Materials & methods: 10 formulations were prepared, five without PBA (control) and five with PBA (test). Formulations were used to microencapsulate pancreatic β cells and the microcapsules were examined for morphology, cell viability, insulin release and inflammation. Results & conclusion: PBA improved cell viability, insulin release and reduced inflammation in a formulation-dependent manner, which suggests potential use in cell delivery and diabetes treatment. [Formula: see text]
Different genes encode the a-actin isoforms that are predominantly expressed in heart and muscle.... more Different genes encode the a-actin isoforms that are predominantly expressed in heart and muscle. Mutations in the skeletal muscle α-actin gene (ACTA1) cause muscle diseases that are mostly lethal in the early postnatal period. We previously demonstrated that the disease phenotype of ACTA1 mouse models could be rescued by transgenic over-expression of cardiac α-actin (ACTC1). ACTC1 is the predominant striated α-actin isoform in the heart but is also expressed in developing skeletal muscle. To develop a translatable therapy, we investigated the genetic regulation of Actc1 expression. Using strains from The Collaborative Cross (CC) genetic resource, we found that Actc1 varies in expression by up to 24-fold in skeletal muscle. We defined significant expression quantitative trait loci (eQTL) associated with early adult Actc1 expression in soleus and heart. eQTL in both heart and soleus mapped to the Actc1 locus and replicate an eQTL mapped for Actc1 in BXD heart and quadriceps. We built...
The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although i... more The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although its definitive physiological function is unknown, it may have a pathological role as the source of ectopic beats initiating atrial fibrillation. How the pulmonary myocardium gains pacemaker function is not clearly defined, although recent evidence indicates that changed transcriptional gene expression networks are at fault. The gene expression profile of this distinct cell type in situ was examined to investigate underlying molecular events that might contribute to atrial fibrillation. Via systems genetics a whole lung transcriptome dataset from the BXD recombinant inbred mouse resource was analysed, uncovering a pulmonary cardiomyocyte gene network of 24 transcripts, coordinately regulated by chromosome 1 and 2 loci. Promoter enrichment analysis and interrogation of publicly available ChIP-seq data suggested that transcription of this gene network may be regulated by the concerted activi...
We have investigated the potential use of β-conglutin protein isoforms from narrow-leafed lupin (... more We have investigated the potential use of β-conglutin protein isoforms from narrow-leafed lupin (Lupinus angustifolius L.) as a diabetes treatment. We produced purified recombinant β1-, β2-, β3-, β4-, and β6-conglutin proteins and showed that β1, β3, and β6 could bind to insulin. To assess β-conglutin proteins modulatory effect on insulin activation meditated kinases, whole blood and peripheral blood mononuclear cell cultures from type 2 diabetes (T2D) and healthy control subjects (C) were incubated with conglutin proteins. The treatment of peripheral blood mononuclear cells from T2D patients with β1, β3, and β6 proteins increased up to threefold mRNA and protein levels of genes important in insulin signaling pathways, namely insulin receptor substrate 1/p85/AKT/glucose transporter type 4. This was accompanied by a comparable fold-change decrease in the mRNA expression level of pro-inflammatory genes (iNOS and IL-1β) and proteins compared to healthy controls. The β2 and β4 isoforms ...
Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an algi... more Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an alginate-ursodeoxycholic acid (UDCA) matrix produced microcapsules with good stability and cell viability. In this study, we investigated if translation of this formulation to microencapsulation of primary β-cells harvested from mature double-transgenic healthy mice would also generate stable microcapsules with good cell viability. Islets of Langerhans were isolated from Ngn3-GFP/RIP-DsRED mice by intraductal collagenase P digestion and density gradient centrifugation, dissociated into single cells and the β-cell population purified by Fluorescence Activated Cell Sorting. β-cells were microencapsulated using either alginate-poly-l-ornithine (F1; control) or alginate-poly-l-ornithine-UDCA (F2; test) formulations. Microcapsules were microscopically examined and microencapsulated cells were analyzed for viability, insulin and cytokine release, 2 days post-microencapsulation. Microcapsules showe...
Pharmaceutical development and technology, Jan 9, 2017
Ideal cell-containing microcapsules should be capable of maintaining cell viability and exhibit s... more Ideal cell-containing microcapsules should be capable of maintaining cell viability and exhibit significant structural stability to support cellular functionality. To date, such microcapsules remain unavailable; thus, this study used our well-established microencapsulating methods to examine a total of 32 different microencapsulating formulations and correlate polymers' molecular weights (Mwt) and UDCA addition, with cell viability and microcapsules' stability, postmicroencapsulation. MIN6 mouse-cloned pancreatic β-cells were microencapsulated using control (n = 16; without UDCA) and test (n = 16; with UDCA) different polymers. Confocal microscopic imaging, cell viability, and microcapsules' stability were assessed. Best cell viability (>50%) was obtained at average Mwt of 50,000 g/mol (poly-l-ornithine), followed by 110,000 g/mol (poly-l-lysine). There was no linear correlation between Mwt and viability. Confocal imagining showed similar microcapsules' shape and ...
The major complication of peritoneal dialysis (PD) is the development of peritonitis, an infectio... more The major complication of peritoneal dialysis (PD) is the development of peritonitis, an infection within the abdominal cavity, primarily caused by bacteria. PD peritonitis is associated with significant morbidity, mortality and health care costs. Staphylococcus epidermidis is the most frequently isolated cause of PD-associated peritonitis. Mesothelial cells are integral to the host response to peritonitis, and subsequent clinical outcomes, yet the effects of infection on mesothelial cells are not well characterised. We systematically investigated the early mesothelial cell response to clinical and reference isolates of S. epidermidis using primary mesothelial cells and the mesothelial cell line Met-5A. Using an unbiased whole genome microarray, followed by a targeted panel of genes known to be involved in the human antibacterial response, we identified 38 differentially regulated genes (adj. p-value < 0.05) representing 35 canonical pathways after 1 hour exposure to S. epidermid...
Genetic studies have identified 61 variants associated with the risk of developing Type 1 Diabete... more Genetic studies have identified 61 variants associated with the risk of developing Type 1 Diabetes (T1D). The functions of most of the non-HLA (Human Leukocyte Antigen) genetic variants remain unknown. We found that only 16 of these risk variants could potentially be linked to a protein-coding change. Therefore, we investigated whether these variants affected susceptibility by regulating changes in gene expression. To do so, we examined whole transcriptome profiles of 600 samples from the Type 1 Diabetes Genetics Consortium (T1DGC). These comprised four different immune cell types (Epstein-Barr virus (EBV)-transformed B cells, either basal or after stimulation; and cluster of differentiation (CD)4+ and CD8+ T cells). Many of the T1D-associated risk variants regulated expression of either neighboring (cis-) or distant (trans-) genes. In brief, 24 of the non-HLA T1D variants affected the expression of 31 nearby genes (cis) while 25 affected 38 distant genes (trans). The effects were h...
Gut dysbiosis might underlie the pathogenesis of type 1 diabetes. In mice of the non-obese diabet... more Gut dysbiosis might underlie the pathogenesis of type 1 diabetes. In mice of the non-obese diabetic (NOD) strain, we found that key features of disease correlated inversely with blood and fecal concentrations of the microbial metabolites acetate and butyrate. We therefore fed NOD mice specialized diets designed to release large amounts of acetate or butyrate after bacterial fermentation in the colon. Each diet provided a high degree of protection from diabetes, even when administered after breakdown of immunotolerance. Feeding mice a combined acetate- and butyrate-yielding diet provided complete protection, which suggested that acetate and butyrate might operate through distinct mechanisms. Acetate markedly decreased the frequency of autoreactive T cells in lymphoid tissues, through effects on B cells and their ability to expand populations of autoreactive T cells. A diet containing butyrate boosted the number and function of regulatory T cells, whereas acetate- and butyrate-yieldin...
Developmental stage-specific differentiation of stem or progenitor cells into safe and functional... more Developmental stage-specific differentiation of stem or progenitor cells into safe and functional cells is of fundamental importance in regenerative medicine, including β-cell replacement. However, the differentiation of islet progenitor cells (IPCs) into insulin-secreting β cells remains elusive. Here, we report that the multifunctional molecule nicotinamide (NIC) is a specific differentiation regulator of mouse IPCs. The differentiated cells regulated by NIC exhibited many characteristics of adult β cells, including ameliorating preclinical diabetes and a highly comparable transcriptome profile. Gene set enrichment analysis showed that during differentiation, numerous IPC transcription factor genes, including Ngn3, Pax4, Fev, and Mycl1, were all down regulated. Pharmacological, biochemical, and gene knockdown analyses collectively demonstrated that NIC regulated the differentiation via inhibiting Sirt1 (silent information regulator transcript 1). Finally, NIC also regulates human ...
Pancreatic insulin-secreting β cells are essential in maintaining normal glucose homeostasis acco... more Pancreatic insulin-secreting β cells are essential in maintaining normal glucose homeostasis accomplished by highly specialized transcription of insulin gene, of which occupies up to 40% their transcriptome. Deficiency of these cells causes diabetes mellitus, a global public health problem. Although tremendous endeavors have been made to generate insulin-secreting cells from human pluripotent stem cells (i.e., primitive cells capable of giving rise to all cell types in the body), a regenerative therapy to diabetes has not yet been established. Furthermore, the nomenclature of β cells has become inconsistent, confusing and controversial due to the lack of standardized positive controls of developmental stage-matched in vivo cells. In order to minimize this negative impact and facilitate critical research in this field, a post-genomic concept of pancreatic β cells might be helpful. In this review article, we will briefly describe how β cells were discovered and islet lineage is develo...
Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACT... more Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACTA1 cause mostly fatal congenital myopathies. Cardiac α-actin (ACTC) is the major striated actin in adult heart and fetal skeletal muscle. It is unknown why ACTC and ACTA1 expression switch during development. We investigated whether ACTC can replace ACTA1 in postnatal skeletal muscle. Two ACTC transgenic mouse lines were crossed with Acta1 knockout mice (which all die by 9 d after birth). Offspring resulting from the cross with the high expressing line survive to old age, and their skeletal muscles show no gross pathological features. The mice are not impaired on grip strength, rotarod, or locomotor activity. These findings indicate that ACTC is sufficiently similar to ACTA1 to produce adequate function in postnatal skeletal muscle. This raises the prospect that ACTC reactivation might provide a therapy for ACTA1 diseases. In addition, the mouse model will allow analysis of the precise functional differences between ACTA1 and ACTC.
Genetic variants that are associated with susceptibility to type 2 diabetes (T2D) are important f... more Genetic variants that are associated with susceptibility to type 2 diabetes (T2D) are important for identification of individuals at risk and can provide insights into the molecular basis of disease. Analysis of T2D in domestic animals provides both the opportunity to improve veterinary management and breeding programs as well as to identify novel T2D risk genes. Australian-bred Burmese (ABB) cats have a 4-fold increased incidence of type 2 diabetes (T2D) compared to Burmese cats bred in the United States. This is likely attributable to a genetic founder effect. We investigated this by performing a genome-wide association scan on ABB cats. Four SNPs were associated with the ABB T2D phenotype with p values <0.005. All exons and splice junctions of candidate genes near significant single-nucleotide polymorphisms (SNPs) were sequenced, including the genes DGKG, IFG2BP2, SLC8A1, E2F6, ETV5, TRA2B and LIPH. Six candidate polymorphisms were followed up in a larger cohort of ABB cats wi...
Immunoglobulin G (IgG) glycosylation is essential for function of the immune system, but the gene... more Immunoglobulin G (IgG) glycosylation is essential for function of the immune system, but the genetic and environmental factors that underlie its inter-individual variability are not well defined. The Collaborative Cross (CC) genetic resource harnesses over 90% of the common genetic variation of the mouse. By analyzing the IgG glycome composition of 95 CC strains, we made several important observations: (i) glycome variation between mouse strains was higher than between individual humans, despite all mice having the same environmental influences; (ii) five genetic loci were found to be associated with murine IgG glycosylation; (iii) variants outside traditional glycosylation site motifs affected glycome variation; (iv) bisecting N-acetylglucosamine (GlcNAc) was produced by several strains although most previous studies have reported the absence of glycans containing the bisecting GlcNAc on murine IgGs; and (v) common laboratory mouse strains are not optimal animal models for studying...
The Journal of investigative dermatology, Jan 11, 2017
Giant congenital nevi are associated with clinical complications such as neurocutaneous melanosis... more Giant congenital nevi are associated with clinical complications such as neurocutaneous melanosis and melanoma. Virtually nothing is known about why some individuals develop these lesions. We previously identified the sonic hedgehog (Shh) pathway regulator Cdon as a candidate nevus modifier gene. Here we validate this by studying Cdon knockout mice, and go on to establishment the mechanism by which Shh exacerbates nevogenesis. Cdon knockout mice develop blue nevi without the need for somatic melanocyte oncogenic mutation. In a mouse model carrying melanocyte NRASQ61K we found that strain backgrounds that carry genetic variants that cause increased keratinocyte Shh pathway activity, as measured by Gli1 and Gli2 expression, develop giant congenital nevi. Shh components are also active adjacent to human congenital nevi. Mechanistically, this exacerbation of nevogenesis is driven via the release of the melanocyte mitogen endothelin-1 from keratinocytes. We then suppressed nevus developm...
In previous studies, we developed a new technique (ionic gelation vibrational jet flow; IGVJF) in... more In previous studies, we developed a new technique (ionic gelation vibrational jet flow; IGVJF) in order to encapsulate pancreatic β-cells, for insulin in vivo delivery, and diabetes treatment. The fabricated microcapsules showed good morphology but limited cell functions. Thus, this study aimed to optimize the IGVJF technique, by utilizing integrated electrode tension, coupled with high internal vibration, jet-flow polymer stream rate, ionic bath-gelation concentrations, and gelation time stay. The study also utilized double inner/outer nozzle segmented-ingredient flow of microencapsulating dispersion, in order to form β-cell microcapsules. Furthermore, a microcapsule-stabilizing bile acid was added, and microcapsule's stability and cell functions measured. Buchi-based built-in system utilizing IGVJF technology was screened to produce best microcapsule-containing β-cells with or without a stabilizing-enhancing bile acid. Formed microcapsules were examined, for physical character...
Aim: A semisynthetic primary bile acid (PBA) has exerted hypoglycemic effects in Type 1 diabetic ... more Aim: A semisynthetic primary bile acid (PBA) has exerted hypoglycemic effects in Type 1 diabetic animals, which were hypothesized to be due to its anti-inflammatory and cellular glucose-regulatory effects. Thus, the research purpose aimed to examine antidiabetic effects of a PBA, in terms of cellular inflammation and survival and insulin release, in the context of supporting β-cell delivery and Type 1 diabetic treatment. Materials & methods: 10 formulations were prepared, five without PBA (control) and five with PBA (test). Formulations were used to microencapsulate pancreatic β cells and the microcapsules were examined for morphology, cell viability, insulin release and inflammation. Results & conclusion: PBA improved cell viability, insulin release and reduced inflammation in a formulation-dependent manner, which suggests potential use in cell delivery and diabetes treatment. [Formula: see text]
Different genes encode the a-actin isoforms that are predominantly expressed in heart and muscle.... more Different genes encode the a-actin isoforms that are predominantly expressed in heart and muscle. Mutations in the skeletal muscle α-actin gene (ACTA1) cause muscle diseases that are mostly lethal in the early postnatal period. We previously demonstrated that the disease phenotype of ACTA1 mouse models could be rescued by transgenic over-expression of cardiac α-actin (ACTC1). ACTC1 is the predominant striated α-actin isoform in the heart but is also expressed in developing skeletal muscle. To develop a translatable therapy, we investigated the genetic regulation of Actc1 expression. Using strains from The Collaborative Cross (CC) genetic resource, we found that Actc1 varies in expression by up to 24-fold in skeletal muscle. We defined significant expression quantitative trait loci (eQTL) associated with early adult Actc1 expression in soleus and heart. eQTL in both heart and soleus mapped to the Actc1 locus and replicate an eQTL mapped for Actc1 in BXD heart and quadriceps. We built...
The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although i... more The pulmonary myocardium is a muscular coat surrounding the pulmonary and caval veins. Although its definitive physiological function is unknown, it may have a pathological role as the source of ectopic beats initiating atrial fibrillation. How the pulmonary myocardium gains pacemaker function is not clearly defined, although recent evidence indicates that changed transcriptional gene expression networks are at fault. The gene expression profile of this distinct cell type in situ was examined to investigate underlying molecular events that might contribute to atrial fibrillation. Via systems genetics a whole lung transcriptome dataset from the BXD recombinant inbred mouse resource was analysed, uncovering a pulmonary cardiomyocyte gene network of 24 transcripts, coordinately regulated by chromosome 1 and 2 loci. Promoter enrichment analysis and interrogation of publicly available ChIP-seq data suggested that transcription of this gene network may be regulated by the concerted activi...
We have investigated the potential use of β-conglutin protein isoforms from narrow-leafed lupin (... more We have investigated the potential use of β-conglutin protein isoforms from narrow-leafed lupin (Lupinus angustifolius L.) as a diabetes treatment. We produced purified recombinant β1-, β2-, β3-, β4-, and β6-conglutin proteins and showed that β1, β3, and β6 could bind to insulin. To assess β-conglutin proteins modulatory effect on insulin activation meditated kinases, whole blood and peripheral blood mononuclear cell cultures from type 2 diabetes (T2D) and healthy control subjects (C) were incubated with conglutin proteins. The treatment of peripheral blood mononuclear cells from T2D patients with β1, β3, and β6 proteins increased up to threefold mRNA and protein levels of genes important in insulin signaling pathways, namely insulin receptor substrate 1/p85/AKT/glucose transporter type 4. This was accompanied by a comparable fold-change decrease in the mRNA expression level of pro-inflammatory genes (iNOS and IL-1β) and proteins compared to healthy controls. The β2 and β4 isoforms ...
Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an algi... more Recently we demonstrated that microencapsulation of a murine pancreatic β-cell line using an alginate-ursodeoxycholic acid (UDCA) matrix produced microcapsules with good stability and cell viability. In this study, we investigated if translation of this formulation to microencapsulation of primary β-cells harvested from mature double-transgenic healthy mice would also generate stable microcapsules with good cell viability. Islets of Langerhans were isolated from Ngn3-GFP/RIP-DsRED mice by intraductal collagenase P digestion and density gradient centrifugation, dissociated into single cells and the β-cell population purified by Fluorescence Activated Cell Sorting. β-cells were microencapsulated using either alginate-poly-l-ornithine (F1; control) or alginate-poly-l-ornithine-UDCA (F2; test) formulations. Microcapsules were microscopically examined and microencapsulated cells were analyzed for viability, insulin and cytokine release, 2 days post-microencapsulation. Microcapsules showe...
Pharmaceutical development and technology, Jan 9, 2017
Ideal cell-containing microcapsules should be capable of maintaining cell viability and exhibit s... more Ideal cell-containing microcapsules should be capable of maintaining cell viability and exhibit significant structural stability to support cellular functionality. To date, such microcapsules remain unavailable; thus, this study used our well-established microencapsulating methods to examine a total of 32 different microencapsulating formulations and correlate polymers' molecular weights (Mwt) and UDCA addition, with cell viability and microcapsules' stability, postmicroencapsulation. MIN6 mouse-cloned pancreatic β-cells were microencapsulated using control (n = 16; without UDCA) and test (n = 16; with UDCA) different polymers. Confocal microscopic imaging, cell viability, and microcapsules' stability were assessed. Best cell viability (>50%) was obtained at average Mwt of 50,000 g/mol (poly-l-ornithine), followed by 110,000 g/mol (poly-l-lysine). There was no linear correlation between Mwt and viability. Confocal imagining showed similar microcapsules' shape and ...
The major complication of peritoneal dialysis (PD) is the development of peritonitis, an infectio... more The major complication of peritoneal dialysis (PD) is the development of peritonitis, an infection within the abdominal cavity, primarily caused by bacteria. PD peritonitis is associated with significant morbidity, mortality and health care costs. Staphylococcus epidermidis is the most frequently isolated cause of PD-associated peritonitis. Mesothelial cells are integral to the host response to peritonitis, and subsequent clinical outcomes, yet the effects of infection on mesothelial cells are not well characterised. We systematically investigated the early mesothelial cell response to clinical and reference isolates of S. epidermidis using primary mesothelial cells and the mesothelial cell line Met-5A. Using an unbiased whole genome microarray, followed by a targeted panel of genes known to be involved in the human antibacterial response, we identified 38 differentially regulated genes (adj. p-value < 0.05) representing 35 canonical pathways after 1 hour exposure to S. epidermid...
Genetic studies have identified 61 variants associated with the risk of developing Type 1 Diabete... more Genetic studies have identified 61 variants associated with the risk of developing Type 1 Diabetes (T1D). The functions of most of the non-HLA (Human Leukocyte Antigen) genetic variants remain unknown. We found that only 16 of these risk variants could potentially be linked to a protein-coding change. Therefore, we investigated whether these variants affected susceptibility by regulating changes in gene expression. To do so, we examined whole transcriptome profiles of 600 samples from the Type 1 Diabetes Genetics Consortium (T1DGC). These comprised four different immune cell types (Epstein-Barr virus (EBV)-transformed B cells, either basal or after stimulation; and cluster of differentiation (CD)4+ and CD8+ T cells). Many of the T1D-associated risk variants regulated expression of either neighboring (cis-) or distant (trans-) genes. In brief, 24 of the non-HLA T1D variants affected the expression of 31 nearby genes (cis) while 25 affected 38 distant genes (trans). The effects were h...
Gut dysbiosis might underlie the pathogenesis of type 1 diabetes. In mice of the non-obese diabet... more Gut dysbiosis might underlie the pathogenesis of type 1 diabetes. In mice of the non-obese diabetic (NOD) strain, we found that key features of disease correlated inversely with blood and fecal concentrations of the microbial metabolites acetate and butyrate. We therefore fed NOD mice specialized diets designed to release large amounts of acetate or butyrate after bacterial fermentation in the colon. Each diet provided a high degree of protection from diabetes, even when administered after breakdown of immunotolerance. Feeding mice a combined acetate- and butyrate-yielding diet provided complete protection, which suggested that acetate and butyrate might operate through distinct mechanisms. Acetate markedly decreased the frequency of autoreactive T cells in lymphoid tissues, through effects on B cells and their ability to expand populations of autoreactive T cells. A diet containing butyrate boosted the number and function of regulatory T cells, whereas acetate- and butyrate-yieldin...
Developmental stage-specific differentiation of stem or progenitor cells into safe and functional... more Developmental stage-specific differentiation of stem or progenitor cells into safe and functional cells is of fundamental importance in regenerative medicine, including β-cell replacement. However, the differentiation of islet progenitor cells (IPCs) into insulin-secreting β cells remains elusive. Here, we report that the multifunctional molecule nicotinamide (NIC) is a specific differentiation regulator of mouse IPCs. The differentiated cells regulated by NIC exhibited many characteristics of adult β cells, including ameliorating preclinical diabetes and a highly comparable transcriptome profile. Gene set enrichment analysis showed that during differentiation, numerous IPC transcription factor genes, including Ngn3, Pax4, Fev, and Mycl1, were all down regulated. Pharmacological, biochemical, and gene knockdown analyses collectively demonstrated that NIC regulated the differentiation via inhibiting Sirt1 (silent information regulator transcript 1). Finally, NIC also regulates human ...
Pancreatic insulin-secreting β cells are essential in maintaining normal glucose homeostasis acco... more Pancreatic insulin-secreting β cells are essential in maintaining normal glucose homeostasis accomplished by highly specialized transcription of insulin gene, of which occupies up to 40% their transcriptome. Deficiency of these cells causes diabetes mellitus, a global public health problem. Although tremendous endeavors have been made to generate insulin-secreting cells from human pluripotent stem cells (i.e., primitive cells capable of giving rise to all cell types in the body), a regenerative therapy to diabetes has not yet been established. Furthermore, the nomenclature of β cells has become inconsistent, confusing and controversial due to the lack of standardized positive controls of developmental stage-matched in vivo cells. In order to minimize this negative impact and facilitate critical research in this field, a post-genomic concept of pancreatic β cells might be helpful. In this review article, we will briefly describe how β cells were discovered and islet lineage is develo...
Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACT... more Skeletal muscle α-actin (ACTA1) is the major actin in postnatal skeletal muscle. Mutations of ACTA1 cause mostly fatal congenital myopathies. Cardiac α-actin (ACTC) is the major striated actin in adult heart and fetal skeletal muscle. It is unknown why ACTC and ACTA1 expression switch during development. We investigated whether ACTC can replace ACTA1 in postnatal skeletal muscle. Two ACTC transgenic mouse lines were crossed with Acta1 knockout mice (which all die by 9 d after birth). Offspring resulting from the cross with the high expressing line survive to old age, and their skeletal muscles show no gross pathological features. The mice are not impaired on grip strength, rotarod, or locomotor activity. These findings indicate that ACTC is sufficiently similar to ACTA1 to produce adequate function in postnatal skeletal muscle. This raises the prospect that ACTC reactivation might provide a therapy for ACTA1 diseases. In addition, the mouse model will allow analysis of the precise functional differences between ACTA1 and ACTC.
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Papers by Grant Morahan