Preserved DNA Damage Checkpoint Pathway Protects against Complications in Long-Standing Type 1 Diabetes

A visually-induced optogenetically-engineered system enables autonomous glucose homeostasis in mice

With the global population increasing and the demographic shifting toward an aging society, the number of patients diagnosed with conditions such as peripheral neuropathies resulting from diabetes is expected to rise significantly. This growing health burden has emphasized the need for innovative solutions, such as brain-computer interfaces. brain-computer interfaces, a multidisciplinary field that integrates neuroscience, engineering, and computer science, enable direct communication between the human brain and external devices. In this study, we developed an autonomous diabetes therapeutic system that employs visually-induced electroencephalography devices to capture and decode event-related potentials using machine learning techniques. We present the visually-induced optogenetically-engineered system for therapeutic expression regulation (VISITER), which generates diverse output commands to control illumination durations. This system regulates insulin expression through optogenetically-engineered cells, achieving blood glucose homeostasis in mice. Our results demonstrate that VISITER effectively and precisely modulates therapeutic protein expression in mammalian cells, facilitating the rapid restoration of blood glucose homeostasis in diabetic mice. These findings underscore the potential for diabetic patients to manage insulin levels autonomously by focusing on target images, paving the way for a more self-directed approach to blood glucose control.

Unraveling the Enigma of Organismal Death: Insights, Implications, and Unexplored Frontiers

Significant knowledge gaps exist regarding the responses of cells, tissues, and organs to organismal death. Examining the survival mechanisms influenced by metabolism and environment, this research has the potential to transform regenerative medicine, redefine legal death, and provide insights into life's physiological limits, paralleling inquiries in embryogenesis.

Protective Factors and the Pathogenesis of Complications in Diabetes

Chronic complications of diabetes are due to myriad disorders of numerous metabolic pathways that are responsible for most of the morbidity and mortality associated with the disease. Traditionally, diabetes complications are divided into those of microvascular and macrovascular origin. We suggest revising this antiquated classification into diabetes complications of vascular, parenchymal, and hybrid (both vascular and parenchymal) tissue origin, since the profile of diabetes complications ranges from those involving only vascular tissues to those involving mostly parenchymal organs. A major paradigm shift has occurred in recent years regarding the pathogenesis of diabetes complications, in which the focus has shifted from studies on risks to those on the interplay between risk and protective factors. While risk factors are clearly important for the development of chronic complications in diabetes, recent studies have established that protective factors are equally significant in modulating the development and severity of diabetes complications. These protective responses may help explain the differential severity of complications, and even the lack of pathologies, in some tissues. Nevertheless, despite the growing number of studies on this field, comprehensive reviews on protective factors and their mechanisms of action are not available. This review thus focused on the clinical, biochemical, and molecular mechanisms that support the idea of endogenous protective factors, and their roles in the initiation and progression of chronic complications in diabetes. In addition, this review also aimed to identify the main needs of this field for future studies.

Genetics of diabetes

Diabetes mellitus is a complicated disease characterized by a complex interplay of genetic, epigenetic, and environmental variables. It is one of the world's fastest-growing diseases, with 783 million adults expected to be affected by 2045. Devastating macrovascular consequences (cerebrovascular disease, cardiovascular disease, and peripheral vascular disease) and microvascular complications (like retinopathy, nephropathy, and neuropathy) increase mortality, blindness, kidney failure, and overall quality of life in individuals with diabetes. Clinical risk factors and glycemic management alone cannot predict the development of vascular problems; multiple genetic investigations have revealed a clear hereditary component to both diabetes and its related complications. In the twenty-first century, technological advancements (genome-wide association studies, next-generation sequencing, and exome-sequencing) have led to the identification of genetic variants associated with diabetes, however, these variants can only explain a small proportion of the total heritability of the condition. In this review, we address some of the likely explanations for this "missing heritability", for diabetes such as the significance of uncommon variants, gene-environment interactions, and epigenetics. Current discoveries clinical value, management of diabetes, and future research directions are also discussed.

Elevated markers of DNA damage and senescence are associated with the progression of albuminuria and restrictive lung disease in patients with type 2 diabetes

BACKGROUND

This study was conducted to investigate the cascade involving DNA damage, senescence, and senescence-associated secretory phenotype (SASP) in experimental diabetes and in a four-year follow-up study in patients with pre-diabetes and type 2 diabetes.

METHODS

Kidney, lung, and liver were studied in 4 months diabetic db/db mice and age-matched controls for the presence of DNA damage and fibrosis. DNA damage (comet-tail-length and ɤH2Ax-positivity in white blood cells), urinary p21-excretion, and plasma IL-6 and TGF-β1 were determined from 115 healthy participants, 34 patients with pre-diabetes and 221 with type 2 diabetes. Urinary albumin-creatinine-ratio, lung function, and transient elastography of the liver were performed in a prospective follow-up study over 4 years.

FINDINGS

db/db mice showed an increased nuclear ɤH2AX signal in all tissues as compared to the background control. Markers for DNA damage, senescence, and SASP were increased in patients with diabetes. The presence of nephropathy, restrictive lung disease (RLD), and increased liver stiffness was in a cross-sectional design associated with increased markers for DNA damage, senescence, and SASP. The progression of nephropathy over 4 years was predicted by increased DNA damage, senescence, and SASP, while the progression of RLD was associated with increased DNA damage and IL-6 only. The progression of liver stiffness was not associated with any of these parameters. HbA1c was not predictive for progression.

INTERPRETATION

In db/db mice, the cascade of DNA damage is associated with diabetes-related complications. In patients with diabetes, the progression of complications in the kidney and lung is predicted by markers reflecting DNA damage, and senescence-triggered organ fibrosis.

FUNDING

This work was supported by the German Research Foundation (DFG) in the CRC 1118 and CRC 1158, by the GRK DIAMICOM, by the German Center for Diabetes Research (DZD e.V.), and by the Ministry of Science, Research and the Arts, Baden-Württemberg (Kompetenznetzwerk Präventivmedizin).

Enhancement of glycolysis-dependent DNA repair regulated by FOXO1 knockdown via PFKFB3 attenuates hyperglycemia-induced endothelial oxidative stress injury

The accumulation of DNA damage induced by oxidative stress is a crucial pathogenic factor of endothelial loss in diabetic vascular complications, but it is still unknown whether aberrant glucose metabolism leads to defective DNA repair and accounts for hyperglycemia-induced endothelial oxidative stress injury. Here, we showed that Foxo1 knockdown alleviated diabetes-associated retinal DNA damage and vascular dysfunction. Mechanistically, FOXO1 knockdown avoided persistent DNA damage and cellular senescence under high glucose in endothelial cells by promoting DNA repair mediated by the MRN (MRE11-RAD50-NBS1 complex)-ATM pathway in response to oxidative stress injury. Moreover, FOXO1 knockdown mediated robust DNA repair by restoring glycolysis capacity under high glucose. During this process, the key glycolytic enzyme PFKFB3 was stimulated and, in addition to its promoting effect on glycolysis, directly participated in DNA repair. Under genotoxic stress, PFKFB3 relocated into oxidative stress-induced DNA damage sites and promoted DNA repair by interaction with the MRN-ATM pathway. Our study proposed that defective glycolysis-dependent DNA repair is present in diabetic endothelial cells and contributes to hyperglycemia-induced vascular dysfunction, which could provide novel therapeutic targets for diabetic vascular complications.

Telomeres do not always shorten over time in individuals with type 1 diabetes

AIMS

We aimed to determine how white blood cell (WBC) telomeres and telomere length change over time are associated with health status in type 1 diabetes.

METHODS

Relative telomere length (rTL) was measured in WBC DNA from two time-points (median 6.8 years apart) in 618 individuals from the Finnish Diabetic Nephropathy Study by quantitative PCR, with interassay CV ≤ 4%.

RESULTS

Baseline rTL correlated inversely with age and was shorter in men. Individuals in the shortest vs. longest rTL tertile had adverse cardiometabolic profiles, worse renal function, and were prescribed more antihypertensive and lipid-lowering drugs. While overall rTL tended to decrease during the median 6.8-years of follow-up, telomeres shortened in 55.3% of subjects, lengthened in 40.0%, and did not change in 4.7%. Baseline rTL correlated inversely with rTL change. Telomere lengthening was associated with higher HDL-Cholesterol (HDL-C), HDL-C/ApoA1, and with antihypertensive drug and (inversely) with lipid-lowering drug commencement during follow-up. Correlates of rTL percentage change per-annum (adjusted model) were baseline BMI, eGFR, previous retinal laser treatment, HDL-C, and HDL-C/ApoA1.

CONCLUSIONS

Telomere length measurements may facilitate the treatment and monitoring of the health status of individuals with type 1 diabetes.

"Clinical status and mortality in older adults with type 1 diabetes: Results from a public health system"

AIM

To evaluate clinical status and mortality in older adults with long-standing type 1 diabetes mellitus (T1D).

METHODS

Cross-sectional analysis of all patients with T1D for 50 years or more from a cohort followed since 2010 at Castilla-La Mancha Public Health Service (Spain). Primary outcome was HbA1c change during the follow-up (2010-2020 period). Secondary outcomes included evaluation of insulin and continuous glucose monitoring (CGM) use, cardiovascular risk factors (CVRF), diabetes chronic complications and mortality.

RESULTS

A total of fifty-five T1D patients were analysed. Mean age was 69.5 ± 8.3 yrs. and T1D duration of 54.7 ± 4.7 yrs. We detected a HbA1c reduction of -0.5% (-6 mmol/mol) [95% CI -0.1, -0.9 (-2, -10); P = 0.016]. CGM was used by 26% of the patients. More patients suffered from hypertension and obesity in 2020 (66% vs. 78%, P = 0.016; and 26% vs. 31%, P = 0.016; respectively). An increase of diabetic polyneuropathy was detected (45% vs. 67%, P = 0.008). Rate of mortality was higher among patients with long-standing T1D (26% vs. 3.5%, P < 0.001), due to cardiovascular disease (57%).

CONCLUSIONS

Older adults with long-standing T1D patients improved glycemic control although a worsening of CVRF and higher mortality rateweredetected.

Far-red light-activated human islet-like designer cells enable sustained fine-tuned secretion of insulin for glucose control

Diabetes affects almost half a billion people, and all individuals with type 1 diabetes (T1D) and a large portion of individuals with type 2 diabetes rely on self-administration of the peptide hormone insulin to achieve glucose control. However, this treatment modality has cumbersome storage and equipment requirements and is susceptible to fatal user error. Here, reasoning that a cell-based therapy could be coupled to an external induction circuit for blood glucose control, as a proof of concept we developed far-red light (FRL)-activated human islet-like designer (FAID) cells and demonstrated how FAID cell implants achieved safe and sustained glucose control in diabetic model mice. Specifically, by introducing a FRL-triggered optogenetic device into human mesenchymal stem cells (hMSCs), which we encapsulated in poly-(l-lysine)-alginate and implanted subcutaneously under the dorsum of T1D model mice, we achieved FRL illumination-inducible secretion of insulin that yielded improvements in glucose tolerance and sustained blood glucose control over traditional insulin glargine treatment. Moreover, the FAID cell implants attenuated both oxidative stress and development of multiple diabetes-related complications in kidneys. This optogenetics-controlled "living cell factory" platform could be harnessed to develop multiple synthetic designer therapeutic cells to achieve long-term yet precisely controllable drug delivery.

Signaling defects associated with insulin resistance in nondiabetic and diabetic individuals and modification by sex

Insulin resistance is present in one-quarter of the general population, predisposing these people to a wide range of diseases. Our aim was to identify cell-intrinsic determinants of insulin resistance in this population using induced pluripotent stem cell-derived (iPSC-derived) myoblasts (iMyos). We found that these cells exhibited a large network of altered protein phosphorylation in vitro. Integrating these data with data from type 2 diabetic iMyos revealed critical sites of conserved altered phosphorylation in IRS-1, AKT, mTOR, and TBC1D1 in addition to changes in protein phosphorylation involved in Rho/Rac signaling, chromatin organization, and RNA processing. There were also striking differences in the phosphoproteome in cells from men versus women. These sex-specific and insulin-resistance defects were linked to functional differences in downstream actions. Thus, there are cell-autonomous signaling alterations associated with insulin resistance within the general population and important differences between men and women, many of which also occur in diabetes, that contribute to differences in physiology and disease.

Discoveries from the study of longstanding type 1 diabetes

Award programmes that acknowledge the remarkable accomplishments of long-term survivors with type 1 diabetes have naturally evolved into research programmes to determine the factors associated with survivorship and resistance to chronic complications. In this review, we present an overview of the methodological sources of selection bias inherent in survivorship research (selection of those with early-onset diabetes, incidence-prevalence bias and bias from losses to follow-up in cohort studies) and the breadth and depth of literature focusing on this special study population. We focus on the learnings from the study of longstanding type 1 diabetes on discoveries about the natural history of insulin production loss and microvascular complications, and mechanisms associated with them that may in future offer therapeutic targets. We detail descriptive findings about the prevalence of preserved insulin production and resistance to complications, and the putative mechanisms associated with such resistance. To date, findings imply that the following mechanisms exist: strategies to maintain or recover beta cells and their function; activation of specific glycolytic enzymes such as pyruvate kinase M2; modification of AGE production and processing; novel mechanisms for modification of renin-angiotensin-aldosterone system activation, in particular those that may normalise afferent rather than efferent renal arteriolar resistance; and activation and modification of processes such as retinol binding and DNA damage checkpoint proteins. Among the many clinical and public health insights, research into this special study population has identified putative mechanisms that may in future serve as therapeutic targets, knowledge that likely could not have been gained without studying long-term survivors.

Diabetic Pneumopathy-A New Diabetes-Associated Complication: Mechanisms, Consequences and Treatment Considerations

Patients with diabetes are over-represented among the total cases reported with "idiopathic" pulmonary fibrosis (IPF). This raises the question, whether this is an association only or whether diabetes itself can cause pulmonary fibrosis. Recent studies in mouse models of type 1 and type 2 diabetes demonstrated that diabetes causes pulmonary fibrosis. Both types of diabetes trigger a cascade, starting with increased DNA damage, an impaired DNA repair, and leading to persistent DNA damage signaling. This response, in turn, induces senescence, a senescence-associated-secretory phenotype (SASP), marked by the release of pro-inflammatory cytokines and growth factors, finally resulting in fibrosis. Restoring DNA repair drives fibrosis into remission, thus proving causality. These data can be translated clinically to patients with type 2 diabetes, characterized by long-term diabetes and albuminuria. Hence there are several arguments, to substitute the term "idiopathic" pulmonary fibrosis (IPF) in patients with diabetes (and exclusion of other causes of lung diseases) by the term "diabetes-induced pulmonary fibrosis" (DiPF). However, future studies are required to establish this term and to study whether patients with diabetes respond to the established therapies similar to non-diabetic patients.

A Cell-Autonomous Signature of Dysregulated Protein Phosphorylation Underlies Muscle Insulin Resistance in Type 2 Diabetes

Skeletal muscle insulin resistance is the earliest defect in type 2 diabetes (T2D), preceding and predicting disease development. To what extent this reflects a primary defect or is secondary to tissue cross talk due to changes in hormones or circulating metabolites is unknown. To address this question, we have developed an in vitro disease-in-a-dish model using iPS cells from T2D patients differentiated into myoblasts (iMyos). We find that T2D iMyos in culture exhibit multiple defects mirroring human disease, including an altered insulin signaling, decreased insulin-stimulated glucose uptake, and reduced mitochondrial oxidation. More strikingly, global phosphoproteomic analysis reveals a multidimensional network of signaling defects in T2D iMyos going beyond the canonical insulin-signaling cascade, including proteins involved in regulation of Rho GTPases, mRNA splicing and/or processing, vesicular trafficking, gene transcription, and chromatin remodeling. These cell-autonomous defects and the dysregulated network of protein phosphorylation reveal a new dimension in the cellular mechanisms underlying the fundamental defects in T2D.

Leptin Receptor Signaling Regulates Protein Synthesis Pathways and Neuronal Differentiation in Pluripotent Stem Cells

The role of leptin receptor (OB-R) signaling in linking pluripotency with growth and development and the consequences of dysfunctional leptin signaling on progression of metabolic disease is poorly understood. Using a global unbiased proteomics approach we report that embryonic fibroblasts (MEFs) carrying the db/db mutation exhibit metabolic abnormalities, while their reprogrammed induced pluripotent stem cells (iPSCs) show altered expression of proteins involved in embryonic development. An upregulation in expression of eukaryotic translation initiation factor 4e (Eif4e) and Stat3 binding to the Eif4e promoter was supported by enhanced protein synthesis in mutant iPSCs. Directed differentiation of db/db iPSCs toward the neuronal lineage showed defects. Gene editing to correct the point mutation in db/db iPSCs using CRISPR-Cas9, restored expression of neuronal markers and protein synthesis while reversing the metabolic defects. These data imply a direct role for OB-R in regulating metabolism in embryonic fibroblasts and key developmental pathways in iPSCs.

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Pluripotency markers are decreased in db/db iPSCs (lacking functional OB-R)

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Mouse db/db iPSCs exhibit higher protein synthesis mediated by the Stat3/Eif4e axis

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OB-R signaling regulates neuronal development markers—NOGGIN, NESTIN, GFAP

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CRISPR correction reverses defects in db/db iPSCs

The diabetic microenvironment causes mitochondrial oxidative stress in glomerular endothelial cells and pathological crosstalk with podocytes

BACKGROUND

In the setting of diabetes mellitus, mitochondrial dysfunction and oxidative stress are important pathogenic mechanisms causing end organ damage, including diabetic kidney disease (DKD), but mechanistic understanding at a cellular level remains obscure. In mouse models of DKD, glomerular endothelial cell (GEC) dysfunction precedes albuminuria and contributes to neighboring podocyte dysfunction, implicating GECs in breakdown of the glomerular filtration barrier. In the following studies we wished to explore the cellular mechanisms by which GECs become dysfunctional in the diabetic milieu, and the impact to neighboring podocytes.

METHODS

Mouse GECs were exposed to high glucose media (HG) or 2.5% v/v serum from diabetic mice or serum from non-diabetic controls, and evaluated for mitochondrial function (oxygen consumption), structure (electron microscopy), morphology (mitotracker), mitochondrial superoxide (mitoSOX), as well as accumulation of oxidized products (DNA lesion frequency (8-oxoG, endo-G), double strand breaks (γ-H2AX), endothelial function (NOS activity), autophagy (LC3) and apoptotic cell death (Annexin/PI; caspase 3). Supernatant transfer experiments from GECs to podocytes were performed to establish the effects on podocyte survival and transwell experiments were performed to determine the effects in co-culture.

RESULTS

Diabetic serum specifically causes mitochondrial dysfunction and mitochondrial superoxide release in GECs. There is a rapid oxidation of mitochondrial DNA and loss of mitochondrial biogenesis without cell death. Many of these effects are blocked by mitoTEMPO a selective mitochondrial anti-oxidant. Secreted factors from dysfunctional GECs were sufficient to cause podocyte apoptosis in supernatant transfer experiments, or in co-culture but this did not occur when GECs had been previously treated with mitoTEMPO.

CONCLUSION

Dissecting the impact of the diabetic environment on individual cell-types from the kidney glomerulus indicates that GECs become dysfunctional and pathological to neighboring podocytes by increased levels of mitochondrial superoxide in GEC. These studies indicate that GEC-signaling to podocytes contributes to the loss of the glomerular filtration barrier in DKD. Video abstract.

Compromised DNA repair is responsible for diabetes-associated fibrosis

Diabetes-associated organ fibrosis, marked by elevated cellular senescence, is a growing health concern. Intriguingly, the mechanism underlying this association remained unknown. Moreover, insulin alone can neither reverse organ fibrosis nor the associated secretory phenotype, favoring the exciting notion that thus far unknown mechanisms must be operative. Here, we show that experimental type 1 and type 2 diabetes impairs DNA repair, leading to senescence, inflammatory phenotypes, and ultimately fibrosis. Carbohydrates were found to trigger this cascade by decreasing the NAD⁺ /NADH ratio and NHEJ-repair in vitro and in diabetes mouse models. Restoring DNA repair by nuclear over-expression of phosphomimetic RAGE reduces DNA damage, inflammation, and fibrosis, thereby restoring organ function. Our study provides a novel conceptual framework for understanding diabetic fibrosis on the basis of persistent DNA damage signaling and points to unprecedented approaches to restore DNA repair capacity for resolution of fibrosis in patients with diabetes.

High Concentration of Medium-Sized HDL Particles and Enrichment in HDL Paraoxonase 1 Associate With Protection From Vascular Complications in People With Long-standing Type 1 Diabetes

OBJECTIVE

A subset of people with long-standing type 1 diabetes (T1D) appears to be protected from microvascular and macrovascular complications. Previous studies have focused on improved abilities to respond to glucose and its downstream effects as protective mechanisms. It is unclear whether lipoproteins play a role in the vascular health of these people. We therefore determined whether HDL particle concentration, size, function, and/or protein composition associate with protection from vascular complications.

RESEARCH DESIGN AND METHODS

We studied two independent cross-sectional cohorts with T1D: the T1D Exchange Living Biobank (n = 47) and the Joslin Medalist Study (n = 100). Some of the subjects had vascular complications, whereas others never exhibited vascular complications, despite an average duration of diabetes in the cohorts of 45 years. We assessed HDL particle size and concentration by calibrated ion mobility analysis, the HDL proteome by targeted mass spectrometry, and HDL function ex vivo by quantifying cholesterol efflux capacity and inhibition of monocyte adhesion to endothelial cells.

RESULTS

In both cohorts, people without vascular complications exhibited significantly higher concentrations of medium-sized HDL particles (M-HDL) independently of total and HDL cholesterol levels. While no consistent differences in HDL functions were observed ex vivo, people without vascular complications had higher levels of HDL-associated paraoxonase 1 (PON1), an enzyme that inhibits atherosclerosis in animal models.

CONCLUSIONS

Elevated concentrations of M-HDL particles and elevated levels of HDL-associated PON1 may contribute to long-term protection from the vascular complications of diabetes by pathways that are independent of total cholesterol and HDL cholesterol.

Insulin receptor-mediated signaling regulates pluripotency markers and lineage differentiation

Objectives

Insulin receptor (IR)-mediated signaling is involved in the regulation of pluripotent stem cells; however, its direct effects on regulating the maintenance of pluripotency and lineage development are not fully understood. The main objective of this study is to understand the role of IR signaling in pluripotency and lineage development.

Methods

To explore the role of IR signaling, we generated IR knock-out (IRKO) mouse induced pluripotent stem cells (miPSCs) from E14.5 mouse embryonic fibroblasts (MEFs) of global IRKO mice using a cocktail of four reprogramming factors: Oct4, Sox2, Klf4, cMyc. We performed pluripotency characterization and directed the differentiation of control and IRKO iPSCs into neural progenitors (ectoderm), adipocyte progenitors (mesoderm), and pancreatic beta-like cells (endoderm). We mechanistically confirmed these findings via phosphoproteomics analyses of control and IRKO iPSCs.

Results

Interestingly, expression of pluripotency markers including Klf4, Lin28a, Tbx3, and cMyc were upregulated, while abundance of Oct4 and Nanog were enhanced by 4-fold and 3-fold, respectively, in IRKO iPSCs. Analyses of signaling pathways demonstrated downregulation of phospho-STAT3, p-mTor and p-Erk and an increase in the total mTor and Erk proteins in IRKO iPSCs in the basal unstimulated state. Stimulation with leukemia inhibitory factor (LIF) showed a ∼33% decrease of phospho-ERK in IRKO iPSCs. On the contrary, Erk phosphorylation was increased during in vitro spontaneous differentiation of iPSCs lacking IRs. Lineage-specific directed differentiation of the iPSCs revealed that cells lacking IR showed enhanced expression of neuronal lineage markers (Pax6, Tubb3, Ascl1 and Oligo2) while exhibiting a decrease in adipocyte (Fas, Acc, Pparγ, Fabp4, C/ebpα, and Fsp27) and pancreatic beta cell markers (Ngn3, Isl1, and Sox9). Further molecular characterization by phosphoproteomics confirmed the novel IR-mediated regulation of the global pluripotency network including several key proteins involved in diverse aspects of growth and embryonic development.

Conclusion

We report, for the first time to our knowledge, the phosphoproteome of insulin, IGF1, and LIF stimulation in mouse iPSCs to reveal the importance of insulin receptor signaling for the maintenance of pluripotency and lineage determination.

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Insulin receptor signaling regulates expression of key pluripotency genes including Oct4 and Nanog.

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IRKO iPSCs show upregulation of neuronal markers during differentiation.

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Adipocyte and pancreatic beta cell differentiation are perturbed in IRKO iPSCs.

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Phosphoproteomics analyses confirmed the role of IR in regulation of pluripotency and developmental proteins.

Circulating miRNA Profiles Associated With Hyperglycemia in Patients With Type 1 Diabetes

We investigated plasma microRNA (miRNA) profiles associated with variation of hyperglycemia, measured as hemoglobin A_1c (HbA_1c), in two panels of patients with type 1 diabetes (T1D). Using the HTG Molecular Diagnostics EdgeSeq platform, 2,083 miRNAs were measured in plasma from 71 patients included in a screening panel. Quantitative real-time PCR was used to measure the candidate miRNAs in plasma from 95 patients included in an independent replication panel. We found 10 miRNAs replicated in both panels and 4 with high statistical significance. The strongest positive correlations with HbA_1c were found with miR-125b-5p (r_s = 0.40, P = 6.0 × 10^-5) and miR-365a-3p (r_s = 0.35, P = 5.9 × 10^-4). The strongest negative correlations were found with miR-5190 (r_s = -0.30, P = 0.003) and miR-770-5p (r_s = -0.27, P = 0.008). Pathway analysis revealed that 50 Kyoto Encyclopedia of Genes and Genomes pathways were significantly enriched by genes targeted by these four miRNAs. The axon guidance signaling pathway was enriched (P < 1 × 10^-7) by genes targeted by all four miRNAs. In addition, three other pathways (Rap1 signaling, focal adhesion, and neurotrophin signaling) were also significantly enriched but with genes targeted by only by three of the identified miRNAs. In conclusion, our study identified four circulating miRNAs that were influenced by variation in hyperglycemia. Dysregulation of these miRNAs, which are associated with hyperglycemia in patients with T1D, may contribute to the development of diabetes complications. However, there are multitudes of possible mechanisms/pathways through which dysregulation of these miRNAs may impact risk of diabetes complications.

High-glucose toxicity is mediated by AICAR-transformylase/IMP cyclohydrolase and mitigated by AMP-activated protein kinase in Caenorhabditis elegans

The enzyme AICAR-transformylase/IMP cyclohydrolase (ATIC) catalyzes the last two steps of purine de novo synthesis. It metabolizes 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), which is an AMP analogue, leading to activation of AMP-activated kinase (AMPK). We investigated whether the AICAR-ATIC pathway plays a role in the high glucose (HG)-mediated DNA damage response and AICAR-mediated AMPK activation, explaining the detrimental effects of glucose on neuronal damage and shortening of the lifespan. HG up-regulated the expression and activity of the Caenorhabditis elegans homologue of ATIC, C55F2.1 (atic-1), and increased the levels of reactive oxygen species and methylglyoxal-derived advanced glycation end products. Overexpression of atic-1 decreased the lifespan and head motility and increased neuronal damage under both standard and HG conditions. Inhibition of atic-1 expression, by RNAi, under HG was associated with increased lifespan and head motility and reduced neuronal damage, reactive oxygen species, and methylglyoxal-derived advanced glycation end product accumulation. This effect was independent of an effect on DNA damage or antioxidant defense pathways, such as superoxide dismutase (sod-3) or glyoxalase-1 (glod-4), but was dependent on AMPK and accumulation of AICAR. Through AMPK, AICAR treatment also reduced the negative effects of HG. The mitochondrial inhibitor rotenone abolished the AICAR/AMPK-induced amelioration of HG effects, pointing to mitochondria as a prime target of the glucotoxic effects in C. elegans We conclude that atic-1 is involved in glucotoxic effects under HG conditions, either by blocked atic-1 expression or via AICAR and AMPK induction.

MicroRNAs in type 1 diabetes: new research progress and potential directions

MicroRNAs (miRNAs) are a class of noncoding single-stranded RNA molecules encoded by endogenous genes of about 22 nucleotides, which are involved in post-transcriptional gene expression regulation in animals and plants. Type 1 diabetes (T1D) is an autoimmune disease that is clinically silent until the majority of β cells are destroyed, and a large number of studies have shown that miRNAs are involved in the pathological mechanism of T1D. In this review, we searched the related research in recent years and summarized the important roles of miRNAs in T1D diagnosis and treatment. Furthermore, we summarized the current understanding of miRNA-mediated regulation mechanisms of gene expression in the T1D pathogenesis as well as related signaling pathways with a focus on the important roles of miRNAs and their antagonists in T1D pathogenesis, and brought insight into the potential therapeutic value of miRNAs for T1D patients. In view of the important roles of miRNAs in T1D pathology, disordered miRNAs may be important diagnostic markers and therapeutic targets for patients with T1D.

The Vasoreparative Function of Myeloid Angiogenic Cells Is Impaired in Diabetes Through the Induction of IL1β

Myeloid angiogenic cells (MACs) promote revascularization through the paracrine release of angiogenic factors and have been harnessed as therapeutic cells for many ischemic diseases. However, their proangiogenic properties have been suggested to be diminished in diabetes. This study investigates how the diabetic milieu affects the immunophenotype and function of MACs. Both MACs isolated from diabetic conditions and healthy cells exposed to a diabetic environment were used to determine the potential of MACs as a cell therapy for diabetic‐related ischemia. MACs were isolated from human peripheral blood and characterized alongside proinflammatory macrophages M (LPS + IFNγ) and proangiogenic macrophages M (IL4). Functional changes in MACs in response to high‐d‐glucose were assessed using an in vitro 3D‐tubulogenesis assay. Phenotypic changes were determined by gene and protein expression analysis. Additionally, MACs from type 1 diabetic (T1D) patients and corresponding controls were isolated and characterized. Our evidence demonstrates MACs identity as a distinct macrophage subtype that shares M2 proangiogenic characteristics, but can be distinguished by CD163^hi expression. High‐d‐glucose treatment significantly reduced MACs proangiogenic capacity, which was associated with a significant increase in IL1β mRNA and protein expression. Inhibition of IL1β abrogated the antiangiogenic effect induced by high‐d‐glucose. IL1β was also significantly upregulated in MACs isolated from T1D patients with microvascular complications compared to T1D patients without microvascular complications or nondiabetic volunteers. This study demonstrates that Type 1 diabetes and diabetic‐like conditions impair the proangiogenic and regenerative capacity of MACs, and this response is mediated by IL‐1β. Stem Cells2018;36:834–843

iPSC technology-based regenerative therapy for diabetes

The directed differentiation of human pluripotent stem cells, such as embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), into pancreatic endocrine lineages has been vigorously examined by reproducing the in vivo developmental processes of the pancreas. Recent advances in this research field have enabled the generation from hESCs/iPSCs of functionally mature β-like cells in vitro that show glucose-responsive insulin secretion ability. The therapeutic potentials of hESC/iPSC-derived pancreatic cells have been evaluated using diabetic animal models, and transplantation methods including immunoprotective devices that prevent immune responses from hosts to the implanted pancreatic cells have been investigated towards the development of regenerative therapies against diabetes. These efforts led to the start of a clinical trial that involves the implantation of hESC-derived pancreatic progenitors into type 1 diabetes patients. In addition, patient-derived iPSCs have been generated from diabetes-related disorders towards the creation of novel in vitro disease models and drug discovery, although few reports so far have analyzed the disease mechanisms. Considering recent advances in differentiation methods that generate pancreatic endocrine lineages, we will see the development of novel cell therapies and therapeutic drugs against diabetes based on iPSC technology-based research in the next decade.

Diabetes Care Disparities in Long-standing Type 1 Diabetes in Canada and the U.S.: A Cross-sectional Comparison

OBJECTIVE

To assess national differences in diabetes care and quality of life (QOL) between individuals with long-standing type 1 diabetes (≥50 years) in Canada and the U.S.

RESEARCH DESIGN AND METHODS

Cross-sectional data from identical surveys administered in the Canadian Study of Longevity in Diabetes and the Joslin Medalist Study, collected in 2013-2016 and 2005-2011, respectively, were compared. Laboratory values and ophthalmic examination were completed by clinical care physicians for Canadians and the Joslin Clinic for Americans. Univariate comparisons and multivariable regression for HbA_1c, QOL, insulin pump use, and coronary artery disease (CAD) were performed. Nephropathy, CAD, and peripheral arterial disease (PAD) were self-reported; neuropathy was defined by a Michigan Neuropathy Screening Instrument (Questionnaire component) score ≥3, and proliferative retinopathy was documented from ophthalmic examination. QOL was self-reported on an ordinal scale.

RESULTS

Three hundred sixty-one Canadians and 668 Americans had similar ages (mean 65.78 years [SD 8.67] vs. 66.38 years [7.66], P = 0.27) and durations of diabetes (median 53.00 years [interquartile range 51.00, 58.00] vs. 53.00 years [51.00, 57.00], P = 0.51). Canadians had higher HbA_1c (mean 7.53% [SD 1.03] [59 mmol/mol] vs. 7.22% [0.98] [55 mmol/mol], P < 0.0001), lower QOL (36.9% vs. 48.7% with "excellent" QOL, P = 0.0002), and less CAD (29.7% vs. 41.2%, P = 0.0003) and insulin pump use (43.3% vs. 55.6%, P = 0.0002). Other complication rates were similar. Residual differences for Canadians compared with Americans remained after adjustment for age, sex, CAD, PAD, education, and relevant a priori selected variables: 0.28% higher HbA_1c (P = 0.0004); and odds ratios of 0.68 (95% CI 0.51, 0.90), 0.46 (0.31, 0.68), and 0.71 (0.52, 0.96) for higher QOL, CAD, and insulin pump use, respectively.

CONCLUSIONS

Although Canadians and Americans have similar rates of complications other than CAD, further research is required to understand why Canadians have higher HbA_1c levels, lower QOL, and less insulin pump use.

The Quest for more Research on Painful Diabetic Neuropathy

A 62-year-old diabetologist diagnosed himself to have diabetes type-2, with an HbA1c of 9.5. Five months after lifestyle intervention and a multi-drug approach, HbA1c was 6.3, systolic blood pressure was below 135mmHg and BMI reduced to 27. But he suffered from severe painful diabetic neuropathy. Therefore he decided to visit his friend, a famous neuroscientist at an even more famous university. He asked him several plain questions: 1. What is the natural course of painful diabetic neuropathy? 2. Why do I have, despite almost normalizing HbA1c, more problems than before? 3. Are you sure my problems are due to diabetes or should we do a nerve biopsy? 4. Are there imaging techniques helpful for the diagnosis of this diabetic complication, starting in the distal nerve endings of the foot and slowly moving ahead? 5. Can you suggest any drug, specific and effective, for relieving painful diabetic neuropathy? This review will use the experts' answers to the questions of the diabetologist, not only to give a summary of the current knowledge, but even more to highlight areas of research needed for improving the fate of patients with painful diabetic neuropathy. Based on the unknowns, which exceed the knowns in diabetic neuropathy, a quest for more public support of research is made.

Importance of long-term care of diabetic women starting in pregnancy

Large scale, multi-center, controlled studies have demonstrated the importance of glycemic control, as indicated by HbA_1c levels, in reducing the incidence and progression of diabetic complications. However, Yasue Omori, who began practicing medicine in Tokyo 60 years ago, in 1957, has the vantage point of long-term continuing care for women with type 2 diabetes, some for several decades. An internist who specializes in diabetic pregnancy, Dr Omori began caring for many of her patients during their pregnancies and continued to care for them following their deliveries, some now more than 50 years. Surprisingly, despite lack of optimal HbA_1c levels, they have suffered relatively few diabetic complications. As reported in "The importance of nonstop treatment after delivery for pregnant women with type 2 diabetes" in Diabetes/Metabolism Research and Reviews, Omori and colleagues present a historical perspective that provides evidence that a long-term patient-care giver relationship following pregnancy can be valuable in reducing the onset and progression of diabetic complications.

Concise Review: Challenges in Regenerating the Diabetic Heart: A Comprehensive Review

Stem cell therapy is one of the promising regenerative strategies developed to improve cardiac function in patients with ischemic heart diseases (IHD). However, this approach is limited in IHD patients with diabetes due to a progressive decline in the regenerative capacity of stem cells. This decline is mainly attributed to the metabolic memory incurred by diabetes on stem cell niche and their systemic cues. Understanding the molecular pathways involved in the diabetes-induced deterioration of stem cell function will be critical for developing new cardiac regeneration therapies. In this review, we first discuss the most common molecular alterations occurring in the diabetic stem cells/progenitor cells. Next, we highlight the key signaling pathways that can be dysregulated in a diabetic environment and impair the mobilization of stem/progenitor cells, which is essential for the transplanted/endogenous stem cells to reach the site of injury. We further discuss the possible methods of preconditioning the diabetic cardiac progenitor cell (CPC) with an aim to enrich the availability of efficient stem cells to regenerate the diseased diabetic heart. Finally, we propose new modalities for enriching the diabetic CPC through genetic or tissue engineering that would aid in developing autologous therapeutic strategies, improving the proliferative, angiogenic, and cardiogenic properties of diabetic stem/progenitor cells. Stem Cells 2017;35:2009-2026.

Induced Pluripotent Stem Cells: Global Research Trends

The induced pluripotent stem cell (iPSC) was first described more than 10 years ago and is currently used in various basic science and clinical research fields. The aim of this report is to examine the trends in research using iPSCs over the last 10 years. The 2006-2016 PubMed database was searched using the MeSH term "induced pluripotent stem cells." Only original research articles were selected, with a total of 3323 articles. These were classified according to research theme into reprogramming, differentiation protocols for specific cells and/or tissues, pathophysiological research on diseases, and discovery of new drugs, and then the trends over the years were analyzed. We also focused on 232 research publications on the pathophysiological causes of diseases and drug discovery with impact factor (IF; Thomson Reuters) of six or more. The IF of each article was summed up by year, by main target disease, and by country, and the total IF score was expressed as trends of research. The trends of research activities of reprogramming and differentiation on specific cells and/or tissues reached maxima in 2013/2014. On the other hand, research on pathophysiology and drug discovery increased continuously. The 232 articles with IF ≥6 dealt with neurological, immunological/hematological, cardiovascular, and digestive tract diseases, in that order. The majority of articles were published from the United States, followed by Japan, Germany, and United Kingdom. In conclusion, iPSCs have become a general tool for pathophysiological research on disease and drug discovery.

An 'alpha-beta' of pancreatic islet microribonucleotides

MicroRNAs (miRNAs) are cellular, short, non-coding ribonucleotides acting as endogenous posttranscriptional repressors following incorporation in the RNA-induced silencing complex. Despite being chemically and mechanistically very similar, miRNAs exert a multitude of different cellular effects by acting on mRNA species, whose gene-products partake in a wide array of processes. Here, the aim was to review the knowledge of miRNA expression and action in the islet of Langerhans. We have focused on: 1) physiological consequences of islet or beta cell specific inhibition of miRNA processing, 2) mechanisms regulating processing of miRNAs in islet cells, 3) presence and function of miRNAs in alpha versus beta cells - the two main cell types of islets, and 4) miRNA mediators of beta cell decompensation. It is clear that miRNAs regulate pancreatic islet development, maturation, and function in vivo. Moreover, processing of miRNAs appears to be altered by obesity, diabetes, and aging. A number of miRNAs (such as miR-7, miR-21, miR-29, miR-34a, miR-212/miR-132, miR-184, miR-200 and miR-375) are involved in mediating beta cell dysfunction and/or compensation induced by hyperglycemia, oxidative stress, cytotoxic cytokines, and in rodent models of fetal metabolic programming prediabetes and overt diabetes. Studies of human type 2 diabetic islets underline that these miRNA families could have important roles also in human type 2 diabetes. Furthermore, there is a genuine gap of knowledge regarding miRNA expression and function in pancreatic alpha cells. Progress in this area would be enhanced by improved in vitro alpha cell models and better tools for islet cell sorting.

The current state of the art of quantitative phosphoproteomics and its applications to diabetes research

Protein phosphorylation is a fundamental regulatory mechanism in many cellular processes and aberrant perturbation of phosphorylation has been implicated in various human diseases. Kinases and their cognate inhibitors have been considered as hotspots for drug development. Therefore, the emerging tools, which enable a system-wide quantitative profiling of phosphoproteome, would offer a powerful impetus in unveiling novel signaling pathways, drug targets and/or biomarkers for diseases of interest. This review highlights recent advances in phosphoproteomics, the current state of the art of the technologies and the challenges and future perspectives of this research area. Finally, some exemplary applications of phosphoproteomics in diabetes research are underscored.

Is Transforming Stem Cells to Pancreatic Beta Cells Still the Holy Grail for Type 2 Diabetes?

Diabetes is a progressive disease affecting millions of people worldwide. There are several medications and treatment options to improve the life quality of people with diabetes. One of the strategies for the treatment of diabetes could be the use of human pluripotent stem cells or induced pluripotent stem cells. The recent advances in differentiation of stem cells into insulin-secreting beta-like cells in vitro make the transplantation of the stem cell-derived beta-like cells an attractive approach for treatment of type 1 and type 2 diabetes. While stem cell-derived beta-like cells provide an unlimited cell source for beta cell replacement therapies, these cells can also be used as a platform for drug screening or modeling diseases.

Revisiting multiple models of progression of β-cell loss of function in type 1 diabetes: Significance for prevention and cure

Type 1 diabetes (T1D) results from a chronic autoimmune process that leads to β-cell destruction and exogenous insulin dependence. The natural history of T1D proposed by Eisenbarth suggested six relatively independent stages over the course of the entire disease process, which was considered to be linear and chronic. Based on this classical theory, immunotherapies aim to prevent or reverse all these periods of β-cell loss. Over the past 30 years, much novel information about the pathogenesis of T1D proved that there are complex metabolic changes occurring throughout the entire disease process. Therefore, new possible models for the natural history of the disease have been proposed; these models, in turn, may help facilitate fresh avenues for the prevention and cure of T1D. Herein, we briefly review recent findings in this field of research, with the aim of providing a better theoretical basis for clinical practice.

Proinflammatory Cytokines Induce Endocrine Differentiation in Pancreatic Ductal Cells via STAT3-Dependent NGN3 Activation

A major goal of diabetes research is to develop strategies that replenish pancreatic insulin-producing beta cells. One emerging strategy is to harness pancreatic plasticity-the ability of pancreatic cells to undergo cellular interconversions-a phenomenon implicated in physiological stress and pancreatic injury. Here, we investigate the effects of inflammatory cytokine stress on the differentiation potential of ductal cells in a human cell line, in mouse ductal cells by pancreatic intraductal injection, and during the progression of autoimmune diabetes in the non-obese diabetic (NOD) mouse model. We find that inflammatory cytokine insults stimulate epithelial-to-mesenchymal transition (EMT) as well as the endocrine program in human pancreatic ductal cells via STAT3-dependent NGN3 activation. Furthermore, we show that inflammatory cytokines activate ductal-to-endocrine cell reprogramming in vivo independent of hyperglycemic stress. Together, our findings provide evidence that inflammatory cytokines direct ductal-to-endocrine cell differentiation, with implications for beta cell regeneration.

The cytoskeleton adaptor protein ankyrin-1 is upregulated by p53 following DNA damage and alters cell migration

The integrity of the genome is maintained by a host of surveillance and repair mechanisms that are pivotal for cellular function. The tumour suppressor protein p53 is a major component of the DNA damage response pathway and plays a vital role in the maintenance of cell-cycle checkpoints. Here we show that a microRNA, miR-486, and its host gene ankyrin-1 (ANK1) are induced by p53 following DNA damage. Strikingly, the cytoskeleton adaptor protein ankyrin-1 was induced over 80-fold following DNA damage. ANK1 is upregulated in response to a variety of DNA damage agents in a range of cell types. We demonstrate that miR-486-5p is involved in controlling G1/S transition following DNA damage, whereas the induction of the ankyrin-1 protein alters the structure of the actin cytoskeleton and sustains limited cell migration during DNA damage. Importantly, we found that higher ANK1 expression correlates with decreased survival in cancer patients. Thus, these observations highlight ANK1 as an important effector downstream of the p53 pathway.

Type 1 Diabetes and MicroRNA: It's Complicated

Type 1 diabetes is an autoimmune disease that manifests as impaired insulin secretion, with compounding complications over time. Bhatt et al. (2015) investigate protective mechanisms in survivors of type 1 diabetes by using induced pluripotent stem cells as genetic models, uncovering novel interactions between microRNA and the DNA damage checkpoint pathway.