Abstract
Chronic, low-grade systemic inflammation and impaired microvascular function are critical hallmarks in the development of insulin resistance. Accordingly, insulin resistance is a major risk ...factor for type 2 diabetes and cardiovascular disease. Accumulating studies demonstrate that restoration of impaired function of the diabetic macro- and microvasculature may ameliorate a range of cardiovascular disease states and diabetes-associated complications. In this review, we focus on the emerging role of microRNAs (miRNAs), noncoding RNAs that fine-tune target gene expression and signaling pathways, in insulin-responsive tissues and cell types important for maintaining optimal vascular homeostasis and preventing the sequelae of diabetes-induced end organ injury. We highlight current pathophysiological paradigms of miRNAs and their targets involved in regulating the diabetic microvasculature in a range of diabetes-associated complications such as retinopathy, nephropathy, wound healing, and myocardial injury. We provide an update of the potential use of circulating miRNAs diagnostically in type I or type II diabetes. Finally, we discuss emerging delivery platforms for manipulating miRNA expression or function as the next frontier in therapeutic intervention to improve diabetes-associated microvascular dysfunction and its attendant clinical consequences.
RATIONALE:The pathogenesis of insulin resistance involves dysregulated gene expression and function in multiple cell types, including endothelial cells (ECs). Post-transcriptional mechanisms such as ...microRNA-mediated regulation of gene expression could affect insulin action by modulating EC function.
OBJECTIVE:To determine whether microRNA-181b (miR-181b) affects the pathogenesis of insulin resistance by regulating EC function in white adipose tissue during obesity.
METHODS AND RESULTS:MiR-181b expression was reduced in adipose tissue ECs of obese mice, and rescue of miR-181b expression improved glucose homeostasis and insulin sensitivity. Systemic intravenous delivery of miR-181b robustly accumulated in adipose tissue ECs, enhanced insulin-mediated Akt phosphorylation at Ser473, and reduced endothelial dysfunction, an effect that shifted macrophage polarization toward an M2 anti-inflammatory phenotype in epididymal white adipose tissue. These effects were associated with increased endothelial nitric oxide synthase and FoxO1 phosphorylation as well as nitric oxide activity in epididymal white adipose tissue. In contrast, miR-181b did not affect insulin-stimulated Akt phosphorylation in liver and skeletal muscle. Bioinformatics and gene profiling approaches revealed that Pleckstrin homology domain leucine-rich repeat protein phosphatase, a phosphatase that dephosphorylates Akt at Ser473, is a novel target of miR-181b. Knockdown of Pleckstrin homology domain leucine-rich repeat protein phosphatase increased Akt phosphorylation at Ser473 in ECs, and phenocopied miR-181b’s effects on glucose homeostasis, insulin sensitivity, and inflammation of epididymal white adipose tissue in vivo. Finally, ECs from diabetic subjects exhibited increased Pleckstrin homology domain leucine-rich repeat protein phosphatase expression.
CONCLUSIONS:Our data underscore the importance of adipose tissue EC function in controlling the development of insulin resistance. Delivery of miR-181b or Pleckstrin homology domain leucine-rich repeat protein phosphatase inhibitors may represent a new therapeutic approach to ameliorate insulin resistance by improving adipose tissue endothelial Akt–endothelial nitric oxide synthase–nitric oxide signaling.
OBJECTIVE—In response to tissue injury, the appropriate progression of events in angiogenesis is controlled by a careful balance between pro and antiangiogenic factors. We aimed to identify and ...characterize microRNAs that regulate angiogenesis in response to tissue injury.
APPROACH AND RESULTS—We show that in response to tissue injury, microRNA-615-5p (miR-615-5p) is rapidly induced and serves as an antiangiogenic microRNA by targeting endothelial cell VEGF (vascular endothelial growth factor)-AKT (protein kinase B)/eNOS (endothelial nitric oxide synthase) signaling in vitro and in vivo. MiR-615-5p expression is increased in wounds of diabetic db/db mice, in plasma of human subjects with acute coronary syndromes, and in plasma and skin of human subjects with diabetes mellitus. Ectopic expression of miR-615-5p markedly inhibited endothelial cell proliferation, migration, network tube formation in Matrigel, and the release of nitric oxide, whereas miR-615-5p neutralization had the opposite effects. Mechanistic studies using transcriptomic profiling, bioinformatics, 3′ untranslated region reporter and microribonucleoprotein immunoprecipitation assays, and small interfering RNA dependency studies demonstrate that miR-615-5p inhibits the VEGF-AKT/eNOS signaling pathway in endothelial cells by targeting IGF2 (insulin-like growth factor 2) and RASSF2 (Ras-associating domain family member 2). Local delivery of miR-615-5p inhibitors, markedly increased angiogenesis, granulation tissue thickness, and wound closure rates in db/db mice, whereas miR-615-5p mimics impaired these effects. Systemic miR-615-5p neutralization improved skeletal muscle perfusion and angiogenesis after hindlimb ischemia in db/db mice. Finally, modulation of miR-615-5p expression dynamically regulated VEGF-induced AKT signaling and angiogenesis in human skin organoids as a model of tissue injury.
CONCLUSIONS—These findings establish miR-615-5p as an inhibitor of VEGF-AKT/eNOS–mediated endothelial cell angiogenic responses and that manipulating miR-615-5p expression could provide a new target for angiogenic therapy in response to tissue injury.
The Krüppel-like transcription factor (KLF) family participates in diverse aspects of cellular growth, development, differentiation, and activation. Recently, several groups have identified new ...connections between the function of these factors and leukocyte responses in health and disease. Gene targeting of individual KLFs in mice has uncovered novel and unexpected physiologic roles among myeloid and lymphocyte cell lineage maturation, particularly in the bone marrow niche and blood. In addition, several KLF family members are downstream targets of stimuli and signaling pathways critical to T-cell trafficking, T regulatory cell differentiation or suppressor function, monocyte/macrophage activation or renewal, and B memory cell maturation or activation. Indeed, KLFs have been implicated in subtypes of leukemia, lymphoma, autoimmunity, and in acute and chronic inflammatory disease states, such as atherosclerosis, diabetes, and airway inflammation, raising the possibility that KLFs and their upstream signals are of therapeutic interest. This review focuses on the relevant literature of Krüppel-like factors in leukocyte biology and their implications in clinical settings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
RATIONALE:The rapid induction and orchestration of new blood vessels are critical for tissue repair in response to injury, such as myocardial infarction, and for physiological angiogenic responses, ...such as embryonic development and exercise.
OBJECTIVE:We aimed to identify and characterize microRNAs (miR) that regulate pathological and physiological angiogenesis.
METHODS AND RESULTS:We show that miR-26a regulates pathological and physiological angiogenesis by targeting endothelial cell (EC) bone morphogenic protein/SMAD1 signaling in vitro and in vivo. MiR-26a expression is increased in a model of acute myocardial infarction in mice and in human subjects with acute coronary syndromes. Ectopic expression of miR-26a markedly induced EC cycle arrest and inhibited EC migration, sprouting angiogenesis, and network tube formation in matrigel, whereas blockade of miR-26a had the opposite effects. Mechanistic studies demonstrate that miR-26a inhibits the bone morphogenic protein/SMAD1 signaling pathway in ECs by binding to the SMAD1 3′-untranslated region, an effect that decreased expression of Id1 and increased p21 and p27. In zebrafish, miR-26a overexpression inhibited formation of the caudal vein plexus, a bone morphogenic protein-responsive process, an effect rescued by ectopic SMAD1 expression. In mice, miR-26a overexpression inhibited EC SMAD1 expression and exercise-induced angiogenesis. Furthermore, systemic intravenous administration of an miR-26a inhibitor, locked nucleic acid-anti–miR-26a, increased SMAD1 expression and rapidly induced robust angiogenesis within 2 days, an effect associated with reduced myocardial infarct size and improved heart function.
CONCLUSIONS:These findings establish miR-26a as a regulator of bone morphogenic protein/SMAD1-mediated EC angiogenic responses, and that manipulating miR-26a expression could provide a new target for rapid angiogenic therapy in ischemic disease states.
Endothelial cells (ECs) within the microvasculature of brown adipose tissue (BAT) are important in regulating the plasticity of adipocytes in response to increased metabolic demand by modulating the ...angiogenic response. However, the mechanism of EC-adipocyte crosstalk during this process is not completely understood. We used RNA sequencing to profile microRNAs derived from BAT ECs of obese mice and identified an anti-angiogenic microRNA, miR-409-3p. MiR-409-3p overexpression inhibited EC angiogenic properties; whereas, its inhibition had the opposite effects. Mechanistic studies revealed that miR-409-3p targets ZEB1 and MAP4K3. Knockdown of ZEB1/MAP4K3 phenocopied the angiogenic effects of miR-409-3p. Adipocytes co-cultured with conditioned media from ECs deficient in miR-409-3p showed increased expression of BAT markers, UCP1 and CIDEA. We identified a pro-angiogenic growth factor, placental growth factor (PLGF), released from ECs in response to miR-409-3p inhibition. Deficiency of ZEB1 or MAP4K3 blocked the release of PLGF from ECs and PLGF stimulation of 3T3-L1 adipocytes increased UCP1 expression in a miR-409-3p dependent manner. MiR-409-3p neutralization improved BAT angiogenesis, glucose and insulin tolerance, and energy expenditure in mice with diet-induced obesity. These findings establish miR-409-3p as a critical regulator of EC-BAT crosstalk by modulating a ZEB1-MAP4K3-PLGF signaling axis, providing new insights for therapeutic intervention in obesity.
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EMUNI, FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract Wound healing is a physiological reparative response to injury and a well-orchestrated process that involves hemostasis, cellular migration, proliferation, angiogenesis, extracellular matrix ...deposition, and wound contraction and re-epithelialization. However, patients with type 2 diabetes mellitus (T2D) are frequently afflicted with impaired wound healing that progresses into chronic wounds or diabetic ulcers, and may lead to complications including limb amputation. Herein, we investigate the potential role of microRNA-26a (miR-26a) in a diabetic model of wound healing. Expression of miR-26a is rapidly induced in response to high glucose in endothelial cells (ECs). Punch skin biopsy wounding of db/db mice revealed increased expression of miR-26a (~ 3.5-fold) four days post-wounding compared to that of WT mice. Local administration of a miR-26a inhibitor, LNA-anti-miR-26a, induced angiogenesis (up to ~ 80%), increased granulation tissue thickness (by 2.5-fold) and accelerated wound closure (53% after nine days) compared to scrambled anti-miR controls in db/db mice. These effects were independent of altered M1/M2 macrophage ratios. Mechanistically, inhibition of miR-26a increased its target gene SMAD1 in ECs nine days post-wounding of diabetic mice. In addition, high glucose reduced activity of the SMAD1-3′-UTR. Diabetic dermal wounds treated with LNA-anti-miR-26a had increased expression of ID1, a downstream modulator or SMAD1, and decreased expression of the cell cycle inhibitor p27. These findings establish miR-26a as an important regulator on the progression of skin wounds of diabetic mice by specifically regulating the angiogenic response after injury, and demonstrate that neutralization of miR-26a may serve as a novel approach for therapy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Angiogenesis is critical for tissue repair following myocardial infarction (MI), which is exacerbated under insulin resistance or diabetes. MicroRNAs are regulators of angiogenesis. We examined the ...metabolic regulation of miR-409-3p in post-infarct angiogenesis. miR-409-3p was increased in patients with acute coronary syndrome (ACS) and in a mouse model of acute MI. In endothelial cells (ECs), miR-409-3p was induced by palmitate, while vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) decreased its expression. Overexpression of miR-409-3p decreased EC proliferation and migration in the presence of palmitate, whereas inhibition had the opposite effects. RNA sequencing (RNA-seq) profiling in ECs identified DNAJ homolog subfamily B member 9 (DNAJB9) as a target of miR-409-3p. Overexpression of miR-409-3p decreased DNAJB9 mRNA and protein expression by 47% and 31% respectively, while enriching DNAJB9 mRNA by 1.9-fold after Argonaute2 microribonucleoprotein immunoprecipitation. These effects were mediated through p38 mitogen-activated protein kinase (MAPK). Ischemia-reperfusion (I/R) injury in EC-specific miR-409-3p knockout (KO) mice (miR-409ECKO) fed a high-fat, high-sucrose diet increased isolectin B4 (53.3%), CD31 (56%), and DNAJB9 (41.5%). The left ventricular ejection fraction (EF) was improved by 28%, and the infarct area was decreased by 33.8% in miR-409ECKO compared with control mice. These findings support an important role of miR-409-3p in the angiogenic EC response to myocardial ischemia.
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Icli and colleagues examined the metabolic regulation of miR-409-3p in endothelial cells and how it regulates angiogenesis following acute myocardial infarction. Endothelial cell-specific genetic deletion of miR-409-3p in mice improves angiogenesis and heart function in response to myocardial ischemia and targets the DNAJB9/p38 mitogen-activated protein kinase (MAPK) signaling pathway.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Clinical studies using bone marrow–derived proangiogenic cells (PACs) have demonstrated modest improvements of function and/or perfusion of ischemic myocardium or skeletal muscle. Because the ...identities of these PACs and their functional ability to promote neovascularization remain poorly understood, it is possible that a subset of robust PACs exists but is obscured by the heterogeneous nature of this cell population. Herein, we found that common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs) preferentially differentiate into PACs compared with megakaryocyte-erythrocyte progenitors, hematopoietic stem cells, and common lymphoid progenitors. In vivo hindlimb ischemia studies and Matrigel plug assays verified the enhanced neovascularization properties uniquely associated with PACs derived from CMPs and GMPs. Taken together, these observations identify CMPs and GMPs as key bone marrow progenitors for optimal PAC function in vitro and in vivo and provide a foundation for novel therapeutic approaches to modulate angiogenesis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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