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Westermeier F, Riquelme JA, Pavez M, Garrido V, Díaz A, Verdejo HE, Castro PF, García L, Lavandero S. New Molecular Insights of Insulin in Diabetic Cardiomyopathy. Front Physiol 2016; 7:125. [PMID: 27148064 PMCID: PMC4828458 DOI: 10.3389/fphys.2016.00125] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/22/2016] [Indexed: 12/12/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a highly prevalent disease worldwide. Cardiovascular disorders generated as a consequence of T2DM are a major cause of death related to this disease. Diabetic cardiomyopathy (DCM) is characterized by the morphological, functional and metabolic changes in the heart produced as a complication of T2DM. This cardiac disorder is characterized by constant high blood glucose and lipids levels which eventually generate oxidative stress, defective calcium handling, altered mitochondrial function, inflammation and fibrosis. In this context, insulin is of paramount importance for cardiac contractility, growth and metabolism and therefore, an impaired insulin signaling plays a critical role in the DCM development. However, the exact pathophysiological mechanisms leading to DCM are still a matter of study. Despite the numerous questions raised in the study of DCM, there have also been important findings, such as the role of micro-RNAs (miRNAs), which can not only have the potential of being important biomarkers, but also therapeutic targets. Furthermore, exosomes also arise as an interesting variable to consider, since they represent an important inter-cellular communication mechanism and therefore, they may explain many aspects of the pathophysiology of DCM and their study may lead to the development of therapeutic agents capable of improving insulin signaling. In addition, adenosine and adenosine receptors (ARs) may also play an important role in DCM. Moreover, the possible cross-talk between insulin and ARs may provide new strategies to reverse its defective signaling in the diabetic heart. This review focuses on DCM, the role of insulin in this pathology and the discussion of new molecular insights which may help to understand its underlying mechanisms and generate possible new therapeutic strategies.
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Affiliation(s)
- Francisco Westermeier
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Jaime A Riquelme
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Mario Pavez
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Valeria Garrido
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Ariel Díaz
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Hugo E Verdejo
- Faculty of Medicine, Advanced Center for Chronic Diseases, Pontifical Catholic University of ChileSantiago, Chile; Division of Cardiovascular Diseases, Faculty of Medicine, Pontifical Catholic University of ChileSantiago, Chile
| | - Pablo F Castro
- Faculty of Medicine, Advanced Center for Chronic Diseases, Pontifical Catholic University of ChileSantiago, Chile; Division of Cardiovascular Diseases, Faculty of Medicine, Pontifical Catholic University of ChileSantiago, Chile
| | - Lorena García
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of Chile Santiago, Chile
| | - Sergio Lavandero
- Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Advanced Center for Chronic Diseases, University of ChileSantiago, Chile; Department of Internal Medicine (Division of Cardiology), University of Texas Southwestern Medical CenterDallas, TX, USA
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Tao H, Chen ZW, Yang JJ, Shi KH. MicroRNA-29a suppresses cardiac fibroblasts proliferation via targeting VEGF-A/MAPK signal pathway. Int J Biol Macromol 2016; 88:414-23. [PMID: 27060017 DOI: 10.1016/j.ijbiomac.2016.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 03/18/2016] [Accepted: 04/04/2016] [Indexed: 10/25/2022]
Abstract
Cardiac fibroblasts proliferation is the most important pathophysiological character of cardiac fibrosis while the underlying mechanisms are still incompletely known. MicroRNAs (miRNAs) regulate gene expression by binding to specific sites. Studies have been indicated that miRNA-29a play a key role in cardiac fibrosis. VEGF-A carries out its functions through MAPK signaling pathway in cardiac fibrosis. Existing proofs predict that the VEGF-A is one of the potential targets of miRNA-29a. We therefore probe the role of miRNA-29a and its latent target VEGF-A during cardiac fibrosis. In our study, miRNA-29a was down-regulated while VEGF-A was up-regulated in cardiac fibrosis tissues. The rat cardiac fibroblasts that were transfected with miRNA-29a inhibitor exhibited low-expression of miRNA-29a, enhanced VEGF-A protein and mRNA expression. Nevertheless, the cardiac fibroblasts transfected with miRNA-29a mimics obtained the opposite expression result. Furthermore, over-expression of miRNA-29a suppresses cardiac fibroblasts proliferation. In conclusion, these results suggested that miRNA-29a suppresses cardiac fibrosis and fibroblasts proliferation via targeting VEGF-A/MAPK signal pathway implicating that miRNA-29a might play a role in the treatment of cardiac fibrosis.
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Affiliation(s)
- Hui Tao
- Department of Cardiothoracic Surgery, The Second Hospital of Anhui Medical University, Hefei 230601, China; Cardiovascular Research Center, Anhui Medical University, Hefei 230601, China
| | - Ze-Wen Chen
- Department of Cardiothoracic Surgery, The Second Hospital of Anhui Medical University, Hefei 230601, China; Cardiovascular Research Center, Anhui Medical University, Hefei 230601, China
| | - Jing-Jing Yang
- Department of Pharmacology, The Second Hospital of Anhui Medical University, Hefei 230601, China
| | - Kai-Hu Shi
- Department of Cardiothoracic Surgery, The Second Hospital of Anhui Medical University, Hefei 230601, China; Cardiovascular Research Center, Anhui Medical University, Hefei 230601, China.
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Deletion of interleukin-6 alleviated interstitial fibrosis in streptozotocin-induced diabetic cardiomyopathy of mice through affecting TGFβ1 and miR-29 pathways. Sci Rep 2016; 6:23010. [PMID: 26972749 PMCID: PMC4789642 DOI: 10.1038/srep23010] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 02/09/2016] [Indexed: 02/06/2023] Open
Abstract
Interleukin 6 (IL-6) has been shown to be an important regulator of cardiac interstitial fibrosis. In this study, we explored the role of interleukin-6 in the development of diabetic cardiomyopathy and the underlying mechanisms. Cardiac function of IL-6 knockout mice was significantly improved and interstitial fibrosis was apparently alleviated in comparison with wildtype (WT) diabetic mice induced by streptozotocin (STZ). Treatment with IL-6 significantly promoted the proliferation and collagen production of cultured cardiac fibroblasts (CFs). High glucose treatment increased collagen production, which were mitigated in CFs from IL-6 KO mice. Moreover, IL-6 knockout alleviated the up-regulation of TGFβ1 in diabetic hearts of mice and cultured CFs treated with high glucose or IL-6. Furthermore, the expression of miR-29 reduced upon IL-6 treatment, while increased in IL-6 KO hearts. Overexpression of miR-29 blocked the pro-fibrotic effects of IL-6 on cultured CFs. In summary, deletion of IL-6 is able to mitigate myocardial fibrosis and improve cardiac function of diabetic mice. The mechanism involves the regulation of IL-6 on TGFβ1 and miR-29 pathway. This study indicates the therapeutic potential of IL-6 suppression on diabetic cardiomyopathy disease associated with fibrosis.
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Abstract
Diabetes mellitus is a metabolic homeostasis disease that contributes to additional comorbidities such as cardiovascular disease (CVD) and cancer. It has a long undiagnosed latent period during which there can be irreparable damage to the pancreas and cardiovascular tissues. Recent studies have highlighted the roles of several microRNAs in CVD. Determining the microRNAs that link diabetes mellitus and CVD is an important topic to be explored. In the present review, we discuss the microRNAs that contribute to the progression of diabetes mellitus and CVD and focus on the miR-29 family microRNAs whose expression is upregulated by hyperglycemia and proinflammatory cytokines, the hallmarks of diabetes mellitus. Upregulation of miR-29 expression is a key factor in the loss of pancreatic β cells and development of the first stage of type 1 diabetes mellitus (T1DM). Additionally, miR-29-mediated suppression of myeloid cell leukemia 1 (MCL-1), an important prosurvival protein, underlies Marfan's syndrome, abdominal aortic aneurysm, and diabetes mellitus-associated cardiomyocyte disorganization. Suppression of miR-29 expression and subsequent increase in the prosurvival MCL-1, however, promotes tumor development. Therefore, miR-29 mimics that suppress MCL-1 are hailed as tumor suppressors. The critical question is whether an increase in miR-29 levels is well tolerated in conditions of comorbidities in which insulin resistance is an underlying disease. In light of increasing awareness of the interconnection of diabetes mellitus, CVD, and cancer, it is of utmost importance to understand the mechanism of action of current treatment options on all of the comorbidities and careful evaluation of cardiovascular toxicity must accompany any treatment paradigm that increases miR-29 levels.
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Affiliation(s)
- Anna Ślusarz
- aDepartment of Medicine bDepartment of Biochemistry, University of Missouri cHarry S. Truman Memorial Veterans Affairs Hospital dDepartment of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, USA
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Grinnan D, Farr G, Fox A, Sweeney L. The Role of Hyperglycemia and Insulin Resistance in the Development and Progression of Pulmonary Arterial Hypertension. J Diabetes Res 2016; 2016:2481659. [PMID: 27376089 PMCID: PMC4916286 DOI: 10.1155/2016/2481659] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/11/2016] [Indexed: 11/18/2022] Open
Abstract
Pulmonary hypertension is a progressive disorder which often leads to right ventricular failure and death. While the existing classification system for pulmonary hypertension does not account for the impact of diabetes mellitus, evidence is emerging that suggests that diabetes is associated with pulmonary hypertension and that diabetes modifies the course of pulmonary hypertension. There is also growing radiographic, hemodynamic, biochemical, and pathologic data supporting an association between diabetes and pulmonary hypertension. More robust epidemiologic studies are needed to confirm an association between diabetes and pulmonary hypertension and to show that diabetes is a disease modifier in pulmonary hypertension. In addition, evaluating the effects of glucose control in animals with pulmonary hypertension and diabetes (as well as in humans) is warranted.
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Affiliation(s)
- Daniel Grinnan
- Division of Pulmonary and Critical Care Medicine, Virginia Commonwealth University Health System, Richmond, VA 23298, USA
- *Daniel Grinnan:
| | - Grant Farr
- Division of Pulmonary and Critical Care Medicine, Virginia Commonwealth University Health System, Richmond, VA 23298, USA
| | - Adam Fox
- Department of Internal Medicine, Virginia Commonwealth University Health System, Richmond, VA 23298, USA
| | - Lori Sweeney
- Division of Endocrinology, Virginia Commonwealth University Health System, Richmond, VA 23298, USA
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Sfera A, Osorio C, Inderias L, Cummings M. The Ticking of the Epigenetic Clock: Antipsychotic Drugs in Old Age. Front Endocrinol (Lausanne) 2016; 7:122. [PMID: 27630617 PMCID: PMC5005952 DOI: 10.3389/fendo.2016.00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 08/23/2016] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Exposed to antipsychotic drugs (APDs), older individuals with dementing illness are at risk of cerebrovascular adverse effects (CVAE), including sudden death. Transient microvascular dysfunctions are known to occur in younger persons exposed to APDs; however, they seldom progress to CVAE, suggesting that APDs alone are insufficient for engendering this untoward effect. It is, therefore, believed that a preexistent microvascular damage is necessary for CVAE to take place, but the exact nature of this lesion remains unclear. CNS small vessel disease (SVD) is a well-known age-related risk factor for strokes, dementia, and sudden death, which may constitute the initial CVAE-predisposing pathology. Therefore, we propose the two strikes CVAE paradigm, in which SVD represents the first strike, while exposure to APDs, the second. In this model, both strikes must be present for CVAE to take place, and the neuroimaging load of white matter hyperintensities may be directly proportional with the CVAE risk. To investigate this hypothesis at the molecular level, we focused on a seemingly unrelated phenomenon: both APDs and SVD were found protective against a similar repertoire of cancers and their spread to the brain (1-4). Since microRNA-29 has shown efficacy against the same malignancies and has been associated with small vessels pathology, we narrowed our search down to this miR, hypothesizing that the APDs mechanism of action includes miR-29 upregulation, which in turn facilitates the development of SVD. AIM To assess whether miR-29 can be utilized as a peripheral blood biomarker for SVD and CVAE risk. METHOD We conducted a search of experimentally verified miR-29 target genes utilizing the public domain tools miRanda, RNA22 and Weizemann Institute of Science miRNA Analysis. We identified in total 67 experimentally verified target genes for miR-29 family, 18 of which correlate with microvascular integrity and may be relevant for CVAE. CONCLUSION Upregulated microRNA-29 silences the expression of 18 genes connected with capillary stability, engendering a major vulnerability for SVD (first strike) which in turn increases the risk for CVAE after exposure to APDs (second strike).
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Affiliation(s)
- Adonis Sfera
- Psychiatry, Patton State Hospital, Patton, CA, USA
- *Correspondence: Adonis Sfera,
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Melnik BC. Milk: an epigenetic amplifier of FTO-mediated transcription? Implications for Western diseases. J Transl Med 2015; 13:385. [PMID: 26691922 PMCID: PMC4687119 DOI: 10.1186/s12967-015-0746-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/04/2015] [Indexed: 12/14/2022] Open
Abstract
Single-nucleotide polymorphisms within intron 1 of the FTO (fat mass and obesity-associated) gene are associated with enhanced FTO expression, increased body weight, obesity and type 2 diabetes mellitus (T2DM). The N6-methyladenosine (m6A) demethylase FTO plays a pivotal regulatory role for postnatal growth and energy expenditure. The purpose of this review is to provide translational evidence that links milk signaling with FTO-activated transcription of the milk recipient. FTO-dependent demethylation of m6A regulates mRNA splicing required for adipogenesis, increases the stability of mRNAs, and affects microRNA (miRNA) expression and miRNA biosynthesis. FTO senses branched-chain amino acids (BCAAs) and activates the nutrient sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), which plays a key role in translation. Milk provides abundant BCAAs and glutamine, critical components increasing FTO expression. CpG hypomethylation in the first intron of FTO has recently been associated with T2DM. CpG methylation is generally associated with gene silencing. In contrast, CpG demethylation generally increases transcription. DNA de novo methylation of CpG sites is facilitated by DNA methyltransferases (DNMT) 3A and 3B, whereas DNA maintenance methylation is controlled by DNMT1. MiRNA-29s target all DNMTs and thus reduce DNA CpG methylation. Cow´s milk provides substantial amounts of exosomal miRNA-29s that reach the systemic circulation and target mRNAs of the milk recipient. Via DNMT suppression, milk exosomal miRNA-29s may reduce the magnitude of FTO methylation, thereby epigenetically increasing FTO expression in the milk consumer. High lactation performance with increased milk yield has recently been associated with excessive miRNA-29 expression of dairy cow mammary epithelial cells (DCMECs). Notably, the galactopoietic hormone prolactin upregulates the transcription factor STAT3, which induces miRNA-29 expression. In a retrovirus-like manner milk exosomes may transfer DCMEC-derived miRNA-29s and bovine FTO mRNA to the milk consumer amplifying FTO expression. There is compelling evidence that obesity, T2DM, prostate and breast cancer, and neurodegenerative diseases are all associated with increased FTO expression. Maximization of lactation performance by veterinary medicine with enhanced miRNA-29s and FTO expression associated with increased exosomal miRNA-29 and FTO mRNA transfer to the milk consumer may represent key epigenetic mechanisms promoting FTO/mTORC1-mediated diseases of civilization.
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Affiliation(s)
- Bodo C Melnik
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, Sedanstrasse 115, 49090, Osnabrück, Germany.
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Differential Effects of β-Blockers, Angiotensin II Receptor Blockers, and a Novel AT2R Agonist NP-6A4 on Stress Response of Nutrient-Starved Cardiovascular Cells. PLoS One 2015; 10:e0144824. [PMID: 26691397 PMCID: PMC4686716 DOI: 10.1371/journal.pone.0144824] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 11/24/2015] [Indexed: 12/18/2022] Open
Abstract
In order to determine differences in cardiovascular cell response during nutrient stress to different cardiovascular protective drugs, we investigated cell responses of serum starved mouse cardiomyocyte HL-1 cells and primary cultures of human coronary artery vascular smooth muscles (hCAVSMCs) to treatment with β-blockers (atenolol, metoprolol, carvedilol, nebivolol, 3μM each), AT1R blocker losartan (1μM) and AT2R agonists (CGP42112A and novel agonist NP-6A4, 300nM each). Treatment with nebivolol, carvedilol, metoprolol and atenolol suppressed Cell Index (CI) of serum-starved HL-1 cells (≤17%, ≤8%, ≤15% and ≤15% respectively) as measured by the Xcelligence Real-Time Cell Analyzer (RTCA). Conversely, CI was increased by Ang II (≥9.6%), CGP42112A (≥14%), and NP-6A4 (≥25%) respectively and this effect was blocked by AT2R antagonist PD123319, but not by AT1R antagonist losartan. Thus, the CI signature for each drug could be unique. MTS cell proliferation assay showed that NP-6A4, but not other drugs, increased viability (≥20%) of HL-1 and hCAVSMCs. Wheat Germ Agglutinin (WGA) staining showed that nebivolol was most effective in reducing cell sizes of HL-1 and hCAVSMCs. Myeloid Cell Leukemia 1 (MCL-1) is a protein critical for cardiovascular cell survival and implicated in cell adhesion. β-blockers significantly suppressed and NP-6A4 increased MCL-1 expression in HL-1 and hCAVSMCs as determined by immunofluorescence. Thus, reduction in cell size and/or MCL-1 expression might underlie β-blocker-induced reduction in CI of HL-1. Conversely, increase in cell viability and MCL-1 expression by NP-6A4 through AT2R could have resulted in NP-6A4 mediated increase in CI of HL-1. These data show for the first time that activation of the AT2R-MCL-1 axis by NP-6A4 in nutrient-stressed mouse and human cardiovascular cells (mouse HL-1 cells and primary cultures of hCAVSMCs) might underlie improved survival of cells treated by NP-6A4 compared to other drugs tested in this study.
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Gul R, Mahmood A, Luck C, Lum-Naihe K, Alfadda AA, Speth RC, Pulakat L. Regulation of cardiac miR-208a, an inducer of obesity, by rapamycin and nebivolol. Obesity (Silver Spring) 2015; 23:2251-9. [PMID: 26381051 PMCID: PMC4633375 DOI: 10.1002/oby.21227] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/23/2015] [Accepted: 06/24/2015] [Indexed: 01/10/2023]
Abstract
OBJECTIVE Resistance to obesity is observed in rodents and humans treated with rapamycin (Rap) or nebivolol (Neb). Because cardiac miR-208a promotes obesity, this study tested whether the modes of actions of Rap and Neb involve inhibition of miR-208a. METHODS Mouse cardiomyocyte HL-1 cells and Zucker obese (ZO) rats were used to investigate regulation of cardiac miR-208a. RESULTS Angiotensin II (Ang II) increased miR-208a expression in HL-1 cells. Pretreatment with an AT1 receptor (AT1R) antagonist, losartan (1 μM), antagonized this effect, whereas a phospholipase C inhibitor, U73122 (10 μM), and an NADPH oxidase inhibitor, apocynin (0.5 mM), did not. Ang II-induced increase in miR-208a was suppressed by Rap (10 nM), an inhibitor of nutrient sensor kinase mTORC1, and Neb (1 μM), a 3rd generation β-blocker that suppressed bioavailable AT1R binding of (125) I-Ang II. Thus, suppression of AT1R expression by Neb, inhibition of AT1R activation by losartan, and inhibition of AT1R-induced activation of mTORC1 by Rap attenuated the Ang II-induced increase in miR-208a. In ZO rats, Rap treatment (750 μg kg(-1) day(-1) ; 12 weeks) reduced obesity despite similar food intake, suppressed cardiac miR-208a, and increased cardiac MED13, a suppresser of obesity. CONCLUSIONS Rap and Neb suppressed cardiac miR-208a. Suppression of miR-208a and increase in MED13 correlated with attenuated weight gain despite leptin resistance.
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Affiliation(s)
- Rukhsana Gul
- Department of Medicine, University of Missouri, Columbia, MO
- Harry S Truman Memorial Veterans Affairs Hospital, Columbia, MO
- Obesity Research Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Abuzar Mahmood
- Department of Medicine, University of Missouri, Columbia, MO
- Harry S Truman Memorial Veterans Affairs Hospital, Columbia, MO
| | - Christian Luck
- Department of Medicine, University of Missouri, Columbia, MO
- Harry S Truman Memorial Veterans Affairs Hospital, Columbia, MO
| | - Kelly Lum-Naihe
- Department of Medicine, University of Missouri, Columbia, MO
- Harry S Truman Memorial Veterans Affairs Hospital, Columbia, MO
| | - Assim A Alfadda
- Obesity Research Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Robert C. Speth
- College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328-2018
- Department of Pharmacology and Physiology, Georgetown University, Washington, D.C. 20057
| | - Lakshmi Pulakat
- Department of Medicine, University of Missouri, Columbia, MO
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO
- Harry S Truman Memorial Veterans Affairs Hospital, Columbia, MO
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Melnik BC. The pathogenic role of persistent milk signaling in mTORC1- and milk-microRNA-driven type 2 diabetes mellitus. Curr Diabetes Rev 2015; 11:46-62. [PMID: 25587719 PMCID: PMC4428476 DOI: 10.2174/1573399811666150114100653] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Revised: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 12/12/2022]
Abstract
Milk, the secretory product of the lactation genome, promotes growth of the newborn mammal. Milk delivers insulinotropic amino acids, thus maintains a molecular crosstalk with the pancreatic β-cell of the milk recipient. Homeostasis of β-cells and insulin production depend on the appropriate magnitude of mTORC1 signaling. mTORC1 is activated by branched-chain amino acids (BCAAs), glutamine, and palmitic acid, abundant nutrient signals of cow´s milk. Furthermore, milk delivers bioactive exosomal microRNAs. After milk consumption, bovine microRNA-29b, a member of the diabetogenic microRNA-29- family, reaches the systemic circulation and the cells of the milk consumer. MicroRNA-29b downregulates branchedchain α-ketoacid dehydrogenase, a potential explanation for increased BCAA serum levels, the metabolic signature of insulin resistance and type 2 diabetes mellitus (T2DM). In non-obese diabetic mice, microRNA-29b downregulates the antiapoptotic protein Mcl-1, which leads to early β-cell death. In all mammals except Neolithic humans, milk-driven mTORC1 signaling is physiologically restricted to the postnatal period. In contrast, chronic hyperactivated mTORC1 signaling has been associated with the development of age-related diseases of civilization including T2DM. Notably, chronic hyperactivation of mTORC1 enhances endoplasmic reticulum stress that promotes apoptosis. In fact, hyperactivated β-cell mTORC1 signaling induced early β-cell apoptosis in a mouse model. The EPIC-InterAct Study demonstrated an association between milk consumption and T2DM in France, Italy, United Kingdom, Germany, and Sweden. In contrast, fermented milk products and cheese exhibit an inverse correlation. Since the early 1950´s, refrigeration technology allowed widespread consumption of fresh pasteurized milk, which facilitates daily intake of bioactive bovine microRNAs. Persistent uptake of cow´s milk-derived microRNAs apparently transfers an overlooked epigenetic diabetogenic program that should not reach the human food chain.
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Affiliation(s)
- Bodo C Melnik
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabruck, Sedanstraße 115, D-49090 Osnabrück, Germany.
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