Anuradha Pandey

Histone H2AK119 and H2BK120 mono-ubiquitination modulate SET7/9 and SUV39H1 in type 1 diabetes-induced renal fibrosis.

Hyperglycaemia-induced expression of extracellular matrix (ECM) components plays a major role in the development of diabetic nephropathy (DN). The epigenetic mechanisms that modulate ECM gene expression in DN remain unclear. Therefore, we examined the role of histone H2A and H2B monoubiquitination on epigenetic chromatin marks, such as histone H3 lysine dimethylation (H3K4Me2, H3K9Me2 and H3K79Me2) in type 1 diabetic rat kidney. Hyperglycaemia increased collagen deposition and Col1a1 gene expression. In whole kidney of diabetic animals, both H2AK119 mono-ubiquitination (H2AK119Ub) and H2BK120 mono-ubiquitination (H2BK120Ub) were found to be increased, whereas, in glomeruli of diabetic animals, expression of both H2AK119Ub and H2BK120Ub was reduced. Changes in ubiquitin proteasome system components like increased Rnf2 (H2A-specific E3 ligase) and decreased H2A- and H2B-specific deubiquitinases (ubiquitin-specific proteases 7, 16, 21 and 22) were also observed. Globally increased levels of chromatin marks associated with active genes (H3K4Me2 and H3K79Me2) and decreased levels of repressive marks (H3K9Me2) were also observed. Hyperglycaemia also increased the protein expression of SET7/9 and decreased the expression of SUV39H1. We also showed the decreased occupancy of H2AK119Ub and H2BK120Ub on the promoters of Set7/9 and Suv39h1 in diabetic kidney. In addition, methylation marks regulated by H2AK119Ub (H3K27Me2 and H3K36Me2) and H2BK120Ub (H3K4Me2 and H3K79Me2) were also found to be altered on the promoters of Set7/9 and Suv39h1 Taken together, these results show the functional role of H2AK119Ub and H2BK120Ub in regulating histone H3K4Me2 and H3K9Me2 through modulating the expression of SET7/9 and SUV39H1 in the development of diabetic renal fibrosis.

Differential regulation of angiotensin converting enzyme 2 and nuclear factor-κB by angiotensin II receptor subtypes in type 2 diabetic kidney.

Angiotensin II (Ang II) acts through Angiotensin Converting Enzyme (ACE)/Ang II type 1 receptor (AT1R) axis to promote renal failure whereas the Ang II type 2 receptor (AT2R)/Angiotensin Converting Enzyme 2 (ACE2)/Ang1-7/Mas axis constitutes the protective arm of Renin Angiotensin System (RAS). Though Ang II has been known to activate the Nuclear Factor-κB (NF-κB) signalling pathway through different receptor subtype(s) in different tissues under various diseases, the subtype orchestrating this stimulation in type 2 diabetic kidney remains elusive. ACE2, a protective monocarboxypeptidase, responsible for conversion of Ang II to Ang1-7, opposes the deleterious effects of RAS pathway but how its expression is altered with blockade of AT1R and AT2R is not yet known. Hence, the present study was conceived to understand the regulation of NF-κB and ACE2 by using specific AT1 and AT2 receptor antagonists in non-genetic model of type 2 diabetic nephropathy. Our results show that the AT1R and AT2R antagonists lead to the repression and activation of NF-κB signalling pathway, respectively which suggests the role of AT1R in NF-κB activation. The blockade of AT2R led to an increase in ACE2 expression, which may be a compensatory response to the drastically increased inflammatory mediators and oxidative stress in the diabetic kidney. To the best of our knowledge, this is the first study showing the differential regulation of NF-κB and ACE2 by Ang II receptor subtypes and thus this study improves our understanding regarding regulation of inflammatory cascade and ACE2 by AT1R and AT2R in type 2 diabetic kidney, which may help in designing novel strategies to combat the disease in future.

E3 ubiquitin ligases as novel targets for inflammatory diseases.

Ubiquitination is one of the post translational modifications which decide the fate of various proteins in the cells, by either directing them towards proteasomal degradation or participation in several cell signalling pathways. Recently, the role of ubiquitination has been unravelled in pathogenesis and progression of various diseases, where inflammation is critical, like obesity, insulin resistance, atherosclerosis, angiotensin-II induced cardiac inflammation and asthma. E3 ligases are known to be instrumental in regulation of the inflammatory cascade. This review focuses on the role of different E3 ligases in the development of inflammatory diseases and thus may help us to target these E3 ligases in future drug discovery to prevent inflammation.

Insulin sensitizing and cardioprotective effects of Esculetin and Telmisartan combination by attenuating Ang II mediated vascular reactivity and cardiac fibrosis.

The combination of the angiotensin receptor blockers (ARBs) with other synthetic and natural molecules has been reported to have better safety profile and therapeutic efficacy in prevention of diabetes and its associated complications than their monotherapy. Driven by the aforementioned facts, this study was conceived to evaluate the potential additive effect of combination of Telmisartan and Esculetin in prevention of insulin resistance and associated cardiac fibrosis. Recently, we have reported that Esculetin prevented cardiovascular dysfunction associated with insulin resistance (IR) and type 2 diabetes. Insulin resistance was developed by high fat diet (HFD) feeding to Wistar rats. Telmisartan and Esculetin were administered at 10 mg/kg/day and 50 mg/kg/day doses (P.O, 2 weeks), respectively either alone or in combination. Plasma biochemical analyses, vascular reactivity and immunohistochemical experiments were performed to assess the beneficial effect of Telmisartan, Esculetin and their combination on insulin resistance and associated cardiac fibrosis. The study results showed that, co-administered Telmisartan and Esculetin ameliorated the pathological features like metabolic perturbation, morphometric alterations, vascular hyper responsiveness, extracellular matrix accumulation and the expression of fibronectin and TGF-β more effectively than monotherapy in HFD fed rats. Hence, the study urges us to conclude that the solution to IR and associated cardiovascular dysfunction may lie in the Telmisartan and Esculetin combination therapy.

Compound 21 and Telmisartan combination mitigates type 2 diabetic nephropathy through amelioration of caspase mediated apoptosis

The current study aimed to understand the role of novel, highly selective, orally active, non-peptide Angiotensin II type 2 receptor (AT2R) agonist, Compound 21 and its potential additive effect with Telmisartan on apoptosis and underlying posttranslational modifications in a non-genetic murine model for type 2 diabetic nephropathy (T2DN). An experimental model for T2DN was developed by administering low dose Streptozotocin in high fat diet fed male Wistar rats, followed by their treatment with Telmisartan, C21 or their combination. Our results demonstrated that C21 and Telmisartan combination attenuated metabolic and renal dysfunction, renal morphological and micro-architectural aberrations and hemodynamic disturbances in type 2 diabetic rats. The anti-apoptotic and anti-inflammatory effects of Telmisartan were significantly accentuated by C21 indicated by expression of apoptotic markers (Parp1, Caspase 8, Caspase 7, cleaved PARP and cleaved Caspase 3) and NF-κB mediated inflammatory molecules like interleukin 6, tumour necrosis factor alpha; monocyte chemoattractant protein 1 and vascular cell adhesion molecule 1. C21 was found to improve Telmisartan mediated reversal of histone H3 acetylation at lysine 14 and 27 and expression of histone acetyl transferase, p300/CBP-associated factor also known to regulate NF-κB activity and DNA damage response. C21 in combination with Telmisartan markedly mitigates caspase mediated apoptosis and NF-κB signalling in T2D kidney, which could be partially attributed to its influence on PCAF mediated histone H3 acetylation. Hence further research should be done to develop this combination to treat T2DN.

Diminazene aceturate prevents nephropathy by increasing glomerular ACE2 and AT2 receptor expression in a rat model of type1 diabetes

One of the protective actions of angiotensin converting enzyme‐2 (ACE2) is the inactivation of angiotensin II. Expression and activity of ACE2 was reduced in glomeruli of diabetic patients and in animal models of diabetes. Recently the potential role of recombinant ACE2 administration in preventing diabetic nephropathy (DN) has been shown. Here we have tested the effects of the ACE2 activator, diminazene aceturate (DIZE), in a model of DN.Background and Purpose Angiotensin converting enzyme 2 (ACE2) shows its protective actions through degrading Ang II. ACE2 activity and its expression was found to be reduced in glomeruli of diabetic patients as well as in animal models of diabetes. Several recent studies have also showed the potential role of recombinant ACE2 administration in preventing diabetic nephropathy (DN). Hence, we hypothesized that ACE2 activator, diminazene aceturate (DIZE) may be beneficial in preventing DN. Experimental Approach Male Wistar rats were rendered diabetic using a single dose of Streptozotocin (55mg kg-1, i.p.). After 4 weeks, diabetic animals were grouped in to respective groups and the drug, DIZE, low dose (5mg kg-1day-1), high dose (15mg kg-1day-1) and high dose in presence of AT2 blocker (PD123319, 10mg kg-1day-1) was administered. At the end, kidneys from all the groups were collected and processed separately for glomerular isolation, protein isolation, mRNA extraction and for immunohistochemical studies. Key Results DIZE administration restored the ACE2 expression in glomeruli and increased the AT2 expression in whole kidney and isolated glomeruli of diabetic animals. DIZE administration, reduced the Ang II levels and increased Ang 1-7 levels in diabetic kidney. However, AT2 blockade, reversed all these actions of DIZE. Conclusion and Implications DIZE treatment reduced the diabetes induced renal damage through inhibiting fibrosis and apotosis. Moreover, DIZE failed to show its protective actions in presence of AT2 blocker. Taken together, these results suggest the protective role of DIZE in preventing DN through ACE2/Ang 1-7/AT2 axis.

AT2 receptor agonist Compound 21: A silver lining for diabetic nephropathy

Abstract The currently available therapies for diabetic nephropathy, one of the leading causes of renal failure globally are based on inhibition of renin angiotensin system. However, recently, the focus has shifted towards activation of its protective arm rather than the inhibition of deteriorative axis, using specific agonists. Compound 21 (C21), a novel non‐peptide Angiotensin II type 2 receptor (AT2) agonist, recently granted orphan drug status for the treatment of a rare disease, idiopathic pulmonary fibrosis has also shown a potent anti‐inflammatory, anti‐fibrotic, antioxidant and anti‐apoptotic potential in various diseases including heart failure, myocardial infarction, chronic inflammatory diseases, and neurological diseases such as ischemic stroke. A pool of evidences suggest that C21, either alone or in combination with angiotensin receptor blockers could be extremely beneficial in the treatment of diabetic nephropathy, a chronic inflammatory condition sharing its pathogenesis with aforementioned diseases. The review analyses the new therapeutic tool, C21, its mechanisms of action for renoprotection in diabetic nephropathy, and its future perspectives and thereby provides an insight into the potential application of C21 as a novel therapeutic tool in the eradication of diabetic nephropathy. Graphical abstract Figure. No caption available.

Diminazene aceturate prevents type 1 diabetic nephropathy through increasing glomerular ACE2 and AT2 receptor expression

One of the protective actions of angiotensin converting enzyme‐2 (ACE2) is the inactivation of angiotensin II. Expression and activity of ACE2 was reduced in glomeruli of diabetic patients and in animal models of diabetes. Recently the potential role of recombinant ACE2 administration in preventing diabetic nephropathy (DN) has been shown. Here we have tested the effects of the ACE2 activator, diminazene aceturate (DIZE), in a model of DN.Background and Purpose Angiotensin converting enzyme 2 (ACE2) shows its protective actions through degrading Ang II. ACE2 activity and its expression was found to be reduced in glomeruli of diabetic patients as well as in animal models of diabetes. Several recent studies have also showed the potential role of recombinant ACE2 administration in preventing diabetic nephropathy (DN). Hence, we hypothesized that ACE2 activator, diminazene aceturate (DIZE) may be beneficial in preventing DN. Experimental Approach Male Wistar rats were rendered diabetic using a single dose of Streptozotocin (55mg kg-1, i.p.). After 4 weeks, diabetic animals were grouped in to respective groups and the drug, DIZE, low dose (5mg kg-1day-1), high dose (15mg kg-1day-1) and high dose in presence of AT2 blocker (PD123319, 10mg kg-1day-1) was administered. At the end, kidneys from all the groups were collected and processed separately for glomerular isolation, protein isolation, mRNA extraction and for immunohistochemical studies. Key Results DIZE administration restored the ACE2 expression in glomeruli and increased the AT2 expression in whole kidney and isolated glomeruli of diabetic animals. DIZE administration, reduced the Ang II levels and increased Ang 1-7 levels in diabetic kidney. However, AT2 blockade, reversed all these actions of DIZE. Conclusion and Implications DIZE treatment reduced the diabetes induced renal damage through inhibiting fibrosis and apotosis. Moreover, DIZE failed to show its protective actions in presence of AT2 blocker. Taken together, these results suggest the protective role of DIZE in preventing DN through ACE2/Ang 1-7/AT2 axis.

Telmisartan and esculetin combination ameliorates type 2 diabetic cardiomyopathy by reversal of H3, H2A, and H2B histone modifications

OBJECTIVES: Although cardioprotective effects of telmisartan are well explored, its effects on epigenetic alterations associated with type 2 diabetic (T2D) cardiomyopathy remain unmapped. Thus, the present study was designed to evaluate the potential of esculetin and telmisartan combination to reverse histone posttranslational modifications (PTMs) in curbing T2D cardiomyopathy. MATERIALS AND METHODS: T2D was induced by high-fat diet feeding along with low dose of streptozotocin (35 mg/kg, I.P) in male Wistar rats. T2D rats were treated with either telmisartan (10 mg/kg/day, P.O) or esculetin (50 mg/kg/day doses, P.O) or their combination for 2 weeks. Biochemical estimations, vascular reactivity, immunohistochemistry, and western blotting experiments were performed to evaluate the effects of the treatment in T2D cardiomyopathy. RESULTS: Esculetin and telmisartan combination alleviated the pathological features of T2D cardiomyopathy including metabolic perturbations, morphometric alterations, altered vascular reactivity, increased Keap1 and fibronectin expression more effectively than their respective monotherapy. This is the first report showing that telmisartan attenuates increased level of histone PTMs such as H3K9me2, H3K9Ac, H2AK119Ub, and H2BK120Ub in heart of T2D rats. The combination regimen showed a more significant reduction in augmented histone PTMs associated with T2D cardiomyopathy than their independent treatments. CONCLUSIONS: The present study demonstrates that esculetin and telmisartan combination can be an advanced pharmacological approach to ameliorate T2D cardiomyopathy which could be partially attributed to its ability to reverse the epigenetic alterations.

Curcumin: The epigenetic therapy

Abstract The process of gene expression is tightly regulated by a series of interconnected epigenetic alterations including DNA methylation, covalent modifications of histones, or altered microRNA. The food components which are taken regularly play a significant role in altering the epigenetic modifications, and associated gene expression may act as important tools in curbing the diseases which involve epigenetic alterations. The polyphenolic compound curcumin (diferuloylmethane), possesses a large number of biological activities owing to which its use has been implicated in various diseases including cancer, respiratory diseases, metabolic disorders, and neurodegenerative disorders. These activities could be attributed partially to its DNA hypomethylating and histone acetylating property. In conclusion, curcumin is able to restore the epigenetic regulation balance and appears as an attractive preventive and/or therapeutic approach, and hence there is a need to study the epigenetic modifications promoted by its treatment.