Indra Mani

All-Trans Retinoic Acid and Sodium Butyrate Enhance Natriuretic Peptide Receptor A Gene Transcription: Role of Histone Modification

The objective of the present study was to delineate the mechanisms of GC-A/natriuretic peptide receptor-A (GC-A/NPRA) gene (Npr1) expression in vivo. We used all-trans retinoic acid (ATRA) and histone deacetylase (HDAC) inhibitor, sodium butyrate (NaBu) to examine the expression and function of Npr1 using gene-disrupted heterozygous (1-copy; +/−), wild-type (2-copy; +/+), and gene-duplicated heterozygous (3-copy; ++/+) mice. Npr1+/− mice exhibited increased renal HDAC and reduced histone acetyltransferase (HAT) activity; on the contrary, Npr1++/+ mice showed decreased HDAC and enhanced HAT activity compared with Npr1+/+ mice. ATRA and NaBu promoted global acetylation of histones H3-K9/14 and H4-K12, reduced methylation of H3-K9 and H3-K27, and enriched accumulation of active chromatin marks at the Npr1 promoter. A combination of ATRA-NaBu promoted recruitment of activator-complex containing E26 transformation–specific 1, retinoic acid receptor α, and HATs (p300 and p300/cAMP response element–binding protein-binding protein–associated factor) at the Npr1 promoter, and significantly increased renal NPRA expression, GC activity, and cGMP levels. Untreated 1-copy mice showed significantly increased systolic blood pressure and renal expression of α-smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA) compared with 2- and 3-copy mice. Treatment with ATRA and NaBu synergistically attenuated the expression of α-SMA and PCNA and reduced systolic blood pressure in Npr1+/− mice. Our findings demonstrate that epigenetic upregulation of Npr1 gene transcription by ATRA and NaBu leads to attenuation of renal fibrotic markers and systolic blood pressure in mice with reduced Npr1 gene copy number, which will have important implications in prevention and treatment of hypertension-related renal pathophysiological conditions.

Metabolic Engineering of Biosynthetic Pathway for Production of Renewable Biofuels

Metabolic engineering is an important area of research that involves editing genetic networks to overproduce a certain substance by the cells. Using a combination of genetic, metabolic, and modeling methods, useful substances have been synthesized in the past at industrial scale and in a cost-effective manner. Currently, metabolic engineering is being used to produce sufficient, economical, and eco-friendly biofuels. In the recent past, a number of efforts have been made towards engineering biosynthetic pathways for large scale and efficient production of biofuels from biomass. Given the adoption of metabolic engineering approaches by the biofuel industry, this paper reviews various approaches towards the production and enhancement of renewable biofuels such as ethanol, butanol, isopropanol, hydrogen, and biodiesel. We have also identified specific areas where more work needs to be done in the future.

Subcellular trafficking of guanylyl cyclase/natriuretic peptide receptor-A with concurrent generation of intracellular cGMP.

Atrial natriuretic peptide (ANP) modulates blood pressure and fluid volume by activation of natriuretic peptide receptor-A (NPRA). Immunofluorescence (IF) studies reveal that NPRA is internalized and redistributed into subcellular compartments with concurrent production of cGMP.

Retinoic acid and sodium butyrate suppress the cardiac expression of hypertrophic markers and proinflammatory mediators in Npr1 gene-disrupted haplotype mice

The objective of the present study was to examine the genetically determined differences in the natriuretic peptide receptor-A (NPRA) gene (Npr1) copies affecting the expression of cardiac hypertrophic markers, proinflammatory mediators, and matrix metalloproteinases (MMPs) in a gene-dose-dependent manner. We determined whether stimulation of Npr1 by all-trans retinoic acid (RA) and histone deacetylase (HDAC) inhibitor sodium butyric acid (SB) suppress the expression of cardiac disease markers. In the present study, we utilized Npr1 gene-disrupted heterozygous (Npr1(+/-), 1-copy), wild-type (Npr1(+/+), 2-copy), gene-duplicated (Npr1(++/+), 3-copy) mice, which were treated intraperitoneally with RA, SB, and a combination of RA/SB, a hybrid drug (HB) for 2 wk. Untreated 1-copy mice showed significantly increased heart weight-body weight (HW/BW) ratio, blood pressure, hypertrophic markers, including beta-myosin heavy chain (β-MHC) and proto-oncogenes (c-fos and c-jun), proinflammatory mediator nuclear factor kappa B (NF-κB), and MMPs (MMP-2, MMP-9) compared with 2-copy and 3-copy mice. The heterozygous (haplotype) 1-copy mice treated with RA, SB, or HB, exhibited significant reduction in the expression of β-MHC, c-fos, c-jun, NF-κB, MMP-2, and MMP-9. In drug-treated animals, the activity and expression levels of HDAC were significantly reduced and histone acetyltransferase activity and expression levels were increased. The drug treatments significantly increased the fractional shortening and reduced the systolic and diastolic parameters of the Npr1(+/-) mice hearts. Together, the present results demonstrate that a decreased Npr1 copy number enhanced the expression of hypertrophic markers, proinflammatory mediators, and MMPs, whereas an increased Npr1 repressed the cardiac disease markers in a gene-dose-dependent manner.

Role of FQQI motif in the internalization, trafficking, and signaling of guanylyl-cyclase/natriuretic peptide receptor-A in cultured murine mesangial cells

Binding of the cardiac hormone atrial natriuretic peptide (ANP) to transmembrane guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), produces the intracellular second messenger cGMP in target cells. To delineate the critical role of an endocytic signal in intracellular sorting of the receptor, we have identified a FQQI (Phe(790), Gln(791), Gln(792), and Ile(793)) motif in the carboxyl-terminal region of NPRA. Mouse mesangial cells (MMCs) were transiently transfected with the enhanced green fluorescence protein (eGFP)-tagged wild-type (WT) and mutant constructs of eGFP-NPRA. The mutation FQQI/AAAA, in the eGFP-NPRA cDNA sequence, markedly attenuated the internalization of mutant receptors by almost 49% compared with the WT receptor. Interestingly, we show that the μ1B subunit of adaptor protein-1 binds directly to a phenylalanine-based FQQI motif in the cytoplasmic tail of the receptor. However, subcellular trafficking indicated that immunofluorescence colocalization of the mutated receptor with early endosome antigen-1 (EEA-1), lysosome-associated membrane protein-1 (LAMP-1), and Rab 11 marker was decreased by 57% in early endosomes, 48% in lysosomes, and 42% in recycling endosomes, respectively, compared with the WT receptor in MMCs. The receptor containing the mutated motif (FQQI/AAAA) also produced a significantly decreased level of intracellular cGMP during subcellular trafficking than the WT receptor. The coimmunoprecipitation assay confirmed a decreased level of colocalization of the mutant receptor with subcellular compartments during endocytic processes. The results suggest that the FQQI motif is essential for the internalization and subcellular trafficking of NPRA during the hormone signaling process in intact MMCs.

A Potential Screening of Peptide Deformylase Inhibitors Towards the Control of Aeromonas hydrophila

Currently, the prevalence of multidrug resistance Aeromonas hydrophila is one of the major issues and challenges for aquatic and terrestrial organisms. Therefore, an urgent need arises to control it using a potent and specific drug. Here, we identified a peptide deformylase (PDF) in A. hydrophila , which is a ubiquitous enzyme and one of the most attractive drug targets. We used the PDF protein sequences for generating a 3-D model using homology modeling. The 3-D model was validated and it was found 91% of the present amino acids in allowed regions of the Ramachandran plot. We used the 3-D model of PDF for the screening of drugs through molecular docking and found BB-3497, actinonin, and BBS-02 were more potent than other studied drugs based on binding energy. We have also generated a phylogenetic tree of PDF from A. hydrophila with other homologous bacteria, suggesting that similar drugs could also be applied to the control of those bacteria. These findings provide a new insight for the better understanding of PDF, which is a novel target for the development of more potent inhibitors towards the better control of multidrug resistant A. hydrophila .