Epigenetic silencing of TIMP4 in heart failure

Tissue inhibitor of matrix metalloprotease 4 (TIMP4) is endogenously one of the key modulators of matrix metalloprotease 9 (MMP9) and we have reported earlier that cardiac specific TIMP4 instigates contractility and helps in differentiation of cardiac progenitor cells. Although studies show that the expression of TIMP4 goes down in heart failure but the mechanism is unknown. This study aims to determine the mechanism of silencing of TIMP4 in heart failure progression created by aorta‐vena cava (AV) fistula. We hypothesize that there is epigenetic silencing of TIMP4 in heart failure. To validate this hypothesis, we created heart failure model by creating AV fistula in C57BL/6 mice and looked into the promoter methylation (methylation specific PCR, high resolution melting, methylation sensitive restriction enzyme and Na bisulphite treatment followed by sequencing), histone modification (ChIP assay) and microRNAs that regulate TIMP4 (mir122a) and MMP9 (mir29b and mir455‐5p). The physiological parameters in terms of cardiac function after AV fistula were assessed by echocardiography. We observed that there are 7 CpG islands in the TIMP4 promoter which get methylated during the progression of heart failure which leads to its epigenetic silencing. In addition, the up‐regulated levels of mir122a in part, contribute to regulation of TIMP4. Consequently, MMP9 gets up‐regulated and leads to cardiac remodeling. This is a novel report to explain the epigenetic silencing of TIMP4 in heart failure.     

Photoperiodic effect on some enzymes and metabolites in diapausingAntheraea mylitta pupae andPhilosamia ricini larvae during development

The variation in acid phosphatase (EC 3.1.3.2) activity inAntheraea mylitta was similar in all light and dark groups exposed to different photophases (LD =0:24, 24:0, 18:6, 14:10, 10:14 and 12:12 h) maintaining all along a higher activity than its alkaline counterpart. The highest activity was recorded on day 82 in LD group 10:14 h. The non-diapausingPhilosamia ricini larvae registered highest activity in LD group 0:24 h on day 5. Alkaline phosphatase (EC 3.1.3.1) activity was low all through metamorphosis in both the lepidopterans, although significantly elevated activity was observed on day 5 in larvae of allPhilosamia ricini LD regimens and on day 82 inAntherae mylitta. Photoperiodic effect on Phosphorylase (EC 2.3.1.1) activity, glycogen and inorganic phosphates content have also been studied. Exposure to LD 10:14, 14:10 and 18:6 h provoked early diapause termination inAntheraea mylitta. The non-diapausingPhilosamia ricini was unaffected in moth emergence but the emerged adults of LD 24:0 and 0:24 h groups were unhealthy, small and did not mate or oviposit.     

Effect of heparin and adrenocorticotropin on the hepatic and serum cholesterol in catfish, Heteropneustes fossils.

The administration of heparin with or without ACTH significantly decreased hepatic cholesterol content in catfish. In serum, heparin alone produced first hypercholesterolemia which was followed by hypocholesterolemia whereas it potentiated hypercholesterolemic action of ACTH three hours after administration. It is concluded that heparin normally caused hypercholesterolemia by releasing cholesterol from liver as lipoprotein complex. The hypocholesterolemic action of heparin might be an indirect one.     

Endothelin inhibits the atrial natriuretic factor stimulated cGMP production by activating the protein kinase C in rat aortic smooth muscle cells.

Preincubation of rat thoracic aortic smooth muscle cells with endothelin inhibits the atrial natriuretic factor (ANF)-induced cGMP accumulation in these cells in a concentration dependent manner. The maximal inhibition of 64% was afforded by 1 x 10(-6) M endothelin and the half maximal inhibition (IC50) was achieved with 1 x 10(-9) M endothelin. Endothelin (1 x 10(-6) M) also increased the plasma membrane bound protein kinase C (PKC) activity by 4 fold. Hormone-dependent increase in PKC activity was limited to plasma membranes only and some decrease in cytosolic PKC activity was observed. However, phorbol 12-myristate 13-acetate (PMA) (1 x 10(-6)M) provoked a total loss of cytosolic PKC activity and a net gain in membranous PKC activity indicative of the translocation of the enzyme. Pretreatment of these cells with H-7, a PKC inhibitor, released the endothelin and PMA-mediated attenuation of ANF-stimulated cGMP formation. These results suggest that PKC is involved in the regulation of ANF-induced cGMP accumulation and that the vasoconstrictor activity of endothelin might involve inhibition of the vasorelaxant activity of ANF through the inhibition of cGMP accumulation in smooth muscle cells (SMCs) of the rat aorta.     

Pseudomonas aeruginosa–induced nociceptor activation increases susceptibility to infection

We report a rapid reduction in blink reflexes during in vivo ocular Pseudomonas aeruginosa infection, which is commonly attributed and indicative of functional neuronal damage. Sensory neurons derived in vitro from trigeminal ganglia (TG) were able to directly respond to P. aeruginosa but reacted significantly less to strains of P. aeruginosa that lacked virulence factors such as pili, flagella, or a type III secretion system. These observations led us to explore the impact of neurons on the host’s susceptibility to P. aeruginosa keratitis. Mice were treated with Resiniferatoxin (RTX), a potent activator of Transient Receptor Potential Vanilloid 1 (TRPV1) channels, which significantly ablated corneal sensory neurons, exhibited delayed disease progression that was exemplified with decreased bacterial corneal burdens and altered neutrophil trafficking. Sensitization to disease was due to the increased frequencies of CGRP-induced ICAM-1⁺ neutrophils in the infected corneas and reduced neutrophil bactericidal activities. These data showed that sensory neurons regulate corneal neutrophil responses in a tissue-specific matter affecting disease progression during P. aeruginosa keratitis. Hence, therapeutic modalities that control nociception could beneficially impact anti-infective therapy.     

Lesions of the Basal Forebrain Cholinergic System in Mice Disrupt Idiothetic Navigation

Loss of integrity of the basal forebrain cholinergic neurons is a consistent feature of Alzheimer’s disease, and measurement of basal forebrain degeneration by magnetic resonance imaging is emerging as a sensitive diagnostic marker for prodromal disease. It is also known that Alzheimer’s disease patients perform poorly on both real space and computerized cued (allothetic) or uncued (idiothetic) recall navigation tasks. Although the hippocampus is required for allothetic navigation, lesions of this region only mildly affect idiothetic navigation. Here we tested the hypothesis that the cholinergic medial septo-hippocampal circuit is important for idiothetic navigation. Basal forebrain cholinergic neurons were selectively lesioned in mice using the toxin saporin conjugated to a basal forebrain cholinergic neuronal marker, the p75 neurotrophin receptor. Control animals were able to learn and remember spatial information when tested on a modified version of the passive place avoidance test where all extramaze cues were removed, and animals had to rely on idiothetic signals. However, the exploratory behaviour of mice with cholinergic basal forebrain lesions was highly disorganized during this test. By contrast, the lesioned animals performed no differently from controls in tasks involving contextual fear conditioning and spatial working memory (Y maze), and displayed no deficits in potentially confounding behaviours such as motor performance, anxiety, or disturbed sleep/wake cycles. These data suggest that the basal forebrain cholinergic system plays a specific role in idiothetic navigation, a modality that is impaired early in Alzheimer’s disease.     

Multimodal approach to explore the pathogenicity of BARD1, ARG 658 CYS,and ILE 738 VAL mutants

BARD1–BRCA1 complex plays an important role in DNA damage repair, apoptosis, chromatin remodeling, and other important processes required for cell survival. BRCA1 and BARD1 heterodimer possess E3 ligase activity and is involved in genome maintenance, by functioning in surveillance for DNA damage, thereby regulating multiple pathways including tumor suppression. BRCT domains are evolutionary conserved domains present in different proteins such as BRCA1, BARD1, XRCC, and MDC1 regulating damage response and cell-cycle control through protein–protein interactions. Nonetheless, the role of BARD1BRCT in the recruitment of DNA repair mechanism and structural integrity with BRCA1 complex is still implicit. To explicate the role of BARD1BRCT in the DNA repair mechanism, in silico, in vitro, and biophysical approach were applied to characterize BARD1 BRCT wild-type and Arg658Cys and Ile738Val mutants. However, no drastic secondary and tertiary structural changes in the mutant proteins were observed. Thermal and chemical denaturation studies revealed that mutants Arg658Cys and Ile738Val have a decrease in T_m and ?G than the wild type. In silico studies of BARD1 BRCT (568-777) and mutant protein indicate loss in structural compactness on the Ile738Val mutant. Comparative studies of wild-type and mutants will thus be helpful in understanding the basic role of BARD1BRCT in DNA damage repair.