Posts Tagged: heart diseases

Long Noncoding RNA Discovery in Cardiovascular Disease: Decoding Form to Function

Long Noncoding RNA Discovery in Cardiovascular Disease: Decoding Form to Function

Tamer Sallam, Jaspreet Sandhu, Peter Tontonoz

Pipeline of long noncoding RNA (lncRNA) discovery and characterization. ASO indicates antisense oligonucleotide; ChiRP, chromatin isolation by RNA purification; qPCR, quantitative polymerase chain reaction; RAP, RNA antisense purification; and RIP, RNA immunoprecipitation. [Powerpoint File]

Circulating Noncoding RNAs as Biomarkers of Cardiovascular Disease and Injury

Circulating Noncoding RNAs as Biomarkers of Cardiovascular Disease and Injury

Janika Viereck, Thomas Thum

Biogenesis and function of microRNAs (miRNAs). MiRNAs are transcribed from longer precursors with protein or other noncoding gene sequences and further processed via 2 endonucleolytic processing steps. Mature miRNAs associate with Argonaute proteins (Ago2) forming the RNA-induced silencing complex (miRISC). Within this complex, miRNAs recognize their target sequence and block their expression by translational repression or degradation. MiRNAs can be released or actively secreted into the extracellular space and circulatory system stabilized in vesicles or proteinous binding partners. DGCR8, DiGeorge syndrome critical region 8; TRBP, transactivation-responsive RNA-binding protein. [Powerpoint File]

Circulating Noncoding RNAs as Biomarkers of Cardiovascular Disease and Injury

Circulating Noncoding RNAs as Biomarkers of Cardiovascular Disease and Injury

Janika Viereck, Thomas Thum

Molecular mechanism of long noncoding RNA (lncRNA) activities. LncRNAs regulate the expression of genes in the nucleus by interacting directly with DNA recruiting chromatin modifying complexes and various transcriptional regulators. Cytoplasmatic noncoding transcripts act as sponges for other transcripts like microRNAs (miRNAs) or for proteins, serve as templates for small peptide synthesis or regulate messenger RNA (mRNA) degradation and translation. These transcripts enter the bloodstream bound to proteinous carriers or incorporated into extracellular vesicles that leads to a stabilization of transcripts. Ago2, Argonaute protein 2. [Powerpoint File]

Myocarditis

Myocarditis

Gabriel Fung, Honglin Luo, Ye Qiu, Decheng Yang, Bruce McManus

Putative role of micro-RNAs (miR) in coxsackievirus B3 (CVB3) pathogenesis. Selected miRNAs and their target genes are highlighted with red and purple, respectively. miR-10* targets the CVB3 genome, leading to direct enhancement of virus particle formation. miR-203, miR-126, and miR-141 target mediators of signal transduction pathways regulating cell survival or death, thus benefitting viral replication and particle release. miR-1 and miR-21 target genes encoding component proteins of intercalated disks, resulting in destruction of cardiomyocytes. miR-221 and miR-222 target genes that promote viral replication. AP-1 indicates activator protein-1; BCL2L11, bcl-2-interacting mediator of cell death; BMF, bcl2 modifying factor; CXCL12, chemokine (C-X-C motif) ligand 12; eIF4E, eukaryotic translation initiation factor 4E; ERK1/2, extracellular signal-regulated kinase 1/2; ETS1/2, c-ets-1; IRF2, interferon regulatory factor 2; LRP6, low-density lipoprotein receptor-related protein 6; PKC, protein kinase C; SPRED1, sprout-related EVH1 domain containing 1; TOX, thymocyte selection-associated high mobility group box; VCL, vinculin; WRCH1, Wnt responsive Cdc45 homolog 1; YOD1, YOD1 deubiquitinase; and ZFP-48, zinc finger protein-148 (Illustration Credit: Ben Smith). [Powerpoint File]

Myocarditis

Myocarditis

Gabriel Fung, Honglin Luo, Ye Qiu, Decheng Yang, Bruce McManus

Direct myocardial damage induced by virus-encoded proteinases. A, Dystrophin is an important component of the dystrophin–glycoprotein complex that links the cytoskeleton to the extracellular matrix. coxsackievirus B3–encoded proteinase 2A cleaves dystrophin, contributing to myocardial dysfunction by increasing cell permeability and decreasing force transmission. B, Dysferlin is a transmembrane protein highly expressed in skeletal and cardiac muscles. It is localized to the sarcolemma and cytoplasmic vesicles and plays a key role in Ca2+-dependent membrane repair. Proteolytic processing of dysferlin by proteinase 2A contributes to impaired cardiac function, likely via disrupting membrane repair function. C, Virus-encoded proteinase 2A and 3C can produce direct cytotoxicity in the heart through inducing apoptosis by direct cleavage of caspases and inhibiting host protein translation through processing eukaryotic translation initiation factor 4γ (eIF4G) and poly A-binding protein (PABP). D, Serum response factor (SRF) is a muscle-enriched transcription factor that regulates the expression of many cardiac contractile and regulatory proteins by binding to serum response element (SRE) in the promoter region of target genes. SRF cleavage mediated by proteinase 2A results in cardiac dysfunction by eliminating SRF-mediated gene expression. E, Misfolded protein aggregates are frequently detected in common heart diseases and are thought to be highly toxic to cardiomyocytes. Autophagic adaptor proteins p62 and neighbor of BRCA1 (NBR1), as well as RNA-binding protein transactive response DNA-binding protein-43 (TDP-43) are cleaved by proteinase 2A and 3C, contributing to impaired autophagy and increased accumulation of protein aggregates (Illustration Credit: Ben Smith). [Powerpoint File]

RNA Splicing: Regulation and Dysregulation in the Heart

RNA Splicing: Regulation and Dysregulation in the Heart

Maarten M.G. van den Hoogenhof, Yigal M. Pinto, Esther E. Creemers

Two-step splicing reaction. Splicing occurs by a 2-step trans-esterification reaction to remove introns and to join exons together. In the first step, U1 small nuclear ribonucleoprotein (snRNP) assembles at the 5′ splice site of an exon and U2 snRNP at the branch point sequence (BPS), just upstream of the 3′splice site of the adjacent/downstream exon. This configuration is known as the prespliceosome. Hereafter, U1 and U2 are joined by the snRNPs U5 and U4–U6 complexes to form the precatalytic spliceosome. Next, U4–U6 complexes unwind, releasing U4 and U1 from the prespliceosomal complex. This allows U6 to base pair with the 5′ splice site and the BPS. The 5′ splice site gets cleaved, which leads to a free 3′ OH-group at the upstream exon, and a branched intronic region at the downstream exon, called the intron lariat. During the second step, U5 pairs with sequences in both the 5′ and 3′ splice site, positioning the 2 ends together. The 3′ OH-group of the upstream (5′) exon fuses with the 3′ intron–exon junction, thereby conjoining the 2 exons and excising the intron in the form of a lasso-shaped intron lariat. Finally, the spliceosome disassembles, and all components are recycled for future splicing reactions. [Powerpoint File]

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Conrad P. Hodgkinson, Akshay Bareja, José A. Gomez, Victor J. Dzau

Paracrine factors affect different temporal events after myocardial injury influencing different stages of the reparative and regenerative processes. [Powerpoint File]

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Conrad P. Hodgkinson, Akshay Bareja, José A. Gomez, Victor J. Dzau

Paracrine factors affect different cell types and create a microenvironment that is influenced by concentration gradients, with temporal and spatial summation of cellular responses. Reprinted from Hodgkinson et al149 with permission of the publisher. Copyright ©2015, Elsevier. [Powerpoint File]

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Emerging Concepts in Paracrine Mechanisms in Regenerative Cardiovascular Medicine and Biology

Conrad P. Hodgkinson, Akshay Bareja, José A. Gomez, Victor J. Dzau

Paracrine factors are pleiotropic. For illustration, we show the cellular effects of 2 selective paracrine factors on the cardiomyocyte. Left, Hypoxic-induced Akt regulated stem cell factor (HASF) and secreted frizzled related protein 2 (Sfrp2) inhibit cardiomyocyte apoptosis through divergent pathways. HASF, after binding to a growth factor receptor, inhibits cytochrome release from mitochondria via protein kinase C-ε (PKCε). In contrast, Sfrp2 inhibits Wnt activation of frizzled receptors. This induces β-catenin degradation via the anaphase promoting complex (APC) complex. Right, Abi3bp and Sfrp2 promote cardiac progenitor cell differentiation and inhibiting proliferation. Abi3bp activates integrin-β1. Src and extracellular signal regulated kinase (ERK) activation work together to inhibit proliferation. PKCζ and Akt activation switch on cardiac genes. Sfrp2 sequesters Wnt, preventing the activation of frizzled receptors. This promotes c-Jun N-terminal kinase (JNK) activation and cardiac gene expression. Inhibition of β-catenin blocks the proliferation pathway in these cells. ECM indicates extracellular matrix; FRZ, frizzled; and TF, transcription factor. [Powerpoint File]

Investigating the Transcriptional Control of Cardiovascular Development

Investigating the Transcriptional Control of Cardiovascular Development

Irfan S. Kathiriya*, Elphège P. Nora*, Benoit G. Bruneau

Studying cardiac regulatory elements. A, Left, Evolutionary constraints on some regulatory elements render them identifiable by comparative genomics, as exemplified by enhancers upstream of mouse Nkx2-5.86 Right, Combinations of specific chromatin features can reveal potential regulatory elements active in a given cell type. B, Left, Enhancer activity is classically tested by an ability of candidate elements to drive tissue- or stage-specific activity of a reporter. Middle, New technologies, such as SIF-seq,87 allow screening of large genomic neighborhoods for tissue-specific enhancers. Right, Genome Regulatory Organization Mapping with Integrated Transposons92 is a technology that can reveal integrated regulatory inputs exerted at a locus. [Powerpoint FIle]

Investigating the Transcriptional Control of Cardiovascular Development

Investigating the Transcriptional Control of Cardiovascular Development

Irfan S. Kathiriya*, Elphège P. Nora*, Benoit G. Bruneau

Molecular players for transcriptional regulation. A, Cis-regulatory elements containing DNA-binding sites are bound by transcription factors and (B) modulate the assembly of the preinitiation complex at promoters through (C) physical contacts driven by a 3-dimensional arrangement of chromatin, thereby acting as (D) a molecular platform between cellular signaling and gene activity. [Powerpoint File]

The Clinical Profile and Pathophysiology of Atrial Fibrillation: Relationships Among Clinical Features, Epidemiology, and Mechanisms

The Clinical Profile and Pathophysiology of Atrial Fibrillation: Relationships Among Clinical Features, Epidemiology, and Mechanisms

Jason Andrade, Paul Khairy, Dobromir Dobrev, Stanley Nattel

Mechanisms by which fibrosis can promote atrial arrhythmogenesis leading to atrial fibrillation. A, Excess extracellular matrix protein can interrupt cardiac muscle bundle continuity in the longitudinal direction, leading to conduction slowing and block that help to initiate and maintain re-entry. B, Fibroblasts can interact with cardiomyocytes electrically. Because fibroblasts are an inexcitable current sink, they can slow conduction. In addition, because they are less polarized than cardiomyocytes, they can enhance phase-4 depolarization (leading to spontaneous firing), depolarize the cardiomyocyte resting membrane potential, and shorten action potential duration (APD; favoring re-entry). ECM indicates extracellular matrix. [Powerpoint File]

The Clinical Profile and Pathophysiology of Atrial Fibrillation: Relationships Among Clinical Features, Epidemiology, and Mechanisms

The Clinical Profile and Pathophysiology of Atrial Fibrillation: Relationships Among Clinical Features, Epidemiology, and Mechanisms

Jason Andrade, Paul Khairy, Dobromir Dobrev, Stanley Nattel

Evidence that fibrous tissue can act as a barrier to longitudinal conduction in remodeled atrial tissue prone to atrial fibrillation (AF). A, Masson trichrome stains (cardiomyocytes pink, collagen blue) of atrial tissue from a control dog (CTL, top), a dog with congestive heart failure (CHF) induced by 2 weeks of ventricular tachypacing (middle), and a dog subjected to 2-week ventricular tachypacing and then allowed to dhow full hemodynamic recovery through cessation of pacing for 4 weeks (REC, bottom). Note that fibrous tissue separates cardiomyocytes in the longitudinal direction (yellow arrows) for the CHF and REC conditions. Both CHF and REC dogs showed conduction abnormalities and prolonged AF. In the REC case, full hemodynamic recovery allows for normalization of other atrial properties but leaves fibrosis unchanged, pointing to fibrosis as a sufficient condition for the AF substrate. B, Top, Optical mapping of atrial conduction in a CTL (left) and REC (right) dog, showing clear conduction abnormalities in REC. Bottom, Results of realistic mathematical modeling of the same preparations shown above, assuming that fibrous tissue creates a conduction barrier. There is good general agreement between experimental observations and the modeling results, supporting the notion that fibrosis produces conduction barriers. Data reproduced from Burstein et al189 with permission of the American Heart Association Inc. REC indicates recovered heart failure. [Powerpoint File]

Protein Engineering for Cardiovascular Therapeutics: Untapped Potential for Cardiac Repair

Protein Engineering for Cardiovascular Therapeutics: Untapped Potential for Cardiac Repair

Steven M. Jay, Richard T. Lee

Molecular display. A protein or peptide with specific properties can be derived via molecular display after multiple rounds of selection. Polypeptide libraries can be made or purchased and either inserted into molecular hosts such as phage or yeast or appended to carrier molecules such as mRNA or ribosomes. The schematic is representative of phage or cell-surface display, where proteins are displayed on the surfaces of organisms that are subsequently exposed to various substrates, which serve as selection criteria. In the example, protein-mediated binding of the organism with a specific substrate followed by washing away of nonspecific binders and elution enable amplification of those organisms displaying proteins with the desired properties. Repetitive screening with additional or more stringent selection criteria enables ultimate isolation of an optimized protein sequence based on phenotype, which can then be linked with genotype after extraction of genetic material from the organism. Thus, molecular display facilitates discovery of information needed to design a protein with specific properties evolved to match nearly any chosen selection criteria. [Powerpoint File]

Protein Engineering for Cardiovascular Therapeutics: Untapped Potential for Cardiac Repair

Protein Engineering for Cardiovascular Therapeutics: Untapped Potential for Cardiac Repair

Steven M. Jay, Richard T. Lee

Protein engineering methods to enable drug delivery. A number of techniques within the realm of protein engineering could be used to enhance delivery of small molecules, proteins, and nucleic acids to the heart. Examples shown include the targeting of a nanocarrier to a cell type of interest (eg, cardiomyocytes, endothelial cells) by a peptide molecule derived via molecular display and the enhancement of cellular internalization of a therapeutic entity via fusion with a protein transduction domain (PTD). siRNA indicates small interfering RNA. (Illustration credit: Ben Smith). [Powerpoint File]