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2000; Lippincott Williams & Wilkins; Volume: 102; Issue: 25 Linguagem: Inglês

10.1161/01.cir.102.25.3026

1524-4539

Michael Schneider, Robert J. Schwartz,

RNA and protein synthesis mechanisms

HomeCirculationVol. 102, No. 25Chips Ahoy Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBChips Ahoy Gene Expression in Failing Hearts Surveyed by High-Density Microarrays Michael D. Schneider and Robert J. Schwartz Michael D. SchneiderMichael D. Schneider From the Center for Cardiovascular Development (M.D.S., R.J.S.), Departments of Medicine (M.D.S.), Molecular and Cellular Biology (M.D.S, R.J.S.), and Molecular Physiology and Biophysics (M.D.S, R.J.S), Baylor College of Medicine, Houston, Tex. and Robert J. SchwartzRobert J. Schwartz From the Center for Cardiovascular Development (M.D.S., R.J.S.), Departments of Medicine (M.D.S.), Molecular and Cellular Biology (M.D.S, R.J.S.), and Molecular Physiology and Biophysics (M.D.S, R.J.S), Baylor College of Medicine, Houston, Tex. Originally published19 Dec 2000https://doi.org/10.1161/01.CIR.102.25.3026Circulation. 2000;102:3026–3027Organ-level heart failure can result, most obviously, from the death of cardiac myocytes; such death can occur either acutely (with infarction) or more sporadically (in chronic disease). Both types of death can involve a "cell suicide" pathway known as apoptosis.1 Another key factor for cardiac dysfunction is myocardial fibrosis, which can be, in part, a direct consequence of angiotensin II levels; therefore, a possible benefit of therapy with angiotensin-converting enzyme inhibitors is an improvement in fibrosis. A third generic mechanism for defects in macroscopic or clinically evident cardiac performance arises from changes in the intrinsic mechanical properties of individual cardiac muscle cells.2 This phenomenon is understood to occur, in part, through changes in the expression of cardiac genes, both subtle and overt, which are collectively referred to as the hypertrophic gene "program."3 Reprogramming cardiac gene expression encompasses, among its other features, alterations in (1) contractile proteins of the sarcomere, (2) regulators of calcium handling and other aspects of ion transport, and (3) secreted growth factors and cytokines. Therefore, in pursuit of potential targets for therapy, 2 important aspects of contemporary heart failure research are to discover the signaling pathways that confer adverse responses34 and to establish a much more comprehensive understanding of the end-organ changes that actually occur.In the current issue of Circulation, Yang et al5 performed a mammoth screen for altered gene expression in heart failure using a newly developed technology, high-density DNA microarrays.6 Although conceptually simple, these assays are a technical tour de force (Figure). Hundreds, thousands, or tens of thousands of individual DNA segments (presented as short, synthetic DNA strands in their article) are printed on glass slides ("gene chips") by robotic microfabrication techniques. Messenger RNA is purified (in this case, from normal versus failing hearts), modified with a visualizable tag (in this case, biotinylated nucleotides), and used to label the chips using a fluorescent biotin-binding protein. Levels of expression are therefore monitored simultaneously, as levels of fluorescence overlying each DNA spot, for as many genes as are printed on the slides. Publications have begun to appear that use this technology to monitor gene expression in experimental models of heart disease, including myocardial infarction7 and hypertrophy.8 The present study by Yang et al5 is distinctive in seeking to achieve a similar high-throughput expression profile in human heart failure itself.For example, with this technique, the expression of mRNA for a gene known to be associated with human heart failure, atrial natriuretic factor, was detected only in the ventricle of failing hearts. More importantly, >5000 different human transcripts were assayed concurrently, and a number of novel discoveries resulted. One gene whose expression was deficient in heart failure was skeletal muscle LIM protein 1 (SLIM1, FHL1). Beyond the microarray studies, which were performed in only 2 normal and 2 failing hearts, the authors substantiated the downregulation of SLIM1 in a larger number of cases using immunoblotting; this technique also ascertained that the protein (and not merely the mRNA that encodes it) is indeed less highly expressed in heart failure.The LIM motif derives its name from the initials of the 3 transcription factors in which the sequence was first seen (Lin-11, Isl-1, and Mec-3); it comprises 2 cysteine- and histidine-rich zinc-binding regions ("zinc fingers") and mediates the physical interaction between diverse proteins.9 Most notably, this mediation includes both interaction with the cytoskeleton and the assembly of multiprotein transcription factor complexes.9 Some LIM proteins also contain a homeodomain that binds DNA directly, a cysteine-rich protein (CRP) domain, a kinase domain for phosphorylation, or additional protein-binding motifs such as a postsynaptic density disc-large zo-1 (PDZ) domain.910 The PDZ-LIM protein Oracle is most highly expressed in the heart.10 Interestingly, as shown by the use of null mutations in genetically engineered mice, the LIM-only protein LMO-2 is required for angiogenesis and erythropoiesis,11 and mice lacking muscle LIM protein (MLP, CRP3) develop dilated cardiomyopathy and skeletal muscle defects.12 It is still unknown whether this outcome indicates an essential function of MLP in the cytoplasm versus in the nucleus, because MLP is found in both regions of the cell.9 As was recently reported in this journal, MLP expression is decreased 2- to 3-fold in human dilated or ischemic cardiomyopathy.13SLIM1 belongs to the class of striated muscle LIM-only proteins that contain 4.5 LIM domains. Within the cell, SLIM1 is found at focal adhesions and along actin stress fibers.14 An alternatively spliced human isoform, SLIMMER (SLIM1 with extra regions), contains only 3 LIM domains, adds functional signals for nuclear import and export, and localizes to the nuclei of undifferentiated myoblasts and the cytoplasm of differentiated myotubes.14 Most abundant in skeletal muscle, SLIM1 was reportedly localized to the atria in adult rabbit myocardium and, in that species, it was not detected in the ventricle.15 In the context of that study, the presence of SLIM1 in the human ventricle is unexpected, which may reflect species disparities in chamber-specific expression, differences in the threshold for detection (SLIM1 was found, by in situ hybridization, at low levels in embryonic mouse myocardium16 ) or, conceivably, cross-reactivity with closely related transcripts and proteins. SLIM3 (FHL2, DRAL) is preferentially expressed in the human ventricle17 ; however, the antibody used here was generated against a peptide that is seemingly unique to SLIM1. In contrast with the present report, SLIM1 was reportedly upregulated in mouse models of cardiac hypertrophy (aortic banding) and cardiomyopathy (MLP-deficient mice).16 In addition, upregulation of SLIM1 has been inferred from the prevalence of transcripts in cDNA libraries of normal versus hypertrophic human hearts.18 Therefore, additional work to reconcile these differences, including potential clinical disparities in the duration or severity of disease, will be important.Notwithstanding the remarkable power of profiling gene expression with microarrays, of which the current study is a potent illustration, some limitations are noteworthy, including several discussed by the authors. Low-abundance transcripts that are not detected by more standard hybridization techniques and are found only by reverse transcriptase polymerase chain reaction amplification are unlikely to be seen. Like all other probes and reagents, specificity can be an issue, particularly for gene families with multiple related members, unless the regions incorporated in the array are chosen with this in mind. Beyond these merely technical issues lie 3 broader considerations. First, casting the net for genome-wide changes in gene expression ("transcriptomes") will inevitably identify variations. Establishing which of these is functionally important will require better informatics (computational approaches to sift through the titanic amounts of raw expression data and help define meaningful patterns) and a more efficient means of confirming gene function experimentally than conventional methods of genetic engineering in mice. Second, changes in mRNA need not accompany changes in the corresponding protein's abundance or its state of activation. Third, protein microarrays have an additional "blind spot," at least for the moment. Until all possible genes are both known and represented in arrays, alternative technologies that do not depend on prior knowledge of the genes involved, including subtractive hybridization1019 and serial analysis of gene expression,20 can bypass this gap in knowledge or reagents and provide a complementary strategy to unmask instructive differences in cardiovascular biology and disease.The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.Download figureDownload PowerPoint Figure 1. High-throughput analysis of gene expression in heart failure by hybridization with high-density DNA arrays.FootnotesCorrespondence to Michael D. Schneider, MD, Molecular Cardiology Unit, Baylor College of Medicine, One Baylor Plaza, Room 506C, Houston, TX 77030. E-mail [email protected] References 1 Kang PM, Izumo S. Apoptosis and heart failure: a critical review of the literature. Circ Res.2000; 86:1107–1113.CrossrefMedlineGoogle Scholar2 Houser SR, Lakatta EG. Function of the cardiac myocyte in the conundrum of end-stage, dilated human heart failure. Circulation.1999; 99:600–604.CrossrefMedlineGoogle Scholar3 Hunter JJ, Chien KR. Mechanisms of disease: signaling pathways for cardiac hypertrophy and failure. N Engl J Med.1999; 341:1276–1283.CrossrefMedlineGoogle Scholar4 Zhang D, Gaussin V, Taffet GE, et al. TAK1 is activated in the myocardium following pressure overload and is sufficient to provoke heart failure in transgenic mice. Nat Med.2000; 6:556–563.CrossrefMedlineGoogle Scholar5 Yang J, Moravec CS, Sussman MA, et al. Decreased SLIM1 expression and increased gelsolin expression in failing human hearts measured by high-density oligonucleotide arrays. Circulation.2000; 102:3046–3052.CrossrefMedlineGoogle Scholar6 Lockhart DJ, Winzeler EA. Genomics, gene expression and DNA arrays. Nature.2000; 405:827–836.CrossrefMedlineGoogle Scholar7 Stanton LW, Garrard LJ, Damm D, et al. Altered patterns of gene expression in response to myocardial infarction. Circ Res.2000; 86:939–945.CrossrefMedlineGoogle Scholar8 Friddle CJ, Koga T, Rubin EM, et al. Expression profiling reveals distinct sets of genes altered during induction and regression of cardiac hypertrophy. Proc Natl Acad Sci USA.2000; 97:6745–6750.Google Scholar9 Bach I. The LIM domain: regulation by association. Mech Dev.2000; 91:5–17.CrossrefMedlineGoogle Scholar10 Passier R, Richardson JA, Olson EN. Oracle, a novel PDZ-LIM domain protein expressed in heart and skeletal muscle. Mech Dev.2000; 92:277–284.CrossrefMedlineGoogle Scholar11 Yamada Y, Pannell R, Forster A, et al. The oncogenic LIM-only transcription factor Lmo2 regulates angiogenesis but not vasculogenesis in mice. ProcNatl Acad Sci USA.2000; 97:320–324.Google Scholar12 Arber S, Hunter JJ, Ross J Jr, et al. MLP-deficient mice exhibit a disruption of cardiac cytoarchitectural organization, dilated cardiomyopathy, and heart failure. Cell.1997; 88:393–403.CrossrefMedlineGoogle Scholar13 Zolk O, Caroni P, Bohm M. Decreased expression of the cardiac LIM domain protein MLP in chronic human heart failure. Circulation.2000; 101:2674–2677.CrossrefMedlineGoogle Scholar14 Brown S, McGrath MJ, Ooms LM, et al. Characterization of two isoforms of the skeletal muscle LIM protein 1, SLIM1: localization of SLIM1 at focal adhesions and the isoform slimmer in the nucleus of myoblasts and cytoplasm of myotubes suggests distinct roles in the cytoskeleton and in nuclear-cytoplasmic communication. J Biol Chem.1999; 274:27083–27091.CrossrefMedlineGoogle Scholar15 Brown S, Biben C, Ooms LM, et al. The cardiac expression of striated muscle LIM protein 1 (SLIM1) is restricted to the outflow tract of the developing heart. J Mol Cell Cardiol.1999; 31:837–843.CrossrefMedlineGoogle Scholar16 Chu P, Ruiz-Lozano P, Zhou Q, et al. Expression patterns of FHL/SLIM family members suggest important functional roles in skeletal muscle and cardiovascular system. Mech Dev.2000; 95:259–265.CrossrefMedlineGoogle Scholar17 Genini M, Schwalbe P, Scholl FA, et al. Subtractive cloning and characterization of DRAL, a novel LIM-domain protein down-regulated in rhabdomyosarcoma. DNA Cell Biol.1997; 16:433–442.CrossrefMedlineGoogle Scholar18 Hwang DM, Dempsey AA, Wang RX, et al. A genome-based resource for molecular cardiovascular medicine: toward a compendium of cardiovascular genes. Circulation.1997; 96:4146–4203.CrossrefMedlineGoogle Scholar19 Johnatty SE, Dyck JR, Michael LH, et al. Identification of genes regulated during mechanical load-induced cardiac hypertrophy. J Mol Cell Cardiol.2000; 32:805–815.CrossrefMedlineGoogle Scholar20 Velculescu VE, Zhang L, Vogelstein B, et al. Serial analysis of gene expression. Science.1995; 270:484–487.CrossrefMedlineGoogle Scholar eLetters(0) eLetters should relate to an article recently published in the journal and are not a forum for providing unpublished data. Comments are reviewed for appropriate use of tone and language. Comments are not peer-reviewed. Acceptable comments are posted to the journal website only. Comments are not published in an issue and are not indexed in PubMed. Comments should be no longer than 500 words and will only be posted online. References are limited to 10. Authors of the article cited in the comment will be invited to reply, as appropriate. Comments and feedback on AHA/ASA Scientific Statements and Guidelines should be directed to the AHA/ASA Manuscript Oversight Committee via its Correspondence page. Sign In to Submit a Response to This Article Previous Back to top Next FiguresReferencesRelatedDetailsCited By Podesser B (2011) Editorial: The old and multimorbid patient – a challenge in cardiac surgery and cardiology, European Surgery, 10.1007/s10353-011-0605-y, 43:2, (62-62), Online publication date: 1-Apr-2011. Schmidt W, Mitterer G and Podesser B (2011) Gene expression profiles characterizing the progression of heart failure in patients with aortic valve stenosisGenexpressionsprofile als Progressionsmarker der Herzinsuffizienz bei Patienten mit Aortenklappenstenose, European Surgery, 10.1007/s10353-011-0602-1, 43:2, (110-119), Online publication date: 1-Apr-2011. Hu S, Duan H, Li Q, Yang Y, Chen J, Wang L and Wang H (2009) Hepatocyte growth factor protects endothelial cells against gamma ray irradiation-induced damage, Acta Pharmacologica Sinica, 10.1038/aps.2009.133, 30:10, (1415-1420), Online publication date: 1-Oct-2009. Kaufman B, Desai M, Reddy S, Osorio J, Chen J, Mosca R, Ferrante A and Mital S (2008) Genomic Profiling of Left and Right Ventricular Hypertrophy in Congenital Heart Disease, Journal of Cardiac Failure, 10.1016/j.cardfail.2008.06.002, 14:9, (760-767), Online publication date: 1-Nov-2008. Mueller J and Wallukat G (2007) Patients who Have Dilated Cardiomyopathy Must Have a Trial of Bridge to Recovery (Pro), Heart Failure Clinics, 10.1016/j.hfc.2007.05.006, 3:3, (299-315), Online publication date: 1-Jul-2007. (2005) Transcriptional Profiling in Heart Failure Molecular Mechanisms of Cardiac Hypertrophy and Failure, 10.3109/9780203503249-50, (863-882) Hon J and Yacoub M (2003) Bridge to recovery with the use of left ventricular assist device and clenbuterol, The Annals of Thoracic Surgery, 10.1016/S0003-4975(03)00460-0, 75:6, (S36-S41), Online publication date: 1-Jun-2003. Yussman M, Toyokawa T, Odley A, Lynch R, Wu G, Colbert M, Aronow B, Lorenz J and Dorn G (2002) Mitochondrial death protein Nix is induced in cardiac hypertrophy and triggers apoptotic cardiomyopathy, Nature Medicine, 10.1038/nm719, 8:7, (725-730), Online publication date: 1-Jul-2002. December 19, 2000Vol 102, Issue 25 Advertisement Article Information Metrics Copyright © 2000 by American Heart Associationhttps://doi.org/10.1161/01.CIR.102.25.3026 Originally publishedDecember 19, 2000 KeywordsEditorialsgeneticsheart failurePDF download Advertisement