Identification of differentially expressed genes in cardiac hypertrophy by analysis of expressed sequence tags

Association of Vitamin K Status with Arterial Calcification and Stiffness in Chronic Kidney Disease: The Chronic Renal Insufficiency Cohort

Background

Arterial calcification and stiffness are common in people with chronic kidney disease (CKD). Higher vitamin K status has been associated with less arterial calcification and stiffness in CKD in cross-sectional studies.

Objectives

To determine the association of vitamin K status with coronary artery calcium (CAC) and arterial stiffness [pulse wave velocity (PWV)] at baseline and over 2-4 follow-up years in adults with mild-to-moderate CKD.

Methods

Participants (n = 2722) were drawn from the well-characterized Chronic Renal Insufficiency Cohort. Two vitamin K status biomarkers, plasma phylloquinone and plasma dephospho-uncarboxylated matrix gla protein [(dp)ucMGP], were measured at baseline. CAC and PWV were measured at baseline and over 2-4 y of follow-up. Differences across vitamin K status categories in CAC prevalence, incidence, and progression (defined as ≥100 Agatston units/y increase) and PWV at baseline and over follow-up were evaluated using multivariable-adjusted generalized linear models.

Results

CAC prevalence, incidence, and progression did not differ across plasma phylloquinone categories. Moreover, CAC prevalence and incidence did not differ according to plasma (dp)ucMGP concentration. Compared with participants with the highest (dp)ucMGP (≥450 pmol/L), those in the middle category (300-449 pmol/L) had a 49% lower rate of CAC progression (incidence rate ratio: 0.51; 95% CI: 0.33, 0.78). However, CAC progression did not differ between those with the lowest (<300 pmol/L) and those with the highest plasma (dp)ucMGP concentration (incidence rate ratio: 0.82; 95% CI: 0.56, 1.19). Neither vitamin K status biomarker was associated with PWV at baseline or longitudinally.

Conclusions

Vitamin K status was not consistently associated with CAC or PWV in adults with mild-to-moderate CKD.

EGR1 Is Implicated in Right Ventricular Cardiac Remodeling Associated with Pulmonary Hypertension

Background: Pulmonary hypertension (PH) is a vasoconstrictive disease characterized by elevated mean pulmonary arterial pressure (mPAP) at rest. Idiopathic pulmonary arterial hypertension (iPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) represent two distinct subtypes of PH. Persisting PH leads to right ventricular (RV) hypertrophy, heart failure, and death. RV performance predicts survival and surgical interventions re-establishing physiological mPAP reverse cardiac remodeling. Nonetheless, a considerable number of PH patients are deemed inoperable. The underlying mechanism(s) governing cardiac regeneration, however, remain largely elusive. Methods: In a longitudinal approach, we profiled the transcriptional landscapes of hypertrophic RVs and recovered hearts 3 months after surgery of iPAH and CTEPH patients. Results: Genes associated with cellular responses to inflammatory stimuli and metal ions were downregulated, and cardiac muscle tissue development was induced in iPAH after recovery. In CTEPH patients, genes related to muscle cell development were decreased, and genes governing cardiac conduction were upregulated in RVs following regeneration. Intriguingly, early growth response 1 (EGR1), a profibrotic regulator, was identified as a major transcription factor of hypertrophic RVs in iPAH and CTEPH. A histological assessment confirmed our biocomputational results, and suggested a pivotal role for EGR1 in RV vasculopathy. Conclusion: Our findings improved our understanding of the molecular events driving reverse cardiac remodeling following surgery. EGR1 might represent a promising candidate for targeted therapy of PH patients not eligible for surgical treatment.

Vitamin K status, all-cause mortality, and cardiovascular disease in adults with chronic kidney disease: the Chronic Renal Insufficiency Cohort

BACKGROUND

Vascular calcification contributes to cardiovascular disease (CVD) and mortality in individuals with chronic kidney disease (CKD). Vitamin K-dependent proteins function as calcification inhibitors in vascular tissue.

OBJECTIVES

We sought to determine the association of vitamin K status with mortality and CVD events in adults with CKD.

METHODS

Plasma dephospho-uncarboxylated matrix gla protein ((dp)ucMGP), which increases when vitamin K status is low, and plasma phylloquinone (vitamin K1), which decreases when vitamin K status is low, were measured in 3066 Chronic Renal Insufficiency Cohort participants (median age = 61 y, 45% female, 41% non-Hispanic black, median estimated glomerular filtration rate [eGFR] = 41 mL/min/1.73m2). The association of vitamin K status biomarkers with all-cause mortality and atherosclerotic-related CVD was determined using multivariable Cox proportional hazards regression.

RESULTS

There were 1122 deaths and 599 atherosclerotic CVD events over the median 12.8 follow-up years. All-cause mortality risk was 21-29% lower among participants with plasma (dp)ucMGP <450 pmol/L (n = 2361) compared with those with plasma (dp)ucMGP ≥450 pmol/L (adjusted HRs [95% CIs]: <300 pmol/L = 0.71 [0.61, 0.83], 300-449 pmol/L = 0.77 [0.66, 0.90]) and 16-19% lower among participants with plasma phylloquinone ≥0.50 nmol/L (n = 2421) compared to those with plasma phylloquinone <0.50 nmol/L (adjusted HRs: 0.50, 0.99 nmol/L = 0.84 [0.72, 0.99], ≥1.00 nmol/L = 0.81 [0.70, 0.95]). The risk of atherosclerotic CVD events did not significantly differ across plasma (dp)ucMGP or phylloquinone categories.

CONCLUSIONS

Two biomarkers of vitamin K status were associated with a lower all-cause mortality risk but not atherosclerotic CVD events. Additional studies are needed to clarify the mechanism underlying this association and evaluate the impact of improving vitamin K status in people with CKD.

Understanding the molecular basis of cardiomyopathy

Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.

Vitamin K2-a neglected player in cardiovascular health: a narrative review

Vitamin K₂ serves an important role in cardiovascular health through regulation of calcium homeostasis. Its effects on the cardiovascular system are mediated through activation of the anti-calcific protein known as matrix Gla protein. In its inactive form, this protein is associated with various markers of cardiovascular disease including increased arterial stiffness, vascular and valvular calcification, insulin resistance and heart failure indices which ultimately increase cardiovascular mortality. Supplementation of vitamin K₂ has been strongly associated with improved cardiovascular outcomes through its modification of systemic calcification and arterial stiffness. Although its direct effects on delaying the progression of vascular and valvular calcification is currently the subject of multiple randomised clinical trials, prior reports suggest potential improved survival among cardiac patients with vitamin K₂ supplementation. Strengthened by its affordability and Food and Drug Adminstration (FDA)-proven safety, vitamin K₂ supplementation is a viable and promising option to improve cardiovascular outcomes.

FHL-1 is not involved in pressure overload-induced maladaptive right ventricular remodeling and dysfunction

AIMS

The cytoskeletal signaling protein four and-a-half LIM domains 1 (FHL-1) has recently been identified as a novel key player in pulmonary hypertension as well as in left heart diseases. In this regard, FHL-1 has been implicated in dysregulated hypertrophic signaling in pulmonary arterial smooth muscle cells leading to pulmonary hypertension. In mice, FHL-1-deficiency (FHL-1^-/-) led to an attenuated hypertrophic signaling associated with a blunted hypertrophic response of the pressure-overloaded left ventricle (LV). However, the role of FHL-1 in right heart hypertrophy has not yet been addressed.

METHODS AND RESULTS

We investigated FHL-1 expression in C57Bl/6 mice subjected to chronic biomechanical stress and found it to be enhanced in the right ventricle (RV). Next, we subjected FHL-1^-/- and corresponding wild-type mice to pressure overload of the RV by pulmonary arterial banding for various time points. However, in contrast to the previously published study in LV-pressure overload, which was confirmed here, RV hypertrophy and hypertrophic signaling was not diminished in FHL-1^-/- mice. In detail, right ventricular pressure overload led to hypertrophy, dilatation and fibrosis of the RV from both FHL-1^-/- and wild-type mice. RV remodeling was associated with impaired RV function as evidenced by reduced tricuspid annular plane systolic excursion. Additionally, PAB induced upregulation of natriuretic peptides and slight downregulation of phospholamban and ryanodine receptor 2 in the RV. However, there was no difference between genotypes in the degree of expression change.

CONCLUSION

FHL-1 pathway is not involved in the control of adverse remodeling in the pressure overloaded RV.

Scaffold Proteins: From Coordinating Signaling Pathways to Metabolic Regulation

Among their pleiotropic functions, scaffold proteins are required for the accurate coordination of signaling pathways. It has only been within the past 10 years that their roles in glucose homeostasis and metabolism have emerged. It is well appreciated that changes in the expression or function of signaling effectors, such as receptors or kinases, can influence the development of chronic diseases such as diabetes and obesity. However, little is known regarding whether scaffolds have similar roles in the pathogenesis of metabolic diseases. In general, scaffolds are often underappreciated in the context of metabolism or metabolic diseases. In the present review, we discuss various scaffold proteins and their involvement in signaling pathways related to metabolism and metabolic diseases. The aims of the present review were to highlight the importance of scaffold proteins and to raise awareness of their physiological contributions. A thorough understanding of how scaffolds influence metabolism could aid in the discovery of novel therapeutic approaches to treat chronic conditions, such as diabetes, obesity, and cardiovascular disease, for which the incidence of all continue to increase at alarming rates.

Four and a half LIM domain protein signaling and cardiomyopathy

Four and a half LIM domain (FHL) protein family members, FHL1 and FHL2, are multifunctional proteins that are enriched in cardiac muscle. Although they both localize within the cardiomyocyte sarcomere (titin N2B), they have been shown to have important yet unique functions within the context of cardiac hypertrophy and disease. Studies in FHL1-deficient mice have primarily uncovered mitogen-activated protein kinase (MAPK) scaffolding functions for FHL1 as part of a novel biomechanical stretch sensor within the cardiomyocyte sarcomere, which acts as a positive regulator of pressure overload-mediated cardiac hypertrophy. New data have highlighted a novel role for the serine/threonine protein phosphatase (PP5) as a deactivator of the FHL1-based biomechanical stretch sensor, which has implications in not only cardiac hypertrophy but also heart failure. In contrast, studies in FHL2-deficient mice have primarily uncovered an opposing role for FHL2 as a negative regulator of adrenergic-mediated signaling and cardiac hypertrophy, further suggesting unique functions targeted by FHL proteins in the "stressed" cardiomyocyte. In this review, we provide current knowledge of the role of FHL1 and FHL2 in cardiac muscle as it relates to their actions in cardiac hypertrophy and cardiomyopathy. A specific focus will be to dissect the pathways and protein-protein interactions that underlie FHLs' signaling role in cardiac hypertrophy as well as provide a comprehensive list of FHL mutations linked to cardiac disease, using evidence gained from genetic mouse models and human genetic studies.

Involvement of human monogenic cardiomyopathy genes in experimental polygenic cardiac hypertrophy

Hypertrophic cardiomyopathy thickens heart muscles, reducing functionality and increasing risk of cardiac disease and morbidity. Genetic factors are involved, but their contribution is poorly understood. We used the hypertrophic heart rat (HHR), a unique normotensive polygenic model of cardiac hypertrophy and heart failure, to investigate the role of genes associated with monogenic human cardiomyopathy. We selected 42 genes involved in monogenic human cardiomyopathies to study: 1) DNA variants, by sequencing the whole genome of 13-wk-old HHR and age-matched normal heart rat (NHR), its genetic control strain; 2) mRNA expression, by targeted RNA-sequencing in left ventricles of HHR and NHR at 5 ages (2 days old and 4, 13, 33, and 50 wk old) compared with human idiopathic dilated cardiomyopathy data; and 3) microRNA expression, with rat microRNA microarrays in left ventricles of 2-day-old HHR and age-matched NHR. We also investigated experimentally validated microRNA-mRNA interactions. Whole-genome sequencing revealed unique variants mostly located in noncoding regions of HHR and NHR. We found 29 genes differentially expressed in at least 1 age. Genes encoding desmoglein 2 ( Dsg2) and transthyretin ( Ttr) were significantly differentially expressed at all ages in the HHR, but only Ttr was also differentially expressed in human idiopathic cardiomyopathy. Lastly, only two microRNAs differentially expressed in the HHR were present in our comparison of validated microRNA-mRNA interactions. These two microRNAs interact with five of the genes studied. Our study shows that genes involved in monogenic forms of human cardiomyopathies may also influence polygenic forms of the disease.

Novel Muscle-Specific Genes TCAP, TNNI1, and FHL1 in Cattle: SNVs, Linkage Disequilibrium, Combined Genotypes, Association Analysis of Growth Performance, and Carcass Quality Traits and Expression Studies

TCAP, TNNI1, and FHL1 regulate muscle growth and development. In this study, four single nucleotide variants (SNVs) were discovered in almost all of the exon and intron regions of the TCAP, TNNI1, and FHL1 genes using DNA pooled sequencing, polymerase chain reaction (PCR)-RFLP, and forced-PCR-RFLP methods in 576 cattle. Four SNVs were significantly associated with the growth performance and carcass quality traits of the cattle. In addition, the haplotype, haplotype frequency, and linkage disequilibrium coefficient of three sequence variants were also evaluated in the cattle population. Haplotype analysis demonstrated that eight haplotypes were present in the Qinchuan cattle population and no haplotypes were present in the Chinese Holstein population; haplotype 1 had the highest frequency in the Qinchuan (42.7%) population. Statistical analyses of 12 combined genotypes indicated that some were significantly associated with the growth performance and carcass quality traits of the Qinchuan cattle population. Moreover, the quantitative real-time polymerase chain reaction results demonstrated that the bovine TCAP, TNNI1, and FHL1 genes were exclusively expressed in muscle tissue. These data support the high potentials of the TCAP, TNNI1, and FHL1 as marker genes to improve the growth performance and carcass quality traits of Qinchuan cattle or other animals selection programs.

Scaffold Proteins Regulating Extracellular Regulated Kinase Function in Cardiac Hypertrophy and Disease

The mitogen activated protein kinase (MAPK)-extracellular regulated kinase 1/2 (ERK1/2) pathway is a central downstream signaling pathway that is activated in cardiac muscle cells during mechanical and agonist-mediated hypertrophy. Studies in genetic mouse models deficient in ERK-associated MAPK components pathway have further reinforced a direct role for this pathway in stress-induced cardiac hypertrophy and disease. However, more recent studies have highlighted that these signaling pathways may exert their regulatory functions in a more compartmentalized manner in cardiac muscle. Emerging data has uncovered specific MAPK scaffolding proteins that tether MAPK/ERK signaling specifically at the sarcomere and plasma membrane in cardiac muscle and show that deficiencies in these scaffolding proteins alter ERK activity and phosphorylation, which are then critical in altering the cardiac myocyte response to stress-induced hypertrophy and disease progression. In this review, we provide insights on ERK-associated scaffolding proteins regulating cardiac myofilament function and their impact on cardiac hypertrophy and disease.

The abnormal status of uncarboxylated matrix Gla protein species represents an additional mortality risk in heart failure patients with vascular disease

BACKGROUND

Matrix Gla protein (MGP) is a natural inhibitor of tissue calcification. In a previous study, we observed the positive association between abnormal concentrations of uncarboxylated MGP species and increased mortality risk in stable vascular patients. We explore whether co-incidence of abnormal status of uncarboxylated MPG and heart failure (HF) affects the mortality risk.

METHODS

We examined 799 patients (mean age 65.1 years) with stable vascular disease and followed them in a prospective study. Both, desphospho-uncarboxylated and total uncarboxylated MGP (dp-ucMGP or t-ucMGP) were quantified by pre-commercial ELISA assays.

RESULTS

Elevated (>100 ng/L) circulating brain natriuretic peptide (BNP) and abnormal status of plasma uncarboxylated MGP species (i.e.: dp-ucMGP ≥ 977 pmol/L or t-ucMGP ≤ 2825 nmol/L) were all identified as robust predictors of all-cause 5-year mortality. However, their co-incidence represented a substantial additional risk. We observed the highest mortality risk in patients with elevated BNP plus high dp-ucMGP compared to those with normal BNP plus low dp-ucMGP; fully adjusted HRR's were 4.86 (3.15-7.49). Likewise, the risk was increased when compared with patients with elevated BNP plus low dp-ucMGP; HRR 2.57 (1.60-4.10). Similar result we observed when co-incidence of elevated BNP and low t-ucMGP was analyzed [corresponding HRR's were 4.16 (2.62-6.61) and 1.96 (1.24-3.12)].

CONCLUSIONS

The concomitant abnormality of uncarboxylated MGP and mild elevation of BNP leads in chronic patients with vascular disease to about two-fold increase of the relative mortality risk. We hypothesize that abnormal homeostasis of MGP is involved in the pathophysiology of HF.

Whole transcriptome analysis with sequencing: methods, challenges and potential solutions

Whole transcriptome analysis plays an essential role in deciphering genome structure and function, identifying genetic networks underlying cellular, physiological, biochemical and biological systems and establishing molecular biomarkers that respond to diseases, pathogens and environmental challenges. Here, we review transcriptome analysis methods and technologies that have been used to conduct whole transcriptome shotgun sequencing or whole transcriptome tag/target sequencing analyses. We focus on how adaptors/linkers are added to both 5' and 3' ends of mRNA molecules for cloning or PCR amplification before sequencing. Challenges and potential solutions are also discussed. In brief, next generation sequencing platforms have accelerated releases of the large amounts of gene expression data. It is now time for the genome research community to assemble whole transcriptomes of all species and collect signature targets for each gene/transcript, and thus use known genes/transcripts to determine known transcriptomes directly in the near future.

Mechanotransduction in cardiac hypertrophy and failure

Cardiac muscle cells have an intrinsic ability to sense and respond to mechanical load through a process known as mechanotransduction. In the heart, this process involves the conversion of mechanical stimuli into biochemical events that induce changes in myocardial structure and function. Mechanotransduction and its downstream effects function initially as adaptive responses that serve as compensatory mechanisms during adaptation to the initial load. However, under prolonged and abnormal loading conditions, the remodeling processes can become maladaptive, leading to altered physiological function and the development of pathological cardiac hypertrophy and heart failure. Although the mechanisms underlying mechanotransduction are far from being fully elucidated, human and mouse genetic studies have highlighted various cytoskeletal and sarcolemmal structures in cardiac myocytes as the likely candidates for load transducers, based on their link to signaling molecules and architectural components important in disease pathogenesis. In this review, we summarize recent developments that have uncovered specific protein complexes linked to mechanotransduction and mechanotransmission within the sarcomere, the intercalated disc, and at the sarcolemma. The protein structures acting as mechanotransducers are the first step in the process that drives physiological and pathological cardiac hypertrophy and remodeling, as well as the transition to heart failure, and may provide better insights into mechanisms driving mechanotransduction-based diseases.

Matrix Gla protein species and risk of cardiovascular events in type 2 diabetic patients

OBJECTIVE

To investigate the relationship of circulating matrix Gla protein (MGP) species with incident cardiovascular disease (CVD) or coronary heart disease (CHD) in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

EPIC-NL is a prospective cohort study among 40,011 Dutch men and women. At baseline (1993-1997), 518 participants were known to have type 2 diabetes. MGP levels were measured by ELISA techniques in baseline plasma samples. The incidence of fatal and nonfatal CVD and CVD subtypes-CHD, peripheral arterial disease (PAD), heart failure, and stroke-were obtained by linkage to national registers. Cox proportional hazard models were used to calculate hazard ratios (HRs), adjusted for sex, waist-to-hip ratio, physical activity, and history of CVD.

RESULTS

During a median 11.2 years of follow-up, 160 cases of CVD were documented. Higher circulating desphospho-uncarboxylated MGP (dp-ucMGP) levels were significantly associated with higher risk of CVD, with an HR per SD (HRSD) of 1.21 (95% CI 1.06-1.38), PAD (HRSD 1.32 [95% CI 1.07-1.65]), and heart failure (HRSD 1.75 [95% CI 1.42-2.17]) after adjustment. Higher circulating dp-ucMGP levels were not related to risk of CHD (HRSD 1.12 [95% CI 0.94-1.34]) or stroke (HRSD 1.05 [95% CI 0.73-1.49]). Circulating desphospho-carboxylated MGP and circulating total-uncarboxylated MGP levels were not associated with CVD or CVD subtypes.

CONCLUSIONS

High dp-ucMGP levels were associated with increased CVD risk among type 2 diabetic patients, especially with the subtypes PAD and heart failure, while other MGP species were not related to CVD risk. These results suggest that a poor vitamin K status is associated with increased CVD risk.

Key role of ERK1/2 molecular scaffolds in heart pathology

The ability of cardiomyocytes to detect mechanical and humoral stimuli is critical for adaptation of the myocardium in response to new conditions and for sustaining the increased workload during stress. While certain stimuli mediate a beneficial adaptation to stress conditions, others result in maladaptive remodelling, ultimately leading to heart failure. Specific signalling pathways activating either adaptive or maladaptive cardiac remodelling have been identified. Paradoxically, however, in a number of cases, the transduction pathways involved in such opposing responses engage the same signalling proteins. A notable example is the Raf-MEK1/2-ERK1/2 signalling pathway that can control both adaptive and maladaptive remodelling. ERK1/2 signalling requires a signalosome complex where a scaffold protein drives the assembly of these three kinases into a linear pathway to facilitate their sequential phosphorylation, ultimately targeting specific effector molecules. Interestingly, a number of different Raf-MEK1/2-ERK1/2 scaffold proteins have been identified, and their role in determining the adaptive or maladaptive cardiac remodelling is a promising field of investigation for the development of therapeutic strategies capable of selectively potentiating the adaptive response.

AT1 blockade abolishes left ventricular hypertrophy in heterozygous cMyBP-C null mice: role of FHL1

This research investigated the impact of angiotensin AT1 receptor (Agtr1) blockade on left ventricular (LV) hypertrophy in a mouse model of human hypertrophic cardiomyopathy (HCM), which carries one functional allele of Mybpc3 gene coding cardiac myosin-binding protein C (cMyBP-C). Five-month-old heterozygous cMyBP-C knockout (Het-KO) and wild-type mice were treated with irbesartan (50 mg/kg/day) or vehicle for 8 weeks. Arterial blood pressure was measured by tail cuff plethysmography. LV dimension and function were accessed by echocardiography. Myocardial gene expression was evaluated using RT-qPCR. Compared with wild-type littermates, Het-KO mice had greater LV/body weight ratio (4.0 ± 0.1 vs. 3.3 ± 0.1 mg/g, P < 0.001), thicker interventricular septal wall (0.70 ± 0.02 vs. 0.65 ± 0.01 mm, P < 0.02), lower Mybpc3 mRNA level (-43%, P < 0.02), higher four-and-a-half LIM domains 1 (Fhl1, +110%, P < 0.01), and angiotensin-converting enzyme 1 (Ace1, +67%, P < 0.05), but unchanged Agtr1 mRNA levels in the septum. Treatment with irbesartan had no effect in wild-type mice but abolished septum-predominant LV hypertrophy and Fhl1 upregulation without changes in Ace1 but with an increased Agtr1 (+42%) in Het-KO mice. Thus, septum-predominant LV hypertrophy in Het-KO mice is combined with higher Fhl1 expression, which can be abolished by AT1 receptor blockade, indicating a role of the renin-angiotensin system and Fhl1 in cMyBP-C-related HCM.

Dysregulation of FHL1 spliceforms due to an indel mutation produces an Emery-Dreifuss muscular dystrophy plus phenotype

Emery-Dreifuss muscular dystrophy (EDMD) is characterised by early-onset joint contractures, progressive muscular weakness and wasting and late-onset cardiac disease. The more common X-linked recessive form of EDMD is caused by mutations in either EMD (encoding emerin) or FHL1 (encoding four and a half LIM domains 1), while mutations in LMNA (encoding lamin A/C), SYNE1 (encoding nesprin-1) and SYNE2 (encoding nesprin-2) lead to autosomal dominant forms of the condition. Here, we identify a three-generation family with an extended EDMD phenotype due to a novel indel mutation in FHL1 that differentially affects the relative expression of the three known transcript isoforms produced from this locus. The additional phenotypic manifestations in this family-proportionate short stature, facial dysmorphism, pulmonary valvular stenosis, thoracic scoliosis, brachydactyly, pectus deformities and genital abnormalities-are reminiscent of phenotypes seen with dysregulated Ras-mitogen-activated protein kinase (RAS-MAPK) signalling [Noonan syndrome (NS) and related disorders]. The misexpression of FHL1 transcripts precipitated by this mutation, together with the role of FHL1 in the regulation of RAS-MAPK signalling, suggests that this mutation confers a complex phenotype through both gain- and loss-of-function mechanisms. This indel mutation in FHL1 broadens the spectrum of FHL1-related disorders and implicates it in the pathogenesis of NS spectrum disorders.

Defining molecular and cellular responses after low and high linear energy transfer radiations to develop biomarkers of carcinogenic risk or therapeutic outcome

The variability in radiosensitivity across the human population is governed in part by genetic factors. The ability to predict therapeutic response, identify individuals at greatest risk for adverse clinical responses after therapeutic radiation doses, or identify individuals at high risk for carcinogenesis from environmental or medical radiation exposures has a medical and economic impact on both the individual and society at large. As radiotherapy incorporates particles, particularly particles larger than protons, into therapy, the need for such discriminators, (i.e., biomarkers) will become ever more important. Cellular assays for survival, DNA repair, or chromatid/chromosomal analysis have been used to identify at-risk individuals, but they are not clinically applicable. Newer approaches, such as genome-wide analysis of gene expression or single nucleotide polymorphisms and small copy number variations within chromosomes, are examples of technologies being applied to the discovery process. Gene expression analysis of primary or immortalized human cells suggests that there are distinct gene expression patterns associated with radiation exposure to both low and high linear energy transfer radiations and that those most radiosensitive are discernible by their basal gene expression patterns. However, because the genetic alterations that drive radio response may be subtle and cumulative, the need for large sample sizes of specific cell or tissue types is required. A systems biology approach will ultimately be necessary. Potential biomarkers from cell lines or animal models will require validation in a human setting where possible and before being considered as a credible biomarker some understanding of the molecular mechanism is necessary.

A novel mechanism involving four-and-a-half LIM domain protein-1 and extracellular signal-regulated kinase-2 regulates titin phosphorylation and mechanics

Understanding mechanisms underlying titin regulation in cardiac muscle function is of critical importance given recent compelling evidence that highlight titin mutations as major determinants of human cardiomyopathy. We previously identified a cardiac biomechanical stress-regulated complex at the cardiac-specific N2B region of titin that includes four-and-a-half LIM domain protein-1 (Fhl1) and components of the mitogen-activated protein signaling cascade, which impacted muscle compliance in Fhl1 knock-out cardiac muscle. However, direct regulation of these molecular components in mediating titin N2B function remained unresolved. Here we identify Fhl1 as a novel negative regulator of titin N2B levels and phosphorylation-mediated mechanics. We specifically identify titin N2B as a novel substrate of extracellular signal regulated-kinase-2 (Erk2) and demonstrate that Fhl1 directly interferes with Erk2-mediated titin-N2B phosphorylation. We highlight the critical region in titin-N2B that interacts with Fhl1 and residues that are dependent on Erk2-mediated phosphorylation in situ. We also propose a potential mechanism for a known titin-N2B cardiomyopathy-causing mutation that involves this regulatory complex. These studies shed light on a novel mechanism regulating titin-N2B mechano-signaling as well as suggest that dysfunction of these pathways could be important in cardiac disease states affecting muscle compliance.

Cardiac structural and hemodynamic changes associated with physiological heart hypertrophy of pregnancy are reversed postpartum

Pregnancy is associated with ventricular hypertrophy and volume overload. Here we investigated whether late pregnancy is associated with cardiac structural and hemodynamic changes, and if these changes are reversed postpartum. Female mice (C57BL/6) were used in nonpregnant diestrus (NP), late-pregnant (LP), or 7-day postpartum (PP7) stages. Echocardiography and cardiac catheterization were performed to monitor cardiac hemodynamics. Transcript expression of proangiogenic vascular endothelial growth factor, cardiac fetal gene osteopontin, cardiac extracellular matrix-degrading enzymes matrix metalloproteinase-2, and a disintegrin and metalloproteinase-15 and -17 were assessed by RT-PCR. Masson trichrome staining for cardiac fibrosis and endothelial marker CD31 immunostaining for angiogenesis were performed. Heart hypertrophy in LP was fully reversed in PP7 (heart weight: NP = 114 ± 4 mg; LP = 147 ± 2 mg; PP7 = 117 ± 8 mg, P < 0.05 for LP vs. PP7). LP had elevated left ventricular (LV) pressure (119 ± 5 mmHg in LP vs. 92 ± 7 mmHg in NP, P < 0.05) that was restored at PP7 (95 ± 8 mmHg, P < 0.001 vs. LP). LP had increased LV contractility (maximal rate of increase of LV pressure = 6,664 ± 297 mmHg/s in LP vs. 4,294 ± 568 mmHg/s in NP, P < 0.01) that was restored at PP7 (5,313 ± 636 mmHg/s, P < 0.05 vs. LP). LV ejection fraction was reduced in LP (LP = 58 ± 1% vs. NP = 70 ± 4%, P < 0.001) and was already restored at PP1 (77 ± 2%, P < 0.001 vs. LP). Myocardial angiogenesis was significantly increased in LP (capillary density = 1.25 ± 0.02 vs. 0.95 ± 0.01 capillaries/myocyte in NP, P < 0.001) and was fully restored in PP7 (0.98 ± 0.01, P < 0.001 vs. LP). Vascular endothelial growth factor was upregulated in LP (LP = 1.4 ± 0.1 vs. NP = 1 ± 0.1, normalized to NP, P < 0.001) and was restored in PP7 (PP7 = 0.83 ± 0.1, P < 0.001 vs. LP). There was no increase in cardiac fibrosis in LP. Matrix metalloproteinase-2 transcript levels were downregulated in LP (LP = 0.47 ± 0.03 vs. NP = 1 ± 0.01, normalized to NP, P < 0.001) and was restored at PP7 (0.70 ± 0.1, P < 0.001 vs. LP). In conclusion, pregnancy-induced heart hypertrophy is associated with transient cardiac dysfunction, increased cardiac angiogenesis, lack of fibrosis, and decreased expression of remodeling enzymes that are reversed postpartum.

Reverse right ventricular structural and extracellular matrix remodeling by estrogen in severe pulmonary hypertension

Chronic pulmonary hypertension (PH) leads to right-ventricular failure (RVF) characterized by RV remodeling. Ventricular remodeling is emerging as an important process during heart failure and recovery. Remodeling in RVF induced by PH is not fully understood. Recently we discovered that estrogen (E2) therapy can rescue severe preexisting PH. Here, we focused on whether E2 (42.5 μg·kg(-1)·day(-1), 10 days) can reverse adverse RV structural and extracellular matrix (ECM) remodeling induced by PH using monocrotaline (MCT, 60 mg/kg). RV fibrosis was evident in RVF males. Intact females developed less severe RV remodeling compared with males and ovariectomized (OVX) females. Novel ECM-degrading disintegrin-metalloproteinases ADAM15 and ADAM17 transcripts were elevated ∼2-fold in all RVF animals. E2 therapy reversed RV remodeling in all groups. In vitro, E2 directly inhibited ANG II-induced expression of fibrosis markers as well as the metalloproteinases in cultured cardiac fibroblasts. Estrogen receptor-β agonist diarylpropionitrile (DPN) but not estrogen receptor-α agonist 4,4',4″-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) was as effective as E2 in inhibiting expression of these genes. Expression of ECM-interacting cardiac fetal-gene osteopontin (OPN) also increased ∼9-fold in RVF males. Intact females were partially protected from OPN upregulation (∼2-fold) but OVX females were not. E2 reversed OPN upregulation in all groups. Upregulation of OPN was also reversed in vitro by E2. Plasma OPN was elevated in RVF (∼1.5-fold) and decreased to control levels in the E2 group. RVF resulted in elevated Akt phosphorylation, but not ERK, in the RV, and E2 therapy restored Akt phosphorylation. In conclusion, E2 therapy reverses adverse RV remodeling associated with PH by reversing fibrosis and upregulation of novel ECM enzymes ADAM15, ADAM17, and OPN. These effects are likely mediated through estrogen receptor-β.

Benzo[a]pyrene exposure influences the cardiac development and the expression of cardiovascular relative genes in zebrafish (Danio rerio) embryos

It is reported that the most abundant polycyclic aromatic hydrocarbons (PAHs) in weathered crude oils are cardiotoxic. However, the action mechanism of PAHs on vertebrate cardiovascular development and disease is unclear. In the present study, the cardiac morphology and functioning of zebrafish embryos exposed to benzo[a]pyrene [B(a)P], as a high-ring PAHs, for 72 h were observed and determined. The results showed that B(a)P exposure resulted in cardiac developmental defects in zebrafish embryos. Significant changes in expression level of multiple genes potentially critical for regulating the B(a)P-induced cardiovascular developmental defects were also found. A gene network regulating cardiac development perturbed by B(a)P exposure was identified and established by computational analysis and employment of some databases. The information from the network could provide a clue for further mechanistic studies explaining molecular events regulating B(a)P-mediated cardiovascular defects and consequences.

Circulating levels of non-phosphorylated undercarboxylated matrix Gla protein are associated with disease severity in patients with chronic heart failure

We recently demonstrated that circulating MGP [matrix Gla (γ-carboxylated glutamate) protein] levels were associated with left ventricular dysfunction and increased mortality in patients with symptomatic aortic stenosis. We hypothesized that patients with chronic HF (heart failure) would have dysregulated MGP levels. We examined plasma dp-cMGP (non-phosphorylated carboxylated MGP) and dp-ucMGP (non-phosphorylated undercarboxylated MGP) in 179 patients with chronic HF and matched healthy controls as well as the relationship between MGP and cardiac dysfunction as assessed by echocardiographic measurements, inflammation [CRP (C-reactive protein)] and neurohormonal activation [NT-proBNP (N-terminal proB-type natriuretic peptide)] and the prognostic value of MGP levels in relation to mortality in these patients. We found markedly enhanced plasma dp-cMGP and, in particular, of dp-ucMGP in chronic HF with increasing levels with disease severity. Elevated MGP species were associated with ischaemic aetiology, increased CRP and NT-proBNP levels, as well as systolic and diastolic dysfunction. Finally, dp-ucMGP was associated with long-term heart transplant-free survival (n=48) in univariate, but not in multivariate, analysis. However, plasma dp-ucMGP was markedly higher in patients who died because of progression of HF (n=12) and gave prognostic information also in multivariate analysis. In conclusion, a dysregulated MGP system could be involved in left ventricular dysfunction in patients with chronic HF.

Four and a half LIM protein 1 gene mutations cause four distinct human myopathies: a comprehensive review of the clinical, histological and pathological features

Mutations in the four and a half LIM protein 1 (FHL1) gene were recently identified as the cause of four distinct skeletal muscle diseases. Since the initial report outlining the first fhl1 mutation in 2008, over 25 different mutations have been identified in patients with reducing body myopathy, X-linked myopathy characterized by postural muscle atrophy, scapuloperoneal myopathy and Emery-Dreifuss muscular dystrophy. Reducing body myopathy was first described four decades ago, its underlying genetic cause was unknown until the discovery of fhl1 mutations. X-linked myopathy characterized by postural muscle atrophy is a novel disease where fhl1 mutations are the only cause. This review will profile each of the FHL1, with a comprehensive analysis of mutations, a comparison of the clinical and histopathological features and will present several hypotheses for the possible disease mechanism(s).

Role of the estrogen/estrogen-receptor-beta axis in the genomic response to pressure overload-induced hypertrophy

Cardiac hypertrophy, the adaptive response of the heart to overload, is a major risk factor for heart failure and sudden death. Estrogen (E2) and estrogen receptor beta (ERbeta) offer protection against hypertrophy and in the transition to heart failure. However, the underlying pathways remain incompletely defined. We employed a publicly available microarray dataset of female wild-type (WT) and ERbeta knockout (BERKO) mice subjected to pressure overload-induced hypertrophy to perform a systematic investigation of the mechanisms involved in the protection conferred by the E2/ERbeta axis. We show that considerably more genes were modulated in response to pressure overload in BERKO mice than in WT mice. The majority of the identified candidates in BERKO mice were induced, while those in WT mice were repressed. Pathway analysis revealed a similar pattern. This study is the first to demonstrate that the lack of ERbeta led to a significant increase of inflammatory pathways. Mitochondrial bioenergetics- and oxidative stress-related pathways were also modulated. In conclusion, ERbeta acquires the role of gatekeeper of the genomic response of the heart to pressure overload-induced hypertrophy. This may offer the molecular explanation for its cardioprotective role. We consider the present study to be a useful resource and that it will contribute to downstream functional analysis and to the characterization of pathways with previously unknown role in hypertrophy.

Identification of an FHL1 protein complex containing ACTN1, ACTN4, and PDLIM1 using affinity purifications and MS-based protein-protein interaction analysis

INTRODUCTION

Four and a half LIM domains protein 1 (FHL1) is the most widely expressed member of the FHL family of proteins, consisting of four and a half highly conserved LIM domains. A multifunctional and integral role for FHL1 has been implicated in muscle development, structural maintenance, and signaling. To date, 27 FHL1 mutations have been identified that result in at least six different X-linked myopathies, with patients often presenting with cardiovascular complications. Since proteins assemble into dynamic complexes within the cell, FHL1 likely mediates its biological functions in conjunction with other proteins. Delineation of FHL1 interactions could provide insight into its regulatory functions.

METHODS

We performed tandem affinity purification from human embryonic kidney 293 (HEK-293) cells to purify FHL1 and interacting proteins. To identify the potential interactors of FHL1 we performed a total of 9 different purifications from HEK-293 cells which included 3 experimental replicates for each biological condition: FHL1, tag control (DPYSL3), and negative control (empty vector). Purified samples were analyzed by liquid chromatography mass spectrometry (LC-MS). Potential interactors were then verified by immunoprecipitation from mouse heart ventricles and interactions visualized in adult cardiomyocytes using 3D fluorescence microscopy.

RESULTS

We identified a total of 310 different proteins from all 9 purifications and by applying stringent filtering criteria we eliminated all proteins found in any of the controls and only allowed those that were detected in two or more bait purification. We identified 34 high confidence potential binding partners of FHL1. We then showed that FHL1 exists as part of a complex that binds with PDLIM1, GSN and ACTN1.

Genes, proteins and complexes: the multifaceted nature of FHL family proteins in diverse tissues

Four and a half LIM domain protein 1 (FHL1) is the founding member of the FHL family of proteins characterized by the presence of four and a half highly conserved LIM domains. The LIM domain is a protein-interaction motif and is involved in linking proteins with both the actin cytoskeleton and transcriptional machinery. To date, more than 25 different protein interactions have been identified for full length FHL1 and its spliced variants, and these interactions can be mapped to a variety of functional classes. Because FHL1 is expressed predominantly in skeletal muscle, all of these proteins interactions translate into a multifunctional and integral role for FHL1 in muscle development, structural maintenance, and signalling. Importantly, 27 FHL1 genetic mutations have been identified that result in at least six different X-linked myopathies, with patients often presenting with cardiovascular disease. FHL1 expression is also significantly up-regulated in a variety of cardiac disorders, even at the earliest stages of disease onset. Alternatively, FHL1 expression is suppressed in a variety of cancers, and ectopic FHL1 expression offers potential for some phenotype rescue. This review focuses on recent studies of FHL1 in muscular dystrophies and cardiovascular disease, and provides a comprehensive review of FHL1s multifunctional roles in skeletal muscle.

Pressure load: the main factor for altered gene expression in right ventricular hypertrophy in chronic hypoxic rats

Background

The present study investigated whether changes in gene expression in the right ventricle following pulmonary hypertension can be attributed to hypoxia or pressure loading.

Methodology/Principal Findings

To distinguish hypoxia from pressure-induced alterations, a group of rats underwent banding of the pulmonary trunk (PTB), sham operation, or the rats were exposed to normoxia or chronic, hypobaric hypoxia. Pressure measurements were performed and the right ventricle was analyzed by Affymetrix GeneChip, and selected genes were confirmed by quantitative PCR and immunoblotting. Right ventricular systolic blood pressure and right ventricle to body weight ratio were elevated in the PTB and the hypoxic rats. Expression of the same 172 genes was altered in the chronic hypoxic and PTB rats. Thus, gene expression of enzymes participating in fatty acid oxidation and the glycerol channel were downregulated. mRNA expression of aquaporin 7 was downregulated, but this was not the case for the protein expression. In contrast, monoamine oxidase A and tissue transglutaminase were upregulated both at gene and protein levels. 11 genes (e.g. insulin-like growth factor binding protein) were upregulated in the PTB experiment and downregulated in the hypoxic experiment, and 3 genes (e.g. c-kit tyrosine kinase) were downregulated in the PTB and upregulated in the hypoxic experiment.

Conclusion/Significance

Pressure load of the right ventricle induces a marked shift in the gene expression, which in case of the metabolic genes appears compensated at the protein level, while both expression of genes and proteins of importance for myocardial function and remodelling are altered by the increased pressure load of the right ventricle. These findings imply that treatment of pulmonary hypertension should also aim at reducing right ventricular pressure.

Gene silencing of myofibrillogenesis regulator-1 by adenovirus-delivered small interfering RNA suppresses cardiac hypertrophy induced by angiotensin II in mice

Our previous studies proved that myofibrillogenesis regulator (MR)-1 has a close relationship with cardiac hypertrophy induced by ANG II. In the present study, we developed a recombinant adenoviral vector (AdSiR-MR-1) driving small interfering (si)RNA against MR-1 to evaluate its effect on cardiac hypertrophy in vivo. Cardiac hypertrophy was induced by chronic ANG II infusion in mice; AdSiR-MR-1 was administered via the jugular vein through one bolus injection. Thirteen days after the injection, viral DNA was still detectable in the heart, validating the efficiency of gene transfer. Expression levels of MR-1 mRNA and protein were increased by 2.5-fold in the heart after ANG II infusion; AdSiR-control, which contained a scrambled siRNA sequence, had no effect on them. AdSiR-MR-1 treatment abolished the upregulation of MR-1 induced by ANG II. The silencing effect of AdSiR-MR-1 was observed in many other tissues, such as the liver, lung, and kidney, except skeletal muscle. ANG II-induced cardiac hypertrophy was suppressed in mice treated with AdSiR-MR-1, as determined by echocardiography. Morphological and immnohistochemical examinations revealed that interstitial cardiac fibrosis as well as infiltrating inflammatory cells were increased after ANG II infusion; AdSiR-MR-1 greatly ameliorated these disorders. In ANG II-infused mice, MR-1 silencing also blocked the upregulation of other genes related to cardiac hypertrophy or metabolism of the extracellular matrix. In summary, our results demonstrate the feasibility of MR-1 silencing in vivo and suggest that MR-1 could be a potential new target to treat cardiac hypertrophy induced by ANG II.

Undercarboxylated matrix Gla protein is associated with indices of heart failure and mortality in symptomatic aortic stenosis

OBJECTIVE

Matrix Gla protein (MGP) is a calcification inhibitor and alterations in circulating MGP have been observed in different populations characterized by vascular calcification. We hypothesized that patients with calcific valvular aortic stenosis (AS) would have dysregulated circulating MGP levels.

DESIGN AND SUBJECTS

We examined plasma levels of nonphosphorylated carboxylated and undercarboxylated MGP (dp-cMGP and dp-ucMGP, respectively) in 147 patients with symptomatic severe AS and in matched healthy controls.

MAIN OUTCOME MEASURES

We further investigated the relationship between MGP levels and aortic pressure gradients and valve area by echocardiography and measures of heart failure. Finally, we assessed the prognostic value of elevated plasma dp-ucMGP level in relation to all-cause mortality in patients with AS.

RESULTS

We found markedly enhanced plasma levels of dp-cMGP and in particular of dp-ucMGP in patients with symptomatic AS. Although only weak correlations were found with the degree of AS, circulating dp-ucMGP was associated with cardiac function and long-term mortality in multivariate analysis.

CONCLUSIONS

A dysregulated MGP system may have a role in the development of left ventricular dysfunction in patients with symptomatic AS.

Identification of a core set of genes that signifies pathways underlying cardiac hypertrophy

Although the molecular signals underlying cardiac hypertrophy have been the subject of intense investigation, the extent of common and distinct gene regulation between different forms of cardiac hypertrophy remains unclear. We hypothesized that a general and comparative analysis of hypertrophic gene expression, using microarray technology in multiple models of cardiac hypertrophy, including aortic banding, myocardial infarction, an arteriovenous shunt and pharmacologically induced hypertrophy, would uncover networks of conserved hypertrophy-specific genes and identify novel genes involved in hypertrophic signalling. From gene expression analyses (8740 probe sets, n = 46) of rat ventricular RNA, we identified a core set of 139 genes with consistent differential expression in all hypertrophy models as compared to their controls, including 78 genes not previously associated with hypertrophy and 61 genes whose altered expression had previously been reported. We identified a single common gene program underlying hypertrophic remodelling, regardless of how the hypertrophy was induced. These genes constitute the molecular basis for the existence of one main form of cardiac hypertrophy and may be useful for prediction of a common therapeutic approach. Supplementary material for this article can be found at: http://www.interscience.wiley.com/jpages/1531-6912/suppmat

Gene expression profiling on global cDNA arrays gives hints concerning potential signal transduction pathways involved in cardiac fibrosis of renal failure

Cardiac remodelling with interstitial fibrosis in renal failure, which so far is only poorly understood on the molecular level, was investigated in the rat model by a global gene expression profiling analysis. Sprague–Dawley rats were subjected to subtotal nephrectomy (SNX) or sham operation (sham) and followed for 2 and 12 weeks, respectively. Heart-specific gene expression profiling, with RZPD Rat Unigene-1 cDNA arrays containing about 27 000 gene and EST sequences revealed substantial changes in gene expression in SNX compared to sham animals. Motor protein genes, growth and differentiation markers, and extracellular matrix genes were upregulated in SNX rats. Obviously, not only genes involved in cardiomyocyte hypertrophy, but also genes involved in the expansion of non-vascular interstitial tissue are activated very early in animals with renal failure. Together with earlier findings in the SNX model, the present data suggest the hypothesis that the local renin–angiotensin system (RAS) may be activated by at least two pathways: (a) via second messengers and Gproteins (short-term signalling); and (b) via motor proteins, actins and integrins (longterm signalling). The study documents that complex hybridization analysis yields reproducible and promising results of patterns of gene activation pointing to signalling pathways involved in cardiac remodelling in renal failure. The complete array data are available via http://www.rzpd.de/cgi-bin/services/exp/viewExpressionData.pl.cgi

Transcript profiling of expressed sequence tags from intramuscular fat, longissimus dorsi muscle and liver in Korean cattle (Hanwoo)

A large data set of Hanwoo (Korean cattle) ESTs was analyzed to obtain differential gene expression results for the following three libraries: intramuscular fat, longissimus dorsi muscle and liver. To better understand the gene expression profiles, we identified differentially expressed genes (DEGs) via digital gene expression analysis. Hierarchical clustering of genes was performed according to their relative abundance within the six separate groups (Hanwoo fat versus non-Hanwoo fat, Hanwoo muscle versus non-Hanwoo muscle and Hanwoo liver versus non-Hanwoo liver), producing detailed patterns of gene expression. We determined the quantitative traits associated with the highly expressed genes. We also provide the first list of putative regulatory elements associated with differential tissue expression in Hanwoo cattle. In addition, we conducted evolutionary analysis that suggests a subset of genes accelerated in the bovine lineage are strongly correlated with their expression in Hanwoo muscle.

Molecular distinction between physiological and pathological cardiac hypertrophy: experimental findings and therapeutic strategies

Cardiac hypertrophy can be defined as an increase in heart mass. Pathological cardiac hypertrophy (heart growth that occurs in settings of disease, e.g. hypertension) is a key risk factor for heart failure. Pathological hypertrophy is associated with increased interstitial fibrosis, cell death and cardiac dysfunction. In contrast, physiological cardiac hypertrophy (heart growth that occurs in response to chronic exercise training, i.e. the 'athlete's heart') is reversible and is characterized by normal cardiac morphology (i.e. no fibrosis or apoptosis) and normal or enhanced cardiac function. Given that there are clear functional, structural, metabolic and molecular differences between pathological and physiological hypertrophy, a key question in cardiovascular medicine is whether mechanisms responsible for enhancing function of the athlete's heart can be exploited to benefit patients with pathological hypertrophy and heart failure. This review summarizes key experimental findings that have contributed to our understanding of pathological and physiological heart growth. In particular, we focus on signaling pathways that play a causal role in the development of pathological and physiological hypertrophy. We discuss molecular mechanisms associated with features of cardiac hypertrophy, including protein synthesis, sarcomeric organization, fibrosis, cell death and energy metabolism and provide a summary of profiling studies that have examined genes, microRNAs and proteins that are differentially expressed in models of pathological and physiological hypertrophy. How gender and sex hormones affect cardiac hypertrophy is also discussed. Finally, we explore how knowledge of molecular mechanisms underlying pathological and physiological hypertrophy may influence therapeutic strategies for the treatment of cardiovascular disease and heart failure.

Upregulation of cardiac matrix Gla protein expression in response to hypertrophic stimuli

Matrix Gla protein (MGP) expression is increased in cardiac hypertrophy, but the precise mechanisms regulating its expression are unknown. Here we characterized the effect of pressure overload and myocardial infarction in vivo as well as mechanical stretch and hypertrophic agonists in vitro on MGP expression. When angiotensin II (Ang II) was administered by osmotic minipumps, left ventricular (LV) MGP mRNA levels increased significantly from 6 h to 2 weeks, whereas intravenous arginine(8)-vasopressin increased LV MGP mRNA levels within 4 h. During post-infarction remodeling process, MGP mRNA levels were elevated at 24 h (1.3-fold, p<0.05) and the maximal increase was observed at 4 weeks (2.8-fold, p<0.01). Ang II increased MGP mRNA levels 20% (p<0.05) in neonatal rat cardiac myocytes and 40% (p<0.05) in cardiac fibroblasts, whereas endothelin-1 decreased MGP mRNA levels 30% (p<0.01) in myocytes and had no effect in fibroblasts. Cyclic mechanical stretch resulted in reduction of MGP gene expression in both cardiac myocytes and fibroblasts. These results demonstrate that MGP is rapidly upregulated in response to cardiac overload well before the development of LV hypertrophy and post-infarction remodeling process. Our results also suggest that Ang II may be involved in mediating load-induced activation of MGP expression.

An FHL1-containing complex within the cardiomyocyte sarcomere mediates hypertrophic biomechanical stress responses in mice

The response of cardiomyocytes to biomechanical stress can determine the pathophysiology of hypertrophic cardiac disease, and targeting the pathways regulating these responses is a therapeutic goal. However, little is known about how biomechanical stress is sensed by the cardiomyocyte sarcomere to transduce intracellular hypertrophic signals or how the dysfunction of these pathways may lead to disease. Here, we found that four-and-a-half LIM domains 1 (FHL1) is part of a complex within the cardiomyocyte sarcomere that senses the biomechanical stress-induced responses important for cardiac hypertrophy. Mice lacking Fhl1 displayed a blunted hypertrophic response and a beneficial functional response to pressure overload induced by transverse aortic constriction. A link to the Galphaq (Gq) signaling pathway was also observed, as Fhl1 deficiency prevented the cardiomyopathy observed in Gq transgenic mice. Mechanistic studies demonstrated that FHL1 plays an important role in the mechanism of pathological hypertrophy by sensing biomechanical stress responses via the N2B stretch sensor domain of titin and initiating changes in the titin- and MAPK-mediated responses important for sarcomere extensibility and intracellular signaling. These studies shed light on the physiological regulation of the sarcomere in response to hypertrophic stress.

Translational control of nrf2 protein in activation of antioxidant response by oxidants

Nf-E2 related factor-2 (Nrf2) is a basic leucine zipper transcription factor that binds and activates the antioxidant response element (ARE) in the promoters of many antioxidant and detoxification genes. We found that H(2)O(2) treatment caused a rapid increase in endogenous Nrf2 protein level in rat cardiomyocytes. Semiquantitative or real-time reverse transcription-polymerase chain reaction failed to show an increase of Nrf2 mRNA level by H(2)O(2) treatment. Measurements of Nrf2 protein stability excluded the possibility of Nrf2 protein stabilization. Although inhibiting protein synthesis with cycloheximide prevented H(2)O(2) from elevating Nrf2 protein level, RNA synthesis inhibition with actinomycin D failed to do so. Measurements of new protein synthesis with [(35)S]methionine incorporation confirmed that H(2)O(2) increased the translation of Nrf2 protein. Inhibitors of phosphoinositide 3-kinase were able to abolish the induction of Nrf2 protein by H(2)O(2). Although H(2)O(2) increased phosphorylation of p70 S6 kinase, rapamycin failed to inhibit H(2)O(2) from elevating Nrf2 protein. H(2)O(2) also induced phosphorylation of eukaryotic translation initiation factor (eIF) 4E and eIF2alpha within 30 and 10 min, respectively. Inhibiting eIF4E with small interfering siRNA or increasing eIF2alpha phosphorylation with salubrinal did not affect Nrf2 elevation by H(2)O(2). Our data present a novel phenomenon of quick onset of the antioxidant/detoxification response via increased translation of Nrf2 by oxidants. The mechanism underlying such stress-induced de novo protein translation may involve multiple components of translational machinery.

ERRgamma directs and maintains the transition to oxidative metabolism in the postnatal heart

At birth, the heart undergoes a critical metabolic switch from a predominant dependence on carbohydrates during fetal life to a greater dependence on postnatal oxidative metabolism. This remains the principle metabolic state throughout life, although pathologic conditions such as heart failure and cardiac hypertrophy reactivate components of the fetal genetic program to increase carbohydrate utilization. Disruption of the ERRgamma gene (Esrrg), which is expressed at high levels in the fetal and postnatal mouse heart, blocks this switch, resulting in lactatemia, electrocardiographic abnormalities, and death during the first week of life. Genomic ChIP-on-chip and expression analysis identifies ERRgamma as both a direct and an indirect regulator of a nuclear-encoded mitochondrial genetic network that coordinates the postnatal metabolic transition. These findings reveal an unexpected and essential molecular genetic component of the oxidative metabolic gene program in the heart and highlight ERRgamma in the study of cardiac hypertrophy and failure.

Comparative analysis of differentially expressed genes in normal and white spot syndrome virus infected Penaeus monodon

Background

White spot syndrome (WSS) is a viral disease that affects most of the commercially important shrimps and causes serious economic losses to the shrimp farming industry worldwide. However, little information is available in terms of the molecular mechanisms of the host-virus interaction. In this study, we used an expressed sequence tag (EST) approach to observe global gene expression changes in white spot syndrome virus (WSSV)-infected postlarvae of Penaeus monodon.

Results

Sequencing of the complementary DNA clones of two libraries constructed from normal and WSSV-infected postlarvae produced a total of 15,981 high-quality ESTs. Of these ESTs, 46% were successfully matched against annotated genes in National Center of Biotechnology Information (NCBI) non-redundant (nr) database and 44% were functionally classified using the Gene Ontology (GO) scheme. Comparative EST analyses suggested that, in postlarval shrimp, WSSV infection strongly modulates the gene expression patterns in several organs or tissues, including the hepatopancreas, muscle, eyestalk and cuticle. Our data suggest that several basic cellular metabolic processes are likely to be affected, including oxidative phosphorylation, protein synthesis, the glycolytic pathway, and calcium ion balance. A group of immune-related chitin-binding protein genes is also likely to be strongly up regulated after WSSV infection. A database containing all the sequence data and analysis results is accessible at .

Conclusion

This study suggests that WSSV infection modulates expression of various kinds of genes. The predicted gene expression pattern changes not only reflect the possible responses of shrimp to the virus infection but also suggest how WSSV subverts cellular functions for virus multiplication. In addition, the ESTs reported in this study provide a rich source for identification of novel genes in shrimp.

Up-regulation of skeletal muscle LIM protein 1 gene by 25-hydroxycholesterol may mediate morphological changes of rat aortic smooth muscle cells

Changes in the expression level of the skeletal muscle LIM protein 1 (SLIM1) in cultured A10 cells were monitored in response to 25-hydroxycholesterol (25-HC), an oxidized form of cholesterol present in the oxidized low-density lipoproteins. The level of SLIM1 mRNA was elevated in a time- and concentration-dependent manner by treatment of 25-HC. Expressions of smooth muscle (SM) alpha-actin and calponin-1 (CNN-1), early markers for SMC differentiation, were also increased by the 25-HC treatments. Expressions of all three genes (SLIM1, SM alpha-actin and CNN-1) were simultaneously elevated in the cells treated with 9-cis retinoic acid (RA). On the other hand, the SLIM1 expression induced by the 25-HC or 9-cis RA (as well as SM alpha-actin and CNN-1) was decreased by the treatment of 15d-PGJ2. Since the 25-HC, 9-cis RA and 15d-PGJ2 were ligands for the LXR, RXRalpha and PPARgamma respectively, there might be a functional positive cross-talk between LXR and RXRalpha pathways and a negative cross-talk between PPARgamma and LXR and/or RXRalpha pathways in the regulation of SLIM1 expression. The cells stably transfected with the expressional vector for SLIM1 also showed an elevation in the levels of SM alpha-actin and CNN-1. In addition, an over-production of SLIM1 in the cells resulted in a change in the cell-shape into a spindle-like form, which is identical to that observed after a prolonged treatment of the cells with cholesterol.

Differential gene expression in abdomens of the malaria vector mosquito, Anopheles gambiae, after sugar feeding, blood feeding and Plasmodium berghei infection

BACKGROUND

Large scale sequencing of cDNA libraries can provide profiles of genes expressed in an organism under defined biological and environmental circumstances. We have analyzed sequences of 4541 Expressed Sequence Tags (ESTs) from 3 different cDNA libraries created from abdomens from Plasmodium infection-susceptible adult female Anopheles gambiae. These libraries were made from sugar fed (S), rat blood fed (RB), and P. berghei-infected (IRB) mosquitoes at 30 hours after the blood meal, when most parasites would be transforming ookinetes or very early oocysts.

RESULTS

The S, RB and IRB libraries contained 1727, 1145 and 1669 high quality ESTs, respectively, averaging 455 nucleotides (nt) in length. They assembled into 1975 consensus sequences--567 contigs and 1408 singletons. Functional annotation was performed to annotate probable molecular functions of the gene products and the biological processes in which they function. Genes represented at high frequency in one or more of the libraries were subjected to digital Northern analysis and results on expression of 5 verified by qRT-PCR.

CONCLUSION

13% of the 1965 ESTs showing identity to the A. gambiae genome sequence represent novel genes. These, together with untranslated regions (UTR) present on many of the ESTs, will inform further genome annotation. We have identified 23 genes encoding products likely to be involved in regulating the cellular oxidative environment and 25 insect immunity genes. We also identified 25 genes as being up or down regulated following blood feeding and/or feeding with P. berghei infected blood relative to their expression levels in sugar fed females.

Four and a half LIM protein 1 binds myosin-binding protein C and regulates myosin filament formation and sarcomere assembly

Four and a half LIM protein 1 (FHL1/SLIM1) is highly expressed in skeletal and cardiac muscle; however, the function of FHL1 remains unknown. Yeast two-hybrid screening identified slow type skeletal myosin-binding protein C as an FHL1 binding partner. Myosin-binding protein C is the major myosin-associated protein in striated muscle that enhances the lateral association and stabilization of myosin thick filaments and regulates actomyosin interactions. The interaction between FHL1 and myosin-binding protein C was confirmed using co-immunoprecipitation of recombinant and endogenous proteins. Recombinant FHL2 and FHL3 also bound myosin-binding protein C. FHL1 impaired co-sedimentation of myosin-binding protein C with reconstituted myosin filaments, suggesting FHL1 may compete with myosin for binding to myosin-binding protein C. In intact skeletal muscle and isolated myofibrils, FHL1 localized to the I-band, M-line, and sarcolemma, co-localizing with myosin-binding protein C at the sarcolemma in intact skeletal muscle. Furthermore, in isolated myofibrils FHL1 staining at the M-line appeared to extend partially into the C-zone of the A-band, where it co-localized with myosin-binding protein C. Overexpression of FHL1 in differentiating C2C12 cells induced "sac-like" myotube formation (myosac), associated with impaired Z-line and myosin thick filament assembly. This phenotype was rescued by co-expression of myosin-binding protein C. FHL1 knockdown using RNAi resulted in impaired myosin thick filament formation associated with reduced incorporation of myosin-binding protein C into the sarcomere. This study identified FHL1 as a novel regulator of myosin-binding protein C activity and indicates a role for FHL1 in sarcomere assembly.

Genomic annotation of 15,809 ESTs identified from pooled early gestation human eyes

To complement cDNA libraries from the human eye at early gestation and to discover candidate genes associated with early ocular development, we used freshly dissected human eyeballs from week 9-14 of gestation to construct the early human fetal eye cDNA library. A total of 15,809 clones were isolated and sequenced from the unamplified and unnormalized library. We screened 11,246 good-quality ESTs, leading to the identification of 5,534 nonredundant clusters. Among them, 4,010 (72%) genes matched in the human protein database (Ensembl). The remaining 28% (1,524) corresponded to potentially novel or previously unidentified ESTs. We used BLASTX to compare our EST data with eight organisms and found common expression of a high portion of genes: Caenorhabditis briggsae (26%), Caenorhabditis elegans (27%), Anopheles gambiae (37%), Drosophila melanogaster (32%), Danio rerio (42%), Fugu rubripes (49%), Rattus norvegicusvalitus (52%), and Mus musculus (59%). Nevertheless, 48% (2,680 of 5,534) of the genes expressed in the early developing eye were not shared with current NEIBank human eye cDNA data. In addition, eight known retinal disease genes existed in our ESTs. Among them, six (COL11A1, BBS5, PDE6B, OAT, VMD2, and PGK1) were conserved among the genomes of other organisms, indicating that our annotated EST set provides not only a valuable resource for gene discovery and functional genomic analysis but also for phylogenetic analysis. Our foremost early gestation human eye cDNA library could provide detailed comparisons across species to identify physiological functions of genes and to elucidate evolutionary mechanisms.

Distinct upregulation of extracellular matrix genes in transition from hypertrophy to hypertensive heart failure

Cardiac hypertrophy in response to pressure overload is initially beneficial but eventually leads to heart failure, a major cause of morbidity and mortality in the Western countries. Although abnormalities in left ventricular (LV) diastolic filling are early features associated with pressure overload-induced LV hypertrophy, the molecular mechanisms regulating transition to diastolic heart failure are poorly understood. We analyzed global changes in gene expression in 12-, 16-, and 20-month-old spontaneously hypertensive rats (SHR) and their age-matched controls, Wistar Kyoto rats, using DNA microarrays. In SHR, a progressive LV hypertrophy was associated with increased expression of hypertrophy-associated genes including contractile protein and natriuretic peptide genes. Echocardiography indicated that 16-month-old SHR had features of diastolic dysfunction leading to diastolic failure at age 20 months without significant changes in LV systolic function. Comparison analysis revealed that the extracellular matrix genes strikingly dominated the list of altered genes after transition to the heart failure, whereas there was no major shift in gene expression patterns involved in calcium homeostasis and neurohumoral activation, as well as myofilament contractile and cytoskeletal proteins. The microarray analysis also revealed differential gene expression of several novel factors, such as thrombospondin-4 and matrix Gla protein, as well as unknown expressed sequence tags. Our data show that transition from LV hypertrophy to diastolic hypertensive heart failure is almost exclusively associated with progressive remodeling of the extracellular matrix and provide new insights into the pathogenesis of hypertrophy by suggesting existence of novel regulators of LV remodeling.

Distinct molecular portraits of human failing hearts identified by dedicated cDNA microarrays

AIMS

This study aimed to investigate whether a molecular profiling approach should be pursued for the classification of heart failure patients.

METHODS AND RESULTS

Applying a subtraction strategy we created a cDNA library consisting of cardiac- and heart failure-relevant clones that were used to construct dedicated cDNA microarrays. We measured relative expression levels of the corresponding genes in left ventricle tissue from 17 patients (15 failing hearts and 2 nonfailing hearts). Significance analysis of microarrays was used to select 159 genes that distinguished between all patients. Two-way hierarchical clustering of the 17 patients and the 159 selected genes led to the identification of three major subgroups of patients, each with a specific molecular portrait. The two nonfailing hearts clustered closely together. Interestingly, our classification of patients based on their molecular portraits did not correspond to an identified etiological classification. Remarkably, patients with the highest medical urgency status (United Network for Organ Sharing, Status 1A) clustered together.

CONCLUSION

With this pilot feasibility study we demonstrated a novel classification of end-stage heart failure patients, which encourages further development of this approach in prospective studies on heart failure patients at earlier stages of the disease.

Cloning and characterization of a novel endoplasmic reticulum localized G-patch domain protein, IER3IP1

The endoplasmic reticulum (ER) is the site of protein synthesis, folding, post-translational modifications and export. The ER membrane and its lumen contain various chaperones and enzymes that are involved in every aspect of the ER function. In this report, we identified a novel endoplasmic reticulum protein (immediate early response 3 interacting protein 1, IER3IP1) during the large-scale partial sequencing of a liver cDNA library. The full-length 1304 bp IER3IP1 cDNA has a predicted open reading frame (ORF), which encodes an 82 amino-acid protein possessing a G-patch domain. This domain is found in several RNA associated proteins and has been suggested to be involved in RNA binding. IER3IP1 gene was mapped to the chromosome 18q12 by radiation hybrid analysis. In northern blot hybridization, it was shown that IER3IP1 gene has a high expression in heart, skeletal muscle and kidney, a moderate expression in liver and brain and a low expression in placenta, lung and peripheral blood leukocyte. With the presence of transmembrane domain at the C-terminal, the translated IER3IP1 protein was localized to endoplasmic reticulum of HepG2 cells and was confirmed by co-localization with ER specific marker.