CHD4 and SMYD1 repress common transcriptional programs in the developing heart.

Regulation of chromatin states is essential for proper temporal and spatial gene expression. Chromatin states are modulated by remodeling complexes composed of components that have enzymatic activities. CHD4 is the catalytic core of the nucleosome remodeling and deacetylase (NuRD) complex, which represses gene transcription. However, it remains to be determined how CHD4, a ubiquitous enzyme that remodels chromatin structure, functions in cardiomyocytes to maintain heart development. In particular, whether other proteins besides the NuRD components interact with CHD4 in the heart is controversial. Using quantitative proteomics, we identified that CHD4 interacts with SMYD1, a striated muscle-restricted histone methyltransferase that is essential for cardiomyocyte differentiation and cardiac morphogenesis. Comprehensive transcriptomic and chromatin accessibility studies of Smyd1 and Chd4 null embryonic mouse hearts revealed that SMYD1 and CHD4 repress a group of common genes and pathways involved in glycolysis, response to hypoxia, and angiogenesis. Our study reveals a mechanism by which CHD4 functions during heart development, and a previously uncharacterized mechanism regarding how SMYD1 represses cardiac transcription in the developing heart.

Resistance training up-regulates Smyd1 expression and inhibits oxidative stress and endoplasmic reticulum stress in the heart of middle-aged mice.

Persistent oxidative stress and endoplasmic reticulum (ER) stress are the primary mechanisms of age-related cardiovascular diseases. Although exercise training is viewed as an effective anti-aging approach, further exploration is needed to identify the mechanisms and functional targets. In this study, the impact of resistance training (RT) on the expression of Smyd1, the levels of reactive oxygen species (ROS) and the expression of ER stress-related protein in the hearts of mice of different ages were assessed. In addition, the role of Smyd1 in the aging-induced oxidative stress and ER stress were evaluated in d-galactose (D-gal)-treated H9C2 cells. We demonstrated that RT in middle age increased the expression of Smyd1 and restricted heart aging-induced ER stress. Overexpression of Smyd1 restrained oxidative stress and ER stress in D-gal-treated H9C2 cells, while the inhibition of Nrf2 and Smyd1 escalated ER stress. These findings demonstrate that Smyd1 has significant impact in regulating age-related ER stress. RT in middle age can up-regulates Smyd1 expression and inhibits oxidative stress and ER stress in the heart.

Smyd1: Implications for novel approaches in rhabdomyosarcoma therapy.

Rhabdomyosarcoma (RMS), a tumor that consists of poorly differentiated skeletal muscle cells, is the most common soft-tissue sarcoma in children. Despite considerable progress within the last decades, therapeutic options are still limited, warranting the need for novel approaches. Recent data suggest deregulation of the Smyd1 protein, a sumoylation target as well as H3K4me2/3 methyltransferase and transcriptional regulator in myogenesis, and its binding partner skNAC, in RMS cells. Here, we show that despite the fact that most RMS cells express at least low levels of Smyd1 and skNAC, failure to upregulate expression of these genes in reaction to differentiation-promoting signals can always be observed. While overexpression of the Smyd1 gene enhances many aspects of RMS cell differentiation and inhibits proliferation rate and metastatic potential of these cells, functional integrity of the putative Smyd1 sumoylation motif and its SET domain, the latter being crucial for HMT activity, appear to be prerequisites for most of these effects. Based on these findings, we explored the potential for novel RMS therapeutic strategies, employing small-molecule compounds to enhance Smyd1 activity. In particular, we tested manipulation of (a) Smyd1 sumoylation, (b) stability of H3K4me2/3 marks, and (c) calpain activity, with calpains being important targets of Smyd1 in myogenesis. We found that specifically the last strategy might represent a promising approach, given that suitable small-molecule compounds will be available for clinical use in the future.

Down-regulated Smyd1 participated in the inhibition of myoblast differentiation induced by cigarette smoke extract.

The histone methyltransferase Smyd1 is essential for muscle development; however, its role in smoking-induced skeletal muscle atrophy and dysfunction has not been investigated thus far. In this study, Smyd1 was overexpressed or knocked down in C2C12 myoblasts by an adenovirus vector and cultured in differentiation medium containing 5% cigarette smoke extract (CSE) for 4 days. CSE exposure resulted in inhibition of C2C12 cell differentiation and downregulation of Smyd1 expression, whereas Smyd1 overexpression reduced the degree of inhibition of myotube differentiation caused by CSE exposure. CSE exposure activated P2RX7-mediated apoptosis and pyroptosis, caused increased intracellular reactive oxygen species (ROS) levels, and impaired mitochondrial biogenesis and increased protein degradation by downregulating PGC1α, whereas Smyd1 overexpression partially restored the altered protein levels caused by CSE exposure. Smyd1 knockdown alone produced a phenotype similar to CSE exposure, and Smyd1 knockdown during CSE exposure aggravated the degree of inhibition of myotube differentiation and the degree of activation of P2RX7. CSE exposure suppressed H3K4me2 expression, and chromatin immunoprecipitation confirmed the transcriptional regulation of P2rx7 by H3K4me2 modification. Our findings suggest that CSE exposure mediates C2C12 cell apoptosis and pyroptosis through the Smyd1-H3K4me2-P2RX7 axis, and inhibits PGC1α expression to impair mitochondrial biosynthesis and increase protein degradation by inhibiting Smyd1 expression, ultimately leading to abnormal C2C12 myoblasts differentiation and impaired myotube formation.

SMYD1a protects the heart from ischemic injury by regulating OPA1-mediated cristae remodeling and supercomplex formation.

SMYD1, a striated muscle-specific lysine methyltransferase, was originally shown to play a key role in embryonic cardiac development but more recently we demonstrated that loss of Smyd1 in the murine adult heart leads to cardiac hypertrophy and failure. However, the effects of SMYD1 overexpression in the heart and its molecular function in the cardiomyocyte in response to ischemic stress are unknown. In this study, we show that inducible, cardiomyocyte-specific overexpression of SMYD1a in mice protects the heart from ischemic injury as seen by a > 50% reduction in infarct size and decreased myocyte cell death. We also demonstrate that attenuated pathological remodeling is a result of enhanced mitochondrial respiration efficiency, which is driven by increased mitochondrial cristae formation and stabilization of respiratory chain supercomplexes within the cristae. These morphological changes occur concomitant with increased OPA1 expression, a known driver of cristae morphology and supercomplex formation. Together, these analyses identify OPA1 as a novel downstream target of SMYD1a whereby cardiomyocytes upregulate energy efficiency to dynamically adapt to the energy demands of the cell. In addition, these findings highlight a new epigenetic mechanism by which SMYD1a regulates mitochondrial energetics and functions to protect the heart from ischemic injury.

Identification of Two Homozygous Variants in MYBPC3 and SMYD1 Genes Associated with Severe Infantile Cardiomyopathy.

Mutations in cardiac genes are one of the primary causes of infantile cardiomyopathy. In this study, we report the genetic findings of two siblings carrying variations in the MYBPC3 and SMYD1 genes. The first patient is a female proband exhibiting hypertrophic cardiomyopathy (HCM) and biventricular heart failure carrying a truncating homozygous MYBPC3 variant c.1224-52G>A (IVS13-52G>A) and a novel homozygous variant (c.302A>G; p.Asn101Ser) in the SMYD1 gene. The second patient, the proband's sibling, is a male infant diagnosed with hypertrophic cardiomyopathy and carries the same homozygous MYBPC3 variant. While this specific MYBPC3 variant (c.1224-52G>A, IVS13-52G>A) has been previously reported to be associated with adult-onset hypertrophic cardiomyopathy, this is the first report linking it to infantile cardiomyopathy. In addition, this work describes, for the first time, a novel SMYD1 variant (c.302A>G; p.Asn101Ser) that has never been reported. We performed a histopathological evaluation of tissues collected from both probands and show that these variants lead to myofibrillar disarray, reduced and irregular mitochondrial cristae and cardiac fibrosis. Together, these results provide critical insight into the molecular functionality of these genes in human cardiac physiology.

Sex and diet-dependent gene alterations in human and rat brains with a history of nicotine exposure.

Introduction: Chronic nicotine exposure induces changes in the expression of key regulatory genes associated with metabolic function and neuronal alterations in the brain. Many bioregulatory genes have been associated with exposure to nicotine, but the modulating effects of sex and diet on gene expression in nicotine-exposed brains have been largely unexplored. Both humans and rodents display motivation for nicotine use and the emergence of withdrawal symptoms during abstinence. Research comparing pre-clinical models with human subjects provides an important opportunity to understand common biomarkers of the harmful effects of nicotine as well as information that may help guide the development of more effective interventions for nicotine cessation. Methods: Human postmortem dorsolateral prefrontal cortex (dLPFC) tissue BA9 was collected from female and male subjects, smokers and non-smokers (N = 12 per group). Rat frontal lobes were collected from female and male rats that received a regular diet (RD) or a high-fat diet (HFD) (N = 12 per group) for 14 days following implantation of a osmotic mini-pump (Alzet) that delivered nicotine continuously. Controls (control-s) received a sham surgical procedure. RNA was extracted from tissue from human and rat samples and reversed-transcribed to cDNA. Gene expression of CHRNA10 (Cholinergic receptor nicotinic alpha 10), CERKL (Ceramide Kinase-Like), SMYD1 (SET and MYD Domin Containing 1), and FA2H (Fatty Acid 2-Hydrolase) in humans was compared to rats in each subset of groups and quantified by qPCR methods. Additionally, protein expression of FA2H was analyzed by immunohistochemistry (IHC) in human dLPFC. Results: Humans with a history of smoking displayed decreased CHRNA10 (p = 0.0005), CERKL (p ≤ 0.0001), and SMYD1 (p = 0.0005) expression and increased FA2H (p = 0.0097) expression compared to non-smokers (p < 0.05). Similar patterns of results were observed in nicotine exposed vs. control rats. Interestingly, sex-related differences in gene expression for CERKL and FA2H were observed. In addition, ANCOVA analysis showed a significant effect of nicotine in a sex-different manner, including an increase in CERKL in male and female rats with RD or HFD. In rats exposed to an HFD, FA2H gene expression was lower in nicotine-treated rats compared to RD rats treated with nicotine. Protein expression of FA2H (p = 0.001) by IHC was significantly higher in smokers compared to non-smokers. Conclusion: These results suggest that a history of long-term nicotine exposure in humans alters the expression of sphingolipid metabolism-related (CERKL, SMYD1, and FA2H) and neuronal (CHRNA10) marker genes similarly as compared to rats. Sex- and diet-dependent differences appear in nicotine-exposed rats, critical in regulating sphingolipid metabolism and nicotinic acetylcholine receptors. This research enhances the construct validity of rat models of nicotine usage by showing a similar pattern of changes in gene expression in human subjects with a smoking history.

The Methyltransferase Smyd1 Mediates LPS-Triggered Up-Regulation of IL-6 in Endothelial Cells.

The lysine methyltransferase Smyd1 with its characteristic catalytic SET-domain is highly enriched in the embryonic heart and skeletal muscles, participating in cardiomyogenesis, sarcomere assembly and chromatin remodeling. Recently, significant Smyd1 levels were discovered in endothelial cells (ECs) that responded to inflammatory cytokines. Based on these biochemical properties, we hypothesized that Smyd1 is involved in inflammation-triggered signaling in ECs and therefore, investigated its role within the LPS-induced signaling cascade. Human endothelial cells (HUVECs and EA.hy926 cells) responded to LPS stimulation with higher intrinsic Smyd1 expression. By transfection with expression vectors containing gene inserts encoding either intact Smyd1, a catalytically inactive Smyd1-mutant or Smyd1-specific siRNAs, we show that Smyd1 contributes to LPS-triggered expression and secretion of IL-6 in EA.hy926 cells. Further molecular analysis revealed this process to be based on two signaling pathways: Smyd1 increased the activity of NF-κB and promoted the trimethylation of lysine-4 of histone-3 (H3K4me3) within the IL-6 promoter, as shown by ChIP-RT-qPCR combined with IL-6-promoter-driven luciferase reporter gene assays. In summary, our experimental analysis revealed that LPS-binding to ECs leads to the up-regulation of Smyd1 expression to transduce the signal for IL-6 up-regulation via activation of the established NF-κB pathway as well as via epigenetic trimethylation of H3K4.

Overexpression of Lifeact-GFP Disrupts F-Actin Organization in Cardiomyocytes and Impairs Cardiac Function.

Lifeact-GFP is a frequently used molecular probe to study F-actin structure and dynamic assembly in living cells. In this study, we generated transgenic zebrafish models expressing Lifeact-GFP specifically in cardiac muscles to investigate the effect of Lifeact-GFP on heart development and its application to study cardiomyopathy. The data showed that transgenic zebrafish with low to moderate levels of Lifeact-GFP expression could be used as a good model to study contractile dynamics of actin filaments in cardiac muscles in vivo. Using this model, we demonstrated that loss of Smyd1b, a lysine methyltransferase, disrupted F-actin filament organization in cardiomyocytes of zebrafish embryos. Our studies, however, also demonstrated that strong Lifeact-GFP expression in cardiomyocytes was detrimental to actin filament organization in cardiomyocytes that led to pericardial edema and early embryonic lethality of zebrafish embryos. Collectively, these data suggest that although Lifeact-GFP is a good probe for visualizing F-actin dynamics, transgenic models need to be carefully evaluated to avoid artifacts induced by Lifeact-GFP overexpression.

SMYD1 alleviates septic myocardial injury by inhibiting endoplasmic reticulum stress.

Sepsis-induced cardiomyopathy (SIC) is a major complication of sepsis. SET and MYND domain containing 1 (SMYD1) has central importance in heart development, and its role in SIC has not been identified. Herein, we found that the expression of SMYD1 was downregulated in myocardial tissues of SIC patients (from GEO database: GSE79962) and lipopolysaccharide (LPS)-induced SIC rats, and LPS-induced H9c2 cardiomyocytes. We used LPS-stimulated H9c2 cells that mimic sepsis in vitro to explore the function of SMYD1 in SIC. MTT assay, LDH and CK-MB release assay, flow cytometry, and ELISA assay showed that SMYD1 overexpression enhanced cell viability, alleviated cell injury, impeded apoptosis, and reduced the level of proinflammatory factors and NF-κB activation under the condition of LPS stimulation. Moreover, SMYD1 exerted protective effect on H9c2 cells stimulated with LPS through relieving endoplasmic reticulum (ER) stress. In conclusion, overexpression of SMYD1 alleviates cardiac injury through relieving ER stress during sepsis.

Copper ions impair zebrafish skeletal myofibrillogenesis via epigenetic regulation.

Unbalanced copper (Cu2+ ) homeostasis is associated with the developmental defects of vertebrate myogenesis, but the underlying molecular mechanisms remain elusive. In this study, it was found that Cu2+ stressed zebrafish embryos and larvae showed reduced locomotor speed as well as loose and decreased myofibrils in skeletal muscle, coupled with the downregulated expression of muscle fiber markers mylpfa and smyhc1l and the irregular arrangement of myofibril and sarcomere. Meanwhile, the Cu2+ stressed zebrafish embryos and larvae also showed significant reduction in the expression of H3K4 methyltransferase smyd1b transcripts and H3K4me3 protein as well as in the binding enrichment of H3K4me3 on gene mylpfa promoter in skeletal muscle cells, suggesting that smyd1b-H3K4me3 axis mediates the Cu2+ -induced myofibrils specification defects. Additionally, whole genome DNA methylation sequencing unveiled that the gene smyd5 exhibited significant promoter hyper-methylation and increased expression in Cu2+ stressed embryos, and the ectopic expression of smyd5 in zebrafish embryos also induced the myofibrils specification defects as those observed in Cu2+ stressed embryos. Moreover, Cu2+ was shown to suppress myofibrils specification and smyd1b promoter transcriptional activity directly independent of the integral function of copper transporter cox17 and atp7b. All these data may shed light on the linkage of unbalanced copper homeostasis with specific gene promoter methylation and epigenetic histone protein modification as well as the resultant signaling transduction and the myofibrillogenesis defects.

Smyd1 is essential for myosin expression and sarcomere organization in craniofacial, extraocular, and cardiac muscles.

Skeletal and cardiac muscles are striated myofibers that contain highly organized sarcomeres for muscle contraction. Recent studies revealed that Smyd1, a lysine methyltransferase, plays a key role in sarcomere assembly in heart and trunk skeletal muscles. However, Smyd1 expression and function in craniofacial muscles are not known. Here, we analyze the developmental expression and function of two smyd1 paralogous genes, smyd1a and smyd1b, in craniofacial and cardiac muscles of zebrafish embryos. Our data show that loss of smyd1a (smyd1amb5) or smyd1b (smyd1bsa15678) has no visible effects on myogenic commitment and expression of myod and myosin heavy-chain mRNA transcripts in craniofacial muscles. However, myosin heavy-chain protein accumulation and sarcomere organization are dramatically reduced in smyd1bsa15678 single mutant, and almost completely diminish in smyd1amb5; smyd1bsa15678 double mutant, but not in smyd1amb5 mutant. Similar defects are also observed in cardiac muscles of smyd1bsa15678 mutant. Defective craniofacial and cardiac muscle formation is associated with an upregulation of hsp90α1 and unc45b mRNA expression in smyd1bsa15678 and smyd1amb5; smyd1bsa15678 mutants. Together, our studies indicate that Smyd1b, but not Smyd1a, plays a key role in myosin heavy-chain protein expression and sarcomere organization in craniofacial and cardiac muscles. Loss of smyd1b results in muscle-specific stress response.

Smyd1 Orchestrates Early Heart Development Through Positive and Negative Gene Regulation.

SET and MYND domain-containing protein 1 (Smyd1) is a striated muscle-specific histone methyltransferase. Our previous work demonstrated that deletion of Smyd1 in either cardiomyocytes or the outflow tract (OFT) resulted in embryonic lethality at E9.5, with cardiac structural defects such as truncation of the OFT and right ventricle and impaired expansion and proliferation of the second heart field (SHF). The cardiac phenotype was accompanied by the downregulation of ISL LIM Homeobox 1 (Isl1) and upregulation of atrial natriuretic factor (ANF). However, the mechanisms of Smyd1 regulating Isl1 and ANF during embryonic heart development remain to be elucidated. Here, we employed various biochemical and molecular biological approaches including chromatin immunoprecipitation polymerase chain reaction (ChIP-PCR), pGL3 fluorescence reporter system, and co-immunoprecipitation (CoIP) and found that Smyd1 interacted with absent small homeotic-2-like protein (ASH2L) and activated the promoter of Isl1 by trimethylating H3K4. We also found that Smyd1 associated with HDAC to repress ANF expression using trichostatin A (TSA), a deacetylase inhibitor. In conclusion, Smyd1 participates in early heart development by upregulating the expression of Isl1 and downregulating the expression of ANF.

Stability of Smyd1 in endothelial cells is controlled by PML-dependent SUMOylation upon cytokine stimulation.

Smyd1 is an epigenetic modulator of gene expression that has been well-characterized in muscle cells. It was recently reported that Smyd1 levels are modulated by inflammatory processes. Since inflammation affects the vascular endothelium, this study aimed to characterize Smyd1 expression in endothelial cells. We detected Smyd1 in human endothelial cells (HUVEC and EA.hy926 cells), where the protein was largely localized in PML nuclear bodies (PML-NBs). By transfection of EA.hy926 cells with expression vectors encoding Smyd1, PML, SUMO1, active or mutant forms of the SUMO protease SuPr1 and/or the SUMO-conjugation enzyme UBC9, as well as Smyd1- or PML-specific siRNAs, in the presence or absence of the translation blocker cycloheximide or the proteasome-inhibitor MG132, and supported by computational modeling, we show that Smyd1 is SUMOylated in a PML-dependent manner and thereby addressed for degradation in proteasomes. Furthermore, transfection with Smyd1-encoding vectors led to PML up-regulation at the mRNA level, while PML transfection lowered Smyd1 protein stability. Incubation of EA.hy926 cells with the pro-inflammatory cytokine TNF-α resulted in a constant increase in Smyd1 mRNA and protein over 24 h, while incubation with IFN-γ induced a transient increase in Smyd1 expression, which peaked at 6 h and decreased to control values within 24 h. The IFN-γ-induced increase in Smyd1 was accompanied by more Smyd1 SUMOylation and more/larger PML-NBs. In conclusion, our data indicate that in endothelial cells, Smyd1 levels are regulated through a negative feedback mechanism based on SUMOylation and PML availability. This molecular control loop is stimulated by various cytokines.

The SMYD1 and skNAC transcription factors contribute to neurodegenerative diseases.

SMYD1 and the skNAC isoform of the NAC transcription factor have both previously been characterized as transcription factors in hematopoiesis and cardiac/skeletal muscle. Here we report that comparative analysis of genes deregulated by SMYD1 or skNAC knockdown in differentiating C2C12 myoblasts identified transcripts characteristic of neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's Diseases (AD, PD, and HD). This led us to determine whether SMYD1 and skNAC function together or independently within the brain. Based on meta-analyses and direct experimentation, we observed SMYD1 and skNAC expression within cortical striata of human brains, mouse brains and transgenic mouse models of these diseases. We observed some of these features in mouse myoblasts induced to differentiate into neurons. Finally, several defining features of Alzheimer's pathology, including the brain-specific, axon-enriched microtubule-associated protein, Tau, are deregulated upon SMYD1 loss.

Heart Transplantation from Biventricular Support in Infant with Novel SMYD1 Mutation.

SET and MYND domain-containing protein 1 (SMYD1) has been shown to be responsible for the development of fast twitch and cardiac muscle. Mutations in SMYD1 have been shown to be uniformly fatal in laboratory studies, and not previously described in living humans. We describe here the care of an infant suffering from cardiac failure due to an SMYD1 mutation requiring biventricular assist devices as a bridge to successful heart transplantation. The patient is now doing well 2 years post-transplant and represents a known survivor of a suspected uniformly fatal genetic mutation.

A de novo mutation of SMYD1 (p.F272L) is responsible for hypertrophic cardiomyopathy in a Chinese patient.

Background Hypertrophic cardiomyopathy (HCM) is a serious disorder and one of the leading causes of mortality worldwide. HCM is characterized as left ventricular hypertrophy in the absence of any other loading conditions. In previous studies, mutations in at least 50 genes have been identified in HCM patients. Methods In this research, the genetic lesion of an HCM patient was identified by whole exome sequencing. Real-time polymerase chain reaction (PCR), immunofluorescence and Western blot were used to analyze the effects of the identified mutation. Results According to whole exome sequencing, we identified a de novo mutation (c.814T>C/p.F272L) of SET and MYND domain containing histone methyltransferase 1 (SMYD1) in a Chinese patient with HCM exhibiting syncope. We then generated HIS-SMYD1-pcDNA3.1+ (WT and c.814T>C/p.F272L) plasmids for transfection into AC16 cells to functionalize the mutation. The immunofluorescence experiments indicated that this mutation may block the SMYD1 protein from entering the nucleus. Both Western blot and real-time PCR revealed that, compared with cells transfected with WT plasmids, the expression of HCM-associated genes such as ß-myosin heavy chains, SMYD1 chaperones (HSP90) and downstream targets including TGF-ß were all disrupted in cells transfected with the mutant plasmid. Previous studies have demonstrated that SMYD1 plays a crucial role in sarcomere organization and heart development. Conclusions This novel mutation (c.814T>C/p.F272L) may be the first identified disease-causing mutation of SMYD1 in HCM patients worldwide. Our research expands the spectrum of HCM-causing genes and contributes to genetic counseling for HCM patients.

Histone methyltransferase Smyd1 regulates mitochondrial energetics in the heart.

Smyd1, a muscle-specific histone methyltransferase, has established roles in skeletal and cardiac muscle development, but its role in the adult heart remains poorly understood. Our prior work demonstrated that cardiac-specific deletion of Smyd1 in adult mice (Smyd1-KO) leads to hypertrophy and heart failure. Here we show that down-regulation of mitochondrial energetics is an early event in these Smyd1-KO mice preceding the onset of structural abnormalities. This early impairment of mitochondrial energetics in Smyd1-KO mice is associated with a significant reduction in gene and protein expression of PGC-1α, PPARα, and RXRα, the master regulators of cardiac energetics. The effect of Smyd1 on PGC-1α was recapitulated in primary cultured rat ventricular myocytes, in which acute siRNA-mediated silencing of Smyd1 resulted in a greater than twofold decrease in PGC-1α expression without affecting that of PPARα or RXRα. In addition, enrichment of histone H3 lysine 4 trimethylation (a mark of gene activation) at the PGC-1α locus was markedly reduced in Smyd1-KO mice, and Smyd1-induced transcriptional activation of PGC-1α was confirmed by luciferase reporter assays. Functional confirmation of Smyd1's involvement showed an increase in mitochondrial respiration capacity induced by overexpression of Smyd1, which was abolished by siRNA-mediated PGC-1α knockdown. Conversely, overexpression of PGC-1α rescued transcript expression and mitochondrial respiration caused by silencing Smyd1 in cardiomyocytes. These findings provide functional evidence for a role of Smyd1, or any member of the Smyd family, in regulating cardiac energetics in the adult heart, which is mediated, at least in part, via modulating PGC-1α.

SMYD1 is the underlying gene for the AnWj-negative blood group phenotype.

BACKGROUND: AnWj is a high-incidence blood group antigen associated with three clinical disorders: lymphoid malignancies, immunologic disorders, and autoimmune hemolytic anemia. The aim of this study was to determine the genetic basis of an inherited AnWj-negative phenotype. METHODS: We identified a consanguineous family with two AnWj-negative siblings and 4 additional AnWj-negative individuals without known familial relationship to the index family. We performed exome sequencing in search for rare homozygous variants shared by the two AnWj-negative siblings of the index family and searched for these variants in the four non-related AnWj-negative individuals. RESULTS: Exome sequencing revealed seven candidate genes that showed complete segregation in the index family and for which the two AnWj-negative siblings were homozygous. However, the four additional non-related AnWj-negative subjects were homozygous for only one of these variants, rs114851602 (R320Q) in the SMYD1 gene. Considering the frequency of the minor allele, the chance of randomly finding 4 consecutive such individuals is 2.56 × 10-18 . CONCLUSION: We present genetic and statistical evidence that the R320Q substitution in SMYD1 underlies an inherited form of the AnWj-negative blood group phenotype. The mechanism by which the mutation leads to this phenotype remains to be determined.

DNA methylation levels and expression patterns of Smyd1a and Smyd1b genes during Metamorphosis of the Japanese Flounder (Paralichthys olivaceus).

Japanese flounder (Paralichthys olivaceus) undergoes metamorphosis by changing its body from the larval to the juvenile form, and this process involves muscle development. Smyd1, a histone methyltransferase, plays a role in the skeletal muscle. In the present study, the Smyd1a and Smyd1b expression patterns and their 5' UTR and exon 1 DNA methylation levels were analyzed during metamorphosis of the Japanese flounder. Sample were analyzed 21 days post-hatching (dph) (with no migration of right eye; M1stage), 28 dph (during migration of right eye; M2 stage), and 35 dph (after migration of right eye; M3 stage). The results show that Smyd1a expression was highest in the M2 stage and then decreased, whereas Smyd1b expression continued to rise during the three stages. Methylation levels of CpG sites at positions -2318 and -2217 of the Smyd1a P region (-2462 to -2181 region of the 5' UTR), and the CpG sites at positions -351, -330, -284, -190, and - 92 of the Smyd1b promoter, with both regions containing putative transcription factor binding sites, showed significant differences in the three stages (p < 0.05). Interestingly, the methylation levels of these CpG sites were negatively correlated with mRNA expression. We inferred that binding of the predicted transcription factors might be affected by methylation of the CpG sites and thus modulate gene expression. Taken together, our results suggest that DNA methylation in the Smyd1a and Smyd1b genes participates in the regulation of metamorphosis, and epigenetics may provide clues for further studies of the mechanisms of metamorphosis in the Japanese flounder.