Upregulation of Periostin Through CREB Participates in Myocardial Infarction-induced Myocardial Fibrosis.

ABSTRACT: Myocardial fibrosis after myocardial infarction (MI) leads to heart failure, which has become an important global public health issue. One of the most important features of myocardial fibrosis is the abnormal deposition of extracellular matrix (ECM) proteins. Periostin is one of the ECM proteins. Cyclic AMP response element-binding protein 1 (CREB) is well known for its involvement in multiple signaling in myocardial fibrosis. It has been confirmed that CREB could regulate ECM proteins deposition. However, little is known about the relationship between CREB and periostin post-MI. This study aims to verify the hypothesis that CREB promotes the expression of periostin in MI-induced myocardial fibrosis. To test this hypothesis, primary rat cardiac fibroblasts were cultured and rat model of MI was established. The level of myocardial fibrosis post-MI was identified by histological staining. The expressions of CREB and periostin were detected through western blot and reverse transcription quantity polymerase chain reaction. The upregulation and downregulation of CREB and periostin were established by plasmid, small interfere RNA (siRNA), and lentivirus, respectively. High levels of CREB and periostin were found post-MI in our study. Meanwhile, the expression of periostin was decreased after CREB downregulation both in vivo and in vitro. Finally, with the treatment of pAV-CREB and si-periostin, the expressions of collagen Ⅰ and Ⅲ were attenuated. The expression of periostin was elevated post-MI and participated in MI-induced myocardial fibrosis, which was regulated through CREB. This study provides a novel idea and potential intervention target for MI-induced myocardial fibrosis.

Decreased autophagy of vascular smooth muscle cells was involved in hyperhomocysteinemia-induced vascular ageing.

Ageing and hyperhomocysteinemia (HHcy) are important risk factors for cardiovascular diseases (CVDs). HHcy affects the occurrence of vascular diseases in the elderly. So far, the mechanism of HHcy-induced vascular ageing remains largely unknown. Autophagy level is significantly reduced in the ageing process, and restoring impaired autophagy to a normal state may be one of the possible ways to extend the expected longevity and lifespan in the future. In this study, we established the HHcy rat model by feeding a 2.5% methionine diet. Small animal ultrasound and the tail-cuff method indicated that the vascular pulse wave velocity (PWV) and pulse pressure (PP) of HHcy rats were increased significantly compared with the control group. Vascular morphology and structure have been changed in HHcy rats, including lumen dilation, increased collagen fibre deposition and increased p53/p21/p16 expression. In vitro, under the stimulation of homocysteine (500 µmol/L, 24 hours), the rat vascular smooth muscle cells (VSMCs) presented senescence, which was characterized by the increased expression of ageing-related markers, such as p16, p21 and p53 as well as increased senescence-associated beta-galactosidase (SA-ß-gal) activity. Meanwhile, the autophagy level was decreased both in vivo and in vitro, shown as the increased level of autophagy substrate p62 and the reduced level of autophagy marker LC3 II/I in the thoracic aorta of HHcy rats and in Hcy-treated VSMCs, respectively. The senescence phenotype of VSMCs was reversed by increased autophagy levels induced by rapamycin. Our findings indicate that decreased autophagy of VSMCs is involved in hyperhomocysteinemia-induced vascular ageing.

Nitration of cAMP-Response Element Binding Protein Participates in Myocardial Infarction-Induced Myocardial Fibrosis via Accelerating Transcription of Col1a2 and Cxcl12.

Aims: Myocardial fibrosis after myocardial infarction (MI) leads to heart failure. Nitration of protein can alter its function. cAMP-response element binding protein (CREB) is a key transcription factor involved in fibrosis. However, little is known about the role of nitrated CREB in MI-induced myocardial fibrosis. Meanwhile, downstream genes of transcription factor CREB in myocardial fibrosis have not been identified. This study aims to verify the hypothesis that nitrated CREB promotes MI-induced myocardial fibrosis via regulating the transcription of Col1a2 and Cxcl12. Results: Our study showed that (1) the level of nitrative stress was elevated and nitrated CREB was higher in the myocardium after MI. Tyr182, 307, and 336 were the nitration sites of CREB; (2) with the administration of peroxynitrite (ONOO-) scavengers, CREB phosphorylation, nuclear translocation, and binding activity to TORC2 (transducers of regulated CREB-2) were attenuated; (3) the expressions of extracellular matrix (ECM) proteins were upregulated and downregulated in accordance with the expression alteration of CREB both in vitro and in vivo; (4) CREB accelerated transcription of Col1a2 and Cxcl12 after MI directly. With the administration of ONOO- scavengers, ECM protein expressions were attenuated; meanwhile, the messenger RNA (mRNA) levels of Col1a2 and Cxcl12 were alleviated as well. Innovation and Conclusion: Nitration of transcription factor CREB participates in MI-induced myocardial fibrosis through enhancing its phosphorylation, nuclear translocation, and binding activity to TORCs, among which CREB transcripts Col1a2 and Cxcl12 directly. These data indicated that nitrated CREB might be a potential therapeutic target against MI-induced myocardial fibrosis. Antioxid. Redox Signal. 38, 709-730.

Cystathionine ß-synthase is required for oocyte quality by ensuring proper meiotic spindle assembly.

OBJECTIVES: Poor oocyte quality is detrimental to fertilization and embryo development, which causes infertility. Cystathionine ß-synthase (CBS) is one of the key enzymes modulating the metabolism of homocysteine (Hcy). Studies have shown that CBS plays an important role in female reproduction. However, the role of CBS in regulating oocyte quality during meiotic maturation still needs further investigation. MATERIALS AND METHODS: Immunohistochemistry, immunofluorescence, drug treatment, western blot, cRNA construct and in vitro transcription, microinjection of morpholino oligo and cRNA were performed for this study. RESULTS: We found that CBS was expressed both in human and mouse oocytes of follicles. In mouse oocytes, CBS was distributed in the nucleus at germinal vesicle (GV) stage and localized to spindle from germinal vesicle breakdown (GVBD) to metaphase II (MII). The expression of CBS was reduced in ovaries and oocytes of aged mice. CBS depletion resulted in meiotic arrest, spindle abnormality and chromosome misalignment, disrupted kinetochore-microtubule attachments and provoked spindle assembly checkpoint (SAC). CBS was disassembled when microtubules were disrupted with nocodazole, and co-localized with the stabilized microtubules after taxol treatment. Furthermore, CBS depletion decreased the acetylation of α-tubulin. CONCLUSIONS: These results reveal that CBS is required for the acetylation of α-tubulin to ensure proper spindle assembly in regulating oocyte quality during meiotic maturation.

Insufficient S-Sulfhydration of Methylenetetrahydrofolate Reductase Contributes to the Progress of Hyperhomocysteinemia.

Aims: Hyperhomocysteinemia (HHcy) has been considered as a risk factor for cardiovascular disease, Alzheimer's disease, nonalcoholic fatty liver, and many other pathological conditions. Vitamin B6, Vitamin B12, and folate have been used to treat HHcy in clinics. However, at present, clinical therapies of HHcy display unsatisfactory effects. Here, we would like to explore a new mechanism involved in homocysteine (Hcy) metabolic disorders and a novel target for HHcy treatment. The key enzymes involved in Hcy metabolism deserve more insightful investigation. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme regulating the intracellular Hcy metabolism. Until now, the effect of post-translational modification on the bioactivity of MTHFR still remains unclear. This study aimed at exploring the relationship between MTHFR S-sulfhydration and its bioactivity, and at identifying the contribution of an elevated Hcy level on MTHFR bioactivity. Results: By both in vivo and in vitro studies, we observed the following results: (i) The bioactivity of MTHFR was positively associated with its S-sulfhydration level; (ii) MTHFR was modified at Cys32, Cys130, Cys131, Cys193, and Cys306 by S-sulfhydration under physiological conditions; (iii) Hydrogen sulfide (H2S) deficiency caused the decrease of MTHFR S-sulfhydration level and bioactivity in HHcy, which resulted in further aggravation of HHcy; and (iv) H2S donors reversed the decreased bioactivity of MTHFR in HHcy, thus reducing the excessive Hcy level. Innovation and Conclusion: Our study suggested that H2S could improve MTHFR bioactivity by S-sulfhydration, which might provide a candidate therapeutic strategy for HHcy. Antioxid. Redox Signal. 36, 1-14.

Abnormal nitration and S-sulfhydration modification of Sp1-CSE-H2S pathway trap the progress of hyperhomocysteinemia into a vicious cycle.

Sp1-CSE-H2S pathway plays an important role in homocysteine-metabolism, whose disorder can result in hyperhomocysteinemia. H2S deficiency in hyperhomocysteinemia has been reported, while the underlying mechanism and whether it in turn affects the progress of hyperhomocysteinemia are unclear. This study focused on the post-translational modification of Sp1/CSE and revealed four major findings: (1) Homocysteine-accumulation augmented CSE's nitration, inhibited its bio-activity, thus caused H2S deficiency. (2) H2S deficiency inhibited the S-sulfhydration of Sp1, down-regulated CSE and decreased H2S further, which in turn weakened CSE's own S-sulfhydration. (3) CSE was S-sulfhydrated at Cys84, Cys109, Cys172, Cys229, Cys252, Cys307 and Cys310, among which the S-sulfhydration of Cys172 and Cys310 didn't affect its enzymatic activity, while the S-sulfhydration of Cys84, Cys109, Cys229, Cys252 and Cys307 was necessary for its bio-activity. (4) H2S deficiency trapped homocysteine-metabolism into a vicious cycle, which could be broken by either blocking nitration or restoring S-sulfhydration. This study detected a new mechanism that caused severe hyperhomocysteinemia, thereby provided new therapeutic strategies for hyperhomocysteinemia.

Nitrative Stress-Related Autophagic Insufficiency Participates in Hyperhomocysteinemia-Induced Renal Aging.

The kidneys are important organs that are susceptible to aging. Hyperhomocysteinemia (HHcy) is a risk factor for nephropathy and is associated with chronic nephritis, purpuric nephritis, and nephrotic syndrome. Numerous studies have shown that elevated serum homocysteine levels can damage the kidneys; however, the underlying mechanism of HHcy on kidney damage remains unclear. In this study, we make use of a diet-induced HHcy rat model and in vitro cell culture to explore the role of autophagy in HHcy-induced renal aging and further explored the underlying mechanism. We demonstrated that HHcy led to the development of renal aging. Promoted kidney aging and autophagic insufficiency were involved in HHcy-induced renal aging. HHcy decreased the expression of transcription factor EB (TFEB), the key transcription factor of autophagy-related genes in renal tissue. Further experiments showed that nitrative stress levels were increased in the kidney of HHcy rats. Interestingly, pretreatment with the peroxynitrite (ONOO-) scavenger FeTMPyP not only reduced the Hcy-induced nitrative stress in vitro but also partially attenuated the decrease in TFEB in both protein and mRNA levels. Moreover, our results indicated that HHcy reduced TFEB expression and inhibited TFEB-mediated autophagy activation by elevating nitrative stress. In conclusion, this study showed an important role of autophagic insufficiency in HHcy-induced renal aging, in which downregulation of TFEB plays a major role. Furthermore, downexpression of TFEB was associated with increased nitrative stress in HHcy. This study provides a novel insight into the mechanism and therapeutic strategy for renal aging.

ß2-adrenergic receptor autoantibodies alleviated myocardial damage induced by ß1-adrenergic receptor autoantibodies in heart failure.

Aims: ß1-adrenergic receptor autoantibodies (ß1-AAs) and ß2-adrenergic receptor autoantibodies (ß2-AAs) are present in patients with heart failure (HF); however, their interrelationship with cardiac structure and function remains unknown. This study explored the effects of the imbalance between ß1-AAs and ß2-AAs on cardiac structure and its underlying mechanisms in HF. Methods and results: Patients with left systolic HF who suffered from coronary heart disease (65.9%) or dilated cardiomyopathy (34.1%) were divided into New York Heart Association Classes I-II (n = 51) and Classes III-IV (n = 37) and compared with healthy volunteers as controls (n = 41). Total immunoglobulin G from HF patient serum comprising ß1-AAs and/or ß2-AAs were determined and purified for in vitro studies from neonatal rat cardiomyocytes (NRCMs). In addition, HF was induced by doxorubicin in mice. We observed that the increased ratio of ß1-AAs/ß2-AAs was associated with worsening HF in patients. Moreover, ß2-AAs from patients with HF suppressed the hyper-shrinking and apoptosis of NRCMS induced by ß1-AAs from some patients. Finally, ß2-AAs alleviated both myocardial damage and ß1-AAs production induced by doxorubicin in mice. Conclusion: ß2-AAs were capable of antagonizing the effects imposed by ß1-AAs both in vitro and in vivo. The imbalance of ß1-AAs and ß2-AAs in patients with HF is a mechanism underlying HF progression, and the increasing ratio of ß1-AAs/ß2-AAs should be considered a clinical assessment factor for the deterioration of cardiac function in patients with HF.