Setd4 controlled quiescent c-Kit+ cells contribute to cardiac neovascularization of capillaries beyond activation

TBK1-stabilized ZNF268a recruits SETD4 to methylate TBK1 for efficient interferon signaling

Sufficient activation of interferon signaling is critical for the host to fight against invading viruses, in which post-translational modifications have been demonstrated to play a pivotal role. Here, we demonstrate that the human KRAB-zinc finger protein ZNF268a is essential for virus-induced interferon signaling. We find that cytoplasmic ZNF268a is constantly degraded by lysosome and thus remains low expressed in resting cell cytoplasm. Upon viral infection, TBK1 interacts with cytosolic ZNF268a to catalyze the phosphorylation of Serine 178 of ZNF268a, which prevents the degradation of ZNF268a, resulting in the stabilization and accumulation of ZNF268a in the cytoplasm. Furthermore, we provide evidence that stabilized ZNF268a recruits the lysine methyltransferase SETD4 to TBK1 to induce the mono-methylation of TBK1 on lysine 607, which is critical for the assembly of the TBK1 signaling complex. Notably, ZNF268 S178 is conserved among higher primates but absent in rodents. Meanwhile, rodent TBK1 607th aa happens to be replaced by arginine, possibly indicating a species-specific role of ZNF268a in regulating TBK1 during evolution. These findings reveal novel functions of ZNF268a and SETD4 in regulating antiviral interferon signaling.

Electroacupuncture improves cardiac function after myocardial infarction by regulating the mobilization and migration of endogenous stem cells

OBJECTIVE

The aim of this study was to explore the role and mechanisms of electroacupuncture (EA) in the regulation of chemokines in endogenous stem cell mobilization and myocardial regeneration after myocardial infarction (MI).

METHODS

An MI model was constructed in adult male Sprague-Dawley rats by ligating the left anterior descending coronary artery. After 4 weeks of treatment, echocardiography was used to detect changes in cardiac function, and Masson's trichrome staining was used to detect collagen deposition. In addition, immunofluorescence staining was applied to examine von Willebrand factor (vWF)-positive vessels, the expression of cardiac troponin T (cTnT) and proliferation marker Ki67, and the number of c-kit-positive, C-X-C chemokine receptor type 4 (CXCR4)-positive, and Sca-1-positive endogenous stem cells in the infarcted area. In addition, the expression of stromal cell-derived factor (SDF)-1 and stem cell factor (SCF) was detected.

RESULTS

EA increased the ejection fraction after MI, reduced collagen deposition and cellular apoptosis, and increased the number of blood vessels compared with an untreated model group. EA significantly promoted cellular proliferation, except for myocardial cells, and significantly increased the number of c-kit-, CXCR4- and Sca-1-positive stem cells. Moreover, the expression of SDF-1 and SCF in myocardial tissue in the EA group was significantly higher than that in the (untreated) MI group.

CONCLUSIONS

EA appears to promote angiogenesis and reduce collagen deposition, thus improving the cardiac function of rats with MI. The underlying mechanism of action may involve endogenous stem cell mobilization mediated by SDF-1/CXCR4 and SCF/c-kit.

From ecology to oncology: To understand cancer stem cell dormancy, ask a Brine shrimp (Artemia)

The brine shrimp (Artemia), releases embryos that can remain dormant for up to a decade. Molecular and cellular level controlling factors of dormancy in Artemia are now being recognized or applied as active controllers of dormancy (quiescence) in cancers. Most notably, the epigenetic regulation by SET domain-containing protein 4 (SETD4), is revealed as highly conserved and the primary control factor governing the maintenance of cellular dormancy from Artemia embryonic cells to cancer stem cells (CSCs). Conversely, DEK, has recently emerged as the primary factor in the control of dormancy exit/reactivation, in both cases. The latter has been now successfully applied to the reactivation of quiescent CSCs, negating their resistance to therapy and leading to their subsequent destruction in mouse models of breast cancer, without recurrence or metastasis potential. In this review, we introduce the many mechanisms of dormancy from Artemia ecology that have been translated into cancer biology, and herald Artemia's arrival on the model organism stage. We show how Artemia studies have unlocked the mechanisms of the maintenance and termination of cellular dormancy. We then discuss how the antagonistic balance of SETD4 and DEK fundamentally controls chromatin structure and consequently governs CSCs function, chemo/radiotherapy resistance, and dormancy in cancers. Many key stages from transcription factors to small RNAs, tRNA trafficking, molecular chaperones, ion channels, and links with various pathways and aspects of signaling are also noted, all of which link studies in Artemia to those of cancer on a molecular and/or cellular level. We particularly emphasize that the application of such emerging factors as SETD4 and DEK may open new and clear avenues for the treatment for various human cancers.

Modified Taohong Siwu decoction improves cardiac function after myocardial ischaemia and reperfusion in rats by promoting endogenous stem cell mobilization and regulating metabolites

CONTEXT

Taohong Siwu decoction (THSWD) has been shown to promote heart repair in myocardial infarction.

OBJECTIVE

To determine the effects of modified THSWD (THSWD plus four ingredients) on myocardial ischaemia and reperfusion (I/R) injury.

MATERIALS AND METHODS

Sixty Sprague-Dawley rats were randomly divided into the I/R group and three different modified THSWD dose groups (gavage administration, 1.215, 2.43, and 4.86 g, respectively). 2,3,5-Triphenyltetrazolium chloride and Evans blue staining were used to detect the infarct area at 24 h after treatment. The serum biochemical indexes and cell apoptosis were examined to determine myocardial injury. The number of endogenous stem cells, expression of stromal dell derived factor-1 (SDF-1) and stem cell factor (SCF), and cardiac function were measured at 4 weeks. The serum was collected for metabolomic analysis.

RESULTS

The high-dose modified THSWD group presented a reduced infarction area (decreased by 21.3%), decreased levels of lactate dehydrogenase and creatinine kinase, attenuated cell apoptosis, and enhanced superoxide dismutase activity in early stage I/R compared with other groups. The serum SCF and SDF-1 levels were higher in the high-dose group than in the I/R group. At 4 weeks, the infarct size and collagen content were the lowest, and the ejection fraction and fractional shortening values were the highest in the high-dose group. Moreover, high-dose modified THSWD affected the metabolism of phosphonate and phosphonate, taurine, and hypotaurine.

CONCLUSIONS

Endogenous stem cell mobilization and metabolic regulation were related to the cardioprotection of modified THSWD. We provided a new strategy and direction for the treatment of cardiovascular diseases with traditional Chinese medicine.

SETD4 cells contribute to brain development and maintain adult stem cell reservoir for neurogenesis

Cellular quiescence facilitates maintenance of neural stem cells (NSCs) and their subsequent regenerative functions in response to brain injury and aging. However, the specification and maintenance of NSCs in quiescence from embryo to adulthood remain largely unclear. Here, using Set domain-containing protein 4 (SETD4), an epigenetic determinant of cellular quiescence, we mark a small but long-lived NSC population in deep quiescence in the subventricular zone of adult murine brain. Genetic lineage tracing shows that SETD4⁺ cells appear before neuroectoderm formation and contribute to brain development. In the adult, conditional knockout of Setd4 resulted in quiescence exit of NSCs, generating newborn neurons in the olfactory bulb and contributing to damage repair. However, long period deletion of SETD4 lead to exhaustion of NSC reservoir or SETD4 overexpression caused quiescence entry of NSCs, leading to suppressed neurogenesis. This study reveals the existence of long-lived deep quiescent NSCs and their neurogenetic capacities beyond activation.

Unmasking the mammalian SET domain-containing protein 4

SET domain-containing protein 4 (SETD4) is a member of a unique class of protein lysine methyltransferases. Here, we introduce the basic features of SETD4 and summarize the key findings from recent studies with emphases on its roles in tissue development and tumorigenesis, and its methylation substrates. SETD4 is expressed in stem/progenitor cells. Ablation of Setd4⁺ cells impedes the repopulation of acinar cells after pancreatic injury. Setd4 deletion in mice promotes the recovery of radiation-induced bone marrow (BM) failure by boosting the function of BM niche, facilitates the generation of endothelial cells and neovascularization of capillary vessels in the heart, enhances the proliferation of BM mesenchymal stem cells and disrupts the TLR4 signaling in BM-derived macrophages. SETD4 expression is also associated with the maintenance of quiescent breast cancer stem cells. While mouse Setd4 knockout delays radiation-induced T-lymphoma formation, elevated SETD4 expression has been observed in some proliferative cancer cells and is associated with a pro-survival potential. Oncogenic fusions of SETD4 have also been identified in cancer, albeit rare. In addition, SETD4 methylates lysine-570 in the C-terminal globular domain of KU70, which enables KU70 translocation to cytoplasm to suppress apoptosis.

Interactions between the ERK1/2 signaling pathway and PCAF play a key role in PE‑induced cardiomyocyte hypertrophy

Cardiomyocyte hypertrophy is a compensatory phase of chronic heart failure that is induced by the activation of multiple signaling pathways. The extracellular signal-regulated protein kinase (ERK) signaling pathway is an important regulator of cardiomyocyte hypertrophy. In our previous study, it was demonstrated that phenylephrine (PE)-induced cardiomyocyte hypertrophy involves the hyperacetylation of histone H3K9ac by P300/CBP-associated factor (PCAF). However, the upstream signaling pathway has yet to be fully identified. In the present study, the role of the extracellular signal-regulated protein kinase (ERK)1/2 signaling pathway in PE-induced cardiomyocyte hypertrophy was investigated. The mice cardiomyocyte hypertrophy model was successfully established by treating cells with PE in vitro. The results showed that phospho-(p-)ERK1/2 interacted with PCAF and modified the pattern of histone H3K9ac acetylation. An ERK inhibitor (U0126) and/or a histone acetylase inhibitor (anacardic acid; AA) attenuated the overexpression of phospho-ERK1/2 and H3K9ac hyperacetylation by inhibiting the expression of PCAF in PE-induced cardiomyocyte hypertrophy. Moreover, U0126 and/or AA could attenuate the overexpression of several biomarker genes related to cardiac hypertrophy (myocyte enhancer factor 2C, atrial natriuretic peptide, brain natriuretic peptide and β-myosin heavy chain) and prevented cardiomyocyte hypertrophy. These results revealed a novel mechanism in that AA protects against PE-induced cardiomyocyte hypertrophy in mice via the ERK1/2 signaling pathway, and by modifying the acetylation of H3K9ac. These findings may assist in the development of novel methods for preventing and treating hypertrophic cardiomyopathy.

Methyltransferase SET domain family and its relationship with cardiovascular development and diseases

Abnormal epigenetic modification is closely related to the occurrence and development of cardiovascular diseases. The SET domain (SETD) family is an important epigenetic modifying enzyme containing SETD. They mainly affect gene expression by methylating H3K4, H3K9, H3K36 and H4K20. Additionally, the SETD family catalyzes the methylation of non-histone proteins, thereby affects the signal transduction of signal transduction and activator of transcription (STAT) 1, Wnt/β-catenin, hypoxia-inducible factor (HIF)-1α and Hippo/YAP pathways. The SETD family has the following regulatory effects on cardiovascular development and diseases: regulating coronary artery formation and cardiac development; protecting cardiac tissue from ischemia reperfusion injury; regulating inflammation, oxidative stress and apoptosis in cardiovascular complications of diabetes; participating in the formation of pulmonary hypertension; regulating thrombosis, cardiac hypertrophy and arrhythmia. This article summarizes the basic structures, expression regulation mechanisms and the role of existing SETD family members in cardiovascular development and diseases, in order to provide a basis for understanding the molecular mechanism of cardiovascular disease and exploring the therapeutic targets.