DEC1/STRA13/SHARP2 and DEC2/SHARP1 coordinate physiological processes, including circadian rhythms in response to environmental stimuli

BHLHE41, a transcriptional repressor involved in physiological processes and tumor development

BHLHE41 is a nuclear transcriptional repressor that belongs to the basic helix-loop-helix protein superfamily. BHLHE41 expression tends to be restricted to specific tissues and is regulated by environmental cues and biological events. BHLHE41 homodimerizes or heterodimerizes with various partners, influencing its transcription factor function. BHLHE41 is involved in the regulation of many physiological processes implicated in tissue/organ homeostasis, such as myogenesis, adipogenesis, circadian rhythms and DNA repair. At cellular level, BHLHE41 is involved in the regulation of mesenchymal stem cell properties, tissue-specific macrophage functions and lymphoid lineage physiology. In several cancer types, BHLHE41 modulates the expression of different transcriptional programs influencing cell cycle control, apoptosis, invasiveness, epithelial to mesenchymal transition and hypoxia response in the tumor environment. Depending on the cancer cell type, BHLHE41 can act as a tumor suppressor or an oncogene, and could be a target for innovative therapies. This review summarizes the available knowledge on BHLHE41 structure, biological functions, regulation and potential partners, as well as its role in physiological processes, and its implication in major cancer steps.

IGF-II regulates lysyl oxidase propeptide and mediates its effects in part via basic helix-loop-helix E40

Pulmonary fibrosis (PF) is a clinically severe and commonly fatal complication of Systemic Sclerosis (SSc). Our group has previously reported profibrotic roles for Insulin-like Growth Factor II (IGF-II) and Lysyl Oxidase (LOX) in SSc-PF. We sought to identify downstream regulatory mediators of IGF-II. In the present work, we show that SSc lung tissues have higher baseline levels of the total (N-glycosylated/unglycosylated) LOX-Propeptide (LOX-PP) than control lung tissues. LOX-PP-mediated changes were consistent with the extracellular matrix (ECM) deregulation implicated in SSc-PF progression. Furthermore, Tolloid-like 1 (TLL1) and Bone Morphogenetic Protein 1 (BMP1), enzymes that can cleave ProLOX to release LOX-PP, were increased in SSc lung fibrosis and the bleomycin (BLM)-induced murine lung fibrosis model, respectively. In addition, IGF-II regulated the levels of ProLOX, active LOX, LOX-PP, BMP1, and isoforms of TLL1. The Class E Basic Helix-Loop-Helix protein 40 (BHLHE40) transcription factor localized to the nucleus in response to IGF-II. BHLHE40 silencing downregulated TLL1 isoforms and LOX-PP, and restored features of ECM deregulation triggered by IGF-II. Our findings indicate that IGF-II, BHLHE40, and LOX-PP may serve as targets of therapeutic intervention to halt SSc-PF progression.

Bhlhe40 Regulates Proliferation and Angiogenesis in Mouse Embryoid Bodies under Hypoxia

Knowledge of the molecular mechanisms that underlie the regulation of major adaptive responses to an unbalanced oxygen tension is central to understanding tissue homeostasis and disease. Hypoxia-inducible transcription factors (HIFs) coordinate changes in the transcriptome that control these adaptive responses. Here, we focused on the functional role of the transcriptional repressor basic-helix-loop-helix family member e40 (Bhlhe40), which we previously identified in a meta-analysis as one of the most consistently upregulated genes in response to hypoxia across various cell types. We investigated the role of Bhlhe40 in controlling proliferation and angiogenesis using a gene editing strategy in mouse embryonic stem cells (mESCs) that we differentiated in embryoid bodies (EBs). We observed that hypoxia-induced Bhlhe40 expression was compatible with the rapid proliferation of pluripotent mESCs under low oxygen tension. However, in EBs, hypoxia triggered a Bhlhe40-dependent cell cycle arrest in most progenitor cells and endothelial cells within vascular structures. Furthermore, Bhlhe40 knockout increased the basal vascularization of the EBs in normoxia and exacerbated the hypoxia-induced vascularization, supporting a novel role for Bhlhe40 as a negative regulator of blood vessel formation. Our findings implicate Bhlhe40 in mediating key functional adaptive responses to hypoxia, such as proliferation arrest and angiogenesis.

The circadian clock as a potential biomarker and therapeutic target in pancreatic cancer

Pancreatic cancer (PC) has a very high mortality rate globally. Despite ongoing efforts, its prognosis has not improved significantly over the last two decades. Thus, further approaches for optimizing treatment are required. Various biological processes oscillate in a circadian rhythm and are regulated by an endogenous clock. The machinery controlling the circadian cycle is tightly coupled with the cell cycle and can interact with tumor suppressor genes/oncogenes; and can therefore potentially influence cancer progression. Understanding the detailed interactions may lead to the discovery of prognostic and diagnostic biomarkers and new potential targets for treatment. Here, we explain how the circadian system relates to the cell cycle, cancer, and tumor suppressor genes/oncogenes. Furthermore, we propose that circadian clock genes may be potential biomarkers for some cancers and review the current advances in the treatment of PC by targeting the circadian clock. Despite efforts to diagnose pancreatic cancer early, it still remains a cancer with poor prognosis and high mortality rates. While studies have shown the role of molecular clock disruption in tumor initiation, development, and therapy resistance, the role of circadian genes in pancreatic cancer pathogenesis is not yet fully understood and further studies are required to better understand the potential of circadian genes as biomarkers and therapeutic targets.

DEC1 is involved in circadian rhythm disruption-exacerbated pulmonary fibrosis

BACKGROUND

The alveolar epithelial type II cell (AT2) and its senescence play a pivotal role in alveolar damage and pulmonary fibrosis. Cell circadian rhythm is strongly associated with cell senescence. Differentiated embryonic chondrocyte expressed gene 1 (DEC1) is a very important circadian clock gene. However, the role of DEC1 in AT2 senescence and pulmonary fibrosis was still unclear.

RESULTS

In this study, a circadian disruption model of light intervention was used. It was found that circadian disruption exacerbated pulmonary fibrosis in mice. To understand the underlying mechanism, DEC1 levels were investigated. Results showed that DEC1 levels increased in lung tissues of IPF patients and in bleomycin-induced mouse fibrotic lungs. In vitro study revealed that bleomycin and TGF-β1 increased the expressions of DEC1, collagen-I, and fibronectin in AT2 cells. Inhibition of DEC1 mitigated bleomycin-induced fibrotic changes in vitro and in vivo. After that, cell senescence was observed in bleomycin-treated AT2 cells and mouse models, but these were prevented by DEC1 inhibition. At last, p21 was confirmed having circadian rhythm followed DEC1 in normal conditions. But bleomycin disrupted the circadian rhythm and increased DEC1 which promoted p21 expression, increased p21 mediated AT2 senescence and pulmonary fibrosis.

CONCLUSIONS

Taken together, circadian clock protein DEC1 mediated pulmonary fibrosis via p21 and cell senescence in alveolar epithelial type II cells.

From Chronodisruption to Sarcopenia: The Therapeutic Potential of Melatonin

Sarcopenia is an age-related condition that involves a progressive decline in muscle mass and function, leading to increased risk of falls, frailty, and mortality. Although the exact mechanisms are not fully understood, aging-related processes like inflammation, oxidative stress, reduced mitochondrial capacity, and cell apoptosis contribute to this decline. Disruption of the circadian system with age may initiate these pathways in skeletal muscle, preceding the onset of sarcopenia. At present, there is no pharmacological treatment for sarcopenia, only resistance exercise and proper nutrition may delay its onset. Melatonin, derived from tryptophan, emerges as an exceptional candidate for treating sarcopenia due to its chronobiotic, antioxidant, and anti-inflammatory properties. Its impact on mitochondria and organelle, where it is synthesized and crucial in aging skeletal muscle, further highlights its potential. In this review, we discuss the influence of clock genes in muscular aging, with special reference to peripheral clock genes in the skeletal muscle, as well as their relationship with melatonin, which is proposed as a potential therapy against sarcopenia.

First trimester SHARP1 and second-trimester uterine artery Doppler to predict preeclampsia

OBJECTIVES

The objective of this study was to identify the predictive value of the first-trimester serum SHARP1 level and the second-trimester uterine artery Doppler in singleton pregnancy for the prediction of preeclampsia.

METHODS

A prospective study including singleton pregnancy presenting at an antenatal clinic, King Chulalongkorn Memorial Hospital, Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University from 2019-March 2020 was conducted. Serum SHARP1 was collected at the gestational age (GA) of 11-13+6 weeks, and transabdominal uterine artery Doppler ultrasound was performed at GA of 18-24 weeks. Serum SHARP1 level and uterine artery pulsatility index (PI) were combined to calculate the predictive value for preeclampsia detection.

RESULTS

288 pregnant women were enrolled in the first trimester, but only 249 participants completed the study. Thirteen patients had preeclampsia (5.2%), which three cases (1.2%) had early-onset preeclampsia. The median serum SHARP1 level in the first trimester of pregnant women with preeclampsia was lower than the normal pregnancy group (1392 pg/ml vs. 1941 pg/ml, p = 0.046). The second-trimester uterine artery PI and prevalence of early diastolic notching were higher in the preeclampsia group than in the normal pregnancy group (p = 0.029 and p = 0.001, respectively). When the first-trimester serum SHARP1 level is combined with the second-trimester uterine artery PI, the sensitivity, specificity, PPV, and NPV for preeclampsia prediction were 84.6%, 47.5%, 8.2%, and 98.3%, respectively.

CONCLUSIONS

This study demonstrated that serum SHARP1 level in the first trimester combined with the uterine artery PI in the second trimester had good sensitivity to predict preeclampsia.

Islet-autoreactive CD4+ T cells are linked with response to alefacept in type 1 diabetes

Variation in the preservation of β cell function in clinical trials in type 1 diabetes (T1D) has emphasized the need to define biomarkers to predict treatment response. The T1DAL trial targeted T cells with alefacept (LFA-3-Ig) and demonstrated C-peptide preservation in approximately 30% of new-onset T1D individuals. We analyzed islet antigen-reactive (IAR) CD4+ T cells in PBMC samples collected prior to treatment from alefacept- and placebo-treated individuals using flow cytometry and single-cell RNA sequencing. IAR CD4+ T cells at baseline had heterogeneous phenotypes. Transcript profiles formed phenotypic clusters of cells along a trajectory based on increasing maturation and activation, and T cell receptor (TCR) chains showed clonal expansion. Notably, the frequency of IAR CD4+ T cells with a memory phenotype and a unique transcript profile (cluster 3) were inversely correlated with C-peptide preservation in alefacept-treated, but not placebo-treated, individuals. Cluster 3 cells had a proinflammatory phenotype characterized by expression of the transcription factor BHLHE40 and the cytokines GM-CSF and TNF-α, and shared TCR chains with effector memory-like clusters. Our results suggest IAR CD4+ T cells as a potential baseline biomarker of response to therapies targeting the CD2 pathway and warrant investigation for other T cell-related therapies.

BHLHE40 drives protective polyfunctional CD4 T cell differentiation in the female reproductive tract against Chlamydia

The protein basic helix-loop-helix family member e40 (BHLHE40) is a transcription factor recently emerged as a key regulator of host immunity to infections, autoimmune diseases and cancer. In this study, we investigated the role of Bhlhe40 in protective T cell responses to the intracellular bacterium Chlamydia in the female reproductive tract (FRT). Mice deficient in Bhlhe40 exhibited severe defects in their ability to control Chlamydia muridarum shedding from the FRT. The heightened bacterial burdens in Bhlhe40-/- mice correlated with a marked increase in IL-10-producing T regulatory type 1 (Tr1) cells and decreased polyfunctional CD4 T cells co-producing IFN-γ, IL-17A and GM-CSF. Genetic ablation of IL-10 or functional blockade of IL-10R increased CD4 T cell polyfunctionality and partially rescued the defects in bacterial control in Bhlhe40-/- mice. Using single-cell RNA sequencing coupled with TCR profiling, we detected a significant enrichment of stem-like T cell signatures in Bhlhe40-deficient CD4 T cells, whereas WT CD4 T cells were further down on the differentiation trajectory with distinct effector functions beyond IFN-γ production by Th1 cells. Altogether, we identified Bhlhe40 as a key molecular driver of CD4 T cell differentiation and polyfunctional responses in the FRT against Chlamydia.

TFEB and TFE3 control glucose homeostasis by regulating insulin gene expression

To fulfill their function, pancreatic beta cells require precise nutrient-sensing mechanisms that control insulin production. Transcription factor EB (TFEB) and its homolog TFE3 have emerged as crucial regulators of the adaptive response of cell metabolism to environmental cues. Here, we show that TFEB and TFE3 regulate beta-cell function and insulin gene expression in response to variations in nutrient availability. We found that nutrient deprivation in beta cells promoted TFEB/TFE3 activation, which resulted in suppression of insulin gene expression. TFEB overexpression was sufficient to inhibit insulin transcription, whereas beta cells depleted of both TFEB and TFE3 failed to suppress insulin gene expression in response to amino acid deprivation. Interestingly, ChIP-seq analysis showed binding of TFEB to super-enhancer regions that regulate insulin transcription. Conditional, beta-cell-specific, Tfeb-overexpressing, and Tfeb/Tfe3 double-KO mice showed severe alteration of insulin transcription, secretion, and glucose tolerance, indicating that TFEB and TFE3 are important physiological mediators of pancreatic function. Our findings reveal a nutrient-controlled transcriptional mechanism that regulates insulin production, thus playing a key role in glucose homeostasis at both cellular and organismal levels.

Early prediction of pre-eclampsia using circulating placental exosomes: Newer insights

Pre-eclampsia (PE), a multifactorial de novo hypertensive pregnancy disorder, is one of the leading causes of foeto-maternal morbidity and mortality. Currently, antihypertensive drugs are the first-line therapy for PE and evidence suggests that low-dose aspirin initiated early in high risk pregnancies may reduce the risk of development or severity of PE. However, an early prediction of this disorder remains an unmet clinical challenge. Several potential serum biomarkers associated with maternal immunoregulation and placental angiogenesis have been evaluated but are ineffective and inconsistent for early prediction. Although placental biomarkers would be more specific and sensitive in predicting the risk of PE, accessing the placenta during pregnancy is not feasible. Circulating placental exosomes (pEXO), originating from foeto-maternal interface, are being evaluated as the placenta's surrogate and the best source of non-invasive placental biomarkers. pEXO appear in the maternal circulation starting from six weeks of gestation and its dynamic biological cargo across pregnancy is associated with successful pregnancy outcomes. Therefore, monitoring changes in pEXO expression profiles could provide new insights into the prediction, diagnosis and treatment of PE. This narrative review comprehensively summarizes the available literature on the candidate predictive circulating biomarkers evaluated for PE to date. In particular, the review elucidates the current knowledge of distinct molecular signatures emanating from pEXO in pre-eclamptic women to support the discovery of novel early predictive biomarkers for effective intervention and management of the disease.

GSDMD gene knockout alleviates hyperoxia-induced hippocampal brain injury in neonatal mice

BACKGROUND

Neonatal hyperoxia exposure is associated with brain injury and poor neurodevelopment outcomes in preterm infants. Our previous studies in neonatal rodent models have shown that hyperoxia stimulates the brain's inflammasome pathway, leading to the activation of gasdermin D (GSDMD), a key executor of pyroptotic inflammatory cell death. Moreover, we found pharmacological inhibition of caspase-1, which blocks GSDMD activation, attenuates hyperoxia-induced brain injury in neonatal mice. We hypothesized that GSDMD plays a pathogenic role in hyperoxia-induced neonatal brain injury and that GSDMD gene knockout (KO) will alleviate hyperoxia-induced brain injury.

METHODS

Newborn GSDMD knockout mice and their wildtype (WT) littermates were randomized within 24 h after birth to be exposed to room air or hyperoxia (85% O2) from postnatal days 1 to 14. Hippocampal brain inflammatory injury was assessed in brain sections by immunohistology for allograft inflammatory factor 1 (AIF1) and CD68, markers of microglial activation. Cell proliferation was evaluated by Ki-67 staining, and cell death was determined by TUNEL assay. RNA sequencing of the hippocampus was performed to identify the transcriptional effects of hyperoxia and GSDMD-KO, and qRT-PCR was performed to confirm some of the significantly regulated genes.

RESULTS

Hyperoxia-exposed WT mice had increased microglia consistent with activation, which was associated with decreased cell proliferation and increased cell death in the hippocampal area. Conversely, hyperoxia-exposed GSDMD-KO mice exhibited considerable resistance to hyperoxia as O2 exposure did not increase AIF1 + , CD68 + , or TUNEL + cell numbers or decrease cell proliferation. Hyperoxia exposure differentially regulated 258 genes in WT and only 16 in GSDMD-KO mice compared to room air-exposed WT and GSDMD-KO, respectively. Gene set enrichment analysis showed that in the WT brain, hyperoxia differentially regulated genes associated with neuronal and vascular development and differentiation, axonogenesis, glial cell differentiation, hypoxia-induced factor 1 pathway, and neuronal growth factor pathways. These changes were prevented by GSDMD-KO.

CONCLUSIONS

GSDMD-KO alleviates hyperoxia-induced inflammatory injury, cell survival and death, and alterations of transcriptional gene expression of pathways involved in neuronal growth, development, and differentiation in the hippocampus of neonatal mice. This suggests that GSDMD plays a pathogenic role in preterm brain injury, and targeting GSDMD may be beneficial in preventing and treating brain injury and poor neurodevelopmental outcomes in preterm infants.

Knockdown of DEC2 expression inhibits the proliferation of mesangial cells through suppressed glycolysis and p38 MAPK/Erk pathway in lupus nephritis

BACKGROUND

To elucidate the mechanism by which DEC2 modulates the proliferation of mesangial cells (MCs) in lupus nephritis (LN).

METHODS

The 32-week-old female Fcgr2b-/- mice and their serum-treated MCs were used as in vivo and in vitro LN model. MCs knocked down of DEC2 and overexpressed with DEC2 were also established. The expression of DEC2 was measured in the kidneys of Fcgr2b-/- mice and LN serum-treated MCs using RT-qPCR and Western blot. MCs proliferation was detected by 5-ethynyl-2'-deoxyuridine (EdU) labeling assay and PCNA expression using immunofluorescence. The glucose metabolism was evaluated in LN serum-treated MCs, and the levels of lactate production, glucose consumption, ATP production and mitochondrial membrane potential were assayed. The glycolysis and mitochondrial respiration function of the MCs were measured using the Extracellular Flux Analyzer. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were dynamically monitored and multiple important bioenergetic parameters can be calculated. The expression of Toll like receptor 4 (TLR4) and glucose transporter 1 (GLUT1) were detected in the MCs. Multiple signaling proteins were screened.

RESULTS

DEC2 was found overexpressed in the kidney of Fcgr2b-/- LN mice. Knockdown of DEC2 inhibited LN serum-induced MCs proliferation. DEC2 was associated with the glucose metabolism in LN serum-treated MCs. DEC2 regulated glycolysis in LN serum-treated MCs. DEC2 was associated with mitochondrial fitness in LN serum treated MCs. DEC2 activated MCs glycolysis through TLR4 and glucose transporter 1 (GLUT1) regulation. DEC2 regulated MCs proliferation through two signaling pathways including dependent and independent of glycolysis, which located in the downstream of TLR4 signaling.

CONCLUSION

Knockdown of DEC2 expression inhibits the proliferation of MCs through suppressed glycolysis and p38 MAPK/ERK pathway in LN.

Age-Associated Different Transcriptome Profiling in Zebrafish and Rats: an Insight into the Diversity of Vertebrate Aging

Most mammals, including humans, show obvious aging phenotypes, for example, loss of tissue plasticity and sarcopenia. In this regard, fish can be attractive models to study senescence because of their unique aging characteristics. The lifespan of fish varies widely, and several species can live for over 200 years. Moreover, some fish show anti-aging features and indeterminate growth throughout their life. Therefore, exploring the aging mechanism in fish could provide new insights into vertebrate aging. To this end, we conducted RNA sequencing (RNA-seq) assays for various organs and growth stages of zebrafish and compared the data with previously published RNA-seq data of rats. Age-associated differentially expressed genes (DEGs) for all zebrafish tissue samples reveal the upregulation of circadian genes and downregulation of hmgb3a. On one hand, a comparative analysis of DEG profiles associated with aging between zebrafish and rats identifies upregulation of circadian genes and downregulation of collagen genes as conserved transcriptome changes. On the other hand, in zebrafish, upregulation of autophagy-related genes in muscles and AP-1 transcription factor genes in various tissues is observed, which may imply fish-specific anti-aging characteristics. Consistent with our knowledge of mammalian aging, DEG profiles related to tissue senescence are observed in rats. We also detect age-associated downregulation of muscle homeostasis and differentiation-related genes in zebrafish gills, indicating a fish-specific senescence phenotype. Our results indicate both common and different aging profiles between fish and mammals, which could be used for future translational research.

Co-regulation of circadian clock genes and microRNAs in bone metabolism

Mammalian bone is constantly metabolized from the embryonic stage, and the maintenance of bone health depends on the dynamic balance between bone resorption and bone formation, mediated by osteoclasts and osteoblasts. It is widely recognized that circadian clock genes can regulate bone metabolism. In recent years, the regulation of bone metabolism by non-coding RNAs has become a hotspot of research. MicroRNAs can participate in bone catabolism and anabolism by targeting key factors related to bone metabolism, including circadian clock genes. However, research in this field has been conducted only in recent years and the mechanisms involved are not yet well established. Recent studies have focused on how to target circadian clock genes to treat some diseases, such as autoimmune diseases, but few have focused on the co-regulation of circadian clock genes and microRNAs in bone metabolic diseases. Therefore, in this paper we review the progress of research on the co-regulation of bone metabolism by circadian clock genes and microRNAs, aiming to provide new ideas for the prevention and treatment of bone metabolic diseases such as osteoporosis.

DEC1 represses cardiomyocyte hypertrophy by recruiting PRP19 as an E3 ligase to promote ubiquitination-proteasome-mediated degradation of GATA4

Although the pro-hypertrophic role of GATA binding protein 4 (GATA4) during cardiac hypertrophy has been well established, the negative regulatory mechanism to counteract its hyperactivation remains elusive. We hypothesized that the hyperactivation of GATA4 could be a result of loss of interaction between GATA4 with specific suppressors. Using high throughput mass spectrometry technology, we carried out a proteomic screen for endogenous suppressor of GATA4, which disassociated with GATA4 during the hypertrophic response in a cultured cardiac myoblast cell line (H9C2 cells). We identified differentiated embryo chondrocyte 1 (DEC1) negatively regulated the function of GATA4 through physical interaction and negatively regulated cardiac hypertrophy both in vivo and in vitro. Particularly, DEC1 promoted the ubiquitination and proteasome-mediated degradation of GATA4, but did not function as an E3 ligase. Again, using mass spectrometry technology, we systematically identified pre-mRNA processing factor 19 (PRP19) as a newfound E3 ligase, which promoted the K6-linked ubiquitination of GATA4 at its lysine 256. Functional experiments performed in cultured neonatal rat ventricular myocytes and H9C2 cells demonstrated that both DEC1 and PRP19 negatively regulated agonist-induced cardiomyocyte hypertrophic responses. Furthermore, rescue experiments performed in these cells revealed that DEC1 and PRP19 suppressed cardiomyocyte hypertrophy by inhibiting the function of GATA4. Our study thus defined the novel DEC1-PRP19-GATA4 axis to be a previously unknown mechanism in regulating cardiomyocyte hypertrophy. Although GATA4 is indispensable for normal cardiac function, harnessing DEC1- or PRP19-mediated negative regulation to counteract the hyperactivation of GATA4 might serve as a novel therapeutic strategy for pathological cardiac hypertrophy.

Age-dependent expression changes of circadian system-related genes reveal a potentially conserved link to aging

The circadian clock system influences the biology of life by establishing circadian rhythms in organisms, tissues, and cells, thus regulating essential biological processes based on the day/night cycle. Circadian rhythms change over a lifetime due to maturation and aging, and disturbances in the control of the circadian system are associated with several age-related pathologies.

However, the impact of chronobiology and the circadian system on healthy organ and tissue aging remains largely unknown. Whether aging-related changes of the circadian system’s regulation follow a conserved pattern across different species and tissues, hence representing a common driving force of aging, is unclear.

Based on a cross-sectional transcriptome analysis covering 329 RNA-Seq libraries, we provide indications that the circadian system is subjected to aging-related gene alterations shared between evolutionarily distinct species, such as Homo sapiens, Mus musculus, Danio rerio, and Nothobranchius furzeri. We discovered differentially expressed genes by comparing tissue-specific transcriptional profiles of mature, aged, and old-age individuals and report on six genes (per2, dec2, cirp, klf10, nfil3, and dbp) of the circadian system, which show conserved aging-related expression patterns in four organs of the species examined. Our results illustrate how the circadian system and aging might influence each other in various tissues over a long lifespan and conceptually complement previous studies tracking short-term diurnal and nocturnal gene expression oscillations.

A recurrent chromosomal inversion suffices for driving escape from oncogene-induced senescence via subTAD reorganization

Oncogene-induced senescence (OIS) is an inherent and important tumor suppressor mechanism. However, if not removed timely via immune surveillance, senescent cells also have detrimental effects. Although this has mostly been attributed to the senescence-associated secretory phenotype (SASP) of these cells, we recently proposed that "escape" from the senescent state is another unfavorable outcome. The mechanism underlying this phenomenon remains elusive. Here, we exploit genomic and functional data from a prototypical human epithelial cell model carrying an inducible CDC6 oncogene to identify an early-acquired recurrent chromosomal inversion that harbors a locus encoding the circadian transcription factor BHLHE40. This inversion alone suffices for BHLHE40 activation upon CDC6 induction and driving cell cycle re-entry of senescent cells, and malignant transformation. Ectopic overexpression of BHLHE40 prevented induction of CDC6-triggered senescence. We provide strong evidence in support of replication stress-induced genomic instability being a causative factor underlying "escape" from oncogene-induced senescence.

Endothelial Dec1-PPARγ Axis Impairs Proliferation and Apoptosis Homeostasis Under Hypoxia in Pulmonary Arterial Hypertension

Background: The hypoxia-induced pro-proliferative and anti-apoptotic characteristics of pulmonary arterial endothelial cells (PAECs) play critical roles in pulmonary vascular remodeling and contribute to hypoxic pulmonary arterial hypertension (PAH) pathogenesis. However, the mechanism underlying this hypoxic disease has not been fully elucidated.

Methods: Bioinformatics was adopted to screen out the key hypoxia-related genes in PAH. Gain- and loss-function assays were then performed to test the identified hypoxic pathways in vitro. Human PAECs were cultured under hypoxic (3% O₂) or normoxic (21% O₂) conditions. Hypoxia-induced changes in apoptosis and proliferation were determined by flow cytometry and Ki-67 immunofluorescence staining, respectively. Survival of the hypoxic cells was estimated by cell counting kit-8 assay. Expression alterations of the target hypoxia-related genes, cell cycle regulators, and apoptosis factors were investigated by Western blot.

Results: According to the Gene Expression Omnibus dataset (GSE84538), differentiated embryo chondrocyte expressed gene 1-peroxisome proliferative-activated receptor-γ (Dec1-PPARγ) axis was defined as a key hypoxia-related signaling in PAH. A negative correlation was observed between Dec1 and PPARγ expression in patients with hypoxic PAH. In vitro observations revealed an increased proliferation and a decreased apoptosis in PAECs under hypoxia. Furthermore, hypoxic PAECs exhibited remarkable upregulation of Dec1 and downregulation of PPARγ. Dec1 was confirmed to be crucial for the imbalance of proliferation and apoptosis in hypoxic PAECs. Furthermore, the pro-surviving effect of hypoxic Dec1 was mediated through PPARγ inhibition.

Conclusion: For the first time, Dec1-PPARγ axis was identified as a key determinant hypoxia-modifying signaling that is necessary for the imbalance between proliferation and apoptosis of PAECs. These novel endothelial signal transduction events may offer new diagnostic and therapeutic options for patients with hypoxic PAH.

Circadian Organelles: Rhythms at All Scales

Circadian clocks have evolved in most light-sensitive organisms, from unicellular organisms to mammals. Consequently, a myriad of biological functions exhibits circadian rhythmicity, from behavior to physiology, through tissue and cellular functions to subcellular processes. Circadian rhythms in intracellular organelles are an emerging and exciting research arena. We summarize herein the current literature for rhythmicity in major intracellular organelles in mammals. These include changes in the morphology, content, and functions of different intracellular organelles. While these data highlight the presence of rhythmicity in these organelles, a gap remains in our knowledge regarding the underlying molecular mechanisms and their functional significance. Finally, we discuss the importance and challenges faced by spatio-temporal studies on these organelles and speculate on the presence of oscillators in organelles and their potential mode of communication. As circadian biology has been and continues to be studied throughout temporal and spatial axes, circadian organelles appear to be the next frontier.

Role of differentiated embryo-chondrocyte expressed gene 1 (DEC1) in immunity

Differentiated embryo-chondrocyte expressed gene 1 (DEC1) belongs to the family of basic helix-loop-helix (bHLH)-type transcription factors. DEC1 is expressed in various mammalian cells, but early studies focused on its roles outside the immune system. In recent years, relevant studies have found that DEC1 plays an important role in the immunotherapy of tumors, the functional regulation of the immune system, and the onset of autoimmune diseases. DEC1 promotes interferon (IFN)-γand granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion through the production of CD4⁺ T cells, which promotes inflammatory defense responses and autoimmune diseases. Additionally, DEC1 can inhibit the expression of interleukin (IL)-10 to further strengthen the immune response. In this review, we summarized recent advances in our understanding of the roles of DEC1 in animal models and human cells, including regulating immune cell differentiation, controlling cytokine production, and maintaining the balance of pro- and anti-inflammatory signals.

BHLHE40 modulates post-traumatic stress disorder behaviors with the involvement of the PI3K/AKT signaling pathway

Post-traumatic stress disorder (PTSD) is closely related to the exposure to traumatic events and results in the structural and functional changes of hippocampus. Human basic helix-loop-helix family member e40 (BHLHE40) was reported to be implicated with neuron maturity and neuronal differentiation. The present study aimed to reveal the role of BHLHE40 on single-prolonged stress (SPS) model of PTSD in mice. The morris water maze test, open field test and contextual fear test were conducted to assess memory deficits, anxiety-like behaviors, and freezing of mice. Western blot was performed to identify proteins and reveal their levels in hippocampal tissues. We found that mice receiving SPS exhibited increased anxiety-like behaviors, memory deficits, and prolonged freezing time. The protein levels of BHLHE40 were downregulated in the hippocampal tissues of SPS mice. SPS reduced the protein levels of glutamate receptors, while overexpression of BHLHE40 promoted glutamate receptor protein levels in SPS mice. Moreover, BHLHE40 overexpression activated the PI3K/AKT pathway. BHLHE40 overexpression ameliorated the SPS-induced PTSD-like behavioral deficits. Overall, BHLHE40 promotes glutamate receptor protein levels to ameliorate PTSD-like behaviors with the involvement of the PI3K/AKT pathway. This novel discovery may provide a potential target for the improvement of PTSD.

Inhibition of DEC2 is necessary for exiting cell dormancy in salivary adenoid cystic carcinoma

Background

Patients were prone to have poor prognosis once dormant tumor cells being reactivated. However, the molecular mechanism of tumor cell dormancy remains poorly understood. This study aimed to investigate the function of DEC2 in the dormancy of salivary adenoid cystic carcinoma (SACC) in vitro and vivo.

Methods

The function of DEC2 in tumor dormancy of SACC was investigated in nude mice by establishing primary and lung metastasis model. Meanwhile, the interaction between hypoxia and SACC dormancy and the role of DEC2 were demonstrated through CoCl₂ induced hypoxia–mimicking microenvironments. Furthermore, the expression of DEC2 was detected by immunohistochemical staining in primary SACC samples with and without recurrence.

Results

In the primary SACC, DEC2 overexpression inhibited cell proliferation, increased cell population arrested in G0/G1 phase, and participated in dormancy regulation, which limited tumor growth. Intriguingly, in the model of lung metastasis, the level of DEC2 was reduced significantly and resulted in dormancy exit and growth resumption of SACC cells. Then, we found that DEC2 may associate with hypoxia in contributing to tumor dormancy, which might provide a possible cue to explain the different roles of DEC2 in primary and metastasis lesions. And overexpression of DEC2 induced dormancy and promoted migration and invasion through activating EMT program. Finally, DEC2 positive expression was shown to be significantly correlated with recurrence and dormancy of SACC patients.

Conclusions

These findings provide a novel insight into the role of DEC2 gene in tumor dormancy and metastasis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01956-0.

Environmental chemicals affect circadian rhythms: An underexplored effect influencing health and fitness in animals and humans

Circadian rhythms control the life of virtually all organisms. They regulate numerous aspects ranging from cellular processes to reproduction and behavior. Besides the light-dark cycle, there are additional environmental factors that regulate the circadian rhythms in animals as well as humans. Here, we outline the circadian rhythm system and considers zebrafish (Danio rerio) as a representative vertebrate organism. We characterize multiple physiological processes, which are affected by circadian rhythm disrupting compounds (circadian disrupters). We focus on and summarize 40 natural and anthropogenic environmental circadian disrupters in fish. They can be divided into six major categories: steroid hormones, metals, pesticides and biocides, polychlorinated biphenyls, neuroactive drugs and other compounds such as cyanobacterial toxins and bisphenol A. Steroid hormones as well as metals are most studied. Especially for progestins and glucocorticoids, circadian dysregulation was demonstrated in zebrafish on the molecular and physiological level, which comprise mainly behavioral alterations. Our review summarizes the current state of knowledge on circadian disrupters, highlights their risks to fish and identifies knowledge gaps in animals and humans. While most studies focus on transcriptional and behavioral alterations, additional effects and consequences are underexplored. Forthcoming studies should explore, which additional environmental circadian disrupters exist. They should clarify the underlying molecular mechanisms and aim to better understand the consequences for physiological processes.

Downregulation of DEC1 inhibits proliferation, migration and invasion, and induces apoptosis in ovarian cancer cells via regulation of Wnt/β-catenin signaling pathway

DEC1 has been reported to regulate the expression of multiple target genes, participate in cell differentiation, apoptosis, aging and the development and progression of numerous tumors, but the detailed effects and possible mechanisms of DEC1 in ovarian cancer (OC) remain unknown. The present study aimed to investigate the expression and mechanism of function of DEC1 in OC. The present results demonstrated that DEC1 was highly expressed in OC tissues and cell lines using reverse transcription-quantitative PCR, western blotting and immunohistochemistry, and high expression of DEC1 was negatively associated with the prognosis of patients with OC. In addition, knockdown of DEC1 significantly inhibited proliferation in SKOV3 and OVCAR3 cells compared with control. DEC1 knockdown also induced apoptosis and increased the expression of apoptosis-related proteins in OC cells. The results suggested that knockdown of DEC1 inhibited OC cell migration and invasion via regulation of epithelial-mesenchymal transition-related protein. It was also found that DEC1 knockdown significantly inhibited the Wnt/β-catenin pathway. Collectively, the current results indicated that knockdown of DEC1 inhibited proliferation, migration and invasion, and induced apoptosis in OC cells via modulating the Wnt/β-catenin signaling pathway. Thus, DEC1 may participate in malignant progression of OC, and may be a target for treatment and diagnosis of OC.

Maternal serum split and hairy-related protein 1 in preeclampsia versus normal pregnancy

OBJECTIVE

The primary objective was to compare maternal serum split and hairy related protein-1 (SHARP1) in preeclamptic women versus normal pregnant women. The secondary objectives were to compare maternal and neonatal outcomes between preeclampsia and normal pregnant women.

METHODS

This cross-sectional analytic study included 75 preeclamptic pregnant women and 75 normal pregnant women at Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital between March 2018 and May 2019. Blood was collected into nonheparinized tubes. Blood samples were centrifuged and stored at -80 °C until assayed. Maternal serum SHARP1 levels were measured by enzyme-linked immunosorbent assays. Maternal and neonatal outcomes were recorded.

RESULTS

Median serum SHARP1 level in preeclampsia was significantly higher than in normal pregnancy (5.2 vs. 3.7 ng/mL, p = .007). Preeclamptic women had a higher rate of cesarean section than normal pregnant women (68% vs. 32%, p < .001). Preeclamptic women had lower neonatal birth weight than normal pregnant women (2,546.1 ± 766.3 vs 2,884.5 ± 479.9, p = .001). Neonatal complications were higher in preeclamptic women than normal pregnant women (40% vs. 17.3%, p = .002).

CONCLUSIONS

Serum SHARP1 in preeclampsia was significantly higher than in normal pregnancy.

Transcription Factor Bhlhe40 in Immunity and Autoimmunity

The basic helix-loop-helix transcription factor (TF) Bhlhe40 is emerging as a key regulator of immunity during infection, autoimmunity, and inflammatory conditions. We describe the roles of Bhlhe40 in the circulating and tissue-resident arms of the immune system, with emphasis on recent work on the regulation of cytokine production and proliferation. We explore the mechanisms behind these functions in mouse models and human cells, including interactions with other TFs, and propose that Bhlhe40 is a central mediator of both inflammation and pathogen control, as well as a crucial regulator of a growing number of tissue-resident leukocyte populations. Finally, we suggest areas for further study that may advance our understanding of immunity and disease.

Effects of aging and tumorigenesis on coupling between the circadian clock and cell cycle in colonic mucosa

Aging and tumorigenesis are associated with decline and disruption of circadian rhythms in many tissues and accumulating evidence indicates molecular link between circadian clock and cell cycle. The aim of this study was to investigate the effect of aging and tumorigenesis on coupling between cell cycle and circadian clock oscillators in colon, which undergoes regular rhythmicity of cell cycle and expresses peripheral circadian clock. Using healthy 14-week-old mice and 33-week-old mice with and without colorectal tumors, we showed that the 24-h expression profiles of clock genes and clock-controlled genes were mostly unaffected by aging, whereas the genes of cell cycle and cell proliferation were rhythmic in the young colons but were silenced during aging. On the other hand, tumorigenesis completely silenced or dampened the circadian rhythmicity of the clock genes but only a few genes associated with cell cycle progression and cell proliferation. These results suggest that aging impacts the colonic circadian clock moderately but markedly suppresses the rhythms of cell cycle genes and appears to uncouple the cell cycle machinery from circadian clock control. Conversely, tumorigenesis predominantly affects the rhythms of colonic circadian clocks but is not associated with uncoupling of circadian clock and cell cycle.

Luteinizing hormone signaling is involved in synchronization of Leydig cell's clock and is crucial for rhythm robustness of testosterone production†

In mammals, circadian clock regulates concentration of many reproductive hormones including testosterone. Previously, we characterized pattern of circadian transcription of core clock genes in testosterone-producing Leydig cells. Here, the potential role of luteinizing hormone receptor (LHR)-cAMP signaling in synchronization of Leydig cell's circadian clock and rhythmic testosterone production were examined. Results showed that activation of LHR-cAMP signaling in primary rat Leydig cell culture increased Star/STAR and changed expression of many clock genes (upregulated Per1/PER1, Dec1/2, and Rorb, and downregulated Bmal1 and Rev-erba/b). Inhibition of protein kinase A prevented LHR-triggered increase in transcription of Per1 and Dec1. Effect of stimulated LHR-cAMP signaling on Leydig cell's clock transcription was also confirmed in vivo, using rats treated with single hCG injection. To analyze in vivo effect of low LH-cAMP activity on rhythmical Leydig cell function, rats with experimental hypogonadotropic hypogonadism were used. Characteristics of hypogonadal rats were decreased LH and testosterone secretion without circadian fluctuation; in Leydig cells decreased arrhythmic cAMP and transcription of steroidogenic genes (Cyp11a1 and Cyp17a1) were observed, while decreased Star/STAR expression retains circadian pattern. However, expression of clock genes, despite changes in transcription levels (increased Bmal1, Per2, Cry1, Cry2, Rora, Rorb, Rev-erba/b/REV-ERBB, Dec1, Csnk1e, and decreased Npas2 and PER1) kept circadian patterns observed in control groups. Altogether, the results strengthened the hypothesis about role of LH-cAMP signaling as synchronizer of Leydig cell's clock. However, clock in Leydig cells is not sufficient to sustain rhythmicity of testosterone production in absence of rhythmic activity of LH-cAMP signaling.

Thyroid hormone induces cellular senescence in prostate cancer cells through induction of DEC1

While several studies link a state of hypothyroidism to extended lifespan of humans and mice, the role of thyroid hormone in cancer is more controversial since tumor-promoting as well as tumor-suppressive effects are known. In general, aberrant thyroid hormone levels are associated with increased cancer incidence. For prostate cancer (PCa) a prospective cohort study indicates that lower thyrotropin (TSH) and higher thyroxin (T4) levels are associated with an increased risk of PCa. However, triiodothyronine (T3) can attenuate PCa progression. Here we show that T3 treatment of human PCa cells reduces cell proliferation, by induction of cellular senescence. Interestingly, we could neither detect an increased expression of p16^INK4A nor p21^CIP1 cell cycle inhibitors, which are mediators of the two major pathways for senescence induction. This suggests that the T3-induced cellular senescence of PCa cells is driven by an alternative pathway. We show that T3-mediated cellular senescence is associated with increase of DEC1 expression encoded by the BHLHE40 gene and p15^INK4B encoded by CDKN2B. Each DEC1/BHLHE40 and p15^INK4B/CDKN2B knockdown reduced significantly the level of T3-mediated cellular senescence. The data suggest that DEC1 and p15^INK4B are crucial for the T3-induced cellular senescence. In line with a protective role of cellular senescence in cancer, public databases provide evidence linking low DEC1 expression to poor survival of PCa patients. Further we show that the BHLHE40 promoter is responsive to T3 suggesting BHLHE40 being a target gene for the thyroid hormone receptor (TR). Taken together, the data suggest that T3 mediates cellular senescence in PCa cells through induction of DEC1- and p15^INK4B -dependent pathway.

Seasonally variant gene expression in full-term human placenta

Seasonal exposures influence human health and development. The placenta, as a mediator of the maternal and fetal systems and a regulator of development, is an ideal tissue to understand the biological pathways underlying relationships between season of birth and later life health outcomes. Here, we conducted a differential expression (DE) analysis of season of birth in full-term human placental tissue to evaluate whether the placenta may be influenced by seasonal cues. Of the analyzed transcripts, 583 displayed DE between summer and winter births (False Discovery Rate [FDR] q < .05); among these, BHLHE40, MIR210HG, and HILPDA had increased expression among winter births (Bonferroni P < .05). Enrichment analyses of the seasonally variant genes between summer and winter births indicated overrepresentation of transcription factors HIF1A, VDR, and CLOCK, among others, and of GO term pathways related to ribosomal activity and infection. Additionally, a cosinor analysis found rhythmic expression for approximately 11.9% of all 17 664 analyzed placental transcripts. These results suggest that the placenta responds to seasonal cues and add to the growing body of evidence that the placenta acts as a peripheral clock, which may provide a molecular explanation for the extensive associations between season of birth and health outcomes.

DEC1 directly interacts with estrogen receptor (ER) α to suppress proliferation of ER-positive breast cancer cells

Aberrant ERα signaling and altered circadian rhythms are both features of ER-positive breast cancer, however, the molecular interaction between them is still not fully understood. Herein, we analyzed the interplay between the circadian rhythm molecule DEC1 and ERα and its effect on the proliferation of ER-positive breast cancer cells, providing a new clue for clarifying the pathogenesis of breast cancer. In this study, we revealed that DEC1 negatively regulates the proliferation of ER-positive breast cancer MCF-7 cells through interaction with ERα protein. DEC1 co-localized with ERα in the nucleus of MCF7 cells, stabilized ERα protein independently of its transcriptional activity and without affecting by estrogen stimulation and inhibited the degradation of ERα mediated by CHX in a time-dependent manner. Moreover, results from luciferase reporter assay showed that overexpression of DEC1 significantly inhibits ERα-mediated transcriptional activity in a dose-dependent manner. These results together suggested that DEC1 may serve as a co-repressor of ERα in ER-positive breast cancer. Although DEC1 improved the stability of ERα and alleviated protein degradation, DEC1 inhibited the proliferation of MCF7 cells by decreasing ERα-mediated signal transduction.

Circadian Rhythms in the Pathogenesis and Treatment of Fatty Liver Disease

Circadian clock proteins are endogenous timing mechanisms that control the transcription of hundreds of genes. Their integral role in coordinating metabolism has led to their scrutiny in a number of diseases, including nonalcoholic fatty liver disease (NAFLD). Discoordination between central and peripheral circadian rhythms is a core feature of nearly every genetic, dietary, or environmental model of metabolic syndrome and NAFLD. Restricting feeding to a defined daily interval (time-restricted feeding) can synchronize the central and peripheral circadian rhythms, which in turn can prevent or even treat the metabolic syndrome and hepatic steatosis. Importantly, a number of proteins currently under study as drug targets in NAFLD (sterol regulatory element-binding protein [SREBP], acetyl-CoA carboxylase [ACC], peroxisome proliferator-activator receptors [PPARs], and incretins) are modulated by circadian proteins. Thus, the clock can be used to maximize the benefits and minimize the adverse effects of pharmaceutical agents for NAFLD. The circadian clock itself has the potential for use as a target for the treatment of NAFLD.

Unexpected predicted length variation for the coding sequence of the sleep related gene, BHLHE41 in gorilla amidst strong purifying selection across mammals

There is a molecular basis for many sleep patterns and disorders involving circadian clock genes. In humans, "short-sleeper" behavior has been linked to specific amino acid substitutions in BHLHE41 (DEC2), yet little is known about variation at these sites and across this gene in mammals. We compare BHLHE41 coding sequences for 27 mammals. Approximately half of the coding sequence was invariable at the nucleotide level and close to three-quarters of the amino acid alignment was identical. No other mammals had the same "short-sleeper" amino acid substitutions previously described from humans. Phylogenetic analyses based on the nucleotides of the coding sequence alignment are consistent with established mammalian relationships confirming orthology among the sampled sequences. Significant purifying selection was detected in about two-thirds of the variable codons and no codons exhibited significant signs of positive selection. Unexpectedly, the gorilla BHLHE41 sequence has a 318 bp insertion at the 5' end of the coding sequence and a deletion of 195 bp near the 3' end of the coding sequence (including the two short sleeper variable sites). Given the strong signal of purifying selection across this gene, phylogenetic congruence with expected relationships and generally conserved function among mammals investigated thus far, we suggest the indels predicted in the gorilla BHLHE41 may represent an annotation error and warrant experimental validation.

An insulin-inducible transcription factor, SHARP-1, represses transcription of the SIRT1 longevity gene

The rat enhancer of split- and hairy-related protein (SHARP)-1 genes encode insulin-inducible transcriptional repressors. A longevity gene, sirtuin 1 (SIRT1) encodes protein deacetylase. These play an important role in regulating hepatic glucose metabolism. In this study, to evaluate a correlation with these gene expressions, we examined whether SIRT1 effects on expression of the SHARP-1 gene by a treatment with a SIRT1 inhibitor or activator in rat H4IIE hepatoma cells. Whereas the SIRT1 inhibitor increased the level of SHARP-1 mRNA, the SIRT1 activator decreased it. Next, whether SHARP-1 effect on the transcriptional activity of the human SIRT1 gene using luciferase reporter assays was determined. Promoter activity of the SIRT1 gene was specifically repressed by SHARP-1. Further reporter analysis using 5'- deleted or mutated constructs revealed that an E box sequence (5'-CACGTG-3') of the SIRT1 gene promoter was required for the inhibitory effect of SHARP-1. Thus, we conclude that expressions between the SHARP-1 and the SIRT1 genes show a negative correlation and that SHARP-1 represses transcription of the SIRT1 gene.

Effect of DEC1 on the proliferation, adhesion, invasion and epithelial-mesenchymal transition of osteosarcoma cells

Differentiated embryonic chondrocyte-expressed gene 1 (DEC1) is associated with various types of human cancer; however, there is limited data regarding the functions of DEC1 in osteosarcoma. The present study aimed to examine the expression of DEC1 in human osteosarcoma tissues and cell lines. Furthermore, the effects of DEC1 on the proliferation, adhesion, invasion and epithelial-mesenchymal transition (EMT) of osteosarcoma cells were investigated. Using reverse transcription-quantitative PCR and western blot analysis, it was found that the expression levels of DEC1 were higher in human osteosarcoma tissues and osteosarcoma cell lines than in the controls. Both gain- and loss-of-function experiments suggested that DEC1 promotes the proliferation, adhesion and invasion of osteosarcoma cells in vitro, as determined by MTT, cell adhesion and cell invasion assays, respectively. Additionally, DEC1 was found to upregulate the mesenchymal markers N-cadherin and vimentin, whilst downregulating the epithelial marker E-cadherin. In conclusion, this present study showed increased expression levels of DEC1 in human osteosarcoma tissues and cell lines, and identified that DEC1 may exert its effect on osteosarcoma progression by promoting cell proliferation, adhesion and invasion. Furthermore, DEC1 was shown to have an inducible effect on EMT in osteosarcoma cell lines, thus contributing to the aggressiveness of osteosarcoma cells. This initial study indicated that DEC1 may serve as a novel molecular target for the treatment of osteosarcoma.

Non-circadian aspects of BHLHE40 cellular function in cancer

While many genes specifically act as oncogenes or tumor suppressors, others are tumor promoters or suppressors in a context-dependent manner. Here we will review the basic-helix-loop-helix (BHLH) protein BHLHE40, (also known as BHLHB2, STRA13, DEC1, or SHARP2) which is overexpressed in gastric, breast, and brain tumors; and downregulated in colorectal, esophageal, pancreatic and lung cancer. As a transcription factor, BHLHE40 is expressed in the nucleus, where it binds to target gene promoters containing the E-box hexanucleotide sequence, but can also be expressed in the cytoplasm, where it stabilizes cyclin E, preventing cyclin E-mediated DNA replication and cell cycle progression. In different organs BHLHE40 regulates different targets; hence may have different impacts on tumorigenesis. BHLHE40 promotes PI3K/Akt/mTOR activation in breast cancer, activating tumor progression, but suppresses STAT1 expression in clear cell carcinoma, triggering tumor suppression. Target specificity likely depends on cooperation with other transcription factors. BHLHE40 is activated in lung and esophageal carcinoma by the tumor suppressor p53 inducing senescence and suppressing tumor growth, but is also activated under hypoxic conditions by HIF-1α in gastric cancer and hepatocellular carcinomas, stimulating tumor progression. Thus, BHLHE40 is a multi-functional protein that mediates the promotion or suppression of cancer in a context dependent manner.

Molecular mechanisms and physiological importance of circadian rhythms

To accommodate daily recurring environmental changes, animals show cyclic variations in behaviour and physiology, which include prominent behavioural states such as sleep-wake cycles but also a host of less conspicuous oscillations in neurological, metabolic, endocrine, cardiovascular and immune functions. Circadian rhythmicity is created endogenously by genetically encoded molecular clocks, whose components cooperate to generate cyclic changes in their own abundance and activity, with a periodicity of about a day. Throughout the body, such molecular clocks convey temporal control to the function of organs and tissues by regulating pertinent downstream programmes. Synchrony between the different circadian oscillators and resonance with the solar day is largely enabled by a neural pacemaker, which is directly responsive to certain environmental cues and able to transmit internal time-of-day representations to the entire body. In this Review, we discuss aspects of the circadian clock in Drosophila melanogaster and mammals, including the components of these molecular oscillators, the function and mechanisms of action of central and peripheral clocks, their synchronization and their relevance to human health.

HIF-mediated Suppression of DEPTOR Confers Resistance to mTOR Kinase Inhibition in Renal Cancer

Mechanistic target of rapamycin (mTOR) is a fundamental regulator of cell growth, proliferation, and metabolism. mTOR is activated in renal cancer and accelerates tumor progression. Here, we report that the mTOR inhibitor, DEP domain-containing mTOR-interacting protein (DEPTOR), is strikingly suppressed in clear cell renal cell carcinoma (ccRCC) tumors and cell lines. We demonstrate that DEPTOR is repressed by both hypoxia-inducible factors, HIF-1 and HIF-2, which occurs through activation of the HIF-target gene and transcriptional repressor, BHLHe40/DEC1/Stra13. Restoration of DEPTOR- and CRISPR/Cas9-mediated knockout experiments demonstrate that DEPTOR is growth inhibitory in ccRCC. Furthermore, loss of DEPTOR confers resistance to second-generation mTOR kinase inhibitors through deregulated mTORC1 feedback to IRS-2/PI3K/Akt. This work reveals a hitherto unknown mechanism of resistance to mTOR kinase targeted therapy that is mediated by HIF-dependent reprograming of mTOR/DEPTOR networks and suggests that restoration of DEPTOR in ccRCC will confer sensitivity to mTOR kinase therapeutics.

The Mechanisms Underlying the Cytotoxic Effects of Copper Via Differentiated Embryonic Chondrocyte Gene 1

Copper is an essential trace element within cells, but it also exerts cytotoxic effects through induction of reactive oxygen species (ROS) production. To determine the mechanisms underlying copper-induced ROS production, we examined the effects of copper sulfate in HeLa cells. Exposure to copper sulfate led to dose-dependent decreases in HeLa cell viability, along with increases in the subG1 and G2/M populations and corresponding decreases in the G1 population. Copper sulfate also increased the levels of apoptosis, senescence, mitochondrial dysfunction, autophagy, ROS, and the expression of several stress proteins, including ATF3, c-Fos, DEC1 (differentiated embryonic chondrocyte gene 1), p21, p53, and HIF-1α (hypoxia-inducible factor 1 alpha). The suppression of copper-induced ROS generation by the ROS scavenger N-acetyl cysteine verified copper’s functional role, while the suppression of copper’s effects by the copper chelator disulfiram, confirmed its specificity. Selective induction of HIF-1α, p53, and phosphorylated ERK proteins by copper was blocked by the knockdown of the transcription factor DEC1, suggesting copper’s effects are mediated by DEC1. In addition to HeLa cells, copper also exerted cytotoxic effects in human endometrial (HEC-1-A) and lung (A549) adenocarcinoma cells, but not in normal human kidney (HEK293) or bronchial (Beas-2B) epithelial cells. These findings shed new light on the functional roles of copper within cells.

Serum SHARP1 and uterine artery Doppler for the prediction of preeclampsia

The aim of this study was to identify the value of serum SHARP1 levels and Doppler of the uterine artery in singleton pregnancy at 11–13⁺⁶ weeks for predicting preeclampsia. A prospective observational study was conducted in pregnant women at 11–13⁺⁶ weeks of pregnancy who had antenatal care at King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, Thailand, between January 2017 and January 2018. Serum SHARP1 measurement and transabdominal Doppler of the uterine artery were performed. The predictive values of these tests were determined. Data were obtained from 405 pregnant women. Thirty-five women had preeclampsia (8.6%), and six of these had early-onset preeclampsia (1.5%). Preeclamptic women had significantly lower serum SHARP1 levels than pregnant women without preeclampsia (3.6 ng/ml vs 4.7 ng/ml, p < 0.01). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of serum SHARP1 levels of less than 3.89 ng/ml for predicting preeclampsia were 77.1%, 72.7%, 21.1% and 97.1%, respectively. For uterine artery Doppler, the sensitivity, specificity, PPV and NPV of the mean pulsatility index (PI) > 95^th percentile for predicting preeclampsia were 5.7%, 95.4%, 10.5% and 91.5%, respectively. For the combination of serum SHARP1 levels with a cutoff value of less than 3.89 ng/ml and a mean PI > 95^th percentile, the sensitivity, specificity, PPV and NPV were 77.1%, 70.3%, 19.7% and 97.0%, respectively. This study demonstrated that serum SHARP1 is a promising biomarker for predicting preeclampsia in the first trimester.

Bhlhe40 and Bhlhe41 transcription factors regulate alveolar macrophage self-renewal and identity

Tissues in multicellular organisms are populated by resident macrophages, which perform both generic and tissue-specific functions. The latter are induced by signals from the microenvironment and rely on unique tissue-specific molecular programs requiring the combinatorial action of tissue-specific and broadly expressed transcriptional regulators. Here, we identify the transcription factors Bhlhe40 and Bhlhe41 as novel regulators of alveolar macrophages (AMs)-a population that provides the first line of immune defense and executes homeostatic functions in lung alveoli. In the absence of these factors, AMs exhibited decreased proliferation that resulted in a severe disadvantage of knockout AMs in a competitive setting. Gene expression analyses revealed a broad cell-intrinsic footprint of Bhlhe40/Bhlhe41 deficiency manifested by a downregulation of AM signature genes and induction of signature genes of other macrophage lineages. Genome-wide characterization of Bhlhe40 DNA binding suggested that these transcription factors directly repress the expression of lineage-inappropriate genes in AMs. Taken together, these results identify Bhlhe40 and Bhlhe41 as key regulators of AM self-renewal and guardians of their identity.

Mutual suppression between BHLHE40/BHLHE41 and the MIR301B-MIR130B cluster is involved in epithelial-to-mesenchymal transition of endometrial cancer cells

BHLHE40 and BHLHE41 (BHLHE40/41) are basic helix-loop-helix type transcription factors involved in multiple cell activities including epithelial-to-mesenchymal transition (EMT). However, the expression mechanism of BHLHE40/41 in EMT remains unclear. In the present study, we showed that the expression levels of BHLHE40/41 were negatively correlated with those of the microRNA (MIR) 130 family in endometrial cancer (EC) specimens. Our in vitro assays indicated that the expression of BHLHE40/41 was suppressed directly by the MIR130 family in a 3'-untranslated region-mediated manner. In EC cells, the MIR130 family promoted EMT and tumor cell invasion by suppressing the expression of BHLHE40/41. We identified the critical promoter region of the MIR301B-MIR130B cluster for its basal transcription by the transcription factor, SP1. We also found that BHLHE40/41 suppressed the expression of MIR301B and MIR130B, and we identified a binding site in the promoter region for BHLHE40/41. This study is the first to report that BHLHE40/41 and the MIR301B-MIR130B cluster suppressed each other to regulate EMT and invasion of EC cells. We propose that BHLHE40/41 and the MIR130 family are excellent markers to predict the progression of EC cases, and that molecular therapy targeting the MIR130 family-BHLHE40/41 axis may effectively control EC extension.

Bhlhe40 mediates tissue-specific control of macrophage proliferation in homeostasis and type 2 immunity

Most tissue-resident macrophage populations develop during embryogenesis, self-renew in the steady state and expand during type 2 immunity. Whether shared mechanisms regulate the proliferation of macrophages in homeostasis and disease is unclear. Here we found that the transcription factor Bhlhe40 was required in a cell-intrinsic manner for the self-renewal and maintenance of large peritoneal macrophages (LPMs), but not that of other tissue-resident macrophages. Bhlhe40 was necessary for the proliferation, but not the polarization, of LPMs in response to the cytokine IL-4. During infection with the helminth Heligmosomoides polygyrus bakeri, Bhlhe40 was required for cell cycling of LPMs. Bhlhe40 repressed the expression of genes encoding the transcription factors c-Maf and Mafb and directly promoted expression of transcripts encoding cell cycle-related proteins to enable the proliferation of LPMs. In LPMs, Bhlhe40 bound to genomic sites co-bound by the macrophage lineage-determining factor PU.1 and to unique sites, including Maf and loci encoding cell-cycle-related proteins. Our findings demonstrate a tissue-specific control mechanism that regulates the proliferation of resident macrophages in homeostasis and type 2 immunity.

Circadian rhythms and proteomics: It's all about posttranslational modifications!

The circadian clock is a molecular endogenous timekeeping system and allows organisms to adjust their physiology and behavior to the geophysical time. Organized hierarchically, the master clock in the suprachiasmatic nuclei, coordinates peripheral clocks, via direct, or indirect signals. In peripheral organs, such as the liver, the circadian clock coordinates gene expression, notably metabolic gene expression, from transcriptional to posttranslational level. The metabolism in return feeds back on the molecular circadian clock via posttranslational-based mechanisms. During the last two decades, circadian gene expression studies have mostly been relying primarily on genomics or transcriptomics approaches and transcriptome analyses of multiple organs/tissues have revealed that the majority of protein-coding genes display circadian rhythms in a tissue specific manner. More recently, new advances in mass spectrometry offered circadian proteomics new perspectives, that is, the possibilities of performing large scale proteomic studies at cellular and subcellular levels, but also at the posttranslational modification level. With important implications in metabolic health, cell signaling has been shown to be highly relevant to circadian rhythms. Moreover, comprehensive characterization studies of posttranslational modifications are emerging and as a result, cell signaling processes are expected to be more deeply characterized and understood in the coming years with the use of proteomics. This review summarizes the work studying diurnally rhythmic or circadian gene expression performed at the protein level. Based on the knowledge brought by circadian proteomics studies, this review will also discuss the role of posttranslational modification events as an important link between the molecular circadian clock and metabolic regulation. This article is categorized under: Laboratory Methods and Technologies > Proteomics Methods Physiology > Mammalian Physiology in Health and Disease Biological Mechanisms > Cell Signaling.

Single cell RNA-sequencing identified Dec2 as a suppressive factor for spermatogonial differentiation by inhibiting Sohlh1 expression

Gonocyte-to-spermatogonia transition is a critical fate determination process to initiate sperm production throughout the lifecycle. However, the molecular dynamics of this process has not been fully elucidated mainly due to the asynchronized differentiation stages of neonatal germ cells. In this study, we employed single cell RNA sequencing analyses of P1.5–5.5 germ cells to clarify the temporal dynamics of gene expression during gonocyte-to-spermatogonia transition. The analyses identified transcriptional modules, one of which regulates spermatogonial gene network in neonatal germ cells. Among them, we identified Dec2, a bHLH-type transcription factor, as a transcriptional repressor for a spermatogonial differentiation factor Sohlh1. Deficiency of Dec2 in mice induces significant reduction of undifferentiated spermatogonia, and transplantation assay using Dec2-depleted cells also demonstrated the impaired efficiency of engraftment, suggesting its role in maintaining spermatogonial stem cells (SSCs). Collectively, this study revealed the intrinsic role of a new SSC factor Dec2, which protects germ cells from inadequate differentiation during neonatal testis development.

Genome-wide analysis of insomnia disorder

Insomnia is a worldwide problem with substantial deleterious health effects. Twin studies have shown a heritable basis for various sleep-related traits, including insomnia, but robust genetic risk variants have just recently begun to be identified. We conducted genome-wide association studies (GWAS) of soldiers in the Army Study To Assess Risk and Resilience in Servicemembers (STARRS). GWAS were carried out separately for each ancestral group (EUR, AFR, LAT) using logistic regression for each of the STARRS component studies (including 3,237 cases and 14,414 controls), and then meta-analysis was conducted across studies and ancestral groups. Heritability (SNP-based) for lifetime insomnia disorder was significant (h²_g = 0.115, p = 1.78 × 10^-4 in EUR). A meta-analysis including three ancestral groups and three study cohorts revealed a genome-wide significant locus on Chr 7 (q11.22) (top SNP rs186736700, OR = 0.607, p = 4.88 × 10^-9) and a genome-wide significant gene-based association (p = 7.61 × 10^-7) in EUR for RFX3 on Chr 9. Polygenic risk for sleeplessness/insomnia severity in UK Biobank was significantly positively associated with likelihood of insomnia disorder in STARRS. Genetic contributions to insomnia disorder in STARRS were significantly positively correlated with major depressive disorder (r_g = 0.44, se = 0.22, p = 0.047) and type 2 diabetes (r_g = 0.43, se = 0.20, p = 0.037), and negatively with morningness chronotype (r_g = -0.34, se = 0.17, p = 0.039) and subjective well being (r_g = -0.59, se = 0.23, p = 0.009) in external datasets. Insomnia associated loci may contribute to the genetic risk underlying a range of health conditions including psychiatric disorders and metabolic disease.

Interaction with SP1, but not binding to the E-box motifs, is responsible for BHLHE40/DEC1-induced transcriptional suppression of CLDN1 and cell invasion in MCF-7 cells

Basic helix-loop-helix family member e40 (BHLHE40) is located in 3p26.1 and acts as a transcriptional repressor of the circadian rhythm by suppressing the expression of the clock genes and clock-controlled genes. Recent research indicated that BHLHE40 may be involved in regulating tumor cell progression. However the mechanism by which BHLHE40 regulates the invasion and metastasis of tumor cells is unclear. Our in vitro assays showed that BHLHE40 promoted tumor cell invasion while BHLHE40 silencing by siRNA suppressed tumor cell invasion of MCF-7 cells. BHLHE40 suppressed the mRNA and protein expression of CLDN1 CLDN4 and CDH1 and promoted the expression of SNAI1 and SNAI2. Reporter assays demonstrated that BHLHE40 suppressed CLDN1 transcription but not through direct binding to the E-box motifs in the CLDN1 promoter. Further studies demonstrated BHLHE40 suppressed CLDN1 transcription by preventing the interaction between SP1 and a specific motif within the promoter region of CLDN1. BHLHE40 could not further suppress CLDN1 transactivation after SP1 siRNA transfection that is, BHLHE40-induced suppression of CLDN1 relied on SP1. Furthermore our data indicated that SP1 was a major regulator of CLDN1 transcription by binding to a specific motif that was located at -233 to -61 bp upstream of the transcription start site. Immunoprecipitation and co-localization data revealed an interaction between BHLHE40 and SP1. By constructing deletion mutants we found that the BHLH and Orange regions are both essential for the BHLHE40-SP1 interaction. BHLHE40 probably acts as an inhibitory nuclear cofactor or perhaps recruits other inhibitory cofactors to inhibit the SP1-mediated CLDN1 transactivation. These results suggest that BHLHE40 facilitates cell invasion and may be used as a novel target for breast cancer prevention and treatment.

Dec1 and CLOCK Regulate Na+/K+-ATPase β1 Subunit Expression and Blood Pressure

Blood pressure shows a circadian rhythm, and recent studies have suggested the involvement of a molecular clock system in its control. In the clock system, the CLOCK (circadian locomotor output cycles kaput):BMAL1 (brain and muscle aryl hydrocarbon receptor nuclear translocator-like protein-1) heterodimer enhances promoter activity of clock genes, and DEC1 (BHLHE40/STRA13/SHARP-2) represses CLOCK/BMAL1-enhanced promoter activity through competition for binding to the clock element, CACGTG E-box. However, the molecular mechanisms by which this system regulates blood pressure remain unclear. Here, we show that DEC1 suppressed the expression of ATP1B1, which encodes the β1 subunit of the Na+/K+-ATPase and elevated blood pressure. Using chromatin immunoprecipitation and chromatin immunoprecipitation-on-chip analyses, we found that DEC1 and CLOCK bound to E-boxes in the ATP1B1 promoter. Luciferase assays revealed that CLOCK:BMAL1 heterodimer enhanced transcription from the ATP1B1 promoter, whereas DEC1 suppressed this transactivation. Accordingly, Atp1b1 mRNA and protein levels in mouse kidney, aorta, and heart showed a circadian rhythm that was antiphasic to the blood pressure rhythm. Furthermore, Dec1-deficient mice showed enhanced Atp1b1 expression in these tissues and reduced blood pressure. In contrast, Clock-mutant mice showed reduced Atp1b1 expression and elevated blood pressure. Our results raise the possibility that transcriptional regulation of Atp1b1 by DEC1 and CLOCK:BMAL1 contributes to blood pressure.