A differentiation checkpoint limits hematopoietic stem cell self-renewal in response to DNA damage.

Checkpoints that limit stem cell self-renewal in response to DNA damage can contribute to cancer protection but may also promote tissue aging. Molecular components that control stem cell responses to DNA damage remain to be delineated. Using in vivo RNAi screens, we identified basic leucine zipper transcription factor, ATF-like (BATF) as a major component limiting self-renewal of hematopoietic stem cells (HSCs) in response to telomere dysfunction and γ-irradiation. DNA damage induces BATF in a G-CSF/STAT3-dependent manner resulting in lymphoid differentiation of HSCs. BATF deletion improves HSC self-renewal and function in response to γ-irradiation or telomere shortening but results in accumulation of DNA damage in HSCs. Analysis of bone marrow from patients with myelodysplastic syndrome supports the conclusion that DNA damage-dependent induction of BATF is conserved in human HSCs. Together, these results provide experimental evidence that a BATF-dependent differentiation checkpoint limits self-renewal of HSCs in response to DNA damage.

IL-27 signalling promotes adipocyte thermogenesis and energy expenditure.

Thermogenesis in brown and beige adipose tissue has important roles in maintaining body temperature and countering the development of metabolic disorders such as obesity and type 2 diabetes1,2. Although much is known about commitment and activation of brown and beige adipose tissue, its multiple and abundant immunological factors have not been well characterized3-6. Here we define a critical role of IL-27-IL-27Rα signalling in improving thermogenesis, protecting against diet-induced obesity and ameliorating insulin resistance. Mechanistic studies demonstrate that IL-27 directly targets adipocytes, activating p38 MAPK-PGC-1α signalling and stimulating the production of UCP1. Notably, therapeutic administration of IL-27 ameliorated metabolic morbidities in well-established mouse models of obesity. Consistently, individuals with obesity show significantly decreased levels of serum IL-27, which can be restored after bariatric surgery. Collectively, these findings show that IL-27 has an important role in orchestrating metabolic programs, and is a highly promising target for anti-obesity immunotherapy.

Metabolomic profiling of single enlarged lysosomes.

Lysosomes are critical for cellular metabolism and are heterogeneously involved in various cellular processes. The ability to measure lysosomal metabolic heterogeneity is essential for understanding their physiological roles. We therefore built a single-lysosome mass spectrometry (SLMS) platform integrating lysosomal patch-clamp recording and induced nano-electrospray ionization (nanoESI)/mass spectrometry (MS) that enables concurrent metabolic and electrophysiological profiling of individual enlarged lysosomes. The accuracy and reliability of this technique were validated by supporting previous findings, such as the transportability of lysosomal cationic amino acids transporters such as PQLC2 and the lysosomal trapping of lysosomotropic, hydrophobic weak base drugs such as lidocaine. We derived metabolites from single lysosomes in various cell types and classified lysosomes into five major subpopulations based on their chemical and biological divergence. Senescence and carcinoma altered metabolic profiles of lysosomes in a type-specific manner. Thus, SLMS can open more avenues for investigating heterogeneous lysosomal metabolic changes during physiological and pathological processes.

Telomerase RNA TERC and the PI3K-AKT pathway form a positive feedback loop to regulate cell proliferation independent of telomerase activity.

The core catalytic unit of telomerase comprises telomerase reverse transcriptase (TERT) and telomerase RNA (TERC). Unlike TERT, which is predominantly expressed in cancer and stem cells, TERC is ubiquitously expressed in normal somatic cells without telomerase activity. However, the functions of TERC in these telomerase-negative cells remain elusive. Here, we reported positive feedback regulation between TERC and the PI3K-AKT pathway that controlled cell proliferation independent of telomerase activity in human fibroblasts. Mechanistically, we revealed that TERC activated the transcription of target genes from the PI3K-AKT pathway, such as PDPK1, by targeting their promoters. Overexpression of PDPK1 partially rescued the deficiency of AKT activation caused by TERC depletion. Furthermore, we found that FOXO1, a transcription factor negatively regulated by the PI3K-AKT pathway, bound to TERC promoter and suppressed its expression. Intriguingly, TERC-induced activation of the PI3K-AKT pathway also played a critical role in the proliferation of activated CD4+ T cells. Collectively, our findings identify a novel function of TERC that regulates the PI3K-AKT pathway via positive feedback to elevate cell proliferation independent of telomerase activity and provide a potential strategy to promote CD4+ T cells expansion that is responsible for enhancing adaptive immune reactions to defend against pathogens and tumor cells.

Nicotinamide Mononucleotide Supplementation Alleviates Doxorubicin-Induced Multi-Organ Fibrosis.

Doxorubicin (DOX) is a potent chemotherapeutic agent known for its multi-organ toxicity, especially in the heart, which limits its clinical application. The toxic side effects of DOX, including DNA damage, oxidative stress, mitochondrial dysfunction and cell apoptosis, are intricately linked to the involvement of nicotinamide adenine dinucleotide (NAD+). To assess the effectiveness of the NAD+ precursor nicotinamide mononucleotide (NMN) in counteracting the multi-organ toxicity of DOX, a mouse model was established through DOX administration, which led to significant reductions in NAD+ in tissues with evident injury, including the heart, liver and lungs. NMN treatment alleviated both multi-organ fibrosis and mortality in mice. Mechanistically, tissue fibrosis, macrophage infiltration and DOX-related cellular damage, which are potentially implicated in the development of multi-organ fibrosis, could be attenuated by NAD+ restoration. Our findings provide compelling evidence for the benefits of NMN supplementation in mitigating the adverse effects of chemotherapeutic drugs on multiple organs.

Maternal SMC2 is essential for embryonic development via participating chromosome condensation in mice.

During the oocyte growth, maturation and zygote development, chromatin structure keeps changing to regulate different nuclear activities. Here, we reported the role of SMC2, a core component of condensin complex, in oocyte and embryo development. Oocyte-specific conditional knockout of SMC2 caused female infertility. In the absence of SMC2, oocyte meiotic maturation and ovulation occurred normally, but chromosome condensation showed defects and DNA damages were accumulated in oocytes. The pronuclei were abnormally organized and micronuclei were frequently observed in fertilized eggs, their activity was impaired, and embryo development was arrested at the one-cell stage, suggesting that maternal SMC2 is essential for embryonic development.

The E3 ligase TRIM31 regulates hematopoietic stem cell homeostasis and MLL-AF9 leukemia.

Hematopoietic stem cells (HSC) are kept in a quiescent state to maintain their self-renewal capacity. Proper regulation of cyclin-dependent kinases (CDK) and cyclin proteins is critical for the maintenance of HSC homeostasis. Here, we found that the E3 ligase, TRIM31, regulates HSC homeostasis and leukemia through the accumulation of CDK8. TRIM31 deficiency promotes hematopoietic stem and progenitor cell proliferation and long-term HSC exhaustion. Serial competitive transplantation assays showed that TRIM31-deficient HSC exhibit impaired reconstitution ability. TRIM31 loss led to a lower rate of survival of mice under conditions of stress (5-fluorouracil administration), which was correlated with a lower number of hematopoietic stem and progenitor cells. In a murine model of acute myeloid leukemia, the initiation of leukemia was significantly accelerated upon TRIM31 deletion. Mechanistically, we found that ubiquitin-mediated degradation of CDK8 was impaired by TRIM31 deletion, which further induced transcriptional expression of PBX1 and cyclin D1. Taken together, these findings reveal the function of TRIM31 in the regulation of HSC homeostasis and leukemia initiation, and indicate the physiological importance of TRIM31 in the early stage of the development of leukemia.

Unraveling the connection between calreticulin and myeloproliferative neoplasms via calcium signaling.

Mutations in the form of insertions and deletions (INDEL) in the calreticulin gene lead to essential thrombocythemia (ET) which is characterized by the formation of thrombosis. However, the connection between calreticulin INDEL and ET remains largely elusive. Through combined molecular dynamics simulation, clustered regularly interspaced short palindromic repeats (CRISPR) and calcium imaging studies on the wild type and mutated isoforms of calreticulin, the mechanism underlying the calreticulin INDEL induced ET was investigated at the molecular level. Our results demonstrate that mutations in exon-9 could lead to significant conformational variations of calreticulin structure and thereby reducing its interaction with calcium ions due to decreased electrostatic contributions. The consequence of mutations on calreticulin's structural integrity was revealed by identifying the key residues and their roles in calcium binding. Furthermore, mutations implemented by CRISPR-Cas9 in exon-9 showed diminished calcium signaling in HEK-293T cells, which agree well with our in-silico findings. The current study might help in understanding the variations of molecular interactions between calreticulin's exon-9 and calcium ions during physiological and pathological conditions. The results might also provide useful information for designing novel therapeutic approaches targeting ET.

HuB and HuD repress telomerase activity by dissociating HuR from TERC.

The ubiquitous RNA-binding protein HuR (ELAVL1) promotes telomerase activity by associating with the telomerase noncoding RNA TERC. However, the role of the neural-specific members HuB, HuC, and HuD (ELAVL2-4) in telomerase activity is unknown. Here, we report that HuB and HuD, but not HuC, repress telomerase activity in human neuroblastoma cells. By associating with AU-rich sequences in TERC, HuB and HuD repressed the assembly of the TERT-TERC core complex. Furthermore, HuB and HuD competed with HuR for binding to TERC and antagonized the function of HuR that was previously shown to enhance telomerase activity to promote cell growth. Our findings reveal a novel mechanism controlling telomerase activity in human neuroblastoma cells that involves a competition between HuR and the related, neural-specific proteins HuB and HuD.

Aging, Causes, and Rejuvenation of Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) undergo an age-related functional decline, which leads to a disruption of the blood system and contributes to the development of aging-associated hematopoietic diseases and malignancies. In this section, we provide a summary of the key hallmarks associated with HSC aging. We also examine the causal factors that contribute to HSC aging and emphasize potential approaches to mitigate HSC aging and age-related hematopoietic disorders.

[Intervention effect of Chuanxiong-Chishao herb pair on circRNA/lncRNA expression profile in a myocardial infarction-atherosclerosis model].

This study aimed to explore the intervention effect of Chuanxiong-Chishao herb pair(CX-CS) on a myocardial infarction-atherosclerosis(MI-AS) mouse model and investigate its effect on the expression profile of circular RNAs(circRNAs)/long non-coding RNAs(lncRNAs) in ischemic myocardium and aorta. Sixty male ApoE~(-/-) mice were randomly assigned to a model group, high-, medium-, and low-dose CX-CS groups(7.8, 3.9, and 1.95 g·kg~(-1)), and a positive drug group(metoprolol 26 mg·kg~(-1) and simvastatin 5.2 mg·kg~(-1)), with 12 mice in each group. Male C57BL/6J mice were assigned to the sham group. The mice in the model group and the groups with drug intervention were fed on a high-fat diet for 10 weeks, followed by anterior descending coronary artery ligation. After that, the mice were fed on a high-fat diet for another two weeks to induce the MI-AS model. The mice in the sham group received normal feed, followed by sham surgery without coronary artery ligation. Mice in the groups with drug intervention received CX-CS or positive drug by gavage for four weeks from the 9th week of high-fat feeding, and those in the model group and the sham group received an equal volume of normal saline. Whole transcriptome sequencing was performed on the heart and aorta tissues of the medium-dose CX-CS group, the model group, and the sham group after administration. The results showed that the medium-and high-dose CX-CS groups showed improved cardiac function and reduced myocardial fibrosis area, and the medium-dose CX-CS group showed significantly reduced plaque area. CX-CS treatment could reverse the expression of circRNA＿07227 and circRNA＿11464 in the aorta of AS model and circRNA expression(such as circRNA＿11505) in the heart of the MI model. Differentially expressed circRNAs between the CX-CS-treated mice and the model mice were mainly enriched in lipid synthesis, lipid metabolism, lipid transport, inflammation, and angiogenesis in the aorta, and in angiogenesis, blood pressure regulation, and other processes in the heart. CX-CS treatment could reverse the expression of lncRNAs such as ENSMUST00000162209 in the aorta of the AS model and TCONS＿00002123 in the heart of the MI model. Differentially expressed lncRNAs between the CX-CS-treated mice and model mice were mainly enriched in lipid metabolism, angiogenesis, autophagy, apoptosis, and iron death in the aorta, and in angiogenesis, autophagy, and iron death in the heart. In summary, CX-CS can regulate the expression of a variety of circRNAs and lncRNAs, and its intervention mechanism in coronary heart disease may be related to the regulation of angiogenesis and inflammation in ischemic myocardium, as well as lipid metabolism, lipid transport, inflammation, angiogenesis in AS aorta.

Association between NAD+ levels and anaemia among women in community-based study.

Nicotinamide adenine dinucleotide (NAD+ ) level is the protective factor of cardiovascular diseases (CVDs). In addition, anaemia is a risk factor of adverse cardiovascular outcomes in women. However, there are limited data about the association between NAD+ and anaemia. The aim of this study was to evaluate association of NAD+ with anaemia among women. A total of 727 females from Jidong community were included in the current analysis. NAD+ levels were tested by the cycling assay and HPLC assay using whole blood samples. Anaemia was determined by haemoglobin (Hb) concentration, and the subtypes of anaemia were further defined according to mean corpuscular volume (MCV) in blood. Multivariable logistic analysis was used to analyse the association between NAD+ levels and anaemia or its subtypes. The mean age of recruited subjects was 42.7 years. The proportion of anaemia by NAD+ levels quartiles were 19.7% (35/178), 4.8% (9/189), 3.4% (6/178) and 2.7% (5/182). Haematological parameters including haemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and red blood count (RBC) increased over NAD+ quartiles. Red cell volume distribution width (RDW) decreased over NAD+ quartiles. Compared with the lowest quartile of NAD+ levels (<27.6µM), the adjusted odds ratios with 95% confidence intervals of the top quartile were 0.15 (0.06-0.41) for anaemia, 0.05 (0.01-0.36) for microcytic anaemia and 0.37 (0.10-1.36) for normocytic anaemia respectively. Higher NAD+ levels were significantly associated with lower prevalence of anaemia among women, especially microcytic anaemia and normocytic anaemia. Haematological parameters might serve as a predictor of the blood NAD+ levels.

Aging-induced IL27Ra signaling impairs hematopoietic stem cells.

Hematopoietic stem cell (HSC) aging correlates with an increasing risk of myeloproliferative disease and immunosenescence. In this study, we show that aging-related inflammation promotes HSC aging through tumor necrosis factor-α (TNF-α)→ERK→ETS1→interleukin27Ra (IL27Ra) pathway. TNF-α, a well-known biomarker of inflammation, increases during aging and induces the expression of IL27Ra on HSCs via ERK-ETS1 signaling. Deletion of IL27Ra rescues the functional decline and myeloid bias of HSCs and also reverses the inhibitory effect of TNF-α on HSCs. Aged IL27Ra-/- mice had a reduced proportion of myeloid-biased HSCs and did not display the biased myeloid differentiation that occurs in aged wild-type mice. IL27Ra+ HSCs exhibit impaired reconstitution capacity and myeloid-bias compared with IL27Ra- HSCs and serve as a myeloid-recovery pool upon inflammatory insult. Inflammation-related genes were enriched in IL27Ra+ HSCs and this enrichment increases with aging. Our study demonstrates that age-induced IL27Ra signaling impairs HSCs and raises the possibility that interfering with IL27Ra signaling can counter the physiologically deleterious effect of aging on hematopoietic capacity.

Simultaneous illumination and imaging based on a single multimode fiber.

Due to the small core diameter, a single-core multimode fiber (MMF) has been extensively investigated for endoscopic imaging. However, an extra light path is always utilized for illumination in MMF imaging system, which takes more space and is inapplicable in practical endoscopy imaging. In order to make the imaging system more practical and compact, we proposed a dual-function MMF imaging system, which can simultaneously transmit the illumination light and the images through the same imaging fiber. Meanwhile, a new deep learning-based encoder-decoder network with full-connected (FC) layers was designed for image reconstruction. We conducted an experiment of transmitting images via a 1.6 m long MMF to verify the effectiveness of the dual-function MMF imaging system. The experimental results show that the proposed network achieves the best reconstruction performance compared with the other four networks on different datasets. Besides, it is worth mentioning that the cropped speckle patterns can still be used to reconstruct the original images, which helps to reduce the computing complexity significantly. We also demonstrated the ability of cross-domain generalization of the proposed network. The proposed system shows the potential for more compact endoscopic imaging without external illumination.

Co-targeting WIP1 and PARP induces synthetic lethality in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most fatal cancers. Due to limited strategies for effective treatments, patients with advanced HCC have a very poor prognosis. This study aims to identify new insights in HCC to develop novel strategies for HCC management. METHODS: The role of WIP1 (wild type p53 induced protein phosphatase1) in HCC was analyzed in HCC cells, xenograft model, DEN (Diethylnitrosamine) induced mice liver cancer model with WIP1 knockout mice, and TCGA database. DNA damage was evaluated by Gene Set Enrichment Analysis, western blotting, comet assay, and Immunofluorescence. RESULTS: High expression of WIP1 is associated with the poor prognosis of patients with HCC. Genetically and chemically suppression of WIP1 drastically reduced HCC cell proliferation. Besides, WIP1 knockout retarded DEN induced mice hepato-carcinogenesis. Mechanically, WIP1 inhibition induced DNA damage by increasing H2AX phosphorylation (γH2AX). Therefore, suppression of WIP1 and PARP induced synthetic lethality in HCC in vitro and in vivo by augmenting DNA damage. CONCLUSION: WIP1 plays an oncogenic effect in HCC development, and targeting WIP1-dependent DNA damage repair alone or in combination with PARP inhibition might be a reasonable strategy for HCC management. Video abstract.

Telomere dysfunction impairs epidermal stem cell specification and differentiation by disrupting BMP/pSmad/P63 signaling.

Telomere shortening is associated with aging and age-associated diseases. Additionally, telomere dysfunction resulting from telomerase gene mutation can lead to premature aging, such as apparent skin atrophy and hair loss. However, the molecular signaling linking telomere dysfunction to skin atrophy remains elusive. Here we show that dysfunctional telomere disrupts BMP/pSmad/P63 signaling, impairing epidermal stem cell specification and differentiation of skin and hair follicles. We find that telomere shortening mediated by Terc loss up-regulates Follistatin (Fst), inhibiting pSmad signaling and down-regulating P63 and epidermal keratins in an ESC differentiation model as well as in adult development of telomere-shortened mice. Mechanistically, short telomeres disrupt PRC2/H3K27me3-mediated repression of Fst. Our findings reveal that skin atrophy due to telomere dysfunction is caused by a previously unappreciated link with Fst and BMP signaling that could be explored in the development of therapies.

PGC1α protects against hepatic steatosis and insulin resistance via enhancing IL10-mediated anti-inflammatory response.

Inflammatory responses are pivotal incidences in hepatic metabolic derangements. However, the underlying mechanism remains elusive. The present study aimed to evaluate the role of peroxisome proliferator-activated receptor-gamma, coactivator 1 alpha (PGC1α) in IL10-mediated anti-inflammatory response, and its role in hepatic steatosis and insulin resistance. Hepatocyte-specific PGC1α knock-in (LivPGC1α) mice and the control mice were fed high-fat diet (HFD) for 8 weeks. IL-10 neutralizing antibody was injected into the liver of PGC1α mice. A variety of biological and histological approaches were applied to assess hepatic function. We demonstrated that hepatic PGC1α expression was significantly reduced in mice fed HFD. LivPGC1α livers exhibited enhanced gene expressions involving mitochondrial function, and favored an accelerated lipid metabolism upon HFD. Meanwhile, LivPGC1α mice revealed improved hepatic steatosis and insulin resistance. Mechanistically, PGC1α bound and activated the promotor region of IL-10, thereby attenuating inflammatory response in the liver. Administration of IL10 neutralizing antibody to LivPGC1α mice abolished PGC1α-mediated anti-inflammatory effects in mice. Further, IL-10 neutralizing antibody intervention aggravated hepatic steatosis and insulin resistance in LivPGC1α mice. Taken together, our data indicated that hepatic-specific overexpression of PGC1α exerts a beneficial role in the regulation of hepatic steatosis and insulin resistance via enhancing IL10-mediated anti-inflammatory response. Pharmacological activation of PGC1α-IL10 axis may be promising for the treatment of fatty liver diseases.

Fine-Tuning of PGC1α Expression Regulates Cardiac Function and Longevity.

RATIONALE: PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1α) represents an attractive target interfering bioenergetics and mitochondrial homeostasis, yet multiple attempts have failed to upregulate PGC1α expression as a therapy, for instance, causing cardiomyopathy. OBJECTIVE: To determine whether a fine-tuning of PGC1α expression is essential for cardiac homeostasis in a context-dependent manner. METHODS AND RESULTS: Moderate cardiac-specific PGC1α overexpression through a ROSA26 locus knock-in strategy was utilized in WT (wild type) mice and in G3Terc-/- (third generation of telomerase deficient; hereafter as G3) mouse model, respectively. Ultrastructure, mitochondrial stress, echocardiographic, and a variety of biological approaches were applied to assess mitochondrial physiology and cardiac function. While WT mice showed a relatively consistent PGC1α expression from 3 to 12 months old, age-matched G3 mice exhibited declined PGC1α expression and compromised mitochondrial function. Cardiac-specific overexpression of PGC1α (PGC1αOE) promoted mitochondrial and cardiac function in 3-month-old WT mice but accelerated cardiac aging and significantly shortened life span in 12-month-old WT mice because of increased mitochondrial damage and reactive oxygen species insult. In contrast, cardiac-specific PGC1α knock in in G3 (G3 PGC1αOE) mice restored mitochondrial homeostasis and attenuated senescence-associated secretory phenotypes, thereby preserving cardiac performance with age and extending health span. Mechanistically, age-dependent defect in mitophagy is associated with accumulation of damaged mitochondria that leads to cardiac impairment and premature death in 12-month-old WT PGC1αOE mice. In the context of telomere dysfunction, PGC1α induction replenished energy supply through restoring the compromised mitochondrial biogenesis and thus is beneficial to old G3 heart. CONCLUSIONS: Fine-tuning the expression of PGC1α is crucial for the cardiac homeostasis because the balance between mitochondrial biogenesis and clearance is vital for regulating mitochondrial function and homeostasis. These results reinforce the importance of carefully evaluating the PGC1α-boosting strategies in a context-dependent manner to facilitate clinical translation of novel cardioprotective therapies.