ALDOB/KAT2A interactions epigenetically modulate TGF-β expression and T cell functions in hepatocellular carcinogenesis

BACKGROUND AND AIMS

Cross talk between tumor cells and immune cells enables tumor cells to escape immune surveillance and dictate responses to immunotherapy. Previous studies have identified that downregulation of the glycolytic enzyme fructose-1,6-bisphosphate aldolase B (ALDOB) in tumor cells orchestrated metabolic programming to favor HCC. However, it remains elusive whether and how ALDOB expression in tumor cells affects the tumor microenvironment in HCC.

APPROACH AND RESULTS

We found that ALDOB downregulation was negatively correlated with CD8 + T cell infiltration in human HCC tumor tissues but in a state of exhaustion. Similar observations were made in mice with liver-specific ALDOB knockout or in subcutaneous tumor models with ALDOB knockdown. Moreover, ALDOB deficiency in tumor cells upregulates TGF-β expression, thereby increasing the number of Treg cells and impairing the activity of CD8 + T cells. Consistently, a combination of low ALDOB and high TGF-β expression exhibited the worst overall survival for patients with HCC. More importantly, the simultaneous blocking of TGF-β and programmed cell death (PD) 1 with antibodies additively inhibited tumorigenesis induced by ALDOB deficiency in mice. Further mechanistic experiments demonstrated that ALDOB enters the nucleus and interacts with lysine acetyltransferase 2A, leading to inhibition of H3K9 acetylation and thereby suppressing TGFB1 transcription. Consistently, inhibition of lysine acetyltransferase 2A activity by small molecule inhibitors suppressed TGF-β and HCC.

CONCLUSIONS

Our study has revealed a novel mechanism by which a metabolic enzyme in tumor cells epigenetically modulates TGF-β signaling, thereby enabling cancer cells to evade immune surveillance and affect their response to immunotherapy.

Effectiveness of China-PAR and Framingham risk score in assessment of 10-year cardiovascular disease risk in Chinese hypertensive patients

OBJECTIVES

Estimating the total risk of cardiovascular disease (CVD) using risk prediction models represents a huge improvement in identifying and treating each of the risk factors. The objective of this study was to evaluate the effectiveness of the China-PAR (Prediction of atherosclerotic CVD risk in China) and Framingham risk score (FRS) in predicting the 10-year risk of CVD in Chinese hypertensive patients. The results of the study can be used to design health promotion strategies.

STUDY DESIGN

A large cohort study was used to assess the validity of models by comparing model predictions with actual incidence rates.

METHODS

In total, 10,498 hypertensive patients aged 30-70 years in Jiangsu Province, China, participated in the baseline survey that took place between January and December 2010 and were followed up to May 2020. China-PAR and FRS were used to calculate the predicted 10-year risk of CVD. The 10-year observed incidence of new cardiovascular events was adjusted by the Kaplan-Meier method. The ratio of the predicted risk to the actual incidence was calculated to evaluate the effectiveness of the model. The discrimination Harrell's C statistics and calibration Chi-square value were used to evaluate the predictive reliability of the models.

RESULTS

Of the 10,498 participants, 4411 (42.02%) were male. During the mean follow-up of 8.30 ± 1.45 years, a total of 693 new cardiovascular events occurred. Both models overestimated the risk of morbidity to varying degrees, and the FRS overestimated to a greater extent. After adjustment for covariates, the results of Cox proportional hazards regression showed that the risk of CVD in the high-risk group was higher than in low-risk group. The degree of discrimination in both models was approximately 0.6, which showed that discrimination was not ideal in the models. In addition, Chi-square calibrations of the two models were <20 in males, which showed that calibration of the models was better for men than women.

CONCLUSIONS

The China-PAR and FRS models overestimated the risk of CVD for participants in this study. In addition, the degree of discrimination was not ideal, and both models performed better in males than in females in terms of calibration. The results of this study suggest that a more suitable risk prediction model should be established according to the characteristics of the hypertensive population in Jiangsu Province.

Fructose-1,6-Bisphosphate Aldolase B Depletion Promotes Hepatocellular Carcinogenesis Through Activating Insulin Receptor Signaling and Lipogenesis

BACKGROUND AND AIMS

Insulin receptor (IR) transduces cell surface signal through phosphoinositide 3-kinase (PI3K)-AKT pathways or translocates to the nucleus and binds to the promoters to regulate genes associated with insulin actions, including de novo lipogenesis (DNL). Chronic activation of IR signaling drives malignant transformation, but the underlying mechanisms remain poorly defined. Down-regulation of fructose-1,6-bisphosphate aldolase (ALDO) B in hepatocellular carcinoma (HCC) is correlated with poor prognosis. We aim to study whether and how ALDOB is involved in IR signaling in HCC.

APPROACH AND RESULTS

Global or liver-specific ALDOB knockout (L-ALDOB-/- ) mice were used in N-diethylnitrosamine (DEN)-induced HCC models, whereas restoration of ALDOB expression was achieved in L-ALDOB-/- mice by adeno-associated virus (AAV). 13 C6 -glucose was employed in metabolic flux analysis to track the de novo fatty acid synthesis from glucose, and nontargeted lipidomics and targeted fatty acid analysis using mass spectrometry were performed. We found that ALDOB physically interacts with IR and attenuates IR signaling through down-regulating PI3K-AKT pathways and suppressing IR nuclear translocation. ALDOB depletion or disruption of IR/ALDOB interaction in ALDOB mutants promotes DNL and tumorigenesis, which is significantly attenuated with ALDOB restoration in L-ALDOB-/- mice. Notably, attenuated IR/ALDOB interaction in ALDOB-R46A mutant exhibits more significant tumorigenesis than releasing ALDOB/AKT interaction in ALDOB-R43A, whereas knockdown IR sufficiently diminishes tumor-promoting effects in both mutants. Furthermore, inhibiting phosphorylated AKT or fatty acid synthase significantly attenuates HCC in L-ALDOB-/- mice. Consistently, ALDOB down-regulation is correlated with up-regulation of IR signaling and DNL in human HCC tumor tissues.

CONCLUSIONS

Our study reports a mechanism by which loss of ALDOB activates IR signaling primarily through releasing IR/ALDOB interaction to promote DNL and HCC, highlighting a potential therapeutic strategy in HCC.

Single-cell RNA-seq analysis identifies unique chondrocyte subsets and reveals involvement of ferroptosis in human intervertebral disc degeneration

OBJECTIVE

Nucleus pulposus (NP) plays a central role in disc degeneration pathogenesis, however, as a heterogeneous tissue, cell subsets in NP and their corresponding biological process in intervertebral disc degeneration (IVDD) are unreported.

METHOD

Nucleus pulposus were isolated from normal control and IVDD, and then subjected to single-cell RNA sequencing (scRNA-seq). Unsupervised clustering of the cells based on the gene expression profiles using the Seurat package and passed to tSNE for clustering visualization. Rat model of disc degeneration was built to validate the pathways identified by scRNA-Seq.

RESULTS

Seven chondrocyte subsets were revealed in NP based on differential gene expression, among which 4 subsets (C1-C4) were reported for the first time. Furthermore, GO and KEGG analyses discovered that ferroptosis pathways were enriched. Rat model of disc degeneration was built (n = 6/group, control vs. model) to validate the pathways identified by scRNA-Seq. Iron levels of NP were significantly higher in model group than control group (means 0.712 vs. 0.248, respectively, mg/gpro, p = 0.0026), and the levels of Heme Oxygenase 1 (HO-1) were also elevated in model group (means 14.33 vs. 5.16 IOD, respectively, p = 0.0002). However, the levels of ferritin light chain (FTL) were significantly decreased in model group compared to control group (means 26.17 vs. 9.00 FTL⁺ cell number, respectively, p = 0.0011).

CONCLUSIONS

Novel chondrocyte subsets in nucleus pulposus were discovered through scRNA-Seq, which provided novel insight to understand the pathological change during the development of IVDD. Ferroptosis participated in disc degeneration pathogenesis and it might serve as a new target for intervening IVDD.

Loss of hepatic aldolase B activates Akt and promotes hepatocellular carcinogenesis by destabilizing the Aldob/Akt/PP2A protein complex

Loss of hepatic fructose-1, 6-bisphosphate aldolase B (Aldob) leads to a paradoxical up-regulation of glucose metabolism to favor hepatocellular carcinogenesis (HCC), but the upstream signaling events remain poorly defined. Akt is highly activated in HCC, and targeting Akt is being explored as a potential therapy for HCC. Herein, we demonstrate that Aldob suppresses Akt activity and tumor growth through a protein complex containing Aldob, Akt, and protein phosphatase 2A (PP2A), leading to inhibition of cell viability, cell cycle progression, glucose uptake, and metabolism. Interestingly, Aldob directly interacts with phosphorylated Akt (p-Akt) and promotes the recruitment of PP2A to dephosphorylate p-Akt, and this scaffolding effect of Aldob is independent of its enzymatic activity. Loss of Aldob or disruption of Aldob/Akt interaction in Aldob R304A mutant restores Akt activity and tumor-promoting effects. Consistently, Aldob and p-Akt expression are inversely correlated in human HCC tissues, and Aldob down-regulation coupled with p-Akt up-regulation predicts a poor prognosis for HCC. We have further discovered that Akt inhibition or a specific small-molecule activator of PP2A (SMAP) efficiently attenuates HCC tumorigenesis in xenograft mouse models. Our work reveals a novel nonenzymatic role of Aldob in negative regulation of Akt activation, suggesting that directly inhibiting Akt activity or through reactivating PP2A may be a potential therapeutic approach for HCC treatment.

Polyphenolic Proanthocyanidin-B2 suppresses proliferation of liver cancer cells and hepatocellular carcinogenesis through directly binding and inhibiting AKT activity

The well-documented anticarcinogenic properties of natural polyphenolic proanthocyanidins (OPC) have been primarily attributed to their antioxidant and anti-inflammatory potency. Emerging evidence suggests that OPC may target canonical oncogenic pathways, including PI3K/AKT; however, the underlying mechanism and therapeutic potential remain elusive. Here we identify that proanthocyanidin B2 (OPC-B2) directly binds and inhibits AKT activity and downstream signalling, thereby suppressing tumour cell proliferation and metabolism in vitro and in a xenograft and diethyl-nitrosamine (DEN)-induced hepatocellular carcinoma (HCC) mouse models. We further find that OPC-B2 binds to the catalytic and regulatory PH domains to lock the protein in a closed conformation, similar to the well-studied AKT allosteric inhibitor MK-2206. Molecular docking and dynamic simulation suggest that Lys297 and Arg86 are critical sites of OPC-B2 binding; mutation of Lys297 or Arg86 to alanine completely abolishes the antitumor effects of OPC-B2 but not MK-2206. Together, our study reveals that OPC-B2 is a novel allosteric AKT inhibitor with potent anti-tumour efficacy beyond its antioxidant and anti-inflammatory properties.

Yeast β-D-glucan exerts antitumour activity in liver cancer through impairing autophagy and lysosomal function, promoting reactive oxygen species production and apoptosis

Autophagy is an evolutionarily conserved catabolic process that recycles proteins and organelles in a lysosome-dependent manner and is induced as an alternative source of energy and metabolites in response to diverse stresses. Inhibition of autophagy has emerged as an appealing therapeutic strategy in cancer. However, it remains to be explored whether autophagy inhibition is a viable approach for the treatment of hepatocellular carcinoma (HCC). Here, we identify that water-soluble yeast β-D-glucan (WSG) is a novel autophagy inhibitor and exerts significant antitumour efficacy on the inhibition of HCC cells proliferation and metabolism as well as the tumour growth in vivo. We further reveal that WSG inhibits autophagic degradation by increasing lysosomal pH and inhibiting lysosome cathepsins (cathepsin B and cathepsin D) activities, which results in the accumulation of damaged mitochondria and reactive oxygen species (ROS) production. Furthermore, WSG sensitizes HCC cells to apoptosis via the activation of caspase 8 and the transfer of truncated BID (tBID) into mitochondria under nutrient deprivation condition. Of note, administration of WSG as a single agent achieves a significant antitumour effect in xenograft mouse model and DEN/CCl₄ (diethylnitrosamine/carbon tetrachloride)-induced primary HCC model without apparent toxicity. Our studies reveal, for the first time, that WSG is a novel autophagy inhibitor with significant antitumour efficacy as a single agent, which has great potential in clinical application for liver cancer therapy.

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Water-soluble yeast β-D-glucan (WSG) exerts direct antitumour activity in HCC

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WSG inhibits autophagic degradation by increasing lysosomal pH

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WSG causes accumulation of damaged mitochondria and ROS production

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WSG sensitizes HCC cells to apoptosis via the activation of caspase 8

An Adiponectin Receptor Agonist Reduces Type 2 Diabetic Periodontitis

Periodontitis is twice as prevalent in diabetics as in nondiabetics, and type 2 diabetes (T2D)-associated periodontitis is severe in many cases due to the altered and aberrant functions of bone cells in hyperglycemic conditions. Therefore, developing an effective method to halt the disease process, as well as restore and regenerate lost alveolar bone to reserve the natural teeth in diabetics, is critically important. In the current study, we applied a newly discovered adiponectin receptor agonist AdipoRon (APR) in experimental periodontitis in diabetic animal models and demonstrated the underlying molecular mechanisms. We found that when APR systemically quenched the blood sugar level in diet-induced obesity (DIO) diabetic mice, it reduced osteoclast numbers and alveolar bone loss significantly due to APR's inhibition on osteoclast differentiation shown in our in vitro studies. APR also decreased the production of proinflammatory molecules CC chemokine ligand 2 and interleukin 6 in diseased gingival tissues. On the other hand, APR promoted alveolar bone regeneration through enhancing osteogenic differentiation and decreasing stromal cell-derived factor 1 in the bone marrow that facilitates stem cell migration. Same results were achieved by APR treatment of periodontitis induced in adiponectin (APN) knockout mice, indicating the ability of APR to activate the endogenous APN receptors to exert osteoanabolic effects. In summary, our study supports the notion that APR could be used as an effective multipronged approach to target T2D-associated periodontitis.

A Simple Method of Fabricating Graphene-Polymer Conductive Films

In this study, polydimethylsiloxane and graphene were used to fabricate surface electrodes for electrocardiographic (ECG) sensing. A simple and inexpensive method was developed to fabricate graphene-based polymer films. In this method, graphene was inlaid in polydimethylsiloxane by polymer infiltration. The polymer films were successfully used in ECG measurements and performed as well as conventional silver/silver chloride wet electrodes. Few motion artifacts were observed with the graphene films when body postures were changed and during walking. The presented approach is low-cost and suitable for mass production, holding great promise in fabricating polymer electrodes for medical monitoring.

CDKN2B deletion is essential for pancreatic cancer development instead of unmeaningful co-deletion due to juxtaposition to CDKN2A

Pancreatic cancer is among the deadliest malignancies; however, the genetic events that lead to pancreatic carcinogenesis in adults remain unclear. In vivo models in which these genetic alterations occur in adult animals may more accurately reflect the features of human cancer. In this study, we demonstrate that inactivation of Cdkn2b (p15ink4b) is necessary for induction of pancreatic cancer by oncogenic KRAS^G12D expression and inactivation of Tp53 and Cdkn2a in adult mouse pancreatic ductal cells (P60 or older). KRAS^G12D overexpression in these cells activated transforming growth factor-β signaling and expression of CDKN2B, which, along with CDKN2A, led to cellular senescence and protected cells from KRAS-mediated transformation via inhibition of retinoblastoma phosphorylation. These results show a critical role of CDKN2B inactivation in pancreatic carcinogenesis, and provide a useful adult animal model by genetic engineering via lentiviral delivery.

Sleep disturbances in irritable bowel syndrome: a systematic review

BACKGROUND

Sleep disturbances are well-documented among persons with irritable bowel syndrome (IBS). Difficulty in falling asleep, shorter sleep time, frequent arousal and awakenings, or non-restorative sleep are the most common manifestations. Sleep disturbances are also related to a higher risk of having IBS. Some researchers have provided evidence of a positive association between poorer subjective sleep quality and increased severity and frequency in gastrointestinal (GI) symptoms in those with IBS. However, findings from studies using objective sleep and activity measures, such as polysomnography and actigraphy, are inconclusive.

PURPOSE

This systematic review of the literature between 1990 and 2015 evaluates the evidence of sleep disturbances in adults with IBS and their relationship with GI symptoms.

Blockade of Interleukin-17 Restrains the Development of Acute Lung Injury

The acute respiratory distress syndrome (ARDS), a clinical complication of severe acute lung injury (ALI) in humans, is a leading cause of morbidity and mortality in critically ill patients. Here, we explored the association between IL-17 and development of ALI using LPS-induced murine model. We found that IL-17 level was elevated in bronchoalveolar lavage (BAL) fluid of ALI mice. Upregulation of IL-17 resulted in increased severity of ALI as evidenced by decreased body weight and survival rate, elevated level of total protein and albumin in BAL fluid, as well as more apparent histopathology changes of lung. Induction of ALI was impaired in IL-17-deficient mice. Management of IL-17 could modulate LPS-induced pulmonary inflammation, as reflected by the total cell and neutrophil counts, proinflammatory cytokines, as well as chemokines in BAL fluid. Of note, blockade of IL-17 effectively inhibited the lung inflammation and alleviated ALI severity. Finally, we confirmed the clinical relevance and found that IL-17 expression was elevated and associated with the disease severity in patients with ARDS. In essence, IL-17 was crucial for development of ALI, suggesting a potential application for IL-17-based therapy in clinical practice.

Nutritional status of an elderly population in Southwest China: a cross-sectional study based on comprehensive geriatric assessment

OBJECTIVE

Few data is available on the nutritional status of old Chinese. The present study aimed to describe the nutritional status and clinical correlates for malnutrition risk in the older people.

DESIGN

Cross-sectional study.

SETTING

Hospital- and community-based older people were recruited in the region of Chongqing, China.

PARTICIPANTS

558 individuals aged 60 years old or over between April 2011 and October 2012.

MEASUREMENTS

Comprehensive geriatric assessment was performed and nutritional status was assessed by the Mini Nutritional Assessment Short Form (MNA-SF). Nutrition-associated factors were analyzed, including health status (chronic diseases, depression, cognition, function impaired), social factors (education status, marital status, the type of work before 60 years old) and life style factors (smoking, drinking, diet).

RESULTS

The mean age was 73.1±8.0 years and 43.9% were men. Prevalence of malnutrition and risk for malnutrition were 3.2% and 19.3 %, respectively. Several factors increased poor nutrition independently including self-rated health, comorbidity, chronic obstructive pulmonary disease, gastrointestinal disease and cognitive impairment. Fish decreased the risk of poor nutrition.

CONCLUSIONS

The prevalence was relatively low in older people of Chongqing, Southwest China. Poor nutrition was found to be increased due to the common health problems. Thus the patients with these problems should pay more attention on nutritional status. The older people should often have fish because of their nutritional benefit.

CARD11 blockade suppresses murine collagen-induced arthritis via inhibiting CARD11/Bcl10 assembly and T helper type 17 response

The scaffold protein caspase recruitment domain-containing protein 11 (CARD11) is implicated in the regulation of inflammation and autoimmunity. The present study aimed to explore the role of CARD11 in the pathogenesis of rheumatoid arthritis (RA). Mice with collagen-induced arthritis (CIA) were treated with either CARD11-targeted interfering RNA (CARD11 siRNA) or control siRNA by intraperitoneal injection every 3 days after CIA establishment. The clinical score of arthritis was recorded every other day. Synovial inflammation and cartilage erosion were evaluated by histology and microcomputed tomography (micro-CT). Serum anti-type II collagen (anti-CII) antibodies and cytokines were measured by enzyme-linked immunosorbent assay (ELISA). The CARD11/Bcl10 formation and nuclear factor-kappa B (NF-κB) activation was assessed by immunoprecipitation and immunoblotting, and the percentage of T helper type 17 (Th17) cells was determined by flow cytometry. Systemic administration of CARD11 siRNA significantly reduced the clinical score of CIA severity. As indicated by the histology, joint inflammation and destruction were attenuated by CARD11 siRNA treatment. Micro-CT demonstrated less severe joint destruction in CARD11 siRNA-treated mice than in control mice. CARD11 siRNA treatment resulted in inhibition of CARD11/Bcl10 formation and the subsequent NF-κB activation. In addition, treatment with CARD11 siRNA resulted in a pronounced decrease in proinflammatory cytokines interleukin (IL)-1β, IL-6 and IL-17. Serum anti-CII antibody and the percentage of Th17 cells were also significantly reduced. CARD11 is involved in the pathogenesis of CIA by formation of the CARD11/Bcl10 complex and enhancement of the Th17 cell response. Targeting CARD11 provides a novel research direction in the development of therapeutic strategies for RA.

BET Inhibitor JQ1 Blocks Inflammation and Bone Destruction

BET proteins are a group of epigenetic regulators controlling transcription through reading acetylated histone tails and recruiting transcription complexes. They are considered as potential therapeutic targets in many distinct diseases. A novel synthetic bromodomain and extraterminal domain (BET) inhibitor, JQ1, was proved to suppress oncogene transcription and inflammatory responses. The present study was aimed to investigate the effects of JQ1 on inflammatory response and bone destruction in experimental periodontitis. We found that JQ1 significantly suppressed lipopolysaccharide (LPS)-stimulated inflammatory cytokine transcription, including interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha (TNF-α), as well as receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclast markers, such as c-Fos, nuclear factor of activated T-cells, cytoplasmic, calcineurin-dependent 1 (NFATc1), tartrate-resistant acid phosphatase (TRAP) and cathepsin K in vitro. JQ1 also inhibited toll-like receptors 2/4 (TLR2/4) expression and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) phosphorylation and nuclear translocation. Chromatin immunoprecipitation and quantitative polymerase chain reaction (ChIP-qPCR) revealed that JQ1 neutralized BRD4 enrichment at several gene promoter regions, including NF-κB, TNF-α, c-Fos, and NFATc1. In a murine periodontitis model, systemic administration of JQ1 significantly inhibited inflammatory cytokine expression in diseased gingival tissues. Alveolar bone loss was alleviated in JQ1-treated mice because of reduced osteoclasts in periodontal tissues. These unprecedented results suggest the BET inhibitor JQ1 as a prospective new approach for treating periodontitis.

Transcription factor and bone marrow stromal cells in osseointegration of dental implants

Titanium implants are widely used in dental clinics and orthopaedic surgery. However, bone formation surrounding the implant is relatively slow after inserting the implant. The current study assessed the effects of bone marrow stromal cells (BMSCs) with forced expression of special AT-rich sequence-binding protein 2 (SATB2) on the osseointegration of titanium implants. To determine whether SATB2 overexpression in BMSCs can enhance the osseointegration of implants, BMSCs were infected with the retrovirus encoding Satb2 (pBABE-Satb2) and were locally applied to bone defects before implanting the titanium implants in the mouse femur. Seven and twenty-one days after implantation, the femora were isolated for immunohistochemical (IHC) staining, haematoxylin eosin (H&E) staining, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), and micro-computed tomography (μCT) analysis. IHC staining analysis revealed that SATB2-overexpressing BMSCs were intensely distributed in the bone tissue surrounding the implant. Histological analysis showed that SATB2-overexpressing BMSCs significantly enhanced new bone formation and bone-to-implant contact 3 weeks after implantation. Real-time qRT-PCR results showed that the local delivery of SATB2-overexpressing BMSCs enhanced expression levels of potent osteogenic transcription factors and bone matrix proteins in the implantation sites. μCT analysis demonstrated that SATB2-overexpressing BMSCs significantly increased the density of the newly formed bone surrounding the implant 3 weeks post-operatively. These results conclude that local delivery of SATB2-overexpressing BMSCs significantly accelerates osseointegration of titanium implants. These results provide support for future pharmacological and clinical applications of SATB2, which accelerates bone regeneration around titanium implants.

Cloning and characterization of a novel member of human beta-1,4-galactosyltransferase gene family

By using the EST strategy for identifying novel members belonging to homologous gene families, a novel fulklength cDNA encoding a protein significantly homologous to UDP-Gal: N-acetylglucosamine beta-1, 4-galactosyltransferase (GalT) was isolated from a human testis cDNA library. A nucleotide sequence of 2 173 bp long was determined to contain an open reading frame of 1 032 nucleotides (344 amino acids). In view of the homology to memben of the galactosyltransferase gene family and especially the closest relationship toGallus gallus GalT type I (CK I), the predicted product of the novel cDNA was designated as human beta-1,4-galactosyltransferase homolog I (HumGT-H1). Its mRNA is present in different degrees in 16 tissues examined. Southern analysis of human genomic DNA revealed its locus on chromosome 3.

Osterix enhances BMSC-associated osseointegration of implants

Cellular and molecular events in osseointegration at the dental implant surface remain largely unknown. We hypothesized that bone marrow stromal cells (BMSCs) participate in this process, and that osterix (Osx) promotes implant osseointegration. To prove this hypothesis, we tracked double-labeled BMSCs in implantation sites created in nude mice transplanted with these cells. We also inserted implants into the femurs of our established transgenic mice after local administration of viruses encoding Osx, to determine the osteogenic effects of Osx. Immunohistochemical results demonstrated that BMSCs can recruit from peripheral circulation and participate in wound healing and osseointegration after implantation. Microcomputed tomography (microCT) analysis revealed an increased bone density at the bone-to-implant interface in the Osx group, and histomorphometric analysis indicated an elevated level of bone-to-implant contact in the Osx group. We concluded that exogenous BMSCs participate in the osseointegration after implantation, and that Osx overexpression accelerates osseointegration.

Phenotypic analysis of Dlx5 overexpression in post-natal bone

Dlx5 plays an important role in the embryonic development of mineralized tissues. We hypothesized that Dlx5 also functions in regulating post-natal bone formation in mice. To prove this hypothesis, we infected 5-day-old bone sialoprotein (BSP)/avian retroviral receptor gene (TVA) transgenic mice with replication-competent retroviral vectors expressing wild-type Dlx5 (RCAS-Dlx5WT) and mutated Dlx5 at arginine (R) 31 of its homeodomain (RCAS-Dlx5RH). Immunohistochemistry indicated that RCAS-Dlx5WT increased BSP and osteopontin (OPN) expression, whereas it decreased that of osteocalcin (OC). RCAS-Dlx5RH mediated opposite effects. Semi-quantitative RT-PCR confirmed these results. Ex vivo overexpression of RCAS-Dlx5WT in BSP/TVA calvarial cells promoted, whereas that of RCAS-Dlx5RH inhibited, mineralized nodule formation as compared with that in control cells. Our results suggest that Dlx5 promotes expression of early markers of osteogenic differentiation and increases mineralization post-natally.

Systemically transplanted bone marrow stromal cells contributing to bone tissue regeneration

Bone marrow stromal cells (BMSCs) are a rich source of osteogenic progenitor cells. A fundamental question is whether systemically transplanted BMSCs participate in bone regeneration. Luciferase and GFP double-labeled BMSCs were transplanted into irradiated mice. Five weeks after transplantation, artificial bone wounds were created in the mandibles and calvaria of the recipients. Animals were sacrificed at weeks 2, 4, and 6 after surgery and the expressions of luciferase and GFP were determined using Xenogen IVIS Imaging System, immunohistochemical staining and RT-PCR. The results demonstrated that transplanted BMSCs can be detected in wound sites as early as 2 weeks and lasted the whole experimental period. Luciferase expression peaked at 2 weeks after surgery and decreased thereafter, exhibiting a similar expression pattern as that of BSP, while GFP expression was relatively stable during the experimental period. In conclusion, BMSCs can migrate to bone wound sites and participate in bone regeneration in orocraniofacial region.

Tissue- and bone cell-specific expression of bone sialoprotein is directed by a 9.0 kb promoter in transgenic mice

Bone sialoprotein (BSP) is a phosphorylated glycoprotein that is expressed almost exclusively in mineralizing connective tissues. In bone, expression of BSP correlates with the differentiation of osteoblasts and the onset of mineralization. To determine how the tissue- and differentiation-specific transcription of BSP is regulated, various lengths of promoter sequence were ligated to a luciferase reporter and stably transfected into a rat stromal bone marrow cell line, RBMC-D8 and undifferentiated C3H10T1/2 cells. Luciferase transcription of reporter constructs including 5.4 kb (mBSP5.4Luc) and 9.0 kb (mBSP9.0Luc) of the BSP promoter was strongly up-regulated in parallel with endogenous BSP mRNA in differentiating SBMCs, but not in C3H10T1/2 cells. In contrast, 0.1 kb and 1.4 kb BSP promoter constructs did not show selective expression. To determine tissue-specific expression in vivo, transgenic mice expressing reporter constructs for the 9.0 kb promoter and a 4.8 kb promoter lacking two upstream Cbfa1/Runx2 elements (mBSP9.0Luc and mBSP4.8Luc, respectively) were generated. Analysis of various tissues collected from 1-, 4-, 7-, 14-, and 42-day-old mice revealed extremely high levels of luciferase activity in calvaria, mandible, and tibia of the mBSP9.0Luc mice. In contrast, soft tissues showed negligible luciferase expression. Mice harboring the 4.8 kb transgene also showed selective luciferase expression but displayed a significantly lower activity in mineralized tissues. Northern hybridization of endogenous BSP mRNA and immunostaining of BSP in mBSP9.0Luc mice showed a temporo-spatial expression pattern consistent with the luciferase activity. These results indicate that regulatory elements within the 9.0 kb region of the promoter are required for strong, tissue- and differentiation-specific expression of BSP.

Rickets in cation-sensing receptor-deficient mice: an unexpected skeletal phenotype

The hypothesis that local changes in extracellular calcium may serve a physiological role in regulating osteoblast, osteoclast, and cartilage function through the extracellular cation-sensing receptor, CasR, is gaining widespread support, but lacks definite proof. To examine the effects of CasR deficiency on the skeleton, we performed a detailed analysis of the skeleton in CasR knockout mice (CasR(-/-)) and wild-type littermates (CasR(+/+)). CasR ablation in the parathyroid glands of CasR(-/-) mice resulted in hyperparathyroidism, hypercalcemia, and hypophosphatemia. Except for dwarfism, the expected skeletal manifestations of PTH excess, namely chondrodysplasia and increased mineralized bone formation and resorption, were not the main skeletal features in CasR(-/-) mice. Rather, rickets was the predominant skeletal abnormality in these animals, as evidenced by a widened zone of hypertrophic chondrocytes, impaired growth plate calcification and disorderly deposition of mineral, excessive osteoid accumulation, and prolonged mineralization lag time in metaphyseal bone. CasR transcripts were identified in cartilage and bone marrow of CasR(+/+) mice, but not in mineralized bone containing mature osteoblasts and osteocytes. These findings indicate that a calcium-sensing receptor is present in the skeleton, and its absence results in defective mineralization of cartilage and bone by mechanisms that remain to be elucidated.

Molecular cloning, genomic organization, and mapping of PRKAG2, a heart abundant gamma2 subunit of 5'-AMP-activated protein kinase, to human chromosome 7q36

5'-AMP-activated protein kinase (AMPK) acts as a major regulator of cellular ATP levels and protects cells against stresses that cause ATP depletion. AMPK is a protein heterotrimer composed of a catalytic alpha subunit and two regulatory subunits, beta and gamma. In the present study, a homologue of the AMPK gamma1-subunit cDNA with an open reading frame encoding 328 amino acids was identified. The putative protein sequence is about 76% identical to the 331-amino-acid gamma1 subunit and also has four consecutive cystathionine-beta-synthase (CBS) domains, a characteristic structure of AMPK gamma subunits from various species. This cDNA (tentatively termed PRKAG2-b) is identical to a recently reported cDNA (tentatively termed PRKAG2-a) of human AMPK gamma subunits except in their 5'-end regions, suggesting that these two cDNAs are two different transcripts of the same gene. To determine the expression pattern of the gene, two probes, one from the 3'-UTR of PRKAG2-b and the other from the 5'- unique region of PRKAG2-a, were used to hybridize MTN membranes. Three transcripts (3.8, 3.0, and 2.4 kb) were observed when the first probe was used, whereas only 3.8- and 3.0-kb transcripts were seen when the second probe was used. Thus, the PRKAG2-b corresponded to the 2.4-kb transcript, which is ubiquitously expressed except in liver and thymus. The highest level was detected in heart, while abundant expression also existed in placenta and testis. The expression pattern of PRKAG2-b is completely different from those of PRKAG2-a and PRKAG1, whose expression patterns were also determined in the current study. The PRKAG2 gene was located to human chromosome 7q36 between markers D7S2439 and D7S2462 by radiation hybrid mapping. The genomic organization of PRKAG2-b was identified by comparing its cDNA sequence with two genomic sequences AC006358 and AC006966, which showed that PRKAG2-b spanned an approximately 80-kb region and was composed of 12 exons.

Cloning and mapping of human PKIB and PKIG, and comparison of tissue expression patterns of three members of the protein kinase inhibitor family, including PKIA

Two novel members of the human cAMP-dependent protein kinase inhibitor (PKI) gene family, PKIB and PKIG, were cloned. The deduced proteins showed 70% and 90% identity with mouse PKIbeta and PKIgamma respectively. Both the already identified pseudosubstrate site and leucine-rich nuclear export signal motifs were defined from the 11 PKIs of different species. The PKIB and PKIG genes were mapped respectively to chromosome 6q21-22.1, using a radiation hybrid GB4 panel, and to chromosome 20q13.12-13.13, using a Stanford G3 panel. Northern-blot analysis of three PKI isoforms, including the PKIA identified previously, revealed significant differences in their expression patterns. PKIB had two transcripts of 1.9 kb and 1.4 kb. The former transcript was abundant in both placenta and brain and the latter was expressed most abundantly in placenta, highly in brain, heart, liver, pancreas, moderately in kidney, skeletal muscle and colon, and very little in the other eight tissues tested. PKIG was widely expressed as a 1.5-kb transcript with the highest level in heart, hardly detectable in thymus and peripheral blood leucocytes and was moderately expressed in the other tissues, with slightly different levels. However, PKIA was specifically expressed as two transcripts of 3.3 kb and 1.5 kb in heart and skeletal muscle. The distinct expression patterns of the three PKIs suggest that their roles in various tissues are probably different.

Efficiency of solvent extraction methods for the determination of methyl mercury in forest soils

Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%.

Cloning, characterization and mapping of the human ATP5E gene, identification of pseudogene ATP5EP1, and definition of the ATP5E motif

A cDNA encoding the epsilon subunit of human ATP synthase, ATP5E, was isolated from heart, skeletal muscle and spleen cDNA libraries respectively. Its genome structure was characterized as comprising three exons and two introns within a stretch of 5 kb, according to the genomic sequence AL109840. The gene was mapped to human chromosome 20q13.3 between marker D20S173 and 20qter using the radiation hybrid GB4 panel. Northern blot analysis showed that the ATP5E gene was expressed as a single 0.6 kb transcript in all 16 human tissues tested, with a high level present in heart and skeletal muscle. A new conserved motif composed of 24 residues, termed the ATP5E motif [W(R/K)X(5)YX(2)(Y/F)X(3)(C/A)X(4)RX(3)K], was defined on the basis of sequences of ATP synthase epsilon subunits from ten different organisms. In addition, a pseudogene ATP5EP1 was also identified on the basis of genomic sequence AC004066, localized on human chromosome 4q25. By analysing these results combined with the Southern blot patterns of human DNA hybridized with bovine ATP5E cDNA reported previously [Vinas, Powell, Runswick, Iacobazzi and Walker (1990) Biochem. J. 265, 321-326], we provide evidence of yet further homologous sequences (either gene or pseudogene) of ATP5E, in addition to ATP5E and ATP5EP1 in the human genome.

[The second phase clinical observation of anti-radiation effect by superoxide dismutase]

Multiple center randomized controlled double blind clinical trait was conducted to evaluate the anti-radiotherapy effect by SOD (produced by Hunan Biochemical Work) in 159 patients. Injection of 4000U SOD immediately after receiving radiotherapy significantly reduced the occurrence rate of skin, oral mucosal, pelvic visceral and systematic adverse reaction, only the reduction of leukopenia did not reach the statistical significant level. No adverse effect of SOD injection was observed. The results suggest that SOD is a safe and effective agent to attenuate the radiotherapy reactions.

Cloning, characterization, and chromosome mapping of RPS6KC1, a novel putative member of the ribosome protein S6 kinase family, to chromosome 12q12-q13.1

A novel cDNA encoding a putative Ser/Thr protein kinase was isolated from a human skeletal muscle cDNA library. It contains an open reading frame that extends from nt 104 to 1510 and codes for a protein of 469 amino acids. A catalytic domain containing the conserved residues of the Ser/Thr protein kinase, especially human ribosome protein S6 kinase (RSK), was found to be located in the C-terminal end of the deduced protein. The gene was mapped to human chromosome 12q12-q13.1 by fluorescence in situ hybridization, and this result was confirmed with the Radiation Hybrid GB4 panel. Northern hybridization showed that the novel gene is expressed in all 16 human tissues tested with especially strong expression in testis, skeletal muscle, and brain, whereas weak expression was detected in kidney, thymus, small intestine, liver, lung, heart, and colon.

[Isolation and cloning of human beta 1, 4-galactosyltransferase III gene]

Using the conservative nucleotide sequences encoding the catalytic domain of the beta-1, 4-GalT genes in human, bovine, mouse, chick and snail as probes to search the NCBI GenBank EST database, several ESTs with high homology were obtained. Primers were designed in the flanking sequence of EST contig. Using the PCR product amplified in human placenta cDNA library as probe to perform "walking" hybridization with human placenta cDNA library, a cDNA fragment with the length of 1,907 bp was cloned. It contained an open reading frame (ORF) with the length of 1,179 bp, which encodes 393 amino acid residues. The deduced amino acid sequence of this gene shares 43.8% identity to the human beta-1, 4-GalTI and 60.9% in the catalytic domain especially. The expression mapping showed that it was expressed in human most tissues with a single 2.4 kb transcript, but the relative expression level of the transcript are vary. While this gene was mapped on chromosome 1 using the cDNA hybridization with human/rodent hybrid cell line DNA Southern blot panel.

The active oligomeric state of the minimalistic influenza virus M2 ion channel is a tetramer

The influenza A virus M2 integral membrane protein is an ion channel that permits protons to enter virus particles during uncoating of virions in endosomes and also modulates the pH of the trans-Golgi network in virus-infected cells. The M2 protein is a homo-oligomer of 97 residues, and analysis by chemical cross-linking and SDS/PAGE indicates M2 forms a tetramer. However, a higher order molecular form is sometimes observed and, thus, it is necessary to determine the active form of the molecule. This was done by studying the currents of oocytes that expressed mixtures of the wild-type M2 protein (epitope tagged) and the mutant protein M2-V27S, which is resistant to the inhibitor amantadine. The composition of mixed oligomers of the two proteins expressed at the plasma membrane of individual oocytes was quantified after antibody capture of the cell surface expressed molecules and it was found that the subunits mixed freely. When the ratio of wild-type to mutant protein subunits was 0. 85:0.15, the amantadine sensitivity was reduced to 50% and for a ratio of 0.71:0.29 to 20%. These results are consistent with the amantadine-resistant mutant being dominant and the oligomeric state being a tetramer.

Characterization of inhibition of M2 ion channel activity by BL-1743, an inhibitor of influenza A virus

The influenza A virus M2 integral membrane protein has ion channel activity that can be inhibited by the antiviral drug amantadine. Recently, a spirene-containing compound, BL-1743 (2-[3-azaspiro (5,5)undecanol]-2-imidazoline), that inhibits influenza virus growth was identified (S. Kurtz, G. Lao, K. M. Hahnenberger, C. Brooks, O. Gecha, K. Ingalls, K.-I. Numata, and M. Krystal, Antimicrob. Agents Chemother. 39:2204-2209, 1995). We have examined the ability of BL-1743 to inhibit the M2 ion channel when expressed in oocytes of Xenopus laevis. BL-1743 inhibition is complete as far as can be measured by electrophysiological methods and is reversible, with a reverse reaction rate constant of 4.0 x 10(-3) s(-1). In contrast, amantadine inhibition is irreversible within the time frame of the experiment. However, BL-1743 inhibition and amantadine inhibition have similar properties. The majority of isolated influenza viruses resistant to BL-1743 are also amantadine resistant. In addition, all known amino acid changes which result in amantadine resistance also confer BL-1743 resistance. However, one BL-1743-resistant virus isolated, designated M2-I35T, contained the change Ile-35-->Thr. This virus is >70-fold more resistant to BL-1743 and only 10-fold more resistant to amantadine than the wild-type virus. When the ion channel activity of M2-I35T was examined in oocytes, it was found that M2-I35T is BL-1743 resistant but is reversibly inhibited by amantadine. These findings suggest that these two drugs interact differently with the M2 protein transmembrane pore region.

Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.

Streaming potentials reveal a short ryanodine-sensitive selectivity filter in cardiac Ca2+ release channel

Single cardiac sarcoplasmic reticulum Ca2+ release channels were reconstituted into planar bilayer membranes. Streaming potentials were measured in osmotically asymmetric solutions as a shift in the reversal potential. Potential changes induced by water movement through the bilayer (concentration polarization) and reduced ion activity in the concentrated non-electrolyte solutions were determined using valinomycin. In 400 mM symmetrical CsCH3SO3, the average streaming potential was 2.74 +/- 0.2 mV (n = 5, mean +/- SE; 2 osmol/kg) and independent of the osmoticant used (sucrose or diglycine). Identical streaming potential magnitudes were obtained regardless of which side of the membrane the nonelectrolyte was placed. This suggests that the narrow part of the pore where single file diffusion occurs is relatively short (i.e., accommodates a minimum of 3 H2O molecules). This value is comparable to similar measurements in a variety of surface membrane channels. Ryanodine-modified channels had no measurable streaming potential, an increased Tris+ permeability relative to Cs+, and decreased divalent selectivity (PCs/PTris 5.1 +/- 1.1 to 1.7 +/- 0.3, n = 3; PBa/PCs 8.2 +/- 0.7 to 1.8 +/- 0.5, n = 4). Cation/anion selectivity was essentially unaltered in ryanodine-modified channels. These results suggests that the narrow region of the permeation pathway (i.e., the selectivity filter) is relatively short and widens after ryanodine modification.

Surface charge potentiates conduction through the cardiac ryanodine receptor channel

Single channel currents through cardiac sarcoplasmic reticulum (SR) Ca2+ release channels were measured in very low levels of current carrier (e.g., 1 mM Ba2+). The hypothesis that surface charge contributes to these anomalously large single channel currents was tested by changing ionic strength and surface charge density. Channel identity and sidedness was pharmacologically determined. At low ionic strength (20 mM Cs+), Cs+ conduction in the lumen-->myoplasm (L-->M) direction was significantly greater than in the reverse direction (301.7 +/- 92.5 vs 59.8 +/- 38 pS, P < 0.001; mean +/- SD, t test). The Cs+ concentration at which conduction reached half saturation was asymmetric (32 vs 222 mM) and voltage independent. At high ionic strength (400 mM Cs+), conduction in both direction saturated at 550 +/- 32 pS. Further, neutralization of carboxyl groups on the lumenal side of the channel significantly reduced conduction (333.0 +/- 22.5 vs 216.2 +/- 24.4 pS, P < 0.002). These results indicate that negative surface charge exists near the lumenal mouth of the channel but outside the electric field of the membrane. In vivo, this surface charge may potentiate conduction by increasing the local Ca2+ concentration and thus act as a preselection filter for this poorly selective channel.

Bioaccumulation of the rare earth elements lanthanum, gadolinium and yttrium in carp (Cyprinus carpio)

Widespread use of the rare earth elements (REEs) in China for agricultural purposes, together with many other applications, has resulted in a remarkable increase of REE concentrations in the environment. The comparative bioaccumulations of representative light, medium and heavy REEs in a variety of tissues of carp (Cyprinus carpio L.) were investigated for an evaluation of their impacts on aquatic animals. The fish were exposed continuously to solutions containing 0.50 mg litre(-1) of each element for 45 days at pH 6.0 and sacrificed at time intervals. Skeleton, muscle, gills and internal organs were analysed for REE contents. A method using cation-exchange resin separation and ICP-AES determination was developed for the quatification of individual REEs. The results show that carp has low ability to take up the REEs under the experimental conditions. The order of REEs under the experimental conditions. The order of maximum bioconcentration factors was mostly internal organs > gills > skeleton > muscle. Neither synergistic nor antagonistic effects of the mixed REE solutions for carp were observed. The relative distributions of different REEs in the investigated tissues exhibited similar patterns. Among the selected tissues studied, the concentration of a heavy REE (Y) was the smallest, while concentrations of a medium (Gd) and a light REE (La) showed only a slight difference.