RNA modification-related variants in genomic loci associated with body mass index.

BACKGROUND: Genome-wide association studies (GWASs) have identified hundreds of loci for body mass index (BMI), but functional variants in these loci are less known. The purpose of this study was to identify RNA modification-related SNPs (RNAm-SNPs) for BMI in GWAS loci. BMI-associated RNAm-SNPs were identified in a GWAS of approximately 700,000 individuals. Gene expression and circulating protein levels affected by the RNAm-SNPs were identified by QTL analyses. Mendelian randomization (MR) methods were applied to test whether the gene expression and protein levels were associated with BMI. RESULTS: A total of 78 RNAm-SNPs associated with BMI (P < 5.0 × 10-8) were identified, including 65 m6A-, 10 m1A-, 3 m7G- and 1 A-to-I-related SNPs. Two functional loss, high confidence level m6A-SNPs, rs6713978 (P = 6.4 × 10-60) and rs13410999 (P = 8.2 × 10-59), in the intron of ADCY3 were the top significant SNPs. These two RNAm-SNPs were associated with ADCY3 gene expression in adipose tissues, whole blood cells, the tibial nerve, the tibial artery and lymphocytes, and the expression levels in these tissues were associated with BMI. Proteins enriched in specific KEGG pathways, such as natural killer cell-mediated cytotoxicity, the Rap1 signaling pathway and the Ras signaling pathway, were affected by the RNAm-SNPs, and circulating levels of some of these proteins (ADH1B, DOCK9, MICB, PRDM1, STOM, TMPRSS11D and TXNDC12) were associated with BMI in MR analyses. CONCLUSIONS: Our study identified RNAm-SNPs in BMI-related genomic loci and suggested that RNA modification may affect BMI by affecting the expression levels of corresponding genes and proteins.

RNA-binding protein RPS3 contributes to hepatocarcinogenesis by post-transcriptionally up-regulating SIRT1.

Although several studies indicate that RNA-binding proteins (RBPs) contribute to key steps in a variety of physiological processes and cancer, the detailed biological functions and mechanisms remain to be determined. By performing bioinformatics analysis using well-established hepatocellular carcinoma (HCC) datasets, we identified a set of HCC progression-associated RBPs (HPARBPs) and found that the global expression of HPARBPs was significantly correlated with patient prognosis. Among the 42 HPARBPs, human ribosomal protein S3 (RPS3) was one of the most abundant genes whose role remains uncharacterized in HCC. Gain- and loss-of-function analyses demonstrated that RPS3 promoted HCC tumorigenesis both in vitro and in vivo. Mechanistically, we revealed that silent information regulator 1 (SIRT1) was a critical target of RPS3 and was essential for sustaining the RPS3-induced malignant phenotypes of HCC cells. RPS3 stabilized SIRT1 mRNA by binding to AUUUA motifs in the 3448-3530 region of the 3' untranslated region (UTR) of SIRT1 mRNA. In addition, we found that (5-formylfuran-2-yl) methyl 4-hydroxy-2-methylenebutanoate (FMHM) inhibited HCC progression by repressing the RPS3/SIRT1 pathway. Our study unveils a novel extra-ribosomal role of RPS3 in facilitating hepatocarcinogenesis via the post-transcriptional regulation of SIRT1 expression and proposes that the RPS3/SIRT1 pathway serves as a potential therapeutic target in HCC.

Connection between Unusual Lattice Thermal Expansion and Cooperative Jahn-Teller Effect in Double Perovskites LaPbMSbO6 (M = Mn, Co, Ni).

Lattice thermal expansion (LTE) has been investigated in double perovskites LaPbMSbO6 (M = Mn, Co, Ni). Ordinary LTE behavior with good thermal stability is identified for the Mn sample, whereas unusual LTE with a preferably expanded interplanar distance of (040) is revealed for Co and Ni samples. Temperature-dependent X-ray diffraction patterns ( T-XRD), Raman spectra ( T-Raman), and specific heat capacities ( T- Cp) consistently indicate that a rare isostructural displacive phase transition (IDPT) with a second-order phase transition nature is predominant near the critical temperature. Refinements of neutron powder diffraction (NPD) and in situ T-XRD data present temperature-sensitive bond parameters which are relevant to planar oxygen O1. X-ray photoelectron spectra (XPS) further confirm the Jahn-Teller (J-T) activated Co2+ (HS) or Ni3+ (HS/LS) cations at the B-site sublattice. This unusual LTE behavior could be understood by the cooperative J-T effect contributed by a Pb2+ ion and Co2+/Ni3+ ion from A- and B-site sublattices, respectively. The importance of 6s(Pb)-2p(O)-3d(Co/Ni) extended orbital hybridization on affecting thermal expansion behavior is highlighted on the basis of temperature-induced phonon mode softening. This study presents a microscopic description of connection between anisotropic thermal expansion and a cooperative J-T effect, which inspired exploration of thermal-mechanical coupled functional materials based on LaPbMSbO6 double perovskites.

Study on Structural Evolution, Thermochemistry and Electron Affinity of Neutral, Mono- and Di-Anionic Zirconium-Doped Silicon Clusters ZrSin0/-/2- (n = 6-16).

We have carried out a global search of systematic isomers for the lowest energy of neutral and Zintl anionic Zr-doped Si clusters ZrSin0/-/2- (n = 6-16) by employing the ABCluster global search method combined with the mPW2PLYP double-hybrid density functional. In terms of the evaluated energies, adiabatic electron affinities, vertical detachment energies, and agreement between simulated and experimental photoelectron spectroscopy, the true global minimal structures are confirmed. The results reveal that structural evolution patterns for neutral ZrSin clusters prefer the attaching type (n = 6-9) to the half-cage motif (n = 10-13), and finally to a Zr-encapsulated configuration with a Zr atom centered in a Si cage (n = 14-16). For Zintl mono- and di-anionic ZrSin-/2-, their growth patterns adopt the attaching configuration (n = 6-11) to encapsulated shape (n = 12-16). The further analyses of stability and chemical bonding make it known that two extra electrons not only perfect the structure of ZrSi15 but also improve its chemical and thermodynamic stability, making it the most suitable building block for novel multi-functional nanomaterials.

Silver nanoparticles increase connexin43-mediated gap junctional intercellular communication in HaCaT cells through activation of reactive oxygen species and mitogen-activated protein kinase signal pathway.

Silver nanoparticles (AgNPs) are widely used in health and consumer products that routinely contact skin. However, the biological effects and possible mechanisms of AgNPs on skin remain unclear. Gap junctional intercellular communication (GJIC) plays a critical role in multicellular organisms to maintain tissue homeostasis. The aim of this study is to examine if non-coated AgNPs affect GJIC in human keratinocytes (HaCaT cells), and to identify the possible molecular mechanisms responsible for the effects. GJIC, connexin (Cx)43 protein and mRNA expression, and the effect of siRNA-mediated knockdown of Cx43 on GJIC were assessed. HaCaT cells exposed to non-coated AgNPs at different doses after a 24 hour exposure. To explore further the underlying mechanism, reactive oxygen species and mitogen-activated protein kinase pathway were evaluated after 2, 6, 12 and 24 hours. Our results revealed that non-coated AgNP exposure at subcytotoxic doses increase GJIC partially via Cx43 upregulation. Reactive oxygen species and extracellular signal-regulated kinase and activation of c-Jun N-terminal kinase were involved in the AgNP-induced upregulation of Cx43. This study provides new insight into the potential mechanism of AgNP biological activity.

The relationship between the autonomic nervous function and early renal dysfunction in elderly patients with mild-to-moderate essential hypertension.

OBJECTIVE: This study investigated the relationship between autonomic nervous function and early renal dysfunction in elderly patients with mild-to-moderate essential hypertension (EH). DESIGN: A total of 223 elderly patients with mild-to-moderate EH were enrolled. Urinary albumin excretion (UAE) and urinary creatinine (UCr) were measured in all elderly patients with mild-to-moderate EH, and urinary albumin to creatinine ratio (ACR) was calculated (ACR = UAE/UCr × 0.113). All patients were divided into two groups such as ACR normal group (109 cases) and abnormal ACR group (114 cases) according to the results of ACR. Synchronic 24-hour ambulatory blood pressure monitoring and 24-hour ambulatory electrocardiogram were detected for all patients to simultaneously monitor heart rate variability (HRV) and blood pressure variability (BPV). RESULTS: The level of 24-hour SSD, dSSD, and nSSD and 24-hour PP (parameters of BPV) increased significantly (P < 0.028, P < 0.023, P < 0.027 and P < 0.019, respectively), while the level of RMSSD, pNN50, SDNN, and SDANN (parameters of HRV) decreased significantly(P < 0.048, P < 0.029, P < 0.025 and P < 0.022, respectively) in abnormal ACR group than in normal ACR group. Multiple logistic regression analysis showed that ACR was closely correlated with 24-hour SSD, 24-hour PP, SDANN, and SDNN (ß = 1.261, P = 0.000; ß = 1.121, P = 0.003; ß = -1.741, P = 0.000 and ß = -1.231, P = 0.002, respectively). CONCLUSIONS: HRV (SDANN, SDNN) and BPV (24-hour SSD, dSSD, nSSD) were significantly correlated to ACR in patients with mild-to-moderate EH. This result suggested that sympathetic activation was closely related with early renal dysfunction in elderly patients with mild-to-moderate EH.

Molecular Characterization and Overexpression of SmJMT Increases the Production of Phenolic Acids in Salvia miltiorrhiza.

Jasmonic acid (JA) carboxyl methyltransferase (JMT), a key enzyme in jasmonate-regulated plant responses, may be involved in plant defense and development by methylating JA to MeJA, thus influencing the concentrations of MeJA in plant. In this study, we isolated the JMT gene from Salvia miltiorrhiza, an important medicinal plant widely used to treat cardiovascular disease. We present a genetic manipulation strategy to enhance the production of phenolic acids by overexpresion SmJMT in S. miltiorrhiza. Global transcriptomic analysis using RNA sequencing showed that the expression levels of genes involved in the biosynthesis pathway of phenolic acids and MeJA were upregulated in the overexpression lines. In addition, the levels of endogenous MeJA, and the accumulation of rosmarinic acid (RA) and salvianolic acid (Sal B), as well as the concentrations of total phenolics and total flavonoids in transgenic lines, were significantly elevated compared with the untransformed control. Our results demonstrate that overexpression of SmJMT promotes the production of phenolic acids through simultaneously activating genes encoding key enzymes involved in the biosynthesis pathway of phenolic acids and enhancing the endogenous MeJA levels in S. miltiorrhiza.

FOXA1 mediates p16(INK4a) activation during cellular senescence.

Mechanisms governing the transcription of p16(INK4a), one of the master regulators of cellular senescence, have been extensively studied. However, little is known about chromatin dynamics taking place at its promoter and distal enhancer. Here, we report that Forkhead box A1 protein (FOXA1) is significantly upregulated in both replicative and oncogene-induced senescence, and in turn activates transcription of p16(INK4a) through multiple mechanisms. In addition to acting as a classic sequence-specific transcriptional activator, FOXA1 binding leads to a decrease in nucleosome density at the p16(INK4a) promoter in senescent fibroblasts. Moreover, FOXA1, itself a direct target of Polycomb-mediated repression, antagonizes Polycomb function at the p16(INK4a) locus. Finally, a systematic survey of putative FOXA1 binding sites in the p16(INK4a) genomic region revealed an ∼150 kb distal element that could loop back to the promoter and potentiate p16(INK4a) expression. Overall, our findings establish several mechanisms by which FOXA1 controls p16(INK4a) expression during cellular senescence.

Protein kinase D1 is essential for Ras-induced senescence and tumor suppression by regulating senescence-associated inflammation.

Oncogene-induced senescence (OIS) is an initial barrier to tumor development. Reactive oxygen species (ROS) is critical for oncogenic Ras OIS, but the downstream effectors to mediate ROS signaling are still relatively elusive. Senescent cells develop a senescence-associated secretory phenotype (SASP). However, the mechanisms underlying the regulation of the SASP are largely unknown. Here, we identify protein kinase D1 (PKD1) as a downstream effector of ROS signaling to mediate Ras OIS and SASP. PKD1 is activated by oncogenic Ras expression and PKD1 promotes Ras OIS by mediating inflammatory cytokines interleukin-6 (IL-6) and interleukin-8 (IL-8) via modulation of NF-κB activity. We demonstrate that ROS-protein kinase Cδ (PKCδ)-PKD1 axis is essential for the establishment and maintenance of IL-6/IL8 induction. In addition, ablation of PKD1 causes the bypass of Ras OIS, and promotes cell transformation and tumorigenesis. Together, these findings uncover a previously unidentified role of ROS-PKCδ-PKD1 pathway in Ras OIS and SASP regulation.

HDAC4 stabilizes SIRT1 via sumoylation SIRT1 to delay cellular senescence.

The nicotinamide adenine dinucleotide-dependent protein deacetylase silent information regulator 2 (Sir2) regulates cellular lifespan in several organisms. Histone deacetylase 4 (HDAC4) belongs to the class IIa group of HDACs; this class of HDACs is composed of proteins that are important regulators of gene expression that control pleiotropic cellular functions. However, the role of HDAC4 in cellular senescence is still unknown. This study shows that the expression patterns of HDAC4 and Sirtuin 1 (SIRT1; the mammalian homolog of Sir2) are positively correlated during cellular senescence. Moreover, the overexpression of HDAC4 delays senescence, whereas the knockdown of HDAC4 leads to premature senescence in human fibroblasts. Furthermore, it is demonstrated that HDAC4 increases endogenous SIRT1 expression by enhancing its sumoylation modification levels, thereby stabilizing its protein levels. This study, therefore, provides a new molecular mechanism for the regulation of cellular senescence.

The association between oxidative stress, activator protein-1, inflammatory, total antioxidant status and artery stiffness and the efficacy of olmesartan in elderly patients with mild-to-moderate essential hypertension.

This study investigated the change of oxidative stress, activator protein-1 (AP-1), inflammatory, total antioxidant status (TAS) and artery stiffness, and explored the relationship between these characteristics and the efficacy of olmesartan intervention in elderly patients with mild-to-moderate essential hypertension (EH). In total, 386 elderly patients with EH and 353 normotensive controls were recruited. All study subjects had oxidative stress markers, AP-1, inflammatory factors, TAS and brancial-ankle artery pulse wave velocity (ba-PWV) measured. In total, 193 elderly patients with EH were randomized to olmesartan and were matched with 193 normotensive controls to observe the change of index above mentioned before and after the treatment. Compared with the controls, superoxide dismutase (SOD) and TAS were significantly reduced in patients with EH, and malondialdehyde (MDA), AP-1, high-sensitivity C-reactive protein (Hs-CRP), Monocyte Chemoattractant Protein-1 (MCP-1), heart rate， endothelin-1 (ET-1), TAS and ba-PWV were significantly increased (P < 0.01 for all). Pearson's correlation analysis showed that SOD and TAS were negatively related to AP-1 (P < 0.05 for all), and that blood pressure (BP), age, MDA, Hs-CRP, MCP-1, ET-1 were positively related to AP-1 (P < 0.01 for all). Multivariate linear regression analysis showed that BP, SOD, MDA, AP-1, Hs-CRP, MCP-1, ET-1, TAS, heart rate and age were independent risk factors for ba-PWV. After treatment with olmesartan, SOD and TAS were increased, while BP, heart rate, AP-1 and inflammatory factors were reduced with significant improvement in ba-PWV (P < 0.05 for all). More increase of arterial stiffness was reported in elderly hypertensive patients with greater oxidative stress, inflammatory, AP-1, heart rate, and lower TAS. Higher oxidative stress, AP-1 and inflammatory may predict higher arterial stiffness. Olmesartan may increase TAS, yet inhibit oxidative stress, AP-1, inflammatory, and heart rate with improved artery stiffness in elderly hypertensive patients.

CO2 Fixation into Novel CO2 Storage Materials Composed of 1,2-Ethanediamine and Ethylene Glycol Derivatives.

A new CO2 fixation process into solid CO2 -storage materials (CO2 SMs) under mild conditions has been developed. The novel application of amine-glycol systems to the capture, storage, and utilization of CO2 with readily available 1,2-ethanediamine (EDA) and ethylene glycol derivatives (EGs) was demonstrated. Typically, the CO2 SMs were isolated in 28.9-47.5 % yields, followed by extensive characterization using (13) C NMR, XRD, and FTIR. We found that especially the resulting poly-ethylene-glycol-300-based CO2 SM (PCO2 SM) product could be processed into stable tablets for CO2 storage; the aqueous PCO2 SM solution exhibited remarkable CO2 capturing and releasing capabilities after multiple cycles. Most importantly, the EDA and PEG 300 released from PCO2 SM were found to act as facilitative surfactants for the multiple preparation of CaCO3 microparticles with nano-layer structure.

Calorie restriction upregulated sirtuin 1 by attenuating its ubiquitin degradation in cancer cells.

Sirtuin (SIRT) 1 is a key protein in mediating the benefits of calorie restriction (CR) in mammals. However, the molecular mechanisms underlying CR-induced SIRT1 upregulation in mammals remain unclear. Herein we show that the elevated SIRT1 levels are not due to increased SIRT1 mRNA expression. but rather to enhanced SIRT1 protein stability as a result of reduced ubiquitin-proteasome degradation of SIRT1 under limited nutrient conditions. Our observations have important implications for improving healthy aging in humans.

The impact of environmental regulations on the green development of the mariculture industry: empirical analysis based on provincial panel data in coastal areas of China.

With the continuous increase in global mariculture production and aquaculture areas, the environmental pollution caused by the mariculture industry is becoming increasingly serious. Faced with environmental issues, countries worldwide have formulated environmental regulations to scientifically intervene in marine environmental pollution issues and promote the green development of the mariculture industry. However, we must determine if strict environmental regulations can effectively promote the green development of the mariculture industry. This article uses the inter-provincial panel data of China's coastal areas from 2003 to 2019 as a sample. We use the entropy-technique for order of preference by similarity to ideal solution method to measure the intensity of environmental regulation in China's coastal areas and the level of green development of the mariculture industry. On this basis, an economic geography nested matrix was selected to construct a spatial panel econometric model to empirically explore the impact of environmental regulations on the green development of the mariculture industry. This approach also allows us to examine the heterogeneity of the impact of different types of environmental regulations on the green development of the mariculture industry. The research results indicate that environmental regulations have a "U-shaped" impact on the green development of the local mariculture industry, while they have an inverted "U-shaped" impact on the green development of the nearby mariculture industry. Furthermore, heterogeneity exists in the impact of different types of environmental regulations on the green development of the mariculture industry. Based on the research results, this article proposes policy recommendations from the perspectives of flexibly adjusting the intensity of environmental regulations, accelerating the development of voluntary-based environmental regulations, and regulating competition among local governments, which can provide decision-making references for the government to adjust environmental regulation policies and improve the level of green development in the mariculture industry.

Genome-Wide Identification and Expression Analysis of the MYB Transcription Factor Family in Salvia nemorosa.

The MYB transcription factor gene family is among the most extensive superfamilies of transcription factors in plants and is involved in various essential functions, such as plant growth, defense, and pigment formation. Salvia nemorosa is a perennial herb belonging to the Lamiaceae family, and S. nemorosa has various colors and high ornamental value. However, there is little known about its genome-wide MYB gene family and response to flower color formation. In this study, 142 SnMYB genes (MYB genes of S. nemorosa) were totally identified, and phylogenetic relationships, conserved motifs, gene structures, and expression profiles during flower development stages were analyzed. A phylogenetic analysis indicated that MYB proteins in S. nemorosa could be categorized into 24 subgroups, as supported by the conserved motif compositions and gene structures. Furthermore, according to their similarity with AtMYB genes associated with the control of anthocyanin production, ten SnMYB genes related to anthocyanin biosynthesis were speculated and chosen for further qRT-PCR analyses. The results indicated that five SnMYB genes (SnMYB75, SnMYB90, SnMYB6, SnMYB82, and SnMYB12) were expressed significantly differently in flower development stages. In conclusion, our study establishes the groundwork for understanding the anthocyanin biosynthesis of the SnMYB gene family and has the potential to enhance the breeding of S. nemorosa.

Anemonin ameliorates human diploid fibroblasts 2BS and IMR90 cell senescence by PARP1-NAD+-SIRT1 signaling pathway.

OBJECTIVE: Aging becomes the most predominant risk factor for all age-associated pathological conditions with the increase of life expectancy and the aggravation of social aging. Slowing down the speed of aging is considered an effective way to improve health, but so far, effective anti-aging methods are relatively lacking. METHODS: Anemonin (ANE) was screened from eight existing small-molecule compounds by cell viability assay. The function of ANE was determined by the analysis of cell proliferation, ß -galactosidase (SA-ß -Gal) activity, cell cycle, SASP secretion, NAD+/NADH ratio, and other aging-related indicators. The targets of ANE were predicted by Drug Target Prediction System (DTPS) and Swiss Targe Prediction System. The effect of ANE on PARP-1-NAD+-SIRT1 signaling pathway was assessed by quantitative reverse-transcription polymerase chain reaction (RT-PCR), Western blot, PARP1, NAD+ and SIRT1 activity detection. RESULTS: ANE can delay cell senescence; PARP1 is one of the targets of ANE and plays a crucial role in ANE anti-aging; ANE release more NAD+ by inhibiting PARP1 activity, thereby conversely promoting the function of SIRT1 and delay cell senescence. CONCLUSIONS: Our study indicates that ANE can delay cellular senescence through the PARP1-NAD+-SIRT1 signaling pathway, which may be considered as an effective anti-aging strategy.

Arenobufagin inhibits lung metastasis of colorectal cancer by targeting c-MYC/Nrf2 axis.

BACKGROUND: Colorectal cancer (CRC) is one of the commonest cancers worldwide. Metastasis is the most common cause of death in patients with CRC. Arenobufagin is an active component of bufadienolides, extracted from toad skin and parotid venom. Arenobufagin reportedly inhibits epithelial-to-mesenchymal transition (EMT) and metastasis in various cancers. However, the mechanism through which arenobufagin inhibits CRC metastasis remains unclear. PURPOSE: This study aimed to elucidate the molecular mechanisms by which arenobufagin inhibits CRC metastasis. METHODS: Wound-healing and transwell assays were used to assess the migration and invasion of CRC cells. The expression of nuclear factor erythroid-2-related factor 2 (Nrf2) in the CRC tissues was assessed using immunohistochemistry. The protein expression levels of c-MYC and Nrf2 were detected by immunoblotting. A mouse model of lung metastasis was used to study the effects of arenobufagin on CRC lung metastasis in vivo. RESULTS: Arenobufagin observably inhibited the migration and invasion of CRC cells by downregulating c-MYC and inactivating the Nrf2 signaling pathway. Pretreatment with the Nrf2 inhibitor brusatol markedly enhanced arenobufagin-mediated inhibition of migration and invasion, whereas pretreatment with the Nrf2 agonist tert­butylhydroquinone significantly attenuated arenobufagin-mediated inhibition of migration and invasion of CRC cells. Furthermore, Nrf2 knockdown with short hairpin RNA enhanced the arenobufagin-induced inhibition of the migration and invasion of CRC cells. Importantly, c-MYC acts as an upstream modulator of Nrf2 in CRC cells. c-MYC knockdown markedly enhanced arenobufagin-mediated inhibition of the Nrf2 signaling pathway, cell migration, and invasion. Arenobufagin inhibited CRC lung metastasis in vivo. Together, these findings provide evidence that interruption of the c-MYC/Nrf2 signaling pathway is crucial for arenobufagin-inhibited cell metastasis in CRC. CONCLUSIONS: Collectively, our findings show that arenobufagin could be used as a potential anticancer agent against CRC metastasis. The arenobufagin-targeted c-MYC/Nrf2 signaling pathway may be a novel chemotherapeutic strategy for treating CRC.

[Effects of silver ion of silver nanoparticles on gap junctional intercellular communication of human skin cells].

OBJECTIVE: To further investigate the effects of silver ion (Ag+) dissolved from silver nanoparticles (AgNps) on gap junctional intercellular communication (GJIC) between HaCaT cells. METHODS: In this study, 20 000×g of 1 g/L AgNps suspension were centrifuged at 4 °C for 2 h, then the supernatant was collected as Ag(+) stock solution and measured by inductively coupled plasma mass spectrometry (ICP-MS); GJIC was detected by the scrape loading/dye transfer assay; connexin 43 (Cx43) protein and mRNA level were estimated by Western-blot and RT-PCR, respectively. RESULTS: Different concentrations of Ag(+) (0.01, 0.1 and 1.0 mg/L) did not affect the GJIC significantly. No notable changes were observed in expression of Cx43 protein and mRNA. CONCLUSION: The characteristics of Ag(+) and the effects on gap junctional intercellular communication between HaCaT cells may be different from those of AgNps.

WW domain-containing E3 ubiquitin protein ligase 1 (WWP1) delays cellular senescence by promoting p27(Kip1) degradation in human diploid fibroblasts.

WW domain-containing E3 ubiquitin protein ligase 1 (WWP1) plays an important role in the proliferation of tumor cells and the lifespan of Caenorhabditis elegans. However, the role of WWP1 in cellular senescence is still unknown. Here, we show that the expression patterns of p27(Kip1) and WWP1 are inversely correlated during cellular senescence. Moreover, the overexpression of WWP1 delayed senescence, whereas the knockdown of WWP1 led to premature senescence in human fibroblasts. Furthermore, we demonstrate that WWP1 repressed endogenous p27(Kip1) expression through ubiquitin-proteasome-mediated degradation. Additionally, WWP1 had a strong preference for catalyzing the Lys-48-linked polyubiquitination of p27(Kip1) in vitro. Finally, we demonstrate that WWP1 markedly inhibited the replicative senescence induced by p27(Kip1) by promoting p27(Kip1) degradation. Therefore, our study provides a new molecular mechanism for the regulation of cellular senescence.

B-MYB delays cell aging by repressing p16 (INK4α) transcription.

p16 ( INK4α ), an inhibitor of cyclin-dependent kinase 4 and 6, has been proposed to play an important role in cellular aging and in premature senescence. The expression of the p16 ( INK4α ) is primarily under transcriptional control. Our previous data showed that a negative regulation element lies in its promoter. In that element, a MYB-binding site (MBS) was uncovered by transcription analysis. Here, we report that MBS is a negative regulation element and B-MYB binds to this site in vivo. In human embryonic lung fibroblast cells, B-MYB downregulated p16 ( INK4α ) expression, whereas knocking down of B-MYB upregulated it. Evidence also showed that overexpression of B-MYB in cells could increase the number of utmost passage and decrease G1 block, whereas knocking down of B-MYB could impair their replicative ability. This study provides evidence of the capacity of B-MYB not only to regulate p16 ( INK4α ) expression but also the phenotypic consequence on cellular senescence.