Over-expression of the transcription factor, ZBP-89, leads to enhancement of the C2C12 myogenic program

Selenium alleviates the negative effect of heat stress on myogenic differentiation of C2C12 cells with the response of selenogenome

With the globe warming, heat stress (HS) has frequently affected animal production. Selenium (Se) is an essential trace element for animals and exerts most of its biological functions through selenoproteins. We previously demonstrated that the damage to C2C12 cells by HS accompanied with the response of selenoprotein encoding genes and proteins. The objective of this study was to investigate whether selenium supplementation (sodium selenite, SS and selenomethionine, SeMet) could alleviate the negative effect of heat stress on the differentiation of C2C12 cells, and interpret the potential corresponding selenoproteins response. The differentiated cells were cultured for 4 and 8 days under different condition: at 37 °C, 41.5 °C and 41.5 °C with 0.5 μmol Se/L SS or SeMet, and the HSP70, cell apoptosis, selenoproteins and cell differentiation-related gene or protein were detected. The result showed that HS up-regulated (P < 0.05) mRNA and protein levels of HSP70 and gene expression of AMPKα1 and AMPKα2, and down-regulated (P < 0.05) mRNA or protein levels of MYOGENIN and MYOD. Meanwhile, up to 15 and 17 selenoprotein genes expression were significantly changed response to 4-and 8-days HS challenge, respectively. Relative to the HS group, SS and SeMet supplementation down-regulated the mRNA and protein abundance of HSP70 to different degrees, and partly recovered (P < 0.05) the mRNA or protein abundance of MYOGENIN and MYOD at 4th and 8th day. Especially, 16 and 10 selenoprotein genes expression in cells affected by HS were altered by SS and SeMet supplementation, respectively. Both SS and SeMet supplementation modestly increased (P < 0.05) protein levels of GPX1 and SELENON in cells under HS. In summary, Se supplementation partly alleviated the negative impact of HS on myogenic differentiation of C2C12 cells and the process may associate with the alternation of selenoprotein expression pattern, and SeMet exhibits better effect than SS.

Effects of mineral methionine hydroxy analog chelate in sow diets on epigenetic modification and growth of progeny

The study was conducted to determine the effects of mineral methionine hydroxy analog chelate (MMHAC) partially replacing inorganic trace minerals in sow diets on epigenetic and transcriptional changes in the muscle and jejunum of progeny. The MMHAC is zinc (Zn), manganese (Mn), and copper (Cu) chelated with methionine hydroxy analog (Zn-, Mn-, and Cu-methionine hydroxy analog chelate [MHAC]). On day 35 of gestation, 60 pregnant sows were allotted to two dietary treatments in a randomized completed block design using parity as a block: 1) ITM: inorganic trace minerals with zinc sulfate (ZnSO₄), manganese oxide (MnO), and copper sulfate (CuSO₄) and 2) CTM: 50% of ITM was replaced with MMHAC (MINTREX trace minerals, Novus International Inc., St Charles, MO). Gestation and lactation diets were formulated to meet or exceed NRC requirements. On days 1 and 18 of lactation, milk samples from 16 sows per treatment were collected to measure immunoglobulins (immunoglobulin G, immunoglobulin A, and immunoglobulin M) and micromineral concentrations. Two pigs per litter were selected to collect blood to measure the concentration of immunoglobulins in the serum, and then euthanized to collect jejunal mucosa, jejunum tissues, and longissimus muscle to measure global deoxyribonucleic acid methylation, histone acetylation, cytokines, and jejunal histomorphology at birth and day 18 of lactation. Data were analyzed using Proc MIXED of SAS. Supplementation of MMHAC tended to decrease (P = 0.059) body weight (BW) loss of sows during lactation and tended to increase (P = 0.098) piglet BW on day 18 of lactation. Supplementation of MMHAC increased (P < 0.05) global histone acetylation and tended to decrease myogenic regulatory factor 4 messenger ribonucleic acid (mRNA; P = 0.068) and delta 4-desaturase sphingolipid1 (DEGS1) mRNA (P = 0.086) in longissimus muscle of piglets at birth. Supplementation of MMHAC decreased (P < 0.05) nuclear factor kappa B mRNA in the jejunum and DEGS1 mRNA in longissimus muscle and tended to decrease mucin-2 (MUC2) mRNA (P = 0.057) and transforming growth factor-beta 1 (TGF-β1) mRNA (P = 0.057) in the jejunum of piglets on day 18 of lactation. There were, however, no changes in the amounts of tumor necrosis factor-alpha, interleukin-8, TGF-β, MUC2, and myogenic factor 6 in the tissues by MMHAC. In conclusion, maternal supplementation of MMHAC could contribute to histone acetylation and programming in the fetus, which potentially regulates intestinal health and skeletal muscle development of piglets at birth and weaning, possibly leading to enhanced growth of their piglets.

Gene loci associated with insulin secretion in islets from non-diabetic mice

Genetic susceptibility to type 2 diabetes is primarily due to β-cell dysfunction. However, a genetic study to directly interrogate β-cell function ex vivo has never been previously performed. We isolated 233,447 islets from 483 Diversity Outbred (DO) mice maintained on a Western-style diet, and measured insulin secretion in response to a variety of secretagogues. Insulin secretion from DO islets ranged >1,000-fold even though none of the mice were diabetic. The insulin secretory response to each secretagogue had a unique genetic architecture; some of the loci were specific for one condition, whereas others overlapped. Human loci that are syntenic to many of the insulin secretion QTL from mouse are associated with diabetes-related SNPs in human genome-wide association studies. We report on three genes, Ptpn18, Hunk and Zfp148, where the phenotype predictions from the genetic screen were fulfilled in our studies of transgenic mouse models. These three genes encode a non-receptor type protein tyrosine phosphatase, a serine/threonine protein kinase, and a Krϋppel-type zinc-finger transcription factor, respectively. Our results demonstrate that genetic variation in insulin secretion that can lead to type 2 diabetes is discoverable in non-diabetic individuals.

Klf4, Klf2, and Zfp148 activate autophagy-related genes in smooth muscle cells during aortic aneurysm formation

Abdominal aortic aneurysms (AAAs) are a progressive dilation of the aorta that is characterized by an initial influx of inflammatory cells followed by a pro-inflammatory, migratory, proliferative, and eventually apoptotic smooth muscle cell phenotype. In recent years, the mechanisms related to the initial influx of inflammatory cells have become well-studied; the mechanisms related to chronic aneurysm formation, smooth muscle cell apoptosis and death are less well-characterized. Autophagy is a generally believed to be a protective cellular mechanism that functions to recycle defective proteins and cellular organelles to maintain cellular homeostasis. Our goal with the present study was to investigate the role of autophagy in smooth muscle cells during AAA formation. Levels of the autophagy factors, Beclin, and LC3 were elevated in human and mouse AAA tissue via both qPCR and immunohistochemical analysis. Confocal staining in human and mouse AAA tissue demonstrated Beclin and LC3 were present in smooth muscle cells during AAA formation. Treatment of smooth muscle cells with porcine pancreatic elastase or interleukin (IL)-1β activated autophagy-related genes in vitro while treatment with a siRNA to Kruppel-like transcription factor 4 (Klf4), Kruppel-like transcription factor 2 (Klf2) or Zinc-finger protein 148 (Zfp148) separately inhibited activation of autophagy genes. Chromatin immunoprecipitation assays demonstrated that Klf4, Klf2, and Zfp148 separately bind autophagy genes in smooth muscle cells following elastase treatment. These results demonstrate that autophagy is an important mechanism related to Klfs in smooth muscle cells during AAA formation.

ZFP148 (Zinc-Finger Protein 148) Binds Cooperatively With NF-1 (Neurofibromin 1) to Inhibit Smooth Muscle Marker Gene Expression During Abdominal Aortic Aneurysm Formation

Objective- The goal of this study was to determine the role of ZFP148 (zinc-finger protein 148) in aneurysm formation. Approach and Results- ZFP148 mRNA expression increased at day 3, 7, 14, 21, and 28 after during abdominal aortic aneurysm formation in C57BL/6 mice. Loss of ZFP148 conferred abdominal aortic aneurysm protection using ERTCre+ ZFP148 flx/flx mice. In a third set of experiments, smooth muscle-specific loss of ZFP148 alleles resulted in progressively greater protection using novel transgenic mice (MYH [myosin heavy chain 11] Cre+ flx/flx, flx/wt, and wt/wt). Elastin degradation, LGAL3, and neutrophil staining were significantly attenuated, while α-actin staining was increased in ZFP148 knockout mice. Results were verified in total cell ZFP148 and smooth muscle-specific knockout mice using an angiotensin II model. ZFP148 smooth muscle-specific conditional mice demonstrated increased proliferation and ZFP148 was shown to bind to the p21 promoter during abdominal aortic aneurysm formation. ZFP148 smooth muscle-specific conditional knockout mice also demonstrated decreased apoptosis as measured by decreased cleaved caspase-3 staining. ZFP148 bound smooth muscle marker genes via chromatin immunoprecipitation analysis mediated by NF-1 (neurofibromin 1) promote histone H3K4 deacetylation via histone deacetylase 5. Transient transfections and chromatin immunoprecipitation analyses demonstrated that NF-1 was required for ZFP148 protein binding to smooth muscle marker genes promoters during aneurysm formation. Elimination of NF-1 using shRNA approaches demonstrated that NF-1 is required for binding and elimination of NF-1 increased BRG1 recruitment, the ATPase subunit of the SWI/SWF complex, and increased histone acetylation. Conclusions- ZFP148 plays a critical role in multiple murine models of aneurysm formation. These results suggest that ZFP148 is important in the regulation of proliferation, smooth muscle gene downregulation, and apoptosis in aneurysm development.

MicroRNA-351-5p mediates skeletal myogenesis by directly targeting lactamase-β and is regulated by lnc-mg

Skeletal muscle is an important and complex organ with a variety of functions in humans and animals. Skeletal myogenesis is a multistep and complex process, and increasing evidence suggests that microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play critical roles in skeletal myogenesis. In this study the expression of miR-351-5p is dynamically regulated during skeletal myogenesis in vitro and in vivo. Cell-counting kit-8, qRT-PCR, and EdU immunofluorescence analysis showed that miR-351-5p overexpression promoted the proliferation and inhibited the differentiation of C2C12 myoblast, whereas inhibition of miR-351-5p had the opposite effect. In addition, miR-351-5p mediated the regulation of muscle fiber type transition in vivo. In vitro, loss of miR-351-5p in muscle tissues promoted muscle hypertrophy and increased slow-twitch fibers in the gastrocnemius muscles of mice. Luciferase reporter assay and functional analyses demonstrated that lactamase β ( LACTB) is a direct target of miR-351-5p involved in the regulation of skeletal myogenesis. Expression levels of a myogenesis-associated lncRNA ( lnc-mg) correlated negatively with miR-351-5p and positively with LACTB during C2C12 myoblast proliferation and differentiation. Further analyses showed that lnc-mg acted as a molecular sponge for miR-351-5p, demonstrating its involvement in the negative regulation of LACTB by miR-351-5p during skeletal myogenesis. These findings indicate that miRNA-351-5p functions in skeletal myogenesis by targeting LACTB and is regulated by lnc-mg, supporting the role of the competing endogenous RNA network in skeletal myogenesis.-Du, J., Zhang, P., Zhao, X., He, J., Xu, Y., Zou, Q., Luo, J., Shen, L., Gu, H., Tang, Q., Li, M., Jiang, Y., Tang, G., Bai, L., Li, X., Wang, J., Zhang, S., Zhu, L. MicroRNA-351-5p mediates skeletal myogenesis by directly targeting lactamase β and is regulated by lnc-mg.

Damage to the myogenic differentiation of C2C12 cells by heat stress is associated with up-regulation of several selenoproteins

This study was conducted to profile the selenoprotein encoding genes or proteins in mouse C2C12 cells and integrate their roles in the skeletal cell damage induced by heat stress (HS). Cells were cultured at 37.0 °C or 41.5 °C for 4, 6 or 8 days. The mRNA expression of 24 selenoprotein encoding genes and abundance of 5 selenoproteins were investigated. HS suppressed myogenic differentiation and impaired the development of muscle myotubes. HS down-regulated (P < 0.01) mRNA abundance of MYOD and MYOGENIN, and decreased (P < 0.01) MYOGENIN protein expression, HS elevated (P < 0.01) HSP70 and (P < 0.01) the ratio of BCL-2 to BAX at both mRNA and protein level. Meanwhile, HS up-regulated (P < 0.01–0.05) expressions of 18, 11 and 8 selenoprotein encoding genes after 4, 6 and 8 days of hyperthermia, and only down-regulated (P < 0.01) DIO2 after 6 and 8 days of hyperthermia, respectively. Furthermore, HS influenced expression of selenoproteins and up-regulated (P < 0.01–0.05) GPX1, GPX4 and SEPN1 after 6 days of HS. The damage to development of mouse skeletal muscle myotubes by HS accompanied with the up-regulation of both selenoprotein encoding genes and proteins, which suggested a potential protective effect of selenoprotein on hyperthermia associated damage in C2C12 cells.

Transcription factor ZNF148 is a negative regulator of human muscle differentiation

Muscle differentiation is a complex process in which muscle progenitor cells undergo determination and eventually cellular fusion. This process is heavily regulated by such master transcription factors as MYOD and members of the MEF2 family. Here, we show that the transcription factor ZNF148 plays a direct role in human muscle cell differentiation. Downregulation of ZNF148 drives the formation of a muscle phenotype with rapid expression of myosin heavy chain, even in proliferative conditions. This phenotype was most likely mediated by the robust and swift upregulation of MYOD and MEF2C.

Oncorhynchus mykiss pax7 sequence variations with comparative analyses against other teleost species

The paired box-7 (pax7) transcription factor expressed in satellite cells (SCs) is an essential regulator of skeletal muscle growth and regeneration in vertebrates including fish. Characterization of rainbow trout (Oncorhynchus mykiss) pax7 gene/s may offer novel insights into skeletal myogenesis by SCs in this indeterminate growth species. Further, evaluation of promoters for cis-regulatory regions may shed light on the evolutionary fate of the duplicated genes. Employing standard PCR, cloning and computational approach, we identified and report complete coding sequences of two pax7 paralogs of rainbow trout (rt); rtpax7α and rtpax7β. Both genes show significant identity in the nucleotide (97%) and the predicted amino acid (98%) sequences, and bear the characteristic paired domain (PD), octapeptide (OP) and homeodomain (HD) motifs. We further report several splice variants of each gene and nucleotide differences in coding sequence that predicts six putative amino acid changes between the two genes. Additionally, we noted a trinucleotide deletion in rtpax7β that results in putative serine elimination at the N-terminus and a single nucleotide polymorphism (SNP) in majority of the rtpax7β variants (6/10) that predicts an arginine substitution for a lysine. We also deciphered the genomic organization up to the first three exons and the upstream putative promoter regions of both genes. Comparative in silico analysis of both the trout pax7 promoters with that of zebrafish pax7 duplicates; zfpax7a and zfpax7b; predicts several important cis-elements/transcription factor binding sites (TFBS) in these teleost pax7 promoter regions.

MicroRNA-203 enhances coxsackievirus B3 replication through targeting zinc finger protein-148

Coxsackievirus B3 (CVB3) is the primary causal agent of viral myocarditis. During infection, it hijacks host genes to favour its own replication. However, the underlying mechanism is still unclear. Although the viral receptor is an important factor for viral infectivity, other factors such as microRNAs (miRNA) may also play an essential role in its replication after host cell entry. miRNAs are post-transcriptional gene regulators involved in various fundamental biological processes as well as in diseases. To identify miRNAs involved in CVB3 pathogenesis, we performed microarray analysis of miRNAs using CVB3-infected murine hearts and identified miR-203 as one of the most upregulated candidates. We found that miR-203 upregulation is through the activation of protein kinase C/transcription factor AP-1 pathway. We further identified zinc finger protein-148 (ZFP-148), a transcription factor, as a novel target of miR-203. Ectopic expression of miR-203 downregulated ZFP-148 translation, increased cell viability and subsequently enhanced CVB3 replication. Silencing of ZFP-148 by siRNA showed similar effects on CVB3 replication. Finally, analyses of the signalling cascade downstream of ZFP-148 revealed that miR-203-induced suppression of ZFP-148 differentially regulated the expression of prosurvival and proapoptotic genes of the Bcl-2 family proteins as well as the cell cycle regulators. This altered gene expression promoted cell survival and growth, which provided a favourable environment for CVB3 replication, contributing to the further damage of the infected cells. Taken together, this study identified a novel target of miR-203 and revealed, for the first time, the molecular link between miR-203/ZFP-148 and the pathogenesis of CVB3.

Possible correlation between selenoprotein W and myogenic regulatory factors in chicken embryonic myoblasts

The biological function of selenium (Se) is mainly elicited through Se-containing proteins. Selenoprotein W (SelW), one member of the selenoprotein family, is essential for the normal function of the skeletal muscle system. To investigate the possible relationship of Se in the process of differentiation in chicken myoblasts and the expression of SelW, the cultured chicken embryonic myoblasts were incubated with sodium selenite at different concentrations for 72 h, and then the mRNA levels of SelW and myogenic regulatory factors (MRFs) in myoblasts were determined at 12, 24, 48, and 72 h, respectively. Furthermore, the correlation between SelW mRNA expression and MRF mRNA expression was assessed. The results showed that the sodium selenite medium enhanced the mRNA expression of SelW, Myf-5, MRF4, and myogenin in chicken myoblasts. The mRNA expression levels of MRFs were significantly correlated with those of SelW at 24, 48, and 72 h. These data demonstrate that Se is involved in the differentiation of chicken embryonic myoblasts, and SelW showed correlation with MRFs.

Overexpression of Six1 leads to retardation of myogenic differentiation in C2C12 myoblasts

The Six1 homeoprotein belongs to the Six (sine oculis) transcription factor family, the members of which are known to act as master regulators of development. Six1 is essential for promoting myogenesis during mammalian somitogenesis. Previous studies have shown that Six1 participates in later steps of myogenic differentiation by enhancing early activation of myogenin via binding to the Mef3 site of the myogenin promoter. In the present study, however, we show that overexpression of Six1 via retroviral infection suppresses the expression of myogenin and myosin in C2C12 myoblasts, consequently retarding myogenic differentiation without affecting cell proliferation or expression of Mef2 and Mef3. These findings further demonstrate the functional role of Six1 in myogenesis.

Increased expression of ZBP-89 and its prognostic significance in hepatocellular carcinoma

AIMS

  ZBP-89 plays a role in cell growth and death. Its expression in hepatocellular carcinoma (HCC) is not well documented. This study aimed to analyse ZBP-89 expression in HCC.

METHODS AND RESULTS

  We examined ZBP-89 expression in five HCC cell lines and 182 HCC tissue samples by reverse transcription-polymerase chain reaction (RT-PCR), Western blot analysis and immunofluorescence staining. Our results showed that the expression of ZBP-89 was higher in HCC than adjacent non-tumour liver, at both mRNA and protein levels. ZBP-89 was localized in the nucleus in most HCC tissue samples, but was found in the cytoplasm in 11.5% of cases. Patient survival in those tumours showing high ZBP-89 expression was better than in those with low expression. High ZBP-89 expression tended to be more common in World Health Organization (WHO) grade I than grades II-IV HCC. There was a significant association between HBV positivity and high ZBP-89 expression. Colony formation was reduced dramatically in those HCC cell lines in which ZBP-89 overexpression was demonstrated; this appeared to correlate with increased apoptosis, inferred by finding elevated levels of cleaved poly(ADP-ribose)polymerases (PARP), the probable mechanisms for which may involve increased p53 or p21 expression.

CONCLUSIONS

  ZBP-89 has anti-tumour properties and is a potential biomarker for prognosis of HCC.

Promoter cloning and characterization of the human programmed cell death protein 4 (pdcd4) gene: evidence for ZBP-89 and Sp-binding motifs as essential Pdcd4 regulators

Pdcd4 (programmed cell death protein 4) is an important novel tumour suppressor inhibiting transformation, translation, invasion and intravasation, and its expression is down-regulated in several cancers. However, little is known about the transcriptional regulation and the promoter of this important tumour suppressor. So far the following is the first comprehensive study to describe the regulation of Pdcd4 transcription by ZBP-89 (zinc-finger-binding protein 89), besides characterizing the gene promoter. We identified the transcriptional start sites of the human pdcd4 promoter, a functional CCAAT-box, and the basal promoter region. Within this basal region, computer-based analysis revealed several potential binding sites for ZBPs, especially for Sp (specificity protein) family members and ZBP-89. We identified four Sp1/Sp3/Sp4-binding elements to be indispensable for basal promoter activity. However, overexpression of Sp1 and Sp3 was not sufficient to enhance Pdcd4 protein expression. Analysis in different solid cancer cell lines showed a significant correlation between pdcd4 and zbp-89 mRNA amounts. In contrast with Sp transcription factors, overexpression of ZBP-89 led to an enhanced expression of Pdcd4 mRNA and protein. Additionally, specific knockdown of ZBP-89 resulted in a decreased pdcd4 gene expression. Reporter gene analysis showed a significant up-regulation of basal promoter activity by co-transfection with ZBP-89, which could be abolished by mithramycin treatment. Predicted binding of ZBP-89 to the basal promoter was confirmed by EMSA (electrophoretic mobility-shift assay) data and supershift analysis for ZBP-89. Taken together, data for the first time implicate ZBP-89 as a regulator of Pdcd4 by binding to the basal promoter either alone or by interacting with Sp family members.

Transcription factor ZBP-89 in cancer growth and apoptosis

ZBP-89, a Krüppel-type zinc-finger transcription factor that binds to GC-rich sequences, is involved in the regulation of cell growth and cell death. It maps to chromosome 3q21 and is composed of 794 residues. Having bifunctional regulatory domains, ZBP-89 may function as a transcriptional activator or repressor of variety of genes such as p16 and vimentin. ZBP-89 arrests cell proliferation through its interactions with p53 and p21(waf1). It is able to stabilize p53 through directly binding and enhance p53 transcriptional activity by retaining it in the nucleus. In addition, ZBP-89 potentiates in butyrate-induced endogenous p21(waf1) up-regulation. ZBP-89 is usually over-expressed in human cancer cells, where it can efficiently induce apoptosis through p53-dependent and -independent mechanisms. Moreover, ZBP-89 is capable of enhancing killing effects of several anti-cancer drugs. Therefore, ZBP-89 may be served as a potential target in cancer therapy.

The transcriptional repressor ZBP-89 and the lack of Sp1/Sp3, c-Jun and Stat3 are important for the down-regulation of the vimentin gene during C2C12 myogenesis

Currently, considerable information is available about how muscle-specific genes are activated during myogenesis, yet little is known about how non-muscle genes are down-regulated. The intermediate filament protein vimentin is known to be "turned off" during myogenesis to be replaced by desmin, the muscle-specific intermediate filament protein. Here, we demonstrate that vimentin down-regulation is the result of the combined effect of several transcription factors. Levels of the positive activators, Sp1/Sp3, which are essential for vimentin expression, decrease during myogenesis. In addition, c-Jun and Stat3, two additional positive-acting transcription factors for vimentin gene expression, are also down-regulated. Over-expression via adenoviral approaches demonstrates that the up-regulation of the repressor ZBP-89 is critical to vimentin down-regulation. Elimination of ZBP-89 via siRNA blocks the down-regulation of vimentin and Sp1/Sp3 expression. From these studies we conclude that the combinatorial effect of the down-regulation of positive-acting transcription factors such as Sp1/Sp3, c-Jun and Stat3 versus the up-regulation of the repressor ZBP-89 contributes to the "turning off" of the vimentin gene during myogenesis.