Identification and Expression Analysis of R2R3-MYB Transcription Factors Associated with Flavonoid Biosynthesis in Panax quinquefolius.

Panax quinquefolius L. is an important medicinal plant, and flavonoids are among its main secondary metabolites. The R2R3-MYB transcription factor plays an irreplaceable role in plant growth, development, and secondary metabolism. In our study, we identified 159 R2R3-MYBs and analyzed their physical and chemical properties in P. quinquefolius. The protein length of 159 PqMYBs varied from 107 to 1050 amino acids. The molecular weight ranged from 12.21 to 116.44 kDa. The isoelectric point was between 4.57 and 10.34. We constructed a phylogenetic tree of P. quinquefolius and Arabidopsis thaliana R2R3-MYB family members, and PqMYB members were divided into 33 subgroups. Transcriptome data analysis showed that the expression patterns of PqMYBs in root, leaf, and flower were significantly different. Following the MeJA treatment of seedlings, five candidate PqMYB genes demonstrated a response. A correlation analysis of PqMYBs and candidate flavonoid pathway genes showed that PqMYB2, PqMYB46, and PqMYB72 had correlation coefficients that were higher than 0.8 with PqCHS, PqANS4, and PqCCoAMT10, respectively. Furthermore, a transient expression assay confirmed that the three PqMYBs were localized in the nucleus. We speculated that these three PqMYBs were related to flavonoid biosynthesis in P. quinquefolius. These results provided a theoretical basis and a new perspective for further understanding the R2R3-MYB gene family and the biosynthesis mechanism of secondary metabolites in P. quinquefolius.

Genome­wide analysis of the MYB gene family in pumpkin.

The MYB gene family exerts significant influence over various biological processes and stress responses in plants. Despite this, a comprehensive analysis of this gene family in pumpkin remains absent. In this study, the MYB genes of Cucurbita moschata were identified and clustered into 33 groups (C1-33), with members of each group being highly conserved in terms of their motif composition. Furthermore, the distribution of 175 CmoMYB genes across all 20 chromosomes was found to be non-uniform. Examination of the promoter regions of these genes revealed the presence of cis-acting elements associated with phytohormone responses and abiotic/biotic stress. Utilizing quantitative real-time polymerase chain reaction (qRT-PCR), the expression patterns of 13 selected CmoMYB genes were validated, particularly in response to exogenous phytohormone exposure and various abiotic stressors, including ABA, SA, MeJA, and drought treatments. Expression analysis in different tissues showed that CmoMYB genes are expressed at different levels in different tissues, suggesting that they are functionally divergent in regulating growth and abiotic stresses. These results provide a basis for future studies to characterize the function of the MYB gene family under abiotic stresses in pumpkins.

FvMYB108, a MYB Gene from Fragaria vesca, Positively Regulates Cold and Salt Tolerance of Arabidopsis.

MYB (myoblast) protein comes in large quantities and a wide variety of types and plays a role in most eukaryotes in the form of transcription factors (TFs). One of its important functions is to regulate plant responses to various stresses. However, the role of MYB TFs in regulating stress tolerance in strawberries is not yet well understood. Therefore, in order to investigate the response of MYB family members to abiotic stress in strawberries, a new MYB TF gene was cloned from Fragaria vesca (a diploid strawberry) and named FvMYB108 based on its structural characteristics and evolutionary relationships. After a bioinformatics analysis, it was determined that the gene belongs to the R2R3-MYB subfamily, and its conserved domain, phylogenetic relationships, predicted protein structure and physicochemical properties, subcellular localization, etc. were analyzed. After qPCR analysis of the expression level of FvMYB108 in organs, such as the roots, stems, and leaves of strawberries, it was found that this gene is more easily expressed in young leaves and roots. After multiple stress treatments, it was found that the target gene in young leaves and roots is more sensitive to low temperatures and salt stimulation. After these two stress treatments, various physiological and biochemical indicators related to stress in transgenic Arabidopsis showed corresponding changes, indicating that FvMYB108 may be involved in regulating the plant's ability to cope with cold and high-salt stress. Further research has found that the overexpression of this gene can upregulate the expression of AtCBF1, AtCOR47, AtERD10, and AtDREB1A related to low-temperature stress, as well as AtCCA1, AtRD29a, AtP5CS1, and AtSnRK2.4 related to salt stress, enhancing the ability of overexpressed plants to cope with stress.

MYB alternative promoter activity is increased in adenoid cystic carcinoma metastases and is associated with a specific gene expression signature.

OBJECTIVE: Adenoid cystic carcinoma (ACC) is a head and neck cancer with a poor long-term prognosis that shows frequent local recurrences and distant metastases. The tumors are characterized by MYB oncogene activation and are notoriously unresponsive to systemic therapies. The biological underpinnings behind therapy resistance of disseminated ACC are largely unknown. Here, we have studied the molecular and clinical significance of MYB alternative promoter (TSS2) usage in ACC metastases. MATERIALS AND METHODS: MYB TSS2 activity was investigated in primary tumors and metastases from 26 ACC patients using RNA-sequencing and quantitative real-time PCR analysis. Differences in global gene expression between MYB TSS2 high and low cases were studied, and pathway analyses were performed. RESULTS: MYB TSS2 activity was significantly higher in ACC metastases than in primary tumors (median activity 15.1 vs 3.0, P = 0.0003). MYB TSS2 high ACC metastases showed a specific gene expression signature, including increased expression of multi-drug resistance genes and canonical MYB target genes, and suppression of the p53 and NOTCH pathways. CONCLUSIONS: Collectively, our findings indicate that elevated MYB TSS2 activity is associated with metastases, potential drug resistance, and augmented MYB-driven gene expression in ACC. Our study advocates the need for new therapies that specifically target MYB and drug resistance mechanisms in disseminated ACC.

Genome-wide identification, phylogeny and expression analysis of the R2R3-MYB gene family in quinoa (Chenopodium quinoa) under abiotic stress.

The MYB transcription factor (TF) are among the largest gene families of plants being responsible for several biological processes. The R2R3-MYB gene family are integral player regulating plant primary and secondary metabolism, growth and development, and responses to hormones and stresses. The phylogenetic analysis combined with gene structure analysis and motif determination resulted in division of R2R3-MYB gene family into 27 subgroups. Evidence generated from synteny analyses indicated that CqR2R3-MYBs gene family is featured by tandem and segmental duplication events. On the basis of RNA-Seq data, the expression patterns of different tissues under salt treatment were investigated resulting CqR2R3-MYB genes high expression both in roots and stem of quinoa (Chenopodium quinoa ) plants. More than half of CqR2R3-MYB genes showed expression under salt stress. Based on this result, CqR2R3-MYB s may regulate quinoa plant growth development and resistance to abiotic stresses. These findings provided comprehensive insights on role of CqR2R3-MYBs gene family members in quinoa and candidate MYB gene family members can be further studies on their role for abiotic stress tolerance in crop plants.

The R2R3 MYB gene TaMYB305 positively regulates anther and pollen development in thermo-sensitive male-sterility wheat with Aegilops kotschyi cytoplasm.

MAIN CONCLUSION: The loss of TaMYB305 function down-regulated the expression of jasmonic acid synthesis pathway genes, which may disturb the jasmonic acid synthesis, resulting in abnormal pollen development and reduced fertility. The MYB family, as one of the largest transcription factor families found in plants, regulates plant development, especially the development of anthers. Therefore, it is important to identify potential MYB transcription factors associated with pollen development and to study its role in pollen development. Here, the transcripts of an R2R3 MYB gene TaMYB305 from KTM3315A, a thermo-sensitive cytoplasmic male-sterility line with Aegilops kotschyi cytoplasm (K-TCMS) wheat, was isolated. Quantitative real-time PCR (qRT-PCR) and promoter activity analysis revealed that TaMYB305 was primarily expressed in anthers. The TaMYB305 protein was localized in the nucleus, as determined by subcellular localization analysis. Our data demonstrated that silencing of TaMYB305 was related to abnormal development of stamen, including anther indehiscence and pollen abortion in KAM3315A plants. In addition, TaMYB305-silenced plants exhibited alterations in the transcriptional levels of genes involved in the synthesis of jasmonic acid (JA), indicating that TaMYB305 may regulate the expression of genes related to JA synthesis and play an important role during anther and pollen development of KTM3315A. These results provide novel insight into the function and molecular mechanism of R2R3-MYB genes in pollen development.

Tandemly duplicated MYB genes are functionally diverged in the regulation of anthocyanin biosynthesis in soybean.

Gene duplications have long been recognized as a driving force in the evolution of genes, giving rise to novel functions. The soybean (Glycine max) genome is characterized by a large number of duplicated genes. However, the extent and mechanisms of functional divergence among these duplicated genes in soybean remain poorly understood. In this study, we revealed that 4 MYB genes (GmMYBA5, GmMYBA2, GmMYBA1, and Glyma.09g235000)-presumably generated by tandem duplication specifically in the Phaseoleae lineage-exhibited a stronger purifying selection in soybean compared to common bean (Phaseolus vulgaris). To gain insights into the diverse functions of these tandemly duplicated MYB genes in anthocyanin biosynthesis, we examined the expression, transcriptional activity, induced metabolites, and evolutionary history of these 4 MYB genes. Our data revealed that Glyma.09g235000 is a pseudogene, while the remaining 3 MYB genes exhibit strong transcriptional activation activity, promoting anthocyanin biosynthesis in different soybean tissues. GmMYBA5, GmMYBA2, and GmMYBA1 induced anthocyanin accumulation by upregulating the expression of anthocyanin pathway-related genes. Notably, GmMYBA5 showed a lower capacity for gene induction compared to GmMYBA2 and GmMYBA1. Metabolomics analysis further demonstrated that GmMYBA5 induced distinct anthocyanin accumulation in Nicotiana benthamiana leaves and soybean hairy roots compared to GmMYBA2 and GmMYBA1, suggesting their functional divergence leading to the accumulation of different metabolites accumulation following gene duplication. Together, our data provide evidence of functional divergence within the MYB gene cluster following tandem duplication, which sheds light on the potential evolutionary directions of gene duplications during legume evolution.

Genome-Wide Analysis of R2R3-MYB Genes and Functional Characterization of SmMYB75 in Eggplant Fruit Implications for Crop Improvement and Nutritional Enhancement.

R2R3-MYB represents a substantial gene family that plays diverse roles in plant development. In this study, 102 SmR2R3-MYB genes were identified from eggplant fruit and classified into 31 subfamilies. Analysis indicated that segmental duplication events played a pivotal role in the expansion of the SmR2R3-MYB gene family. Furthermore, the prediction of miRNAs targeting SmR2R3-MYB genes revealed that 60 SmR2R3-MYBs are targeted by 57 miRNAs, with specific miRNAs displaying varying numbers of target genes, providing valuable insights into the regulatory functions of miRNAs in plant growth, development, and responses to stress conditions. Through expression profile analysis under various treatment conditions, including low temperature (4 °C), plant hormone (ABA, Abscisic acid), and drought stress (PEG, Polyethylene glycol), diverse and complex regulatory mechanisms governing SmR2R3-MYB gene expression were elucidated. Notably, EGP21875.1 and EGP21874.1 exhibited upregulation in expression under all treatment conditions. Transcriptome and metabolome analyses demonstrated that, apart from anthocyanins (delphinidin-3-O-glucoside, cyanidin-3-O-(6-O-p-coumaroyl)-glucoside, and malvidin-3-O-(6-O-p-coumaroyl)-glucoside), overexpression of SmMYB75 could also elevate the content of various beneficial compounds, such as flavonoids, phenolic acids, and terpenes, in eggplant pulp. This comprehensive study enhances our understanding of SmR2R3-MYB gene functions and provides a strong basis for further research on their roles in regulating anthocyanin synthesis and improving eggplant fruit quality.

Identification of MYB gene family in medicinal tea tree Melaleuca alternifolia (Maiden and Betche) cheel and analysis of members regulating terpene biosynthesis.

BACKGROUND: The tea tree (Melaleuca alternifolia) is renowned for its production of tea tree oil, an essential oil primarily composed of terpenes extracted from its shoot. MYB transcription factors, which are one of the largest TF families, play a crucial role in regulating primary and secondary metabolite synthesis. However, knowledge of the MYB gene family in M. alternifolia is limited. METHODS AND RESULTS: Here, we conducted a comprehensive genome-wide analysis of MYB genes in M. alternifolia, referred to as MaMYBs, including phylogenetic relationships, structures, promoter regions, and GO annotations. Our findings classified 219 MaMYBs into four subfamilies: one 5R-MYB, four 3R-MYBs, sixty-one MYB-related, and the remaining 153 are all 2R-MYBs. Seven genes (MYB189, MYB146, MYB44, MYB29, MYB175, MYB162, and MYB160) were linked to terpenoid synthesis based on GO annotation. Phylogenetic analysis with Arabidopsis homologous MYB genes suggested that MYB193 and MYB163 may also be involved in terpenoid synthesis. Additionally, through correlation analysis of gene expression and metabolite content, we identified 42 MYB genes associated with metabolite content. CONCLUSION: The results provide valuable insights into the importance of MYB transcription factors in essential oil production in M. alternifolia. These findings lay the groundwork for a better understanding of the MYB regulatory network and the development of novel strategies to enhance essential oil synthesis in M. alternifolia.

Genome-Wide Identification of R2R3-MYB Family Genes and Their Response to Stress in Dendrobium nobile.

BACKGROUND: R2R3-MYB genes comprise one of the largest and most important gene families in plants, and are involved in the regulation of plant growth and development as well as responses to abiotic stresses. However, the functions of R2R3-MYB genes in Dendrobium nobile remains largely unknown. METHODS: Here, a comprehensive genome-wide analysis of D. nobile R2R3-MYB genes was performed, in which phylogenic relationships, gene structures, motif composition, chromosomal locations, collinearity analysis, and cis-acting elements were investigated. Moreover, the expression patterns of selected DnMYB genes were analyzed in various tissues and under different abiotic stresses. RESULTS: In total, 125 DnMYB genes were identified in the D. nobile genome, and were subdivided into 26 groups based on phylogenetic analysis. Most genes in the same subgroup showed similar exon/intron structure and motif composition. All the DnMYB genes were mapped to 19 chromosomes with the co-linearity relationship. Reverse transcription-quantitative real-time PCR (RT-qPCR) results showed that 8 DnMYBs exhibited different expression patterns in different plant tissues, and were differentially expressed in response to abscisic acid, methyl jasmonate, low-temperature stress. CONCLUSIONS: This work contributes to a comprehensive understanding of the R2R3-MYB gene family in D. nobile, and provides candidate genes for future research on abiotic stress in this plant.

Genome-Wide Identification and Characterization of MYB Gene Family and Analysis of Its Sex-Biased Expression Pattern in Spinacia oleracea L.

The members of the myeloblastosis (MYB) family of transcription factors (TFs) participate in a variety of biological regulatory processes in plants, such as circadian rhythm, metabolism, and flower development. However, the characterization of MYB genes across the genomes of spinach Spinacia oleracea L. has not been reported. Here, we identified 140 MYB genes in spinach and described their characteristics using bioinformatics approaches. Among the MYB genes, 54 were 1R-MYB, 80 were 2R-MYB, 5 were 3R-MYB, and 1 was 4R-MYB. Almost all MYB genes were located in the 0-30 Mb region of autosomes; however, the 20 MYB genes were enriched at both ends of the sex chromosome (chromosome 4). Based on phylogeny, conserved motifs, and the structure of genes, 2R-MYB exhibited higher conservation relative to 1R-MYB genes. Tandem duplication and collinearity of spinach MYB genes drive their evolution, enabling the functional diversification of spinach genes. Subcellular localization prediction indicated that spinach MYB genes were mainly located in the nucleus. Cis-acting element analysis confirmed that MYB genes were involved in various processes of spinach growth and development, such as circadian rhythm, cell differentiation, and reproduction through hormone synthesis. Furthermore, through the transcriptome data analysis of male and female flower organs at five different periods, ten candidate genes showed biased expression in spinach males, suggesting that these genes might be related to the development of spinach anthers. Collectively, this study provides useful information for further investigating the function of MYB TFs and novel insights into the regulation of sex determination in spinach.

The Characterization of R2R3-MYB Genes in Ammopiptanthus nanus Uncovers That the miR858-AnaMYB87 Module Mediates the Accumulation of Anthocyanin under Osmotic Stress.

R2R3-MYB transcription factors (TFs) participate in the modulation of plant development, secondary metabolism, and responses to environmental stresses. Ammopiptanthus nanus, a leguminous dryland shrub, tolerates a high degree of environmental stress, including drought and low-temperature stress. The systematic identification, structural analysis, evolutionary analysis, and gene profiling of R2R3-MYB TFs under cold and osmotic stress in A. nanus were performed. Up to 137 R2R3-MYB TFs were identified and clustered into nine clades, with most A. nanus R2R3-MYB members belonging to clade VIII. Tandem and segmental duplication events drove the expansion of the A. nanus R2R3-MYB family. Expression profiling revealed that multiple R2R3-MYB genes significantly changed under osmotic and cold stress conditions. MiR858 and miR159 targeted 88 R2R3-MYB genes. AnaMYB87, an miR858-targeted clade VIII R2R3-MYB TF, was up-regulated under both osmotic and cold stress. A transient expression assay in apples showed that the overexpression of AnaMYB87 promoted anthocyanin accumulation. A luciferase reporter assay in tobacco demonstrated that AnaMYB87 positively affected the transactivation of the dihydroflavonol reductase gene, indicating that the miR858-MYB87 module mediates anthocyanin accumulation under osmotic stress by regulating the dihydroflavonol reductase gene in A. nanus. This study provides new data to understand the roles of R2R3-MYB in plant stress responses.

Genome-Wide Analysis of MYB Genes in Primulina eburnea (Hance) and Identification of Members in Response to Drought Stress.

Due to periodic water deficiency in karst environments, Primulina eburnea experiences sporadic drought stress in its habitat. Despite being one of the largest gene families and functionally diverse in terms of plant growth and development, MYB transcription factors in P. eburnea have not been studied. Here, a total of 230 MYB genes were identified in P. eburnea, including 67 1R-MYB, 155 R2R3-MYB, six 3R-MYB, and two 4R-MYB genes. The R2R3-type PebMYB genes could be classified into 16 subgroups, while the remaining PebMYB genes (1R-MYB, 3R-MYB, and 4R-MYB genes) were divided into 10 subgroups. Notably, the results of the phylogenetic analysis were further supported by the motif and gene structure analysis, which showed that individuals in the same subgroup had comparable motif and structure organization. Additionally, gene duplication and synteny analyses were performed to better understand the evolution of PebMYB genes, and 291 pairs of segmental duplicated genes were found. Moreover, RNA-seq analysis revealed that the PebMYB genes could be divided into five groups based on their expression characteristics. Furthermore, 11 PebMYB genes that may be involved in drought stress response were identified through comparative analysis with Arabidopsis thaliana. Notably, seven of these genes (PebMYB3, PebMYB13, PebMYB17, PebMYB51, PebMYB142, PebMYB69, and PebMYB95) exhibited significant differences in expression between the control and drought stress treatments, suggesting that they may play important roles in drought stress response. These findings clarified the characteristics of the MYB gene family in P. eburnea, augmenting our comprehension of their potential roles in drought stress adaptation.

Identification and expression analysis of R2R3-MYB gene family in Andrographis paniculata / 中国中药杂志

The plant growth, development, and secondary metabolism are regulated by R2 R3-MYB transcription factors. This study identified the R2 R3-MYB genes in the genome of Andrographis paniculata and analyzed the chromosomal localization, gene structure, and conserved domains, phylogenetic relationship, and promoter cis-acting elements of these R2 R3-MYB genes. Moreover, the gene expression profiles of R2 R3-MYB genes under abiotic stress and hormone treatments were generated by RNA-seq and validated by qRT-PCR. The results showed that A. paniculata contained 73 R2 R3-MYB genes on 21 chromosomes. These members belonged to 34 subfamilies, 19 of which could be classified into the known subfamilies in Arabidopsis thaliana. The 73 R2 R3-MYB members included 36 acidic proteins and 37 basic proteins, with the lengths of 148-887 aa. The domains, motifs, and gene structures of R2 R3-MYBs in A. paniculata were conserved. The promoter regions of these genes contains a variety of cis-acting elements related to the responses to environmental factors and plant hormones including light, ABA, MeJA, and drought. Based on the similarity of functions of R2 R3-MYBs in the same subfamily and the transcription profiles, ApMYB13/21/35/67/73(S22) may regulate drought stress through ABA pathway; ApMYB20(S11) and ApMYB55(S2) may play a role in the response of A. paniculata to high temperature and UV-C stress; ApMYB5(S7) and ApMYB33(S20) may affect the accumulation of andrographolide by regulating the expression of key enzymes in the MEP pathway. This study provides theoretical reference for further research on the functions of R2 R3-MYB genes in A. paniculata and breeding of A. paniculata varieties with high andrographolide content.

Identification and expression profiling of R2R3-MYB transcription factors in Erigeron breviscapus / 中国中药杂志

R2 R3-MYB transcription factors are ubiquitous in plants, playing a role in the regulation of plant growth, development, and secondary metabolism. In this paper, the R2 R3-MYB transcription factors were identified by bioinformatics analysis of the genomic data of Erigeron breviscapus, and their gene sequences, structures, physical and chemical properties were analyzed. The functions of R2 R3-MYB transcription factors were predicted by cluster analysis. Meanwhile, the expression patterns of R2 R3-MYB transcription factors in response to hormone treatments were analyzed. A total of 108 R2 R3-MYB transcription factors, named EbMYB1-EbMYB108, were identified from the genome of E. breviscapus. Most of the R2 R3-MYB genes carried 2-4 exons. The phylogenetic tree of MYBs in E. breviscapus and Arabidopsis thaliala was constructed, which classified 234 MYBs into 30 subfamilies. The MYBs in the five MYB subfamilies of A.thaliala were clustered into independent clades, and those in E. breviscapus were clustered into four clades. The transcriptome data showed that MYB genes were differentially expressed in different tissues of E. breviscapus and in response to the treatments with exogenous hormones such as ABA, SA, and GA for different time. The transcription of 13 R2 R3-MYB genes did not change significantly, and the expression patterns of some genes were up-regulated or down-regulated with the extension of hormone treatment time. This study provides a theoretical basis for revealing the mechanisms of R2 R3-MYB transcription factors in regulating the growth and development, stress(hormone) response, and active ingredient accumulation in E. breviscapus.

Molecular Testing of Brain Tumor

The World Health Organization (WHO) classification of central nervous system (CNS) tumors was revised in 2016 with a basis on the integrated diagnosis of molecular genetics. We herein provide the guidelines for using molecular genetic tests in routine pathological practice for an accurate diagnosis and appropriate management. While astrocytomas and IDH-mutant (secondary) glioblastomas are characterized by the mutational status of IDH, TP53, and ATRX, oligodendrogliomas have a 1p/19q codeletion and mutations in IDH, CIC, FUBP1, and the promoter region of telomerase reverse transcriptase (TERTp). IDH-wildtype (primary) glioblastomas typically lack mutations in IDH, but are characterized by copy number variations of EGFR, PTEN, CDKN2A/B, PDGFRA, and NF1 as well as mutations of TERTp. High-grade pediatric gliomas differ from those of adult gliomas, consisting of mutations in H3F3A, ATRX, and DAXX, but not in IDH genes. In contrast, well-circumscribed low-grade neuroepithelial tumors in children, such as pilocytic astrocytoma, pleomorphic xanthoastrocytoma, and ganglioglioma, often have mutations or activating rearrangements in the BRAF, FGFR1, and MYB genes. Other CNS tumors, such as ependymomas, neuronal and glioneuronal tumors, embryonal tumors, meningothelial, and other mesenchymal tumors have important genetic alterations, many of which are diagnostic, prognostic, and predictive markers and therapeutic targets. Therefore, the neuropathological evaluation of brain tumors is increasingly dependent on molecular genetic tests for proper classification, prediction of biological behavior and patient management. Identifying these gene abnormalities requires cost-effective and high-throughput testing, such as next-generation sequencing. Overall, this paper reviews the global guidelines and diagnostic algorithms for molecular genetic testing of brain tumors.

Expression of c-myc and c-myb gene in leukemic bone marrow stromal cells and their correlation / 中国实验血液学杂志

This study was purposed to investigate the expression level of oncogene c-myc and c-myb in leukemic cells and leukemic bone marrow stromal cells (BMSC) and the correlation with each other. The expression levels of c-myc and c-myb in those cells were examined semi-quantitatively by reverse transcription polymerase chain reaction (RT-PCR). Flow cytometry analysis was used to detect the membrane surface antigens of leukemic cells and BMSC. The karyotype was analyzed by G-banding techniques. The results showed that (1) c-myc and c-myb gene were expressed in the normal control group, the leukemic cells and BMSC of patients group. The mean expression levels of c-myb mRNA and c-myc mRNA in abnormal chromosomal leukemic cells were 1.03 ± 0.48 and 1.15 ± 0.38 respectively, which were significantly higher than those in control group (P < 0.05). In the abnormal karyotype stromal cells, the mean expression level of c-myb mRNA and c-myc mRNA were 2.08 ± 0.82 and 1.46 ± 0.29 respectively (P < 0.05). (2) The expression level of c-myc and c-myb mRNA were closely associated with patients' platelet counts (P < 0.05). (3) The expression of c-myc mRNA linearly correlated with the expression of c-myb mRNA in different prognostic groups. (4) In acute leukemic cells and BMSC, c-myc expression positively correlated with c-myb expression. (5) The expression level of c-myc in leukemic cells correlated with the expression levels of c-myc and c-myb in BMSC, respectively. It is concluded that the reduction of c-myc or c-myb expression levels may be a therapeutic regimen for leukemia.

Effect of protooncogene c-myb on progesterone-induced mouse germinal vesicle stage oocyte maturation in vitro / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effects of c-myb on progesterone-induced mouse germinal vesicle(GV) stage denuded oocyte (DO) maturation in vitro.</p><p><b>METHODS</b>We used mouse GV stage oocyte cultured with special concentration progesterone, or/and antisense c-myb ODN, or/and db-cAMP, or/and heparin for 24 h, and observed oocyte maturation and analysed the relationship among them.</p><p><b>RESULTS</b>We cultured DO in the medium 199 for 24 h, and found 10 micromol/L progesterone had more significant effect than 5 micromol/L progesterone (2 h GVBD% P < 0.05, 8 h PB 1% P < 0.05), but had not more significant effect than 20 micromol/L progesterone. We found that 16 micromol/L antisense c-myb ODN significantly inhibited progesterone (10 micromol/L)-induced mouse germinal vesicle stage oocyte maturation in vitro (2 h GVBD% P < 0.05, 8 h PBI% P < 0.01). 1 x 10(-4) micromol/L dbcAMP, 100 microg/ml heparin could single significantly inhibited progesterone-induced mouse GV stage oocyte maturation in vitro (2 h PBI% all P < 0.01, 8 h PBI% all P < 0.01), and could enhanced the inhibition of 16 micromol/L antisense c-myb ODN (2 h GVBD% all P < 0.01, 8h PBI% all P < 0.01).</p><p><b>CONCLUSION</b>Progesterone, protooncogene c-myb,cAMP and calcium all pay important role in regulating oocyte maturation and the mechanism of progesterone, cAMP and calcium in regulating oocyte maturation may be through the expression of protooncogene c-myb.</p>

Correlation analysis and identification of G421C in regulatory region of CYP4F2 gene with essential hypertension / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the correlation between G421C polymorphism in the regulatory region of CYP4F2 gene and essential hypertension and its molecular mechanism.</p><p><b>METHODS</b>Totally 196 hypertensive patients (hypertension group) and 219 normotensive subjects (control group) were genotyped by polymerase chain reaction-restriction fragment length polymorphism. The promoter activity with different alleles was evaluated by reporter assay. A Myb responsive element was identified using gel retardation assay.</p><p><b>RESULTS</b>Significant differences were found in distribution of genotype and allele frequency of G421C between hypertension group and control group (P < 0.05), and homozygous GG genotype was independently associated with hypertension after adjustment for age, gender, body mass index, and other risk factors (odds ratios 1.87, 95% CI 1.11-3.13, P < 0.05). 421G reporter construct showed decreased promoter activity compared with 421C reporter construct. 421G existed in Myb responsive element, whereas 421C damaged this motif.</p><p><b>CONCLUSION</b>G421C polymorphism in the regulatory region of CYP4F2 gene is correlated with essential hypertension. 421G allele inhibits transcription by binding affinity of Myb responsive element.</p>

In vivo distribution of c-myc antisense oligodeoxynucleotides local delivered by gelatin-coated platinum-iridium stents in rabbits and its effect on apoptosis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Post-stenting restenosis is a significant clinical problem, involving vascular smooth muscle cells (VSMCs) proliferation and apoptosis. It is reported that c-myc antisense oligodeoxynucleotides (ASODNs) local delivered by catheter can inhibit VSMCs proliferation. This study was designed to assess tissue distribution of c-myc ASODN local delivered using gelatin-coated platinum-iridium (Pt-Ir) stents, and its effect on apoptosis of VSMCs.</p><p><b>METHODS</b>Gelatin-coated Pt-Ir stents that had absorbed caroboxyfluorescein-5-succimidyl ester (FAM) labeled c-myc ASODNs (550 microg per stent) were implanted into the right carotid arteries of 6 rabbits. Tissue samples were obtained at 45 minutes, 2 hours, and 6 hours. Tissue distribution of c-myc ASODNs was assessed by fluorescence microscopy. In addition, 32 rabbits were randomly divided into two groups. Rabbits in the control group (n = 16) were implanted with gelatin-coated Pt-Ir stents, and those in the treatment group (n = 16) were implanted with gelatin-coated stents that had absorbed c-myc ASODNs. 7, 14, 30, or 90 days (n = 4, respectively, for each group) after the stenting procedure, the stented segments were harvested, and histopathological examinations were performed to calculate neointimal area and mean neointimal thickness. The expression of c-myc was assessed using in situ hybridization (ISH) and immunohistochemical methods. Apoptotic VSMCs were detected using terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope (TEM).</p><p><b>RESULTS</b>According to fluorescence microscopic results, FAM-labeled c-myc ASODNs were concentrated in the target vessel media at the 45 minutes time point, and then dispersed to the adventitia. Morphometric analysis showed that neointimal area and mean neointimal thickness increased continuously up to 90 days after stent implantation, but that total neointimal area and mean neointimal thickness were less in the treatment group than in the control group at all time points (P < 0.0001). At day 7 and day 14 after stenting, there were no detectable apoptotic cells in either group. However, apoptotic cells were present in the neointima 30 and 90 days after stenting, and the number of apoptotic cells was less at 30 days than at 90 days. Meanwhile, c-myc ASODNs appeared to induce apoptosis in more cells in the treatment group than that in the control group. Typical apoptotic VSMCs were observable under TEM. The expression of c-myc was positive in the control group and negative or weakly positive in the c-myc ASODN treatment group, according to both ISH and immunohistochemical examination.</p><p><b>CONCLUSION</b>Gelatin-coated Pt-Ir stent mediated local delivery of c-myc ASODNs is feasible. The localization of c-myc ASODN is primarily in the target vessel walls. c-myc ASODNs can inhibit VSMCs proliferation and induce its apoptosis after local delivery in vivo.</p>