CDKN1B
Cyclin-dependent kinase inhibitor 1B (Cyclin-dependent kinase inhibitor p27) (p27Kip1) [KIP1]
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[i]DNA (cytosine-5)-methyltransferase 3a[/i] ([i]Dnmt3a[/i]) is an enzyme that catalyzes the transfer of methyl groups to specific CpG forms in DNA. In mammals, two variant transcripts of [i]Dnmt3a[/i] have been successfully identified. To the best of our knowledge, no [i]Dnmt3a[/i] transcripts in an avian have been successfully identified. This study was performed to detect different transcripts of [i]Dnmt3a[/i] in chickens and to examine whether a novel [i]Dnmt3a[/i] transcript named [i]Dnmt3a1[/i] may regulate adipogenesis. In addition to cloning, sequencing, transcript detection, and expression studies, a novel [i]Dnmt3a1[/i] transcript overexpression and knockdown were conducted to explore the potential role of [i]Dnmt3a1[/i] in preadipocyte proliferation and the early stage of adipocyte differentiation. In chicken abdominal fat tissue, we detected a novel [i]Dnmt3a1[/i] transcript that differs from [i]Dnmt3a[/i] by lacking 23 amino acids at the exon-1/exon-2 border. [i]Dnmt3a1[/i] mRNA was ubiquitously expressed in a variety of tissues or cells and highly expressed in chicken adipose tissue/cells. The expression of [i]Dnmt3a1[/i] was regulated under different physiological conditions including aging, fasting, and high-fat diet. In addition, overexpression of [i]Dnmt3a1[/i] significantly decreased preadipocyte proliferation and induced cell-cycle arrest while its inhibition increased cell proliferation and S-phase cells. Furthermore, the overexpression of [i]Dnmt3a1[/i] significantly upregulated the mRNA level of cell-cycle-related genes, such as [i]CDKN1A[/i], [i]CDKN1B[/i], [i]CCNB3[/i], [i]CCND2[/i], [i]CCNG2[/i], [i]CDKN2B[/i], and [i]CDK9[/i], or the protein level of CDKN1A, CDKN1B, and CCNG2. Conversely, the knockdown of [i]Dnmt3a1[/i] by siRNA had the opposite effects. Moreover, during early adipocyte differentiation, the overexpression of [i]Dnmt3a1[/i] significantly decreased the mRNA and the protein levels of PPAR-γ, C/EBP-α, ADIPOR1, and STAT3, and the mRNA levels of [i]FAS[/i], [i]LEPR[/i], [i]LPL[/i], [i]PRKAB2[/i], and [i]ATGL.[/i] In contrast, their expression was significantly increased after the knockdown of [i]Dnmt3a1[/i]. Taken together, we identified a novel transcript of [i]Dnmt3a[/i], and it played a potential role in adipogenesis.
Keywords
- Dnmt3a
- Dnmt3a1 transcript
- aging
- early differentiation
- expression
- high-fat diet
- preadipocytes proliferation
The tRNA methyltransferase NSUN2 delays replicative senescence by regulating the translation of CDK1 and CDKN1B mRNAs. However, whether NSUN2 influences premature cellular senescence remains untested. Here we show that NSUN2 methylates SHC mRNA in vitro and in cells, thereby enhancing the translation of the three SHC proteins, p66SHC, p52SHC, and p46SHC. Our results further show that the elevation of SHC expression by NSUN2-mediated mRNA methylation increased the levels of ROS, activated p38MAPK, thereby accelerating oxidative stress- and high-glucose-induced senescence of human vascular endothelial cells (HUVEC). Our findings highlight the critical impact of NSUN2-mediated mRNA methylation in promoting premature senescence.
MeSH Terms
- Blotting, Western
- CDC2 Protein Kinase
- Cells, Cultured
- Cellular Senescence
- Cyclin-Dependent Kinase Inhibitor p27
- Gene Expression Regulation
- HCT116 Cells
- Human Umbilical Vein Endothelial Cells
- Humans
- Methylation
- Methyltransferases
- Oxidative Stress
- RNA Interference
- RNA, Messenger
- Reactive Oxygen Species
- Src Homology 2 Domain-Containing, Transforming Protein 1
- p38 Mitogen-Activated Protein Kinases
Keywords
- Gerotarget
- HUVEC
- NSUN2
- SHC mRNA methylation
- premature senescence
- translational regulation
Mutations of the MEN1 gene predispose to multiple endocrine neoplasia type 1 (MEN1) syndrome. Our group and others have shown that Men1 disruption in mice recapitulates MEN1 pathology. Intriguingly, rare lesions in hormone-dependent tissues, such as prostate and mammary glands, were also observed in the Men1 mutant mice. To study the occurrence of prostate lesions, we followed a male mouse cohort of 47 Men1 /- mice and 23 age-matched control littermates, starting at 18 months of age, and analysed the prostate glands from the cohort. Six Men1 /- mice (12.8%) developed prostate cancer, including two adenocarcinomas and four in situ carcinomas, while none of the control mice developed cancerous lesions. The expression of menin encoded by the Men1 gene was found to be drastically reduced in all carcinomas, and partial LOH of the wild-type Men1 allele was detected in three of the five analysed lesions. Using immunostaining for the androgen receptor and p63, a basal epithelial cell marker, we demonstrated that the menin-negative prostate cancer cells did not display p63 expression and that the androgen receptor was expressed but more heterogeneous in these lesions. Furthermore, our data showed that the expression of the cyclin-dependent kinase inhibitor CDKN1B (p27), a Men1 target gene known to be inactivated during prostate cell tumorigenesis, was notably decreased in the prostate cancers that developed in the mutant mice. Our work suggests the possible involvement of Men1 inactivation in the tumorigenesis of the prostate gland.
MeSH Terms
- Adenocarcinoma
- Aging
- Animals
- Blotting, Southern
- Cyclin-Dependent Kinase Inhibitor p27
- Heterozygote
- Immunoenzyme Techniques
- Loss of Heterozygosity
- Male
- Mice
- Mice, Inbred C57BL
- Phosphoproteins
- Prostatic Neoplasms
- Proto-Oncogene Proteins
- Receptors, Androgen
- Trans-Activators