AgNOR increase in buccal epithelial cells of trisomy 21 infants

Yılmaz, Seçil; Demirtaş, Halil

doi:10.1016/j.micron.2008.03.014

Cited by 7 publications

(6 citation statements)

References 33 publications

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“…Transcription factor genes are encoded by Hsa21 and they are fundamentally nuclear proteins (Gardiner, ). Our previous AgNOR staining studies show that nucleoli in interphase nuclei of lymphocytes (Demirtas et al, ; Imamoglu et al, , ) and buccal epithelial cells (Yilmaz and Demirtas, ) from infants with DS contain more AgNOR proteins in vivo (Imamoglu et al, ; Yilmaz and Demirtas, ) and in vitro (when stimulated with mitogen) (Demirtas et al, ; Imamoglu et al, , ) than those of the healthy controls.…”

Section: Discussionmentioning

confidence: 91%

“…It is a generally admitted consensus that the extra chromosome 21 genes disorganize the global metabolism of the body cells. Our previous studies have demonstrated that the most observable metabolic disorganisation happens during the ribosome biosynthesis in the cells of infants with DS (Demirtas et al, ; Imamoglu et al, , ; Yilmaz and Demirtas, ).…”

Section: Discussionmentioning

confidence: 98%

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Nuclear AgNOR protein enhancement in nucleoplasms of peripheral blood lymphocytes of babies/children with down syndrome

Imamoglu

Eröz

Canatan

et al. 2016

Microscopy Res & Technique

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Down syndrome (DS) is one of the most common chromosomal disorders. The factors contributing to the mental retardation together with other defects in this syndrome have not been fully explained. Individuals with DS have extra rRNA gene family since they carry an extra chromosome 21. The few reports available are on the relationship between the nucleolus organizer regions (NORs) and DS phenotype. The in vivo regulation of NORs expression on the extra chromosome 21 is not completely understood. Previous studies have shown that nucleoli of lymphocytes from infants (mostly neonates) with DS contain more in vivo and in vitro nucleolar AgNOR proteins when compared with healthy infants. The objective of this study is to compare the in vivo nuclear AgNOR protein level in nucleoplasms (also called as karyoplasm) of nonstimulated peripheral blood lymphocytes from babies/children with DS and healthy controls. Peripheral blood samples obtained from 20 babies/children with DS and 20 matched healthy controls were smeared on clean glass slides and then AgNOR staining was performed. The AgNOR protein level in nucleoplasms of lymphocytes from both groups was calculated using a computer program. Nearly 100 interphase nuclei per individual were analysed. Average nuclear AgNOR protein levels in nucleoplasms of lymphocytes from babies/children with DS were found to be significantly higher than those of the controls (P < 0.001). On the basis of our present results, we propose that the increase of nuclear AgNOR protein in in vivo conditions may contribute to the formation of DS phenotypes.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 98%

Nuclear AgNOR protein enhancement in nucleoplasms of peripheral blood lymphocytes of babies/children with down syndrome

Imamoglu

Eröz

Canatan

et al. 2016

Microscopy Res & Technique

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“…Given the central role of ribosome biogenesis regulation in cellular functions and homeostasis, it can be suggested that this extra rDNA content can have a role in DS pathogenesis ( Demirtas 2009 ). Only few studies investigated this aspect so far, mainly measuring ribosome biogenesis by the AgNOR procedure, which consists in the silver staining of a set of acidic and argyrophilic non-histone proteins that are associated with actively transcribed NOR ( Imamoglu et al, 2005 ; Imamoglu et al, 2006 ; Yilmaz and Demirtas 2008 ; Imamoglu et al, 2016 ; Lyapunova et al, 2017 ; Penzo et al, 2019 ). To the best of our knowledge, no study has focused on the factors that can regulate transcription of the rDNA locus, such as DNAm.…”

Section: Introductionmentioning

confidence: 99%

DNA Methylation Analysis of Ribosomal DNA in Adults With Down Syndrome

et al. 2022

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Control of ribosome biogenesis is a critical aspect of the regulation of cell metabolism. As ribosomal genes (rDNA) are organized in repeated clusters on chromosomes 13, 14, 15, 21, and 22, trisomy of chromosome 21 confers an excess of rDNA copies to persons with Down syndrome (DS). Previous studies showed an alteration of ribosome biogenesis in children with DS, but the epigenetic regulation of rDNA genes has not been investigated in adults with DS so far. In this study, we used a targeted deep-sequencing approach to measure DNA methylation (DNAm) of rDNA units in whole blood from 69 adults with DS and 95 euploid controls. We further evaluated the expression of the precursor of ribosomal RNAs (RNA45S) in peripheral blood mononuclear cells (PBMCs) from the same subjects. We found that the rDNA promoter tends to be hypermethylated in DS concerning the control group. The analysis of epihaplotypes (the combination of methylated and unmethylated CpG sites along the same DNA molecule) showed a significantly lower intra-individual diversity in the DS group, which at the same time was characterized by a higher interindividual variability. Finally, we showed that RNA45S expression is lower in adults with DS. Collectively, our results suggest a rearrangement of the epigenetic profile of rDNA in DS, possibly to compensate for the extranumerary rDNA copies. Future studies should assess whether the regulation of ribosome biogenesis can contribute to the pathogenesis of DS and explain the clinical heterogeneity characteristic of the syndrome.

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“…This DNA associates with certain specific, non-histonic acidic proteins with silver affinity called AgNORs [7]. They appear as brown to black dots within the nucleus, and increase in the NOR number has been associated with increase in ribosomal RNA transcription and cellular proliferation, and in certain circumstances they are known to signify DNA ploidy [7,8]. AgNOR counts have earlier been enumerated in biopsies of various inflammatory conditions, carcinomas and tumors, and it has been reported that their counts are significantly higher in neoplastic conditions [9,10,11].…”

Section: Introductionmentioning

confidence: 99%

Exfoliative Cytological Assessment of Apparently Normal Buccal Mucosa among Quid Chewers Using Argyrophilic Nucleolar Organizer Region Counts and Papanicolaou Staining

Mohan¹,

Angadi²

2013

Acta Cytologica

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Objective: Quid chewing is associated with an increased risk of oral cancer. This study aims to analyze argyrophilic nucleolar organizer region (AgNOR) counts along with Papanicolaou (PAP) staining in exfoliative smears of quid chewers and non-chewers to correlate quid chewing habits with possible early cytological changes in apparently normal buccal mucosa. Study Design: Exfoliative smears were obtained from normal buccal mucosa of 30 male quid chewers and non-chewers. The smears were stained using the AgNOR silver staining technique to evaluate the proliferative activity and PAP for cytological appearance. Results: Statistically higher AgNOR counts were observed in chewers as compared to non-chewers. The difference in the mean percentage of nuclei having ≥5 AgNORs in both groups was statistically significant (p = 0.001). In chewers, PAP showed 77% with class I and the remaining 23% were class II, while the non-chewers showed only class I cytology. AgNOR counts between chewers and non-chewers having class I cytological appearance demonstrated a greater mean AgNOR count in chewers (p = 0.0001). Conclusion: Quid chewing seems to have a definite role in promoting proliferative activity of apparently normal buccal mucosal cells. Exfoliative cytological assessment of a combination of AgNOR counts and PAP has the potential for prediction of early quid-associated cellular changes before the appearance of clinical premalignant and malignant lesions.

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AgNOR increase in buccal epithelial cells of trisomy 21 infants

Cited by 7 publications

References 33 publications

Nuclear AgNOR protein enhancement in nucleoplasms of peripheral blood lymphocytes of babies/children with down syndrome

Nuclear AgNOR protein enhancement in nucleoplasms of peripheral blood lymphocytes of babies/children with down syndrome

DNA Methylation Analysis of Ribosomal DNA in Adults With Down Syndrome

Exfoliative Cytological Assessment of Apparently Normal Buccal Mucosa among Quid Chewers Using Argyrophilic Nucleolar Organizer Region Counts and Papanicolaou Staining

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