Increased TERC gene copy number in amniocytes from fetuses with trisomy 18 or a sex chromosome aneuploidy

TERC promotes cellular inflammatory response independent of telomerase

TERC is an RNA component of telomerase. However, TERC is also ubiquitously expressed in most human terminally differentiated cells, which don't have telomerase activity. The function of TERC in these cells is largely unknown. Here, we report that TERC enhances the expression and secretion of inflammatory cytokines by stimulating NK-κB pathway in a telomerase-independent manner. The ectopic expression of TERC in telomerase-negative cells alters the expression of 431 genes with high enrichment of those involved in cellular immunity. We perform genome-wide screening using a previously identified 'binding motif' of TERC and identify 14 genes that are transcriptionally regulated by TERC. Among them, four genes (LIN37, TPRG1L, TYROBP and USP16) are demonstrated to stimulate the activation of NK-κB pathway. Mechanistically, TERC associates with the promoter of these genes through forming RNA-DNA triplexes, thereby enhancing their transcription. In vivo, expression levels of TERC and TERC target genes (TYROBP, TPRG1L and USP16) are upregulated in patients with inflammation-related diseases such as type II diabetes and multiple sclerosis. Collectively, these results reveal an unknown function of TERC on stimulating inflammatory response and highlight a new mechanism by which TERC modulates gene transcription. TERC may be a new target for the development of anti-inflammation therapeutics.

The effect of maternal body mass index (BMI) and telomere function on in vitro fertilization (IVF) outcome: a preliminary cohort study

Telomeres are a specific base sequence of DNA, responsible for chromosome stability and DNA protection. We aimed to investigate the association between telomere systems and IVF outcomes according to patients' BMI. For all telomere characteristics, there was a distinct trend towards shorter telomeres and activation of telomere shortening compensatory mechanisms in the BMI group >25 kg/m², reaching statistical significance for senescence only (r = 0.7, p value <0.01). There was a trend towards a relationship between telomere length and number of oocytes between telomere length and fertilization rate, but these did not reach a statistical significance. For pregnancy outcome, all telomere characteristics were better for the patients who achieved a pregnancy. While there is paucity of data in the literature concerning the association between telomere characteristics and infertility, telomeres might contribute to the association between obesity and sub-optimal IVF results.

Amniocytes from aneuploidy embryos have enhanced random aneuploidy and signs of senescence - can these findings be related to medical problems?

OBJECTIVES

Genomic aneuploidy is a common cause of human genetic disorders. Individuals with aneuploidy tend to develop malignancies. Recent studies correlated aneuploidy with early aging, senescence and organ dysfunction. This study investigated potential explanations for these increased risks by evaluating random aneuploidy and senescence rates in amniocytes from fetuses with aneuploidy.

METHODS

The rates of random aneuploidy in amniocytes from normal pregnancies were evaluated and compared to amniocytes from fetuses with trisomies 21, 18 and 47,XXY using a FISH technique with X+Y, 9 and 18 probes. Senescence was evaluated by calculating the percentage of amniocytes with fragmented nuclei: senescence associated heterochromatin foci (SAHF), using DAPI staining.

RESULTS

Significantly increased rates of cells with aneuploidy were observed in trisomies 18 and 21, and 47,XXY (p<0.001) compared to the control group for the somatic and sex chromosomes. Increased rates of amniocytes with SAHFs were observed among the trisomy samples compared to the control group.

CONCLUSIONS

Higher incidence of random aneuploidy and senescence were observed in amniocytes from fetuses with trisomy. These findings might explain the greater lifetime tendency to develop malignancies and diseases related to early aging in these individuals.

Increased TERC gene copy number and cells in senescence in primary sclerosing cholangitis compared to colitis and control patients

OBJECTIVE

Primary sclerosing cholangitis (PSC) is a chronic cholestatic disorder that involves inflammatory and fibrotic changes in the bile ducts. Up to 80% of patients have concomitant inflammatory bowel disease (IBD) with colitis. PSC patients are predisposed to develop hepatobiliary, colonic and other extrahepatic malignancies, probably related to inflammatory processes that might promote carcinogenesis. Telomerase is an enzyme complex that lengthens telomeres and has enhanced expression in numerous malignancies. In this study, we evaluated the TERC gene copy number, the proportion of cells in senescence and the amount of fragmentation in the senescent state.

METHODS

Fluorescence in situ hybridization (FISH) for the TERC gene was applied to lymphocytes retrieved from PSC (N=19), colitis (N=20) and healthy control patients (N=20) to determine the TERC copy number. On the same FISH slides, cells stained with DAPI were also analyzed for senescence-associated heterochromatin foci (SAHF) status, including the number of cells with fragments and the number of SAHF fragments in each cell.

RESULTS

A higher TERC gene copy number was observed in cells from PSC patients compared to colitis and control group patients. It was also higher in the colitis than in the control group. Significantly more cells in the senescent state and more fragmentation in each cell were observed in the PSC group compared to colitis and control groups.

CONCLUSION

The TERC gene copy number and the number of cells in the senescent state were increased in PSC patients compared to the colitis and control groups. These findings are probably related to the genetic instability parameters that reflect the higher tendency of this patient group to develop malignancies.