Mesenchymal stem cells (MSCs) have been widely used as donor cells for somatic cell nuclear transfer (SCNT) to increase the efficiency of embryo cloning. Since replicative senescence reduces the efficiency of embryo cloning in MSCs during in vitro expansion, transfection of telomerase reverse transcriptase (TERT) into MSCs has been used to suppress the replicative senescence. Here, TERT-transfected MSCs in comparison with early passage MSCs (eMSCs) and sham-transfected MSCs (sMSCs) were used to evaluate the effects of embryo cloning with SCNT in a porcine model. Cloned embryos from tMSC, eMSC, and sMSC groups were indistinguishable in their fusion rate, cleavage rate, total cell number, and gene expression levels of OCT4, SOX2 and NANOG during the blastocyst stage. The blastocyst formation rates of tMSC and sMSC groups were comparable but significantly lower than that of the eMSC group (p < 0.05). In contrast, tMSC and eMSC groups demonstrated significantly reduced apoptotic incidence (p < 0.05), and decreased BAX but increased BCL2 expression in the blastocyst stage compared to the sMSC group (p < 0.05). Therefore, MSCs transfected with telomerase reverse transcriptase do not affect the overall development of the cloned embryos in porcine SCNT, but enables to maintain embryo quality, similar to apoptotic events in SCNT embryos typically achieved by an early passage MSC. This finding offers a bioengineering strategy in improving the porcine cloned embryo quality.

Telomeres are known as a specialized region in the end of chromosomes to protect DNA destruction, but their lengths are shortened by repetition of cell division. This telomere shortening can be preserved or be elongated by telomerase and TERT expression. Although a certain condition in the cells may affect to the cellular and molecular characteristics, the effect of differentiation induction to telomere length and telomerase activity in mesenchymal stem cells (MSCs) has been less studied. Therefore, the present study aimed to uncover periodical alterations of telomere length, telomerase activity and TERT expression in the dental pulp-derived MSCs (DP-MSCs) under condition of differentiation inductions into adipocytes and osteoblasts on a weekly basis up to 3 weeks. Shortening of telomere was significantly (p < 0.05) identified from early-middle stages of both differentiations in comparison with undifferentiated DP-MSCs by non-radioactive chemiluminescent assay and qRT-PCR method. Telomere length in undifferentiated DP-MSCs was 10.5 kb, but the late stage of differentiated DP-MSCs which can be regarded as the adult somatic cell exhibited 8.1-8.6 kb. Furthermore, the relative-quantitative telomerase repeat amplification protocol or western blotting presented significant (p < 0.05) decrease of telomerase activity since early stages of differentiations or TERT expression from middle stages of differentiations than undifferentiated state, respectively. Based on these results, it is supposed that shortened telomere length in differentiated DP-MSCs was remained along with prolonged differentiation durations, possibly due to weakened telomerase activity and TERT expression. We expect that the present study contributes on understanding differentiation mechanism of MSCs, and provides standardizing therapeutic strategies in clinical application of MSCs in the animal biotechnology.

Anti-proliferation of methanol extract of Curcuma rhizome on oral squamous cell carcinoma (KB) and osteosarcoma (HOS) cells were investigated. In order to elucidate the involvement of telomerase inhibitory activity as a part of anti-proliferative effect of Curcuma rhizome on cancer cells, we measured telomerase activity in Curcuma rhizome extract-treated cancer cells. The concentration inhibited cell proliferation to 50% (IC50)of the methanol extract of Curcuma rhizome against oral squamous cell carcinoma (KB) cells and osteosarcoma (HOS) cells were 21.30 μg/mℓ and 39.3μg/mℓ respectively. The methanol extract of Curcuma rhizome showed inhibitory telomerase inhibitory effect which is required for cancer cell immortality. Therefore, it seems that the anticancer effect of methanol extract of Curcuma rhizome is at least partially due to telomerase inhibitory effect. Five fraction samples were prepared according to its polarity differences and analyzed anti-proliferative effects of each fraction samples on oral squamous cell carcinoma and osteosarcoma cells. Anticancer effect was observed in dichloromethane, and ethylacetate fractions. The highest anticancer effect was found in dichloromethane fraction which had IC50value of 23.3 μg/mℓ and 10.5μg/mℓ against oral squamous cell carcinoma (KB) cells and osteosarcoma (HOS) cells, respectively.

텔로미어란 염색체 말단부에 (TTAGGG)n의 반복 염기서열이 단백질과 결합된 형태를 말하는데 이의 역할은 염색체의 안정성에 본질적으로 작용하여 세포의 노화, 사멸 및 암의 발생과 관련이 있다고 알려져 있다. 반면 텔로머레이스는 telomeric DNA 합성에 직접 관여하는 ribonucleoprotein이다. 본 연구에서는 마우스 염색체의 텔로미어 분포 양상을 제시하고, 초기 배 발생단계별 수정란의 텔로미어 함량과 이들 수정란의 텔로머레이스 활성도를 분석하고자 하였다. 본 분석에는 마우스의 섬유아세포, 생식세포, 정자, 난자 및 1세포기, 2세포기, 4세포기, 8세포기, 상실배와 배반포배의 각 단계별 수정란을 대상으로 하였다. 텔로미어의 양적 분석은 human telomeric DNA probe를 이용한 Q-FISH 방법을 이용하였고, 텔로머레이스 활성도는 TRAP 방법을 이용하였다. 분석 결과 마우스 염색체의 텔로미어는 성 염색체를 포함한 모든 염색체의 앙 말단부에 분포되어 있고, 염색체별 다소의 양적 차이를 보이나 대부분의 염색체에서 q-arm 말단이 p-arm 말단에 비해 높은 텔로미어의 함량을 나타내었다. Q-FISH를 이용한 마우스 초기 배 발생단계별 수정란의 텔로미어의 양적 분석에서 수정 직후 1세포기에서부터 상실배까지 거의 비슷한 텔로미어 함유율을 나타내고 있으나 배반포기에서 월등히 증가된 양상을 나타내었다. TRAP 분석을 이용한 초기배아의 텔로머레이스 활성도는 초기 배 발생 모든 단계에서 이의 활성도를 나타내었으며, 특히 상실배 및 배반포기에서 점진적으로 강한 활성을 보였다. 이상의 분석 결과로부터 마우스의 초기 배 분열단계의 각 세포들에 있어 텔로미어의 함유율과 텔로머레이스 활성도는 높은 상관관계가 있는 것으로 나타났다. 따라서 포유동물의 초기 배자에 있어 텔로미어의 함유율과 텔로머레이스 활성도는 배 발생 및 배자의 세포 분화와 매우 밀접한 관련이 있는 것으로 사료되어 텔로미어의 양적 분석 및 텔로머레이스 활성도 분석은 발생학적 연구를 위한 또 다른 좋은 자료로 생각된다.

Telomere란 진핵세포에 존재하는 DNA-protein 복합체로서 염색체의 말단부에 tandem repeated DNA 서열 (TTAGGG)과 특정 단백질로 구성되어 있으며 세포 분열이 진행함에 따라 이의 길이가 짧아지게 되고 일정 길이 이하가 되면 세포의 사망이 유발된다. 반면 telomerase는 ribonucleoprotein으로서 telomeric DNA의 합성에 관여하는 것으로 염색체의 말단에 telomeric DNA의 소실을 보충하는 역할

Telomeres are the end of chromosomes and consist of a tandem repeat sequence of (TTAGGG)n and associated proteins. Telomerase is a ribonucleoprotein which act as a template for the synthesis of telomeric DNA. Telomeres are essential for chromosome stability and are related with cell senescence, apoptosis and cancer. Even though telomeres and telomerase have been studied extensively, very little is known about telomere dynamics in embryonic cells. This study was carried out to analyze the telomeres distribution and telomerase activity of chicken cells during embryonic and developmental stages. The target cells for analysing were sperms, ovulated ova, early embryonic cells and the cells from brain, heart, liver, kidney and germinal tissue in fetus. Telomeres distribution on target cells was analyzed by Q-FISH (Quantitation-Fluorescence in situ Hybridization) techniques using a chicken telomere repeat probe. Telomerase activity was performed by TRAP assay (Telomeric repeat Amplification Protocol) with target DNA. In results, the telomeres of chicken were found at the ends of all chromosomes. In addition, chicken had interstitial telomeres on chromosomes 1, 2 and 3. Telomerase activity was highly detectable in early embryonic cells, germinal tissues and kidney cells. Whereas telomerase activity was gradually down-regulated when the organs, including brain, heart, and liver, were developed from embryos. In the distribution of telomeric DNA on the embryonic and developmental stages, most of the cells was gradually decreased in telomere quantity during ontogenesis.