Recently, it is demonstrate that the invertebrates have a immune memory, called Immune priming (IP). It was partially studied that the IP is mainly regulated by epigenetic modification. Here, to understand the IP on antimicrobial peptides (AMPs) production, we investigated larval mortality and time-dependent expression patterns of AMP genes in T. molitor larvae challenged with E. coli (two-times injection with a one-month interval). Interestingly, the results indicate that the higher and faster expression levels of most AMP genes were detected compared to the non-primed T. molitor larvae. Our results may used to improve the understanding of mechanisms of invertebrate immune memory.

Oct4 and Nanog are well-known transcription factors related with self renewal of embryonic stem cell. In low-dose of Nanog, transcription of oct4 is increased; however, oct4 is down-regulated upon high-dose of Nanog. There is a negative feedback loop between oct4 and Nanog. To identify this regulation, we generated 4 nested sets for mouse oct4 promoter. Luciferase activities of oct4 were declined upon high-dose Nanog in all constructs. The declined effects of oct4 upon high-dose Nanog were moderated with DNMT and HDAC inhibitors (5-AZA-cytidine and trichostatin A) in 3 constructs (1867, 1346, 754). But, one construct (2179) was only sensitive to TSA. Taken together, these effects were also represented in semi-quantitative RT-PCR and Western blotting data. These data suggest that negative regulation of oct4 gene upon high-dose Nanog would be accomplished by DNMT and HDAC. Further, it will be studied whether these constraining molecules bind to CR1-4 region of oct4 promoter upon low- and high-dose of Nanog.

Cloning or somatic cell nuclear transfer (SCNT) using adult somatic cell to derive cloned embryos is a promising new technology with potential applications in both agriculture and regenerative medicine. Mammalian embryos derived by nuclear transfer are capable of development to the blastocyst stage with a relatively high efficiency of 30～ 50%. However, in full-time development, usually only 2% of NT embryos can result in live births due to abnormalities in placenta formation. In SCNT embryos, the donor cell nucleus is epigenetically reprogrammed by oocyte cytoplasm during development. Incomplete reprogramming of the donor cell genome is considered a major reason for low cloning efficiency. Aberrant epigenetic modifications include DNA methylation, histone modification and X-chromosome-inactivation. Due to a lack of basic knowledge regarding the embryos following nuclear transfer, the success rate of cloning is low. Therefore, elucidation of the molecular mechanism of SCNT embryo development will be of great value for further research. MicroRNAs (microRNA) are single-strand RNA molecules of about 19 23 nucleotides in length, which regulate gene expression by imperfect base pairing with target mRNA, subsequently guiding mRNA cleavage or translational repression. Since the first discovery and functional annotation in 1993 of the small RNA, lin-4 and let-7, which are involved in developmental timing and gene regulation during C. elegans larval development, microRNAs have received scientific attention. Now hundreds of microRNAs have been identified in various multicellular organisms, and many microRNAs have been shown to be evolutionarily conserved. The roles proposed for this novel class of tiny RNA molecules are diverse. They are likely to be involved in developmental timing, differentiation, cell proliferation, signaling pathways, apoptosis, metabolism, heterochromatin formation, genome rearrangement, brain development and carcinogenesis. Currently (2006- present) we are working to determine the role of microRNAs on the epigenetic regulation of fertilized and cloned embryo development. The general hypothesis of our research is that genetic and epigenetic factors regulate the development of preimplantation mammalian embryos, and aberrant modulations in cloned embryos are causes of abnormal development and low success rate of cloned embryos.

Somatic cell nuclear transfer (SCNT) has long been envisioned as a means for generating patient-specific stem cells to treat a range of age-related diseases. Until now, only three research groups have reported the successful derivation of SCNT-derived pluripotent stem cells (SCNT-PSCs). Our group has shown for the first time that human SCNT-PSCs can be successfully generated using dermal fibroblasts from 35 and 75 year-old males, and also recently established another SCNT-PSC from a patient with disease. However, despite cloning success in these groups, the derivation of stem cell lines from cloned human embryos has proven elusive. So, several approaches for the optimization of SCNT conditions, such as the use of protein phosphatase inhibitors, oocyte activation method and epigenetic regulation have been applied in order to overcome the obstacle. This study reveals mechanistic insights and establishes a promising method for improving human SCNT for regenerative medicine.

후성유전학적 조절은 DNA 서열상의 변화 없이도 유전자의 기능을 변화시킬 수 있는 현상을 뜻한다. 염색체의 후성유전학적 상태는 히스톤 변형, DNA 변형 그리고 RNAi에 의한 유전자 침묵 등에 의해 조절된다. 본 총설에서는 배아줄기세포에서의 후성 유전학적 조절에 영향을 주는 요인으로서 히스톤(histone)의 메틸화에 초점을 맞추었다. 배아줄기세포에서 발현되는 유전자의 조절에는 두 가지 단백질 복합체가 관여한다. Polycomb repressive c