To characterize CBF/DREB1-homologue in rice, nine OsDREB1 genes have been identified and characterized in this lab. Among these, it was shown that OsDREB1D was induced by drought and slightly by cold stress. We found that OsDREB1A, -1D, and -1E could up-regulate OsDhn1:LUC construct in transactivation assay using rice protoplasts. Transgenic rice plants overexpressing OsDREB1D under the maize ubiquitin promoter (Ubi:OsDREB1D) revealed an enhanced stress tolerance to drought. We also generated transgenic rice of OsDREB1D under OsPOX1 promoter (OsPOX1:OsDREB1D), which is cold stress inducible preferentially in the reproductive organs of rice. We are currently examining the mechanism of the enhanced tolerance of the transgenic plants to drought stress using both molecular physiological and biochemical techniques.

식물 특이 NAC (NAM, ATAF, and CUC) 전사인자는 식물 성장, 발달과 스트레스에 대한 저항성에 관여한다고 알려져 있다. 본 연구에서는 벼의 NAC 전사인자 중의 하나인 OsNAC69 유전자를 분리하였으며 유추된 아미노산 서열을 바탕으로 조사해본 결과 이 유전자는 NAC 전사인자의 5개 group 중에서 group II에 속하였다. 흰잎마름병균인 X. oryzae pv. oryzae (Xoo)를 처리하여 발현을 분석한 결과 접종 1시간 이

The Egr family of zinc finger transcription factors consisting of 4 members (Egr1 to Egr4) regulates critical genetic programs involved in cellular growth, differentiation, and function. They are co-ex-pressed in many different tissues, suggesting that they may have some redundant functions. While it is clear that estrogen regulates Egr1 in estrogen sensitive breast cancer cells, function of Egr1 and mechanisms by which estrogen (E2) and/or progesterone (P4) regulates Egr1 in uterus still remain unexplored. Thus, we have examined regulatory mechanisms by which Egr1 is regulated in the uterus and abnormal uterine phenotypes of Egr1(－/－) mice. Eight-week-old female mice were ovariectomized (OVX) and rested for a week. Uteri of OVX mice treated with various concentrations of E2 and/or other hormones were collected at 2 h after hormone treatment unless otherwise indicated. ICI 182,780 [estrogen receptor (ER) antagonist] or RU486 [progesterone receptor (PR) antagonist] was injected to OVX mice 30 min prior to hormone treatments. OVX Egr1(+/+) and Egr1(－/－) mice were treated with E2 and/or P4 to examine expression patterns of genes important for estrogen responses, and steroid hormone-induced cell proliferation in the uterus. Collected uteri were utilized for RT-PCR, realtime RT-PCR, Western blotting and histological analyses. Egr1 mRNA was rapidly induced with the highest level at 2h after E2 treatment and gradually deceased to basal levels at 12 h. Pretreatment of ICI 182,780 significantly reduced E2-induced increase of Egr1. However, an agonist for GPR30, a membrane estrogen receptor failed to induce mRNA expression of Egr1, suggesting that E2-dependent Egr1 transcription is mainly regulated via nuclear estrogen receptor, ER. P4 effectively dampened E2-dependent Egr1 transcription and its antagonistic effects were partially interfered with RU486 pretreatment. Histological analyses with BrdU incorporation experiments showed that vascular permeability (an early estrogen response) but not cell proliferation (a late response) was significantly impaired in the uteri of E2 treated OVX Egr1(－/－) mice. Interestingly, some genes involved in early estrogen responses such as Bip and HIF-1a but not those in late responses are dysregulated in uteri of Egr1(－/－) mice. Collectively, our results show that E2 transiently induces Egr1 via activation of nuclear ER. P4 antagonizes E2-dependent Egr1 regulation via PR. Impaired early estrogenic responses in Egr1(－/－) uteri could be due to aberrant gene expression affected by loss of Egr1 which act as a master regulator of estrogen actions in the uterus.-ex

Lhx8 is a member of the LIM-homeobox transcription factor family expressed in the mouse ovary. We discovered that Lhx8 knockout females lose oocytes within 7 days after birth. Lhx8–/–ovaries fail to maintain the primordial follicles and growing follicles. Lhx8–/–ovaries misexpress numerous oocyte-specific genes such as H1foo and Nlrp14. The molecular mechanism of there gulation of Lhx8 in the oocyte has not been described. We examined to characterize Lhx8 DNA binding elements and to identify its direct target genes in the oocyte. CAST was performed using glutathione transferase Lhx8 homeodomain fusion protein (GST-LHX8HD). A 15-bp random sequence flanked by 20-bp of fixed sequences were incubated with purified GST-LHX8HD protein. Unbound DNA was washed with binding reaction buffer. Bound DNA was eluted and re-amplified by PCR for the next round of CAST. Final PCR products were cloned and sequenced to derive consensus binding sequence. EMSA was performed using 32P-labeled oligomers. Binding reactions were conducted by incubating 32P-labeled probes with purified protein. Dual luciferase assays were carried out with extracts of total HEK293 cell which was transfected by the pGL4-promoter vector containing three artificial repeats of LBE(3xLBE-Luc) and overexpression vector carrying the Lhx8 homeodomain as recommended by Promega. We identified several cis-acting sites, TGATTG as Lhx8 DNA binding elements (LBE) using a library of randomly generated oligonucleotides by CAST. EMSA reslut shows that Lhx8 preferentially binds to the oligomer including Lhx8 binding element (TGATTG) with high affinity. In addition, we found that the relative luciferase activity of reporter construct containing three copies of TGATTG was increased by 2.3-fold with Lhx8 overexpression. These results suggest that Lhx8 preferentially binds Lhx8 DNA binding element, TGATTG, and can transactivate reporter genes through the LBE. The transcription of Lhx8 target gene in oocytes directly might be regulated by its during early folliculogenesis.

The MYB transcription factors play important roles in the regulation of many secondary metabolites at the transcriptional level. We evaluated the possible roles of the Arabidopsis R2R3-MYB transcription factor genes in flavonoid biosynthesis as they are induced by UV-B irradiation but are largely unexplored in terms of their associated phenotypes. We found that one member of this gene family, AtMYB60, inhibits anthocyanin biosynthesis in the lettuce plant. Wild type lettuce normally accumulates anthocyanin, predominantly cyanidin and traces of delphinidin, and develops a red pigmentation. However, the accumulation of anthocyanin pigments in AtMYB60 overexpressing lettuce was inhibited. We further found a complete absence of DFR transcripts in AtMYB60 overexpressing lettuce, whereas other biosynthetic genes in the anthocyanin metabolism pathway were expressed. To provide genetic tools the regulation of seed color of rapeseed which has been target for fuel, AtMYB was overexpressed in rapeseed. Transgenic plants showed lighter seed color and improved tolerance to abiotic stress than the wild type plants. The elucidation of the roles of the AtMYB60 transcription factor will facilitate further studies and provide genetic tools to better understand the regulation in plants of the genes controlled by the MYB-type transcription factors.