• 한국발생생물학회지:발생과생식
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• 제24권4호
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• pp.249-261
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• 2020

Spermatogonial stem cells (SSCs) have stemness characteristics, including germ cell-specific imprints that allow them to form gametes. Spermatogenesis involves changes in gene expression such as a transition from expression of somatic to germ cell-specific genes, global repression of gene expression, meiotic sex chromosome inactivation, highly condensed packing of the nucleus with protamines, and morphogenesis. These step-by-step processes finally generate spermatozoa that are fertilization competent. Dynamic epigenetic modifications also confer totipotency to germ cells after fertilization. Primordial germ cells (PGCs) in embryos do not enter meiosis, remain in the proliferative stage, and are referred to as gonocytes, before entering quiescence. Gonocytes develop into SSCs at about 6 days after birth in rodents. Although chromatin structural modification by Polycomb is essential for gene silencing in mammals, and epigenetic changes are critical in spermatogenesis, a comprehensive understanding of transcriptional regulation is lacking. Recently, we evaluated the expression profiles of Yin Yang 1 (YY1) and CP2c in the gonads of E14.5 and 12-week-old mice. YY1 localizes at the nucleus and/or cytoplasm at specific stages of spermatogenesis, possibly by interaction with CP2c and YY1-interacting transcription factor. In the present article, we discuss the possible roles of YY1 and CP2c in spermatogenesis and stemness based on our results and a review of the relevant literature.

• The Korean Journal of Physiology and Pharmacology
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• 제21권1호
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• pp.37-44
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• 2017

Regulation of vascular smooth muscle cell (VSMC) phenotype plays an essential role in many cardiovascular diseases. In the present study, we provide evidence that $kr{\ddot{u}}ppel$-like factor 8 (KLF8) is essential for tumor necrosis factor ${\alpha}$ ($TNF{\alpha}$)-induced phenotypic conversion of VSMC obtained from thoracic aorta from 4-week-old SD rats. Stimulation of the contractile phenotype of VSMCs with $TNF{\alpha}$ significantly reduced the VSMC marker gene expression and KLF8. The gene expression of KLF8 was blocked by $TNF{\alpha}$ stimulation in an ERK-dependent manner. The promoter region of KLF8 contained putative Sp1, KLF4, and $NF{\kappa}B$ binding sites. Myocardin significantly enhanced the promoter activity of KLF4 and KLF8. The ectopic expression of KLF4 strongly enhanced the promoter activity of KLF8. Moreover, silencing of Akt1 significantly attenuated the promoter activity of KLF8; conversely, the overexpression of Akt1 significantly enhanced the promoter activity of KLF8. The promoter activity of SMA, $SM22{\alpha}$, and KLF8 was significantly elevated in the contractile phenotype of VSMCs. The ectopic expression of KLF8 markedly enhanced the expression of SMA and $SM22{\alpha}$ concomitant with morphological changes. The overexpression of KLF8 stimulated the promoter activity of SMA. Stimulation of VSMCs with $TNF{\alpha}$ enhanced the expression of KLF5, and the promoter activity of KLF5 was markedly suppressed by KLF8 ectopic expression. Finally, the overexpression of KLF5 suppressed the promoter activity of SMA and $SM22{\alpha}$, thereby reduced the contractility in response to the stimulation of angiotensin II. These results suggest that cross-regulation of KLF family of transcription factors plays an essential role in the VSMC phenotype.

• 한국가금학회지
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• 제39권3호
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• pp.241-244
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• 2012

본 연구는 형질전환 닭에서 주입한 외래 유전자의 세대간 전이와 발현 양상을 조사하고자 하였다. 외래 유전자 전이 양상 조사는 제3세대(G2) GFP 형질전환 수탉을 최초 부계로 사용하여 최종적으로 제9세대(G8) 형질전환 닭을 연속적으로 생산하면서 GFP 유전자 전이 양상을 조사하였다. 형질전환 병아리 유전 분석은 자외선 램프 아래에서 부화한 병아리들의 날개, 부리와 다리에서 녹색형광단백질을 발현하는 병아리들만을 형질전환으로 선발하였다. 형질전환 닭에서 외래 유전자 전이율은 대략 38~58%이었다. 이는 유전자 전이가 멘델의 유전 법칙을 따르고 있음을 보여주고 있다. 연구 결과는 GFP 유전자가 유전자 침묵 없이 멘델의 유전 법칙에 따라 다음 세대로 계속 전이와 발현된다는 것을 보여 주고 있다.

• BMB Reports
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• 제53권6호
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• pp.323-328
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• 2020

Matrix metalloproteinase 1 (MMP-1), a calcium-dependent zinccontaining collagenase, is involved in the initial degradation of native fibrillar collagen. Tissue necrosis factor-alpha (TNFα) is a pro-inflammatory cytokine that is rapidly produced by dermal fibroblasts, monocytes/macrophages, and keratinocytes and regulates inflammation and damaged-tissue remodeling. MMP-1 is induced by TNFα and plays a critical role in tissue remodeling and skin aging processes. However, the regulation of the MMP1 gene by TNFα is not fully understood. We aimed to find additional cis-acting elements involved in the regulation of TNFα-induced MMP1 gene transcription in addition to the nuclear factor-kappa B (NF-κB) and activator protein 1 (AP1) sites. Assessments of the 5'-regulatory region of the MMP1 gene, using a series of deletion constructs, revealed the requirement of the early growth response protein 1 (EGR-1)-binding sequence (EBS) in the proximal region for proper transcription by TNFα. Ectopic expression of EGR-1, a zinc-finger transcription factor that binds to G-C rich sequences, stimulated MMP1 promoter activity. The silencing of EGR-1 by RNA interference reduced TNFα-induced MMP-1 expression. EGR-1 directly binds to the proximal region and transactivates the MMP1 gene promoter. Mutation of the EBS within the MMP1 promoter abolished EGR-1-mediated MMP-1 promoter activation. These data suggest that EGR-1 is required for TNFα-induced MMP1 transcriptional activation. In addition, we found that all three MAPKs, ERK1/2, JNK, and p38 kinase, mediate TNFα-induced MMP-1 expression via EGR-1 upregulation. These results suggest that EGR-1 may represent a good target for the development of pharmaceutical agents to reduce inflammation-induced MMP-1 expression.

• BMB Reports
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• 제49권6호
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• pp.343-348
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• 2016

GATA4 has been reported to act as a negative regulator in osteoblast differentiation by inhibiting the Dlx5 transactivation of Runx2 via the attenuation of the binding ability of Dlx5 to the Runx2 promoter region. Here, we determine the role of GATA4 in the regulation of bone sialoprotein (Bsp) in osteoblasts. We observed that the overexpression of Runx2 or Sox9 induced the Bsp expression in osteoblastic cells. Silencing GATA4 further enhanced the Runx2- and Sox9-mediated Bsp promoter activity, whereas GATA4 overexpression down-regulated Bsp promoter activity mediated by Runx2 and Sox9. GATA4 also interacted with Runx2 and Sox9, by attenuating the binding ability of Runx2 and Sox9 to the Bsp promoter region. Our data suggest that GATA4 acts as a negative regulator of Bsp expression in osteoblasts.

• Molecules and Cells
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• 제39권5호
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• pp.375-381
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• 2016

MicroRNAs (miRNAs) are small non-coding RNAs (~22 nucleotides) regulating gene expression at the post-transcriptional level. By directing the RNA-induced silencing complex (RISC) to bind specific target mRNAs, miRNA can repress target genes and affect various biological phenotypes. Functional miRNA target recognition is known to majorly attribute specificity to consecutive pairing with seed region (position 2-8) of miRNA. Recent advances in a transcriptome-wide method of mapping miRNA binding sites (Ago HITS-CLIP) elucidated that a large portion of miRNA-target interactions in vivo are mediated not only through the canonical "seed sites" but also via non-canonical sites (~15-80%), setting the stage to expand and determine their properties. Here we focus on recent findings from transcriptome-wide non-canonical miRNA-target interactions, specifically regarding "nucleation bulges" and "seed-like motifs". We also discuss insights from Ago HITS-CLIP data alongside structural and biochemical studies, which highlight putative mechanisms of miRNA target recognition, and the biological significance of these non-canonical sites mediating marginal repression.

• BMB Reports
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• 제49권3호
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• pp.137-138
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• 2016

Satiety cues a feeding animal to cease further ingestion of food, thus protecting it from excessive energy gain. Impaired control of satiety is often associated with feeding-related disorders such as obesity. In our recent study, we reported the identification of a neural pathway that expresses the myoinhibitory peptide (MIP), critical for satiety responses in Drosophila. Targeted silencing of MIP neuron activity strikingly increased the body weight (BW) through elevated food intake. Similarly, genetic disruption of the gene encoding MIP also elevated feeding and BW. Suppressing the MIP pathway behaviorally transformed the satiated flies to feed similar to the starved ones, with augmented sensitivity to food. Conversely, temporal activation of MIP neuron markedly reduced the food intake and BW, and blunted the sensitivity of the starved flies to food as if they have been satiated. Shortly after termination of MIP neuron activation, the reduced BW reverted to the normal level along with a strong feeding rebound. Together our results reveal the switch-like role of the MIP pathway in feeding regulation by controlling satiety.

• Asian Pacific Journal of Cancer Prevention
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• 제16권15호
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• pp.6753-6759
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• 2015

Background: Loss of function of the p53 gene is implicated in defective apoptotic responses of tumors to chemotherapy. Although the pro-apoptotic roles of eugenol and capsaicin have been amply reported, their dependence on p53 for apoptosis induction in gastric cancer cells is not well elucidated. The aim of the study was to elucidate the role of p53 in the induction of apoptosis by eugenol and capsaicin in a human gastric cancer cell line, AGS. Materials and Methods: AGS cells were incubated with or without various concentrations of capsaicin and eugenol for 12 hrs, in the presence and absence of p53 siRNA. Cell cycling, annexin V and expression of apoptosis related proteins Bax, Bcl-2 ratio, p21, cyt c-caspase-9 association, caspase-3 and caspase-8 were studied. Results: In the presence of p53, capsaicin was a more potent pro-apoptotic agent than eugenol. However, silencing of p53 significantly abrogated apoptosis induced by capsaicin but not that by eugenol. Western blot analysis of pro-apoptotic markers revealed that as opposed to capsaicin, eugenol could induce caspase-8 and caspase-3 even in the absence of p53. Conclusions: Unlike capsaicin, eugenol could induce apoptosis both in presence and absence of functional p53. Agents which can induce apoptosis irrespective of the cellular p53 status have immense scope for development as potential anticancer agents.

• The Plant Pathology Journal
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• 제29권4호
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• pp.454-459
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• 2013

The Potexvirus Alternanthera mosaic virus (AltMV) has multifunctional triple gene block (TGB) proteins, among which our studies have focused on the properties of the TGB1 protein. The TGB1 of AltMV has functions including RNA binding, RNA silencing suppression, and cell-to-cell movement, and is known to form homologous interactions. The helicase domains of AltMV TGB1 were separately mutated to identify which regions are involved in homologous TGB1 interactions. The yeast two hybrid system and Bimolecular Fluorescence Complementation (BiFC) in planta were utilized to examine homologous interactions of the mutants. Helicase motif I of AltMV TGB1 was found to be critical to maintain homologous interactions. Mutations in the remaining helicase motifs did not inhibit TGB1 homologous interactions. In the absence of homologous interaction of TGB1, subcellular localization of helicase domain I mutants showed distinctively different patterns from that of WT TGB1. These results provide important information to study viral movement and replication of AltMV.

• Biomolecules & Therapeutics
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• 제22권5호
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• pp.384-389
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• 2014

Adiponectin, an adipokine predominantly secreted from adipose tissue, exhibits diverse biological responses, including metabolism of glucose and lipid, and apoptosis in cancer cells. Recently, adiponectin has been shown to modulate autophagy as well. While emerging evidence has demonstrated that autophagy plays a role in the modulation of proliferation and apoptosis of cancer cells, the role of autophagy in apoptosis of cancer cell caused by adiponectin has not been explored. In the present study, we demonstrated that globular adiponectin (gAcrp) induces both apoptosis and autophagy in human hepatoma cell line (HepG2 cells) and breast cancer cells (MCF-7), as evidenced by increase in caspase-3 activity, Bax, microtubule-associated protein light chain 3-II (LC3 II) protein levels, and autophagosome formation. Interestingly, gene silencing of LC3B, an autophagy marker, significantly enhanced gAcrp-induced apoptosis in both HepG2 and MCF-7 cell lines, whereas induction of autophagy by rapamycin, an mTOR inhibitor, significantly prevented gAcrp-induced apoptosis in hepatoma cells HepG2. Furthermore, modulation of autophagy produced similar effects on gAcrp-induced Bax expression in HepG2 cells. These results implicate that induction of autophagy plays a regulatory role in adiponectin-induced apoptosis of cancer cells, and thus inhibition of autophagy would be a novel promising target to enhance the efficiency of cancer cell apoptosis by adiponectin.