Formation of elongated giant mitochondria in DFO-induced cellular senescence: Involvement of enhanced fusion process through modulation of Fis1

Yoon, Young-Sil,Yoon, Dong-Sun,Lim, In Kyoung,Yoon, Soo-Han,Chung, Hae-Young,Rojo, Manuel,Malka, Florence,Jou, Mei-Jie,Martinou, Jean-Claude,Yoon, Gyesoon Liss 2006 Journal of Cellular Physiology Vol.209 No.2

<P>Enlarged or giant mitochondria have often been documented in aged tissues although their role and underlying mechanism remain unclear. We report here how highly elongated giant mitochondria are formed in and related to the senescent arrest. The mitochondrial morphology was progressively changed to a highly elongated form during deferoxamine (DFO)-induced senescent arrest of Chang cells, accompanied by increase of intracellular ROS level and decrease of mtDNA content. Interestingly, under exposure to subcytotoxic doses of H<SUB>2</SUB>O<SUB>2</SUB> (200 µM), about 65% of Chang cells harbored elongated mitochondria with senescent phenotypes whereas ethidium bromide (EtBr) (50 ng/ml) only reformed the cristae structure. Elongated giant mitochondria were also observed in TGF β1- or H<SUB>2</SUB>O<SUB>2</SUB>-induced senescent Mv1Lu cells and in old human diploid fibroblasts (HDFs). In all senescent progresses employed in this study Fis1 protein, a mitochondrial fission modulator, was commonly downexpressed. Overexpression of YFP-Fis1 reversed both mitochondrial elongation and appearance of senescent phenotypes induced by DFO, implying its critical involvement in the arrest. Finally, we found that direct induction of mitochondrial elongation by blocking mitochondrial fission process with Fis1-ΔTM or Drp1-K38A was sufficient to develop senescent phenotypes with increased ROS production. These data suggest that mitochondrial elongation may play an important role as a mediator in stress-induced premature senescence. J. Cell. Physiol. 209: 468–480, 2006. © 2006 Wiley-Liss, Inc.</P>

Direct activation of TGF-β1 transcription by androgen and androgen receptor complex in Huh7 human hepatoma cells and its tumor in nude mice

Yoon, Gyesoon,Kim, Ji Yeon,Choi, Yang Kyu,Won, Young Suk,Lim, In Kyoung Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of cellular biochemistry Vol.97 No.2

<P>Importance of androgen for promotion of hepatocelullar carcinoma (HCC) has long been supported by clinical and experimental evidences. However, mechanisms involved in the carcinogenesis have not yet been fully elucidated. Moreover, unbalanced expression of TGF-β1 during tumor progression results in prooncogenic rather than growth inhibition. To investigate the effect of androgen on transcriptional regulation of TGF-β1, we isolated rat TGF-β1 promoter, based on our previous report (GenBank AF249327), and examined regulation of its promoter activity by dihydrotestosterone in Huh7, LNCaP, and PC3 cells. Several putative transcription factor-binding sites were found, but no TATA box. When the full-length (−4784 to +68) and variously deleted promoter DNAs were evaluated, the promoter region spanning from −2732 to −1203 showed the highest activity towards dihydrotestosterone in a dose-dependent manner in both Huh7 and PC3 cells with androgen receptor (AR) expression. Putative androgen response sequence half site (5′-TGTCCT-3′) was identified to be located within −1932 to −1927, proved by mutant (5′-AGACCT-3′) analysis and chromatin immunoprecipitation (ChIP) assay. AR mediated upregulation of TGF-β1 expression was confirmed by HCC developed in nude mice with AR-overexpressed Huh7-cells. This work presents in vivo and in vitro evidences of activation of TGF-β1 expression by androgen and AR, and implicates the modulation of hepatocarcinogenesis by AR through the regulation of TGF-β1 expression. J. Cell. Biochem. © 2005 Wiley-Liss, Inc.</P>

TGF β1 induces prolonged mitochondrial ROS generation through decreased complex IV activity with senescent arrest in Mv1Lu cells

Yoon, Young-Sil,Lee, Jae-Ho,Hwang, Sung-Chul,Choi, Kyeong Sook,Yoon, Gyesoon Nature Publishing Group 2005 Oncogene Vol.24 No.11

Transforming growth factor β1 (TGF β1) is a well-characterized cytokine that suppresses epithelial cell growth. We report here that TGF β1 arrested lung epithelial Mv1Lu cells at G1 phase of the cell cycle with acquisition of senescent phenotypes in the presence of 10% serum, whereas it gradually induced apoptosis with lower concentrations of serum. The senescent arrest was accompanied by prolonged generation of reactive oxygen species (ROS) and persistent disruption of mitochondrial membrane potential (ΔΨm). We demonstrated that the sustained ROS overproduction was derived from mitochondrial respiratory defect via decreased complex IV activity and was involved in the arrest. Moreover, we verified that hepatocyte growth factor released Mv1Lu cells from the arrest by protecting mitochondrial respiration, thereby preventing both the ΔΨm disruption and the ROS generation. Our present results suggest the TGF β1-induced senescent arrest as another plausible mechanism to suppress cellular growth in vivo and provide a new biochemical association between the mitochondrial functional defects and the cytokine-induced senescent arrest, emphasizing the importance of maintenance of mitochondrial function in cellular protection from the arrest.Oncogene (2005) 24, 1895–1903. doi:10.1038/sj.onc.1208262 Published online 31 January 2005

A comparative analysis of the cell biology of senescence and aging

Hwang, Eun Seong,Yoon, Gyesoon,Kang, Hyun Tae Springer-Verlag 2009 Cellular and molecular life sciences Vol.66 No.15

p31comet Induces cellular senescence through p21 accumulation and Mad2 disruption.

Yun, Miyong,Han, Young-Hoon,Yoon, Sun Hee,Kim, Hee Young,Kim, Bu-Yeo,Ju, Yeun-Jin,Kang, Chang-Mo,Jang, Su Hwa,Chung, Hee-Yong,Lee, Su-Jae,Cho, Myung-Haing,Yoon, Gyesoon,Park, Gil Hong,Kim, Sang Hoon,L American Association for Cancer Research 2009 Molecular Cancer Research Vol.7 No.3

<P>Functional suppression of spindle checkpoint protein activity results in apoptotic cell death arising from mitotic failure, including defective spindle formation, chromosome missegregation, and premature mitotic exit. The recently identified p31(comet) protein acts as a spindle checkpoint silencer via communication with the transient Mad2 complex. In the present study, we found that p31(comet) overexpression led to two distinct phenotypic changes, cellular apoptosis and senescence. Because of a paucity of direct molecular link of spindle checkpoint to cellular senescence, however, the present report focuses on the relationship between abnormal spindle checkpoint formation and p31(comet)-induced senescence by using susceptible tumor cell lines. p31(comet)-induced senescence was accompanied by mitotic catastrophe with massive nuclear and chromosomal abnormalities. The progression of the senescence was completely inhibited by the depletion of p21(Waf1/Cip1) and partly inhibited by the depletion of the tumor suppressor protein p53. Notably, p21(Waf1/Cip1) depletion caused a dramatic phenotypic conversion of p31(comet)-induced senescence into cell death through mitotic catastrophe, indicating that p21(Waf1/Cip1) is a major mediator of p31(comet)-induced cellular senescence. In contrast to wild-type p31(comet), overexpression of a p31 mutant lacking the Mad2 binding region did not cause senescence. Moreover, depletion of Mad2 by small interfering RNA induced senescence. Here, we show that p31(comet) induces tumor cell senescence by mediating p21(Waf1/Cip1) accumulation and Mad2 disruption and that these effects are dependent on a direct interaction of p31(comet) with Mad2. Our results could be used to control tumor growth.</P>

Co-treatment with hepatocyte growth factor and TGF-β1 enhances migration of HaCaT cells through NADPH oxidase-dependent ROS generation

Nam, Hyun-Ja,Park, Yun-Yeon,Yoon, Gyesoon,Cho, Hyeseong,Lee, Jae-Ho Nature Publishing Group 2010 Experimental and molecular medicine Vol.42 No.4

Involvement of Autophagy in Oncogenic K-Ras-induced Malignant Cell Transformation

Kim, Min-Jung,Woo, Soo-Jung,Yoon, Chang-Hwan,Lee, Jae-Seong,An, Sungkwan,Choi, Yung-Hyun,Hwang, Sang-Gu,Yoon, Gyesoon,Lee, Su-Jae American Society for Biochemistry and Molecular Bi 2011 The Journal of biological chemistry Vol.286 No.15

<P>Autophagy has recently been implicated in both the prevention and progression of cancer. However, the molecular basis for the relationship between autophagy induction and the initial acquisition of malignancy is currently unknown. Here, we provide the first evidence that autophagy is essential for oncogenic K-Ras (K-Ras<SUP>V12</SUP>)-induced malignant cell transformation. Retroviral expression of K-Ras<SUP>V12</SUP> induced autophagic vacuole formation and malignant transformation in human breast epithelial cells. Interestingly, pharmacological inhibition of autophagy completely blocked K-Ras<SUP>V12</SUP>-induced, anchorage-independent cell growth on soft agar. Both mRNA and protein levels of ATG5 and ATG7 (autophagy-specific genes 5 and 7, respectively) were increased in cells overexpressing K-Ras<SUP>V12</SUP>. Targeted suppression of ATG5 or ATG7 expression by short hairpin (sh) RNA inhibited cell growth on soft agar and tumor formation in nude mice. Moreover, inhibition of reactive oxygen species (ROS) with antioxidants clearly attenuated K-Ras<SUP>V12</SUP>-induced ATG5 and ATG7 induction, autophagy, and malignant cell transformation. MAPK pathway components were activated in cells overexpressing K-Ras<SUP>V12</SUP>, and inhibition of JNK blunted induction of ATG5 and ATG7 and subsequent autophagy. In addition, pretreatment with antioxidants completely inhibited K-Ras<SUP>V12</SUP>-induced JNK activation. Our results provide novel evidence that autophagy is critically involved in malignant transformation by oncogenic K-Ras and show that reactive oxygen species-mediated JNK activation plays a causal role in autophagy induction through up-regulation of ATG5 and ATG7.</P>

Oncogenic Ras signals through activation of both phosphoinositide 3-kinase and Rac1 to induce c-Jun NH2-terminal kinase-mediated, caspase-independent cell death.

Byun, Joo-Yun,Kim, Min-Jung,Yoon, Chang-Hwan,Cha, Hyukjin,Yoon, Gyesoon,Lee, Su-Jae American Association for Cancer Research 2009 Molecular cancer research Vol.7 No.9

<P>Cells avert the development of malignancy in response to deregulated oncogene expression by activating a regulated cell death pathway. However, the molecular mechanism underlying this oncogene-induced cellular death process remains unclear. Here, we show that retroviral expression of oncogenic H-ras induced cell death in a caspase-independent manner in normal cells. Inhibition of c-Jun NH2-terminal kinase (JNK) by pretreatment with SP600125 or a dominant-negative form of JNK blocked cell death. Rac1 and phosphoinositide 3-kinase (PI3K) were activated in cells overexpressing oncogenic H-ras. Inhibition of Rac1 with RacN17, a dominant-negative form of Rac1, attenuated oncogenic H-ras-induced JNK activation and subsequent cell death. Interestingly, inhibition of PI3K with LY294002 or by small interfering RNA-mediated knockdown of PI3K p85 or p110 subunits also clearly attenuated JNK activation and cell death. No cross talk was observed between Rac1 and PI3K, indicating that these pathways operate in parallel. Our findings show that JNK is necessary for oncogenic H-ras-induced, caspase-independent cell death, and that both PI3K and Rac1 activities are required for JNK activation and cell death. Determining the molecular mechanisms that mediate cell death responses to deregulated oncogenes provides a more refined understanding of cellular disposal processes in normal cells and increases our appreciation of these events as a mechanism for protecting against malignant progression.</P>

Perspective : Mitochondrial defect-responsive gene signature in liver-cancer progression

( Young Kyoung Lee ),( Hyun Goo Woo ),( Gyesoon Yoon ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.11

Mitochondrial respiratory defect is a key bioenergetics feature of hepatocellular carcinoma (HCC) cells. However, their involvement and roles in HCC development and progression remain unclear. Recently, we identified 10 common mitochondrial defect (CMD) signature genes that may be induced by retrograde signaling-mediated transcriptional reprogramming in response to HCC mitochondrial defects. HCC patients with enriched expression of these genes had poor prognostic outcomes, such as shorter periods of overall survival and recurrence- free survival. Nuclear protein 1 (NUPR1), a key transcription regulator, was up-regulated by Ca++-mediated retrograde signaling. NUPR1-centric network analysis and a biochemical promoter-binding assay demonstrated that granulin (GRN) is a key downstream effector of NUPR1 for the regulation of HCC cell invasiveness; association analysis of the NUPR1-GRN pathway supported this conclusion. Mitochondrial respiratory defects and retrograde signaling thus play pivotal roles in HCC progression, highlighting the potential of the NUPR1-GRN axis as a novel diagnostic marker and therapeutic target for HCC. [BMB Reports 2015; 48(11): 597-598]

Mitochondrial dysfunction by complex II inhibition delays overall cell cycle progression via reactive oxygen species production

Byun, Hae-Ok,Kim, Hee Young,Lim, Jin J.,Seo, Yong-Hak,Yoon, Gyesoon Wiley Subscription Services, Inc., A Wiley Company 2008 Journal of cellular biochemistry Vol.104 No.5

<P>Mitochondrial complex II defect has recently been implicated in cellular senescence and in the ageing process of which a critical phenotype is retardation and arrest of cellular growth. However, the underlying mechanisms of how complex II defect affects cellular growth, remain unclear. In this study, we investigated the effect of complex II inhibition using a subcytotoxic dose (400 µM) of 2-thenoyltrifluoroacetone (TTFA), a conventional complex II inhibitor, on cell cycle progression. TTFA (400 µM) directly decreased KCN-sensitive cellular respiration rate to 67% of control and disrupted the mitochondrial membrane potential. In contrast to other respiratory inhibitors such as rotenone, antimycin A, and oligomycin, TTFA prolonged the duration of each phase of the cell cycle (G1, S, and G2/M) equally, thereby delaying overall cell cycle progression. This delay was accompanied by a biphasic increase of reactive oxygen species (ROS) and concurrent glutathione oxidation, in addition to a slight decrease in the cellular ATP level. Finally, the delay in cell cycle progression caused by TTFA was proved to be mainly due to ROS overproduction and subsequent oxidative stress, as evidenced by its reversal following pretreatment with antioxidants. Taken together, these results suggest that an overall delay in cell cycle progression due to complex II defects may contribute to ageing and degenerative diseases via inhibition of cellular growth and proliferation without arrest at any specific phase of the cell cycle. J. Cell. Biochem. 104: 1747–1759, 2008. © 2008 Wiley-Liss, Inc.</P>