Invited Mini Review : The serine threonine kinase RIP3: lost and found

( Michael J. Morgan ),( You Sun Kim ) 생화학분자생물학회(구 한국생화학분자생물학회) 2015 BMB Reports Vol.48 No.6

Receptor-interacting protein kinase-3 (RIP3, or RIPK3) is an essential protein in the “programmed”, or “regulated” necrosis cell death pathway that is activated in response to death receptor ligands and other types of cellular stress. Programmed necrotic cell death is distinguished from its apoptotic counterpart in that it is not characterized by the activation of caspases; unlike apoptosis, programmed necrosis results in plasma membrane rupture, thus spilling the contents of the cell and triggering the activation of the immune system and inflammation. Here we discuss findings, including our own recent data, which show that RIP3 protein expression is absent in many cancer cell lines. The recent data suggests that the lack of RIP3 expression in a majority of these deficient cell lines is due to methylation-dependent silencing, which limits the responses of these cells to pro-necrotic stimuli. Importantly, RIP3 expression may be restored in many cancer cells through the use of hypomethylating agents, such as decitabine. The potential implications of loss of RIP3 expression in cancer are explored, along with possible consequences for chemotherapeutic response. [BMB Reports 2015; 48(6): 303-312]

Roles of RIPK3 in necroptosis, cell signaling, and disease

Morgan Michael J.,Kim You-Sun 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Receptor-interacting protein kinase-3 (RIPK3, or RIP3) is an essential protein in the “programmed” and “regulated” cell death pathway called necroptosis. Necroptosis is activated by the death receptor ligands and pattern recognition receptors of the innate immune system, and the findings of many reports have suggested that necroptosis is highly significant in health and human disease. This significance is largely because necroptosis is distinguished from other modes of cell death, especially apoptosis, in that it is highly proinflammatory given that cell membrane integrity is lost, triggering the activation of the immune system and inflammation. Here, we discuss the roles of RIPK3 in cell signaling, along with its role in necroptosis and various pathways that trigger RIPK3 activation and cell death. Lastly, we consider pathological situations in which RIPK3/necroptosis may play a role.

Membrane-bound Fas ligand requires RIP1 for efficient activation of caspase-8 within the death-inducing signaling complex.

Morgan, Michael J,Kim, You-Sun,Liu, Zheng-gang Williams Wilkins 2009 JOURNAL OF IMMUNOLOGY Vol.183 No.5

<P>The serine-threonine kinase RIP1 was originally identified through its ability to bind to the death domain of Fas (CD95). RIP1 has been shown to be recruited to the Fas death-inducing signaling complex (DISC) and is required for the induction of necrotic cell death. In this study, we show that in Jurkat T lymphocytes, RIP1 is also necessary for the most efficient activation of downstream caspases by Fas when treated with membrane-bound Fas ligand, but not with agonistic Abs or cross-linked soluble Fas ligand. RIP1 participates in the Fas-associated death domain protein-mediated recruitment of caspase-8 to the Fas receptor complex in a manner that promotes caspase-8 activation. Cross-linking Abs, such as CH11, bypass the requirement for RIP1 in caspase activation by initiating larger, though less efficient, DISC complexes, while membrane-bound Fas ligand initiates a smaller but more efficient DISC that functions, in part, by effectively incorporating more RIP1 into the complex. Consequently, RIP1 is likely a more integral part of physiological signaling through the Fas/CD95 receptor complex than previously recognized; at least when the signal is mediated by full-length membrane-bound FasL. Cross-linked soluble FasL, which also occurs physiologically, behaves similarly to the CH11 Ab, and may therefore be more likely to initiate nonapoptotic Fas signaling due to less RIP1 in the receptor complex. Thus, agonists that bind the same Fas receptor initiate mechanistically distinct pathways resulting in differential cytotoxicity.</P>

Reactive Oxygen Species in TNF${\alpha}$-Induced Signaling and Cell Death

Morgan, Michael J.,Liu, Zheng-gang Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.30 No.1

TNF${\alpha}$ is a pleotropic cytokine that initiates many downstream signaling pathways, including NF-${\kappa}$B activation, MAP kinase activation and the induction of both apoptosis and necrosis. TNF${\alpha}$ has shown to lead to reactive oxygen species generation through activation of NADPH oxidase, through mitochondrial pathways, or other enzymes. As discussed, ROS play a role in potentiation or inhibition of many of these signaling pathways. We particularly discuss the role of sustained JNK activation potentiated by ROS, which generally is supportive of apoptosis and "necrotic cell death" through various mechanisms, while ROS could have inhibitory or stimulatory roles in NF-${\kappa}$B signaling.

Reactive Oxygen Species in TNF alpha-Induced Signaling and Cell Death

Michael J. Morgan,Zheng-gang Liu 한국분자세포생물학회 2010 Molecules and cells Vol.30 No.1

TNFα is a pleotropic cytokine that initiates many downstream signaling pathways, including NF-κB activation,MAP kinase activation and the induction of both apoptosis and necrosis. TNFα has shown to lead to reactive oxygen species generation through activation of NADPH oxidase,through mitochondrial pathways, or other enzymes. As discussed, ROS play a role in potentiation or inhibition of many of these signaling pathways. We particularly discuss the role of sustained JNK activation potentiated by ROS,which generally is supportive of apoptosis and “necrotic cell death” through various mechanisms, while ROS could have inhibitory or stimulatory roles in NF-κB signaling.

An eponymous history of the anterolateral ligament complex of the knee

( Allison M. Morgan ),( Andrew S. Bi ),( Daniel J. Kaplan ),( Michael J. Alaia ),( Eric J. Strauss ),( Laith M. Jazrawi ) 대한슬관절학회 2022 대한슬관절학회지 Vol.34 No.-

Background: Recent interest has surged in the anterolateral ligament (ALL) and complex (ALC) of the knee. Its existence and role in rotary stability of the knee, particularly in the setting of anterior cruciate ligament (ACL) reconstruction, remains a contentious and controversial topic. Understanding the ALC: We must review our history and recognize the pioneers who pushed our understanding of the ALL forward before it was popularly recognized as a discrete structure. Additionally, given that many eponyms remain in common use related to the ALC, we must standardize our nomenclature to prevent misuse or misunderstanding of terms in the literature. In this review, modern understanding of the anterolateral ligament complex (ALC) is traced to 1829 by exploring eponymous terms first in anatomy and then in surgical technique. Understanding our history and terminology will allow us to better understand the ALC itself. Conclusion: This review aims to provide historical context, define terminology, and provide insight into the clinical relevance of the ALC.

Essential Role for dlg in Synaptic Clustering of Shaker K^+ Channels In Vivo

Tejedor, Francisco J.,Bokhari, Amr,Rogero, Oscar,Gorczyca, Michael,Zhang, Jiangwen,Kim, Eunjoon,Sheng, Morgan,Budnik, Vivian 부산대학교 유전공학연구소 1997 분자생물학 연구보 Vol.13 No.-

The assemblage of specific ion channels and repectors at synaptic sites is crucial for signaling betweem pre-and postsynaptic cells. However, the mechanism by which proteins are targeted to and cluatered at synapses are poorly understood. Here we show that the producct of the Drosophila discs-large gene, DLG, is colocalized with Shaker K^+ chammels, which are clustered at glutamatergic synapses at the larval neuromuscular juction. In heterologous cells. DLG can cluster Shaker-type K^+ channels,and in the yeast two-hybrid system,the DLG PDZ1-2 domains bind directly to the DLG-Shaker interactions are required in vivo for Shaker clustering at the neuromuscular junction. Synaptic cluatering of Shaker channels is abolished not only by mutations in dlg but also by a mutation in Shaker that deletes its C-terminal DLG binding motif. Analyses of various dlg mutant alleles suggest that channel clustering and synaptic targeting functions depend on distinct DLG domains. These studies demonstrate for the first time that DLG plats an important role in sunaptic organization in vivo that correlates with its ability to bind directly to specific menbrane proteins of the synapse.

Regulation of RIP3 protein stability by PELI1-mediated proteasome-dependent degradation

( Han-hee Park ),( Michael J. Morgan ),( Ho Chul Kang ),( You-sun Kim ) 생화학분자생물학회(구 한국생화학분자생물학회) 2018 BMB Reports Vol.51 No.10

Receptor-interacting protein kinase-3 (RIP3 or RIPK3) is a serine-threonine kinase largely essential for necroptotic cell death; it also plays a role in some inflammatory diseases. High levels of RIP3 are likely sufficient to activate necroptotic and inflammatory pathways downstream of RIP3 in the absence of an upstream stimulus. For example, we have previously detected high levels or RIP3 in the skin of Toxic Epidermal Necrolysis patients; this correlates with increased phosphorylation of MLKL found in these patients. We have long surmised that there are molecular mechanisms to prevent anomalous activity of the RIP3 protein, and so prevent undesirable cell death and inflammatory effects when inappropriately activated. Recent discovery that Carboxyl terminus of Hsp 70-Interacting Protein (CHIP) could mediate ubiquitylation- and lysosomedependent RIP3 degradation provides a potential protein that has this capacity. However, while screening for RIP3-binding proteins, we discovered that pellino E3 ubiquitin protein ligase 1 (PELI1) also interacts directly with RIP3 protein; further investigation in this study revealed that PELI1 also targets RIP3 for proteasome-dependent degradation. Interestingly, unlike CHIP, which targets RIP3 more generally, PELI1 preferentially targets kinase active RIP3 that has been phosphorylated on T182, subsequently leading to RIP3 degradation. [BMB Reports: Perspective 2018; 51(10): 484-485]

Methylation-dependent loss of RIP3 expression in cancer represses programmed necrosis in response to chemotherapeutics

Koo, Gi-Bang,Morgan, Michael J,Lee, Da-Gyum,Kim, Woo-Jung,Yoon, Jung-Ho,Koo, Ja Seung,Kim, Seung Il,Kim, Soo Jung,Son, Mi Kwon,Hong, Soon Sun,Levy, Jean M Mulcahy,Pollyea, Daniel A,Jordan, Craig T,Yan Springer Science and Business Media LLC 2015 Cell research Vol.25 No.6

<P>Receptor-interacting protein kinase-3 (RIP3 or RIPK3) is an essential part of the cellular machinery that executes 'programmed' or 'regulated' necrosis. Here we show that programmed necrosis is activated in response to many chemotherapeutic agents and contributes to chemotherapy-induced cell death. However, we show that RIP3 expression is often silenced in cancer cells due to genomic methylation near its transcriptional start site, thus RIP3-dependent activation of MLKL and downstream programmed necrosis during chemotherapeutic death is largely repressed. Nevertheless, treatment with hypomethylating agents restores RIP3 expression, and thereby promotes sensitivity to chemotherapeutics in a RIP3-dependent manner. RIP3 expression is reduced in tumors compared to normal tissue in 85% of breast cancer patients, suggesting that RIP3 deficiency is positively selected during tumor growth/development. Since hypomethylating agents are reasonably well-tolerated in patients, we propose that RIP3-deficient cancer patients may benefit from receiving hypomethylating agents to induce RIP3 expression prior to treatment with conventional chemotherapeutics.</P>

Sensitization of TRAIL-Induced Cell Death by 20(S)-Ginsenoside Rg₃ via CHOP-Mediated DR5 Upregulation in Human Hepatocellular Carcinoma Cells

Lee, Ju-Yeon,Jung, Kyung Hee,Morgan, Michael J.,Kang, Yi-Rae,Lee, Hee-Seung,Koo, Gi-Bang,Hong, Soon-Sun,Kwon, Sung Won,Kim, You-Sun American Association for Cancer Research 2013 Molecular cancer therapeutics Vol.12 No.3

<P>The TRAIL pathway is a potential therapeutic target for anticancer drugs due to selective cytotoxicity in cancer cells. Despite considerable promise, TRAIL or TRAIL receptor agonists have been used thus far with limited success in multiple clinical trials, in part due to acquired TRAIL resistance during chemotherapeutic treatment. Hepatocellular carcinoma (HCC) is a common solid tumor and the third leading cause of cancer-related death worldwide. Classical chemotherapy is not effective for HCC treatment and targeted therapy is limited to sorafenib. Isolated from <I>Panax ginseng</I> CA Meyer, 20(S)-ginsenoside Rg<SUB>3</SUB> is a steroidal saponin with high pharmacologic activity that has been shown to sensitize cells to some chemotherapeutic agents. We investigated the sensitizing effect of Rg<SUB>3</SUB> on TRAIL-induced cell death in HCC cells. We show Rg<SUB>3</SUB> is capable of promoting TRAIL-induced apoptosis in a number of HCC cell lines, including HepG2, SK-Hep1, Huh-7, and Hep3B, but not in normal HL-7702 hepatocytes, indicating that Rg<SUB>3</SUB> sensitization to TRAIL may be specific to cancer cells. Mechanistically, we found that Rg<SUB>3</SUB> upregulates DR5 expression at the transcriptional level. DR5 upregulation in this case is mediated by C/EBP homology protein (CHOP), an important endoplasmic reticulum stress responsive protein. Furthermore, Rg<SUB>3</SUB> is well tolerated and enhances the therapeutic efficacy of TRAIL in mouse xenograft models, suggesting that chemosensitization also occurs <I>in vivo</I>. Taken together, our study identifies Rg<SUB>3</SUB> as a novel anticancer therapeutic agent and supports the further development of Rg<SUB>3</SUB> as a chemosensitizer in combined therapy with TRAIL. <I>Mol Cancer Ther; 12(3); 274–85. ©2012 AACR</I>.</P>