Showing papers by "Sung Hee Baek published in 2021"

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

Abstract: In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.

Roles of lysine-specific demethylase 1 (LSD1) in homeostasis and diseases

Abstract: Lysine-specific demethylase 1 (LSD1) targets mono- or di-methylated histone H3K4 and H3K9 as well as non-histone substrates and functions in the regulation of gene expression as a transcriptional repressor or activator. This enzyme plays a pivotal role in various physiological processes, including development, differentiation, inflammation, thermogenesis, neuronal and cerebral physiology, and the maintenance of stemness in stem cells. LSD1 also participates in pathological processes, including cancer as the most representative disease. It promotes oncogenesis by facilitating the survival of cancer cells and by generating a pro-cancer microenvironment. In this review, we discuss the role of LSD1 in several aspects of cancer, such as hypoxia, epithelial-to-mesenchymal transition, stemness versus differentiation of cancer stem cells, as well as anti-tumor immunity. Additionally, the current understanding of the involvement of LSD1 in various other pathological processes is discussed.

Unraveling the physiological roles of retinoic acid receptor-related orphan receptor α.

Abstract: Retinoic acid receptor-related orphan receptor-α (RORα) is a member of the orphan nuclear receptor family and functions as a transcriptional activator in response to circadian changes. Circadian rhythms are complex cellular mechanisms regulating diverse metabolic, inflammatory, and tumorigenic gene expression pathways that govern cyclic cellular physiology. Disruption of circadian regulators, including RORα, plays a critical role in tumorigenesis and facilitates the development of inflammatory hallmarks. Although RORα contributes to overall fitness among anticancer, anti-inflammatory, lipid homeostasis, and circadian clock mechanisms, the molecular mechanisms underlying the mode of transcriptional regulation by RORα remain unclear. Nonetheless, RORα has important implications for pharmacological prevention of cancer, inflammation, and metabolic diseases, and understanding context-dependent RORα regulation will provide an innovative approach for unraveling the functional link between cancer metabolism and rhythm changes.

KAI1(CD82) is a key molecule to control angiogenesis and switch angiogenic milieu to quiescent state.

Abstract: BACKGROUND Little is known about endogenous inhibitors of angiogenic growth factors. In this study, we identified a novel endogenous anti-angiogenic factor expressed in pericytes and clarified its underlying mechanism and clinical significance. METHODS Herein, we found Kai1 knockout mice showed significantly enhanced angiogenesis. Then, we investigated the anti-angiogenic roll of Kai1 in vitro and in vivo. RESULTS KAI1 was mainly expressed in pericytes rather than in endothelial cells. It localized at the membrane surface after palmitoylation by zDHHC4 enzyme and induced LIF through the Src/p53 pathway. LIF released from pericytes in turn suppressed angiogenic factors in endothelial cells as well as in pericytes themselves, leading to inhibition of angiogenesis. Interestingly, KAI1 had another mechanism to inhibit angiogenesis: It directly bound to VEGF and PDGF and inhibited activation of their receptors. In the two different in vivo cancer models, KAI1 supplementation significantly inhibited tumor angiogenesis and growth. A peptide derived from the large extracellular loop of KAI1 has been shown to have anti-angiogenic effects to block the progression of breast cancer and retinal neovascularization in vivo. CONCLUSIONS KAI1 from PC is a novel molecular regulator that counterbalances the effect of angiogenic factors.

Protocol for isolation of spermatids from mouse testes.

Abstract: Summary Post-meiotic spermatids become spermatozoa through developmental stages during spermiogenesis. Isolation of spermatid fractions is required to examine the change of protein expression during spermiogenesis. Here, we present a simple method to isolate spermatid fractions from mouse testes using unit gravity sedimentation in a BSA density gradient. Isolation of spermatid fractions can be used to analyze changes of transcript or protein during spermiogenesis. For complete details on the use and execution of this protocol, please refer to Kim et al. (2020) .

Epigenetic Regulation in Breast Cancer.

Abstract: Aberrant epigenetic alteration has been associated with development of various cancers, including breast cancer. Since epigenetic modifications such as DNA methylation and histone modification are reversible, epigenetic enzymes, including histone modifying enzymes and DNA methyltransferases, emerge as attractive targets for cancer therapy. Although epi-drugs targeting histone deacetylation or DNA methylation have received FDA approval for cancer therapy, a very modest anti-tumor activity has been observed with monotherapy in clinical studies of breast cancer. To improve efficacy of epi-drugs in breast cancer, combination of epi-drugs with other therapies currently has been investigated. Additionally, basic researches to elucidate molecular causes of cancer should be extensively and intensively conducted in order to find novel epigenetic druggable targets. In this chapter, we summarize how epigenetic regulation affects the development of breast cancer and how to control cancer phenotype by modulating abnormal epigenetic modifications, and then suggest future research directions in epigenetics for breast cancer treatment.