Seunghyung Lee’s research while affiliated with Kangwon National University and other places

Simple Summary Angiogenesis and apoptosis, which contribute to tissue formation and regression, play a critical role in the corpus luteum and tumors. These processes involve angiogenesis- and apoptosis-related factors, including hormones, growth factors, extracellular factors, cytotoxic factors, and cytokines. Thus, we reviewed similar mechanisms regarding the physiological events of the corpus luteum and tumors in animals. Further, we suggested a novel research animal model for finding animal disease mechanisms in the ovary. Abstract The corpus luteum is a temporary endocrine gland formed in the ovary after ovulation, and it plays a critical role in animal reproductive processes. Tumors rely on the development of an adequate blood supply to ensure the delivery of nutrients and oxygen and the removal of waste products. While angiogenesis occurs in various physiological and pathological contexts, the corpus luteum and tumors share similarities in terms of the signaling pathways that promote angiogenesis. In the corpus luteum and tumors, apoptosis plays a crucial role in controlling cell numbers and ensuring proper tissue development and function. Interestingly, there are similarities between the apoptotic-regulated signaling pathways involved in apoptosis in the corpus luteum and tumors. However, the regulation of apoptosis in both can differ due to their distinct physiological and pathological characteristics. Thus, we reviewed the biological events of the corpus luteum and tumors in similar microenvironments of angiogenesis and apoptosis.

The corpus luteum is a temporary endocrine gland formed in the ovary after ovulation, and it plays a critical role in reproductive processes. Tumors rely on the development of an adequate blood supply to ensure the delivery of nutrients and oxygen and the removal of waste products. While angiogenesis occurs in various physiological and pathological contexts, the corpus luteum and tumors share similarities in the signaling pathways that promote angiogenesis. In the corpus luteum and tumors, apoptosis plays a crucial role in controlling cell numbers and ensuring proper tissue development and function. Interestingly, there are similarities in the apoptotic-regulated signaling pathways involved in apoptosis between the corpus luteum and tumors. However, the regulation of apoptosis can differ due to their distinct physiological and pathological characteristics. Thus, we reviewed the biological events of the corpus luteum and tumors in similar microenvironments of angiogenesis and apoptosis for studying novel research methods.

Simple Summary Sperm has oxidative stress during freezing in boar semen. Oxidative stress causes reactive oxygen species to occur and produces and nitric oxide. The viability and motility of sperm are damaged by oxidative stress. We investigated the effects of melatonin and silymarin on reactive oxygen species, nitric oxide production, sperm viability, and motility in frozen–thawed boar semen. As a result, melatonin and silymarin elevated the viability and motility of sperm, and also reactive oxygen species and nitric oxide production decreased. Therefore, we suggested that melatonin and silymarin are beneficial for antioxidants during freezing sperm in pigs. Abstract Sperm during the freezing and thawing process is damaged by oxidative stress. Thus, its antioxidant scavenger is essential for sperm survival and death in frozen–thawed semen. We used melatonin and silymarin in experiments after the dose-dependent experiment. Our study aimed to identify the effect of melatonin and silymarin on the motility and viability of sperm, reactive oxygen species (ROS), and nitric oxide (NO) production in frozen–thawed boar semen. Melatonin and silymarin were treated alone and cotreated in the fresh boar semen. Boar semen was collected using the gloved-hand method from ten crossbred pigs, and samples were used in the experiments. We evaluated sperm viability using SYBR-14 and PI kit, and ROS and NO production were detected by DCF-DA and DAF-2, respectively. The sperm motility was not significantly different between non-treatment and treatment. ROS and NO production in frozen–thawed sperm were decreased by melatonin and silymarin. Moreover, silymarin significantly reduced NO production more than melatonin. Melatonin and silymarin enhanced the viability of sperm. We suggest that melatonin and silymarin are essential antioxidants in semen cryopreservation for protecting sperm damage and maintaining sperm viability. Melatonin and silymarin may be useful antioxidants in freezing boar sperm.

The corpus luteum is a temporary reproductive endocrine structure established from a ruptured follicle wall after ovulation. In the ovarian cycle of ruminant species, the corpus luteum organ undergoes a repeated pattern of specific cellular proliferation, differentiation, and transformation. The corpus luteum encounters several physiological events, including growth, function, and regression throughout its life span. Also, the corpus luteum comprises granulosa and theca cells and endothelial cells, such as luteal steroidogenic cells and luteal endothelial cells. These cells play an important role in the physiology of the corpus luteum and the maintenance and degeneration of the corpus luteum. Furthermore, the role of reproductive hormones in the ovaries is important. Representative hormones include estrogen, progesterone, prostaglandin F2α, and oxytocin. Understanding their functions is important in studying the physiological phenomena and various mechanisms of the corpus luteum in the ovary. Therefore, the following review will discuss the role of reproductive hormones and luteal cell types in the microenvironment of the corpus luteum in the bovine ovary.

Sperm during the freezing and thawing process is damaged by oxidative stress. Thus, its antioxidant scavenger is essential for sperm survival and death in frozen-thawed semen. We used melatonin and silymarin in experiments. Our study aimed to identify the effect of melatonin and silymarin on the motility and viability of sperm, reactive oxygen species (ROS), and nitric oxide (NO) production in frozen-thawed boar semen. Melatonin and silymarin were treated alone and co-treated in the fresh boar semen. Boar semen was collected using the gloved-hand method from ten crossbred pigs, and the age of the experimental ten male pigs was 28.7 ± 3.2 months. We evaluated sperm viability using SYBR-14 and PI kit, and ROS and NO production were detected by DCF-DA and DAF-2, respectively. The sperm motility was not significantly different between non-treatment and treatment. ROS and NO production in frozen-thawed sperm were decreased by melatonin and silymarin (P < 0.05). Moreover, silymarin significantly reduced NO production more than melatonin (P < 0.05). Melatonin (46.37 ± 1.10) and silymarin (46.13 ± 0.80) enhanced the viability of sperm (P < 0.05). We suggest that melatonin and silymarin are essential antioxidants in semen cryopreservation for protecting sperm damage and maintaining sperm viability. Melatonin and silymarin may be useful antioxidants in freezing boar sperm.

Ral-interacting protein 76 (RLIP76) is a potential factor with vascular endothelial growth factor (VEGF) in the corpus luteum and tumor angiogenesis. RLIP76, VEGF, and hypoxia-inducible factor-1 (HIF-1) are proteins that activate angiogenic functions in tumor and endothelial cells. RLIP76 is a main factor in tumor growth, and VEGF is a major endothelial cell protein for angiogenesis. Also, RLIP76 regulates a small GTPase (R-Ras, oncogene) in cell survival, spreading, and migration. HIF-1 is important in the corpus luteum, tumor angiogenesis, and tumor growth. VEGF and HIF-1 regulate the angiogenic function of RLIP76, and RLIP76 controls vascular growth in endothelial and tumor cells. RLIP76, R-Ras, VEGF, and HIF-1 may be useful in the research of corpus luteum and cancer therapy and the study of mechanisms of tumor angiogenesis. This review will help to elucidate the roles of RLIP76/R-Ras and VEGF via HIF-1 in corpus luteum and tumor angiogenesis, tumorigenesis, and the specific regulation of RLIP76 in luteal, tumor, and endothelial cells. Thus, we reviewed the angiogenesis of the corpus luteum and tumor in the ovarian and tumor microenvironment.

Simple Summary Understanding freezing is essential for stable cryopreservation of sperm. In the freezing process, ice crystal is developed from a change of matter from liquid water to solid water. Unfortunately, they tend to make damage of membrane in frozen sperm. From a perspective, sperm membrane damage due to ice crystal formation, magnetized freezing water that has easy supercooling, and the construction of smaller ice crystals because weaken the hydrogen bonds between the water molecules also has an infinite potential to cryopreserve sperm. Here, we applied the magnetization technique for making of freezing extender, and the extenders were used in the freezing process in sperm cryopreservation. As a result, sperm membrane damage was reduced in frozen sperm by a magnetized freezing extender, and we determined that in vitro fertility of frozen sperm by magnetized extender was improved. In conclusion, the magnetization technique would be useful for sperm cryopreservation. Furthermore, the study suggests that the technique has great potential for storing frozen material for biological aspects. Abstract Magnetized water is defined as the amount of water that has passed through a magnet. The magnetic field weakens the hydrogen bonds between the water molecules, leading to the magnetized liquid acquiring special characteristics such as easy supercooling and forming smaller ice crystals. We researched the influences of a magnetized freezing extender on cell membrane damage and in vitro fertilization of boar sperm during cryopreservation. The freezing extenders were passed through 0, 2000, 4000, and 6000 gausses (G) of magnetic devices using a liquid cycling pump system and then used for the sperm freezing process. The damage to plasma, acrosomal, and mitochondrial membranes in frozen-thawed spermatozoa was investigated by flow cytometry, and motility was assessed using the CASA system. The fertility of frozen-thawed sperm was estimated using in vitro fertilization. The damage to the membranes was significantly decreased in the magnetized freezing extender by the 6000 G magnetic field compared to that of the control in frozen-thawed sperm, and motility was increased in the 6000 G group. Although there were no significant differences in the cleavage rates of in vitro fertilized oocytes among the treatment groups, the ratio of blastocyst formation increased in the magnetized freezing extender groups compared with that in the control group. The number of blastocysts was significantly higher in the 4000 G group than in the 0 G group. In conclusion, these results suggest that a magnetized freezing extender could improve the freezability of sperm and the development of oocytes fertilized in vitro with frozen-thawed sperm.

Simple Summary This review aims to discuss the role of the guanosine nucleotide-binding protein (RAS) family in the biological events that occur during the formation and regression of the corpus luteum in the ovary. RAS proteins mediate extracellular signals, transduce through their receptors via multiple signaling pathways, and regulate a wide array of cellular processes. RAS exhibits a notable function in the regulation of vascular endothelial growth factor, fibroblast growth factor, insulin-like growth factor, angiopoietins (ANPT), and hypoxia-inducible factor (HIF). RAS proteins appear to be involved in several factors that are notably associated with the regulation of the corpus luteum. Further research is necessary to enhance our understanding of the role of the RAS family in the ovarian corpus luteum. Abstract The corpus luteum is a temporary endocrine gland in the ovary. In the ovarian cycle, repeated patterns of specific cellular proliferation, differentiation, and transformation occur that accompany the formation and regression of the corpus luteum. Molecular mechanism events in the ovarian microenvironment, such as angiogenesis and apoptosis, are complex. Recently, we focused on the role of RAS protein in the ovarian corpus luteum. RAS protein plays a vital role in the modulation of cell survival, proliferation, and differentiation by molecular pathway signaling. Additionally, reproductive hormones regulate RAS activity in the cellular physiological function of ovarian follicles during pre-ovulatory maturation and ovulation. Thus, we have reviewed the role of RAS protein related to the biological events of the corpus luteum in the ovary.

Simple Summary Luteolysis is an important event in the control of the corpus luteum function in bovines. However, some aspects of the luteolytic mechanism remain unclear. We evaluated changes in cell adhesion in luteal cells during regression of corpus luteum. Bovine luteal theca cells (LTCs) were treated in vitro with Prostaglandin F2 alpha (PGF2α). Cytokeratin, vimentin and desmoplakin proteins in LTCs were disrupted by PGF2α, affecting cell adhesion. These results suggest that PGF2α plays an important function in cell adhesion during the regression of corpus luteum. Abstract Intermediate filaments (IFs) maintain cell–cell adhesions and are involved in diverse cellular processes such as cytokinesis, cell migration and the maintenance of cell structure. In this study, we investigated the influence of prostaglandin F2 alpha (PGF2α) on cytokeratin and vimentin IFs, Rho-associated protein kinase (ROCK), and cell-cell adhesion in bovine luteal theca cells (LTCs). The luteal cells were isolated from bovine corpus luteum (CL), and the LTCs were treated with 0, 0.01, 0.1 and 1.0 mM PGF2α. Cytokeratin, vimentin and desmoplakin proteins were disrupted and the ROCK protein was significantly increased in PGF2α-treated LTCs. In addition, cell–cell adhesion was significantly (p < 0.05) decreased in the PGF2α-induced LTCs compared to control group (0 mM PGF2α). In conclusion, PGF2α affected the adhesion of cell to cell via disruption of desmoplakin, cytokeratin and vimentin, additionally increasing ROCK in bovine LTCs. These results may provide a better understanding of the mechanism of bovine CL regression.

Uterine has a pivotal role in implantation and conceptus development. To prepare a conducive uterine condition for possibly new gestation during the estrous cycle, uterine endometrium undergoes dramatic remodeling. In addition, angiogenesis is an indispensable biological process of endometrium remodeling. Furthermore, essential protein expressions related to important biological processes of endometrium remodeling, which are vascular endothelial growth factor (VEGF), myoglobin (MYG), collagen type IV (COL4), fucosyltransferase IV (FUT4), and cysteine-rich protein 2 (CRP2), were detected in the endometrial tissue reported in many previous studies and recently discovered in histotroph substrates during the estrous cycle. Those proteins, which are liable for provoking new vessel development, cell proliferation, cell adhesion, and cell migration, were expressed higher in the histotroph during the luteal phase than follicular phase. Histotroph proteins considerably contribute to endometrium remodeling during the estrous cycle. To that end, the following review will discuss and highlight the relevant information and evidence of the uterine fluid proteins as endometrial-secreted factors that adequately indicate the potential role of the uterine secretions to be involved in the endometrial remodeling process.