Yoo Jin Lee

Cellular senescence is characterized by the accumulation of reactive oxygen species (ROS), and the selective elimination of excessive ROS remains a key therapeutic challenge. Through antioxidant screening, we identified the pyrazole-based small molecule KB3409 as a potent regulator that reduces ROS levels in senescent fibroblasts. To elucidate its mechanism of action, we performed target identification and found that KB3409 directly binds to valosin-containing protein (VCP) and reticulocalbin-2 (RCN2). Functionally, KB3409 acts as an allosteric activator of VCP, enhancing its ATPase activity and promoting autophagic flux. This activation facilitates the selective clearance of dysfunctional mitochondria, thereby improving mitochondrial quality control and limiting ROS generation at its source. Concurrently, KB3409 modulates RCN2-dependent Ca²⁺ homeostasis, alleviating mitochondrial Ca²⁺ overload and suppressing the opening of the mitochondrial permeability transition pore (mPTP). This coordinated regulation preserves mitochondrial structural integrity and sustains oxidative phosphorylation efficiency. Collectively, these findings identified the novel mechanism in which KB3409 restores mitochondrial function, reduces ROS levels, and functionally reverses cellular senescence phenotypes.

Oxidative stress induced by reactive oxygen species (ROS) is a major contributor to senescence. Although strategies to mitigate ROS are considered crucial for reversing this process, effective interventions remain limited. Extracts from Polygonum cuspidatum (P. cuspidatum) have shown protective effects against senescence by suppressing mitochondrial ROS production; however, the specific bioactive compound responsible for these effects has not yet been identified. This study aimed to identify the active compound in P. cuspidatum responsible for reducing mitochondrial ROS and to elucidate its mechanism of action in rejuvenating senescence. Bioactive components of P. cuspidatum extract were screened for their ability to decrease mitochondrial ROS production. The most potent compound, 2-methoxystypandrone (2-MS), was further examined for its effects on oxidative phosphorylation (OXPHOS) efficiency, mitochondrial ROS generation, and senescence-associated phenotypes in a skin cell-based model. 2-MS was identified as the most effective compound for reducing mitochondrial ROS. Mechanistically, 2-MS enhanced OXPHOS efficiency, thereby minimizing ROS production resulting from inefficient respiration. Reduction in mitochondrial ROS by 2-MS restored senescence-associated phenotypes and rejuvenated senescence by suppressing ROS-driven melanogenesis and inflammatory responses in skin cells. This study identifies 2-MS as a key active ingredient of P. cuspidatum that exerts anti-aging effects through the reduction in mitochondrial ROS generation. These findings highlight 2-MS as a promising therapeutic and cosmetic candidate for rejuvenating senescence.

Reactive oxygen species (ROS) are a major cause of skin aging, leading to oxidation and cleavage of collagen that supports skin structure. Previous studies have demonstrated that Magnolia officinalis var. officinalis (M. officinalis) dry extract reduces mitochondria-enriched ROS production and improves senescence-related phenotypes in vitro. However, its effects on human skin aging have not been investigated. In this study, we conducted both in vitro and clinical trials using an M. officinalis liquid extract, which can be directly applied to cosmetic formulations. The M. officinalis liquid extract restored mitochondrial function and reduced mitochondria-enriched ROS production. Furthermore, M. officinalis liquid extract activated mitophagy, which removes defective mitochondria, a major source of ROS production. In clinical trials, the M. officinalis liquid extract reduced the mean depth of neck wrinkles by 12.73% and the maximum depth by 17.44%. It also reduced the mean roughness (Ra), root mean square roughness (Rq), and maximum depth of roughness (Rmax) by 12.73%, 10.16%, and 10.81%, respectively. Furthermore, the key to the skin-improving effects of M. officinalis liquid extract lies in its ability to increase skin elasticity by 3.76% and brighten skin tone by 0.76%. In conclusion, this study identified a novel mechanism by which M. officinalis liquid extract rejuvenates skin aging. M. officinalis can be utilized as a cosmetic ingredient to improve skin aging and therapeutic candidate for the development of anti-aging treatments.

Background: Reactive oxygen species (ROS) generated due to mitochondrial dysfunction are one of the primary causes of the initiation and progression of senescence. Although reducing mitochondrial ROS production is known as an effective strategy for the treatment of aging, effective components that reduce mitochondrial ROS production or effective treatments that utilize them have not yet been developed. Methods: Screening of plant-generated secondary metabolites to overcome ROS-mediated stress found that ε-viniferin, a dimer of resveratrol, effectively reduces mitochondrial ROS production. Results: ε-viniferin induced efficient electron transport and reduced mitochondrial ROS, a consequence of inefficient electron transport. In addition, ε-viniferin acted as a senolytic that selectively eliminates senescent fibroblasts, thereby restoring mitochondrial function and senescence-associated phenotypes. RNA sequencing analysis revealed that regulator of G protein signaling 16 (RGS16) was an important gene for ε-viniferin-mediated senescence rejuvenation. Upregulation of RGS16 showed similar effects as ε-viniferin in reducing mitochondrial ROS production and restoring mitochondrial function. Conclusions: This study discovered a novel mechanism by which ε-viniferin rejuvenates senescence by lowering ROS production in mitochondria. The novel mechanism will serve as a basis for developing therapeutics that regulate mitochondrial ROS production to treat aging.

Background: Reactive oxygen species (ROS) generated by mitochondrial dysfunction damage cellular organelles and contribute to skin aging. Therefore, strategies to reduce mitochondrial ROS production are considered important for alleviating skin aging, but no effective methods have been identified. Methods: In this study, we evaluated substances utilized as cosmetic ingredients and discovered Camellia sinensis (C. sinensis) as a substance that reduces mitochondrial ROS levels. Results: C. sinensis extracts were found to act as senolytics that selectively kill senescent fibroblasts containing dysfunctional mitochondria. In addition, C. sinensis extracts facilitated efficient electron transport in the mitochondrial electron transport chain (ETC) by increasing the efficiency of oxidative phosphorylation (OXPHOS), thereby reducing mitochondrial ROS production, a byproduct of the inefficient ETC. This novel mechanism of C. sinensis extracts led to the restoration of skin aging and the skin barrier. Furthermore, epigallocatechin gallate (EGCG) was identified as an active ingredient that plays a key role in C. sinensis extract-mediated skin aging recovery. Indeed, similar to C. sinensis extracts, EGCG reduced ROS and improved skin aging in an artificial skin model. Conclusions: Our data uncovered a novel mechanism by which C. sinensis extract reverses skin aging by reducing mitochondrial ROS production via selective senescent cell death/increased OXPHOS efficiency. Our results suggest that C. sinensis extract or EGCG may be used as a therapeutic agent to reverse skin aging in clinical and cosmetic applications.

Genotoxins cause significant damage to the genetic material of aquatic organisms, requiring rapid and accurate assessment. Fish-derived cells sensitive to genotoxins have proven to be a useful tool for measuring genotoxicity, but the long treatment times required for measurement limit their application in situations requiring rapid testing. Previous studies have shown that fish cells can be kept unstarved for up to 6 h using media containing 1% FBS. In this study, the 1% FBS/6 h parameter was used for genotoxicity assessment. Therefore, genotoxicity assessment was performed after only 6 h of genotoxin treatment in a medium containing 1% FBS. The new genotoxicity assessment method provided faster and more accurate genotoxicity data for climbazole and metolachlor than the existing assessment system using the 15% FBS/96 h parameter. Furthermore, these advantages of the new platform enabled the determination of the genotoxicity of various genotoxins, such as dibenz[a,h]anthracene and ethoprophos. In summary, we have developed a genotoxicity assessment that can generate genotoxicity data rapidly and accurately. This new platform will serve as a foundation for rapid genotoxicity assessment of many genotoxins.

One of the major causes of senescence is oxidative stress caused by ROS, which is mainly generated from dysfunctional mitochondria. Strategies to limit mitochondrial ROS production are considered important for reversing senescence, but effective approaches to reduce them have not yet been developed. In this study, we screened the secondary metabolites that plants produce under oxidative stress and discovered sauchinone as a potential candidate. Sauchinone induced mitochondrial function recovery, enabling efficient electron transport within the electron transport chain (ETC). This led to a decrease in ROS production, a byproduct of inefficient electron transport. The reduction in ROS by sauchinone rejuvenated senescence-associated phenotypes. To understand the underlying mechanism by which sauchinone rejuvenates senescence, we carried out RNA sequencing and found VAMP8 as a key gene. VAMP8 was downregulated by sauchinone. Knockdown of VAMP8 decreased mitochondrial ROS levels and subsequently rejuvenated mitochondrial function, which was similar to the effect of sauchinone. Taken together, these studies revealed a novel mechanism by which sauchinone reduces mitochondrial ROS production by regulating mitochondrial function and VAMP8 expression. Our results open a new avenue for aging research to control senescence by regulating mitochondrial ROS production.

Reactive oxygen species (ROS)-mediated damage to macromolecules and cellular organelles is one of the major causes of senescence. Therapeutic strategies that lower ROS levels have been proposed as important treatments for senescence, but effective mechanisms for reducing ROS levels have not been discovered. Here, we aimed to find a combination that has a synergistic effect on ROS reduction using senomorphics known to reduce ROS. Combination treatment with BRAF inhibitor SB590885 and p38 MAPK inhibitor SB203580 showed a synergistic effect on ROS reduction compared to treatment with either drug alone. The synergistic effect of ROS reduction through this combination led to a synergistic effect that restored mitochondrial function and ameliorated senescence-associated phenotypes. To elucidate the underlying mechanism by which the synergistic effect of the two drugs reverses senescence, we performed RNA sequencing and identified metallothionein 2A (MT2A) as a key gene. MT2A was upregulated in response to combination therapy, and overexpression of MT2A led to a decrease in ROS and subsequent recovery of senescence-associated phenotypes, similar to the effects of combination therapy. Taken together, we found a drug combination that showed synergistic effects on ROS reduction, which contributed to the recovery of senescence-associated phenotypes through MT2A gene regulation. This study opens up a new avenue in aging research by demonstrating that combination therapy with existing senomorphics can enhance the ability to reverse senescence and that similar reversal effects can be achieved through gene regulation regulated by combination therapy.

Heavy metals have serious negative effects on various aquatic organisms, and therefore rapid and accurate ecotoxicological assessments of heavy metals are necessary. Fish-derived cells sensitive to heavy metals have been used as valuable tools for ecotoxicological assessments. However, this method requires a minimum toxicity treatment time of 96 h, which limits its use when rapid ecotoxicological assessments are required or ecotoxicological assessments of a large number of toxicants are performed. In this study, these limitations were overcome by adjusting parameters including the concentration of fetal bovine serum (FBS) in the medium and the treatment time of the toxicant. Specifically, we found that the maximum time for fish cells to remain unstarved was 6 h when using a medium containing 1% FBS. We applied both parameters to the ecotoxicological assessment (using a medium containing 1% FBS for the toxicity assessment and treating the toxicant for only 6 h). Surprisingly, these adjusted parameters allowed us to obtain faster and more accurate data than the traditional assessment. This improvement was due to the new assessment conditions that minimized the possibility that the growth-inducing effects of nutrients present in excess in the medium could interfere with the cellular response to the toxicant. The accuracy of this assessment was not limited to measuring the toxicity of heavy metals. In conclusion, we have established an ecotoxicity assessment that can generate rapid and accurate data on heavy metals. This new platform will become the cornerstone of rapid and accurate ecotoxicity assessments of heavy metals.