Search Results (1,688)

Protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs) constitute two major superfamilies of signaling enzymes in mammals, displaying comparable genomic representation (~100 genes each) and numbers of catalytically active proteins (~80 enzymes each). Both families include receptor and non-receptor forms; however, their distributions differ substantially. PTKs comprise 58 receptor tyrosine kinases (RTKs), whereas PTPs include only 21 receptor protein tyrosine phosphatases (RPTPs). Despite these differences, RTKs and RPTPs share a common structural organization consisting of (i) an extracellular domain responsible for ligand recognition; (ii) a single-pass transmembrane domain anchoring the receptor to the plasma membrane; and (iii) an intracellular catalytic domain containing either kinase or phosphatase activity. Signal transduction mediated by RTKs and RPTPs generally depends on ligand binding and receptor dimerization. Remarkably, although these receptor families regulate signaling through fundamentally opposite molecular mechanisms, both are essential for controlling cell proliferation, adhesion, migration, differentiation, development, and survival. RTKs have been more extensively characterized than RPTPs; nevertheless, both receptor classes function as critical regulators of intercellular and intracellular communication pathways. Moreover, their membrane-associated localization makes them attractive targets for therapy in multiple human diseases, particularly cancer and neurological disorders. Full article

Regular exercise mediates inter-tissue communication between skeletal muscle and the immune system through skeletal muscle-derived secretory factors, providing an important molecular basis for the beneficial effects of exercise on chronic inflammation, metabolic dysregulation, and impaired tissue repair. As key effector cells of the innate immune system, macrophages do not simply conform to a dichotomous classification of classically activated M1 macrophages and alternatively activated M2 macrophages; rather, their functional states constitute a dynamic spectrum shaped by exercise load, recovery time window, tissue microenvironment, and disease context. This review focuses on recent advances in exercise-induced skeletal muscle secretory factors involved in macrophage functional remodeling. Representative signals, including interleukin-6 (IL-6), irisin, meteorin-like protein (METRNL), fibroblast growth factor 21 (FGF21), oncostatin M (OSM), decorin, myostatin, chemokines, and extracellular vesicles, are systematically summarized in terms of their exercise responsiveness, evidence for skeletal muscle origin, and evidence supporting macrophage regulation. Based on these dimensions, an evidence-strength grading framework is further proposed. Moreover, this review integrates key signaling axes, including glycoprotein 130 (gp130)/Janus kinase (JAK)/signal transducer and activator of transcription (STAT), signal transducer and activator of transcription 6 (STAT6)/peroxisome proliferator-activated receptor gamma (PPARγ), AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (Nrf2)/nuclear factor kappa B (NF-κB), transforming growth factor beta (TGF-β)/Smad, and chemokine receptor pathways, to explain how exercise-induced secretory networks participate in the dynamic regulation of the macrophage functional spectrum through immune cell recruitment, inflammatory clearance, immunometabolic reprogramming, matrix remodeling, and repair-niche formation. Current evidence indicates the translational potential of exercise-induced skeletal muscle secretory factors in skeletal muscle repair, metabolic inflammation, aging-related functional decline, and cancer rehabilitation. However, this field still faces several major challenges, including insufficient tracing of skeletal muscle-derived signals, limited direct causal validation, a lack of human tissue-level evidence, and unclear exercise dose–response relationships. Future studies should combine tissue-specific genetic interventions, receptor blockade, single-cell and spatial omics, metabolic flux analysis, and standardized human exercise interventions to further clarify the mechanistic basis and application boundaries of exercise-induced skeletal muscle–macrophage communication, thereby providing a theoretical foundation for precision exercise prescription and chronic inflammation intervention. Full article

Background/Objectives: Achondroplasia is the most common genetic skeletal dysplasia associated with disproportionate short stature and is primarily caused by gain-of-function variants in the fibroblast growth factor receptor 3 (FGFR3) gene. Constitutive FGFR3 activation disrupts growth plate homeostasis and endochondral ossification through complex alterations in chondrocyte proliferation, differentiation, hypertrophy, extracellular matrix organization, and intracellular signaling. The increasing understanding of these mechanisms has enabled the transition from exclusively supportive management toward disease-modifying and precision-based therapeutic strategies. This narrative review aimed to critically synthesize current evidence on the genetic basis, molecular pathogenesis, growth plate abnormalities, and current and emerging targeted therapies in achondroplasia. Methods: A narrative literature review was conducted using PubMed/MEDLINE, Scopus, and Web of Science Core Collection, with Google Scholar used as a supplementary source, together with manual screening of the reference lists of relevant original studies, clinical trials, reviews, consensus documents, and clinical guidelines. The principal literature search covered publications from January 2010 to March 2026, while selected seminal primary studies published before 2010 were included when necessary to document the original identification of pathogenic FGFR3 variants and foundational mechanisms of FGFR3-mediated growth plate regulation. Particular emphasis was placed on FGFR3 variants, receptor activation mechanisms, growth plate dysfunction, intracellular signaling pathways, vosoritide, C-type natriuretic peptide-based therapies, FGFR3 inhibitors, ligand–receptor blockade, drug repurposing, Wnt/β-catenin modulation, and gene-based therapeutic approaches. Results: Achondroplasia is characterized by marked molecular homogeneity, with the recurrent p.Gly380Arg substitution accounting for most cases. Mutant FGFR3 displays sustained activity through partial ligand independence, enhanced receptor dimerization and kinase activation, increased receptor stability, and reduced degradation. Excessive signaling through MAPK/ERK, STAT, PI3K/AKT, IHH/PTHrP, and related pathways impairs chondrocyte proliferation and hypertrophic differentiation, alters extracellular matrix turnover, disrupts primary cilium function, and reduces longitudinal bone growth. Vosoritide provides clinical proof that pharmacological modulation of FGFR3-related signaling can improve growth velocity. Additional therapeutic strategies under clinical or preclinical investigation include long-acting CNP analogues, selective FGFR inhibitors, decoy receptors, RNA aptamers, repurposed drugs, Wnt/DKK1 pathway modulation, and gene- or enhancer-targeted interventions. Conclusions: Achondroplasia is increasingly understood as a disorder of dysregulated growth plate signaling rather than solely a condition of reduced stature. Although vosoritide has established the feasibility of disease-modifying treatment, substantial uncertainty remains regarding final adult height, skeletal proportionality, cranio-spinal development, orthopedic outcomes, and long-term safety. Future progress will depend on mechanistically informed therapeutic combinations, improved biomarkers, advanced cellular and animal models, and long-term clinical and real-world evidence. Full article

Vascular calcification (VC) is a major complication of chronic kidney disease (CKD) that is strongly associated with cardiovascular mortality. While indoxyl sulfate (IS), a protein-bound uremic toxin, has been implicated in the progression of VC, the underlying molecular mechanisms remain unclear. We investigated the procalcific effects of IS using a two-step nephrectomy-induced CKD mouse model and cultured vascular smooth muscle cells. In vivo, progressive renal impairment was associated with elevated circulating IS levels and enhanced VC. In vitro, IS dose- and time-dependently induced calcium deposition, increased reactive oxygen species (ROS) production, and upregulated osteogenic markers, including runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2), and osteocalcin (OCN), whereas N-acetyl-L-cysteine (NAC) partially attenuated IS-induced ROS accumulation and cell injury. Mechanistically, IS exposure activated extracellular signal-regulated kinase (ERK) and Wnt/β-catenin signaling while suppressing nuclear factor erythroid 2-related factor 2 (Nrf2)-related antioxidant responses, as reflected by reductions in the phosphorylated Nrf2 (pNrf2) to total Nrf2 and heme oxygenase-1 (HO-1) expression. Pharmacological inhibition of ERK and Wnt/β-catenin signaling attenuated IS-induced osteogenic responses. These findings indicate that IS promotes VC in association with increased oxidative stress, activation of ERK and Wnt/β-catenin signaling, and impaired Nrf2-related antioxidant defense. These integrated findings provide mechanistic insight into IS-associated VC and highlight oxidative stress-related signaling networks as potential therapeutic targets in CKD. Full article

Ultraviolet B (UVB) irradiation is a major environmental factor contributing to skin photoaging by inducing oxidative stress, apoptosis, inflammation, and extracellular matrix degradation in dermal fibroblasts. This study investigated the photoprotective effects of Thua Nao, a Thai fermented soybean, against UVB-induced human dermal fibroblast damage, and explored its underlying mechanisms. The dichloromethane fraction of Thua Nao (TN-DC) most effectively mitigated UVB-induced cell death. HPLC analysis identified daidzein and glycitein as the major constituent isoflavones in TN-DC that protect fibroblasts against UVB-induced cellular damage. Mechanistically, they reduced apoptosis by suppressing caspase-9 and poly (ADP-ribose) polymerase activation and preserving mitochondrial membrane potential. Additionally, they suppressed inflammatory mediators including interleukin-6, interleukin-8, inducible nitric oxide synthase, and cyclooxygenase-2 and prevented collagen loss. These protective outcomes correlated with decreased intracellular reactive oxygen species and upregulated endogenous antioxidant enzymes including superoxide dismutase 1 and heme oxygenase. Signaling pathway analysis revealed that TN-DC activated the pro-survival extracellular-signal-regulated kinase and Akt pathways in UVB-exposed cells. Conversely, daidzein and glycitein selectively attenuated c-Jun N-terminal kinase activation, downregulating downstream pro-inflammatory cytokines and mediators. Collectively, these findings demonstrate that TN-DC protects human dermal fibroblasts against UVB-induced photoaging primarily by enhancing endogenous antioxidant defense, thereby preserving cellular homeostasis through coordinated regulation of oxidative stress-responsive signaling pathways. Full article

The kallikrein–kinin system (KKS) and the kallikrein-related peptidase (KLK) family are interconnected proteolytic networks that regulate inflammatory signaling, vascular permeability, extracellular matrix remodeling, and tissue barrier dynamics. Beyond their classical vasoactive and inflammatory functions, accumulating evidence indicates that kinin peptides, including bradykinin, Lys-bradykinin, and their des-Arg⁹ metabolites, together with selected KLKs, modulate cell–cell and cell–extracellular matrix adhesion. Through B1 and B2 kinin receptor activation, the KKS influences endothelial adhesion molecule expression, leukocyte integrin activation, neutrophil trafficking, focal adhesion kinase/Src signaling, cytoskeletal remodeling, and matrix metalloproteinase activity. In parallel, KLKs directly reshape the adhesive microenvironment by cleaving junctional proteins, including E-cadherin and desmosomal components, and extracellular matrix substrates such as fibronectin, laminin, vitronectin, fibrinogen, and collagens. These coordinated actions affect epithelial and endothelial barrier integrity, leukocyte transmigration, angiogenesis, fibrosis, epithelial–mesenchymal transition, tumor cell migration, invasion, and metastatic dissemination. This review critically summarizes current evidence linking KKS and KLK activity to adhesion-dependent processes in inflammation and cancer, emphasizing how proteolytic signaling may either preserve tissue homeostasis or promote pathological barrier disruption depending on cellular context, receptor expression, protease activity, and microenvironmental cues. Understanding these mechanisms may refine the identification of adhesion-related biomarkers and support the development of targeted therapeutic strategies for inflammatory disorders, fibrotic remodeling, and cancer progression. Full article

The application of natural bioactive compounds in cosmeceutical products, particularly as skin-lightening agents, has received increasing interest. Caulerpa racemosa, a green macroalga of the Chlorophyta division, contains beneficial nutrients that are applicable as food and cosmeceutical ingredients. This study investigated the in vitro effect of the ethanolic extract of C. racemosa (CR) on regulation of melanogenic-related signaling and gene expression in SK-MEL-5 human melanoma-derived cells. Identification of bioactive components revealed that catechin, rutin, and quercetin as flavonoid contents were found in CR extract, analyzed using HPLC. The expressions of microphthalmia-associated transcription factor (MITF), extracellular signal-regulated kinase (ERK) signaling molecules, and melanogenic-related molecules were analyzed via Western blotting and qPCR. The CR extract treatment applied to SK-MEL-5 cells decreased the MITF protein expression level, which correlated with increased pERK expression, and no cytotoxic effect was observed. The subsequent treatment reduced the expression of melanogenesis-related genes (TYR, TYRP1, MC1R, and DCT) that were downstream targets of MITF. This study provides preliminary evidence that CR extract may modulate melanogenesis-related signaling. However, the specific bioactive compounds responsible for the observed effects remain to be identified, as the extract contains a complex mixture of phytochemicals. Further fractionation studies are needed to pinpoint the active constituents. The variability of extract composition due to seasonal and geographical factors should be considered for future standardization. Full article

Decreased osteoblast differentiation contributes to bone loss induced by mechanical unloading. However, the underlying mechanism is still unclear. We previously found that microtubule actin crosslinking factor 1 (MACF1), a key cytoskeletal protein, plays an important role in regulating osteoblast differentiation, while the role of MACF1 in mechanical unloading suppressing osteoblast differentiation remains unclear. Here, an MACF1-knockdown (MACF1-KD) osteoblast cell line and primary osteoblasts were subjected to mechanical unloading conducted by a random positioning machine (RPM). Osteoblast differentiation was evaluated by alkaline phosphatase (ALP) staining and real-time PCR. F-actin distribution was examined by immunofluorescence staining. Western blot was adopted to detect the protein levels. Moreover, cytochalasin B and PD98059 were applied to disrupt F-actin and inhibit extracellular signal-regulated kinase (ERK) activity, respectively, to confirm the mechanism. The results show that MACF1 is significantly downregulated in osteoblasts by mechanical unloading together with decreased osteoblast differentiation. MACF1-KD osteoblasts exhibit reduced differentiation capacity and are insensitive to mechanical unloading. Mechanistically, MACF1 mediates the suppression of mechanical unloading on osteoblast differentiation by regulating F-actin distribution and the downstream ERK/Runx2 signaling. Furthermore, F-actin disruption and ERK inhibition assays confirm that MACF1 mediates the impairment of mechanical unloading on osteoblast differentiation via the F-actin/ERK/Runx2 axis. In conclusion, this study reveals MACF1 as a mechanotransduction mediator for mechanical unloading, inhibiting osteoblast differentiation via F-actin/ERK/Runx2, and contributes to a novel mechanistic insight of cell mechanotransduction. Full article

The renin–angiotensin–aldosterone system (RAAS) is a fundamental regulator of blood pressure, electrolyte balance, fluid homeostasis, and tissue remodeling. The discovery of the prorenin receptor (PRR), the protein encoded by the ATP6AP2 gene, has substantially expanded the classical RAAS paradigm by demonstrating that prorenin possesses biological activity beyond its proteolytic conversion to renin. Binding of renin or prorenin to PRR enhances local angiotensin II (Ang II) generation while simultaneously initiating Ang II-independent intracellular signaling pathways, including ERK1/2, mitogen-activated protein kinases, PI3K/Akt, transforming growth factor-β, and nuclear factor-κB, thereby promoting inflammation, oxidative stress, fibrosis, cellular proliferation, and extracellular matrix accumulation. Beyond its receptor function, PRR serves as an essential accessory component of the vacuolar H+-ATPase (V-ATPase) complex, regulating vesicular acidification, lysosomal function, autophagy, protein trafficking, cellular metabolism, and Wnt/β-catenin signaling. These diverse functions explain its indispensable role in embryonic development, cell differentiation, and tissue homeostasis, as evidenced by the embryonic lethality associated with ATP6AP2 gene deficiency. PRR is predominantly localized to intracellular organelles, including the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, and autophagic vesicles, although membrane-bound and soluble forms also contribute to physiological and pathological processes. Increasing evidence implies dysregulated PRR signaling in the development and progression of hypertension, cardiovascular disease, chronic kidney disease, diabetes, obesity, and other metabolic disorders. This review summarizes current advances in PRR and soluble PRR biology, discusses unresolved mechanistic and translational questions, and evaluates the potential of PRR as a biomarker and therapeutic target for cardiovascular, renal, and metabolic diseases. Full article

Background/Objectives: Fibroblast-like synoviocytes (FLS) are key contributors to rheumatoid arthritis (RA) pathogenesis, driving synovial inflammation, cartilage degradation, bone erosion and disease persistence. Recent advances have revealed substantial FLS heterogeneity, with distinct fibroblast subsets exhibiting different pathogenic roles within the rheumatoid synovium. Although disease-modifying antirheumatic drugs (DMARDs) constitute the cornerstone of RA treatment, their effects on FLS have not been comprehensively characterised. This review summarises and compares the effects of conventional synthetic DMARDs (csDMARDs), biologic DMARDs (bDMARDs) and targeted synthetic DMARDs (tsDMARDs) on RA-FLS. Methods: A non-systematic literature review was conducted to identify studies investigating the effects of DMARDs on RA-FLS. Studies evaluating the impact of csDMARDs, bDMARDs and tsDMARDs on FLS proliferation, apoptosis, migration, invasion, inflammatory mediator production, extracellular matrix remodelling and osteoclastogenic activity were included. Results: Available evidence indicates that DMARDs modulate multiple pathogenic functions of RA-FLS. Methotrexate, leflunomide, hydroxychloroquine and sulfasalazine regulate inflammatory signalling, apoptosis, autophagy and ferroptosis. Biologic agents, particularly tumour necrosis factor alpha (TNF-α) and interleukin (IL)-6 receptor inhibitors, suppress cytokine production, matrix metalloproteinase expression, osteoclastogenic signalling and FLS migration. Targeted synthetic DMARDs, particularly Janus kinase inhibitors (JAKis), exhibit broad activity across inflammatory, angiogenic, metabolic and tissue-destructive pathways. Despite their distinct molecular targets, all DMARD classes ultimately attenuate key pathogenic FLS functions associated with synovial inflammation and joint destruction. Conclusions: JAKis exert broad effects on RA-FLS function in vitro, likely reflecting their ability to block multiple cytokine-dependent signalling pathways. However, clinical evidence linking these effects to patient outcomes remains limited; further validation is therefore required. Full article

Far-infrared radiation (FIR) may influence vascular endothelial function, but its time-dependent molecular effects in adult arterial endothelial cells remain incompletely defined. We investigated FIR-induced responses in human femoral artery endothelial cells (HFAECs) using transcriptomic, proteomic, and phosphoproteomic analyses with three biological replicates per condition. Transcriptomic profiling 3 h after 30 min of FIR irradiation identified 424 differentially expressed genes (210 upregulated and 214 downregulated) among 16,081 genes, including endothelial-protective, nitric oxide-related, oxidative-stress, and heat-shock response genes. Proteomic analysis identified 13 differentially abundant proteins immediately after irradiation and 23, 75, and 61 proteins at 6, 12, and 24 h, respectively. These temporal changes involved mitogen-activated protein kinase kinase/extracellular signal-regulated kinase signaling, vascular maturation, cytoskeletal organization, cell polarity, calcium/nitric oxide regulation, and stress adaptation. Phosphoproteomic analysis identified 12, 10, and 53 phosphorylation-related changes at 6, 12, and 24 h, respectively, indicating progression from actin and adhesion remodeling to junctional reorganization, focal adhesion maturation, and mechanosensing. Network analysis identified caveolin-1, β-catenin, and lamin B1 as hubs in a Rho guanosine triphosphatase-related module. Collectively, FIR induced a coordinated endothelial adaptive molecular response in HFAECs; functional studies are required to determine whether these changes enhance vascular repair. Full article

Extracellular stimuli, including hormones, growth factors and nutrients in the milieu of cells often initiate intracellular changes via signaling pathways, of which the cyclic 5′, 3′-adnosine monophosphate (cAMP)-dependent protein kinase (PKA) signaling pathway is prototypical. Research in the past decades has demonstrated that PKA plays versatile roles during cell proliferation and differentiation, mainly through phosphorylating a plethora of protein substrates by its protein kinase activity. Studies using model systems including yeast, neurons and mammalian germ cells indicate that PKA functionality is regulated by not only the cell-type-specific expression of its regulatory and catalytic subunits, but also the spatiotemporal distribution of its binding proteins and secondary messengers. How PKA elicits its functional specificity in a spatiotemporal manner constitutes fundamental mechanisms that regulate development, aging and regeneration. In this review, we first summarize basic aspects that drive the functional diversity of PKA and then focus on the less studied regulatory roles of PKA during synthesis of cellular proteins, the functional units of the cell. Direct links between PKA signaling and protein synthesis machinery are yet to be fully characterized. We anticipate that research in this area, combining model systems and newly developed methodologies, will continue to deepen our understanding of animal development and the etiology of human diseases. Full article

Aortic dissection (AD) is a severe vascular condition marked by abrupt onset, rapid progression, and heightened mortality rates. Vascular smooth muscle cells (VSMCs), the predominant cellular component of the arterial media, are essential for maintaining the structural integrity and functionality of blood vessels. Recent studies have associated Cysteine-rich protein 2 (CSRP2) with the advancement of several vascular diseases. The involvement of CSRP2 in AD progression is unclear. Aortic tissues were collected from patients for RNA sequencing and histological analysis. A mouse model of AD was created using β-aminopropionitrile monofumarate (BAPN), while VSMC phenotypic switching was induced by platelet-derived growth factor BB (PDGF-BB). Adeno-associated virus vector was used to overexpress CSRP2 in aorta. A variety of histopathological assays and biochemical analyses were applied to determine gene and protein expression patterns as well as uncover underlying molecular mechanisms. CSRP2 was significantly downregulated in both human and murine AD, and CSRP2 gene overexpression dramatically reduced BAPN-induced AD incidence and prevented animal mortality. CSRP2 could preserve a contractile VSMC phenotype, even though under PDGF-BB stimulation. Mechanistically, our findings reveal that CSRP2 directly interacts with p130 Crk-associated substrate (p130Cas; also known as BCAR1) and reduces its phosphorylation, which in turn inhibits the activation of extracellular signal-regulated kinase (ERK) signaling pathways, thereby preventing VSMC phenotypic switching induced by PDGF-BB. Our findings identify CSRP2 as a novel regulator of VSMC phenotypic modulation and a significant modulator of AD development, suggesting its potential as a target for early intervention for AD. Full article

Syntaphilin (SNPH), initially considered a neuron-specific protein, has recently been found to be widely expressed across various cancers. Mechanistically, SNPH inhibits mitochondrial transport to the cortical cytoskeleton, thereby suppressing cancer cell migration and metastasis. Although SNPH is known to participate in the metastatic progression of multiple malignancies, its precise underlying mechanism remains obscure. In this study, we investigated the role of SNPH in the epithelial–mesenchymal transition (EMT) and invasiveness of gastric cancer cells. Knockdown of SNPH in SNU-638 gastric cancer cells significantly enhanced their migratory and invasive capacities by approximately 1.4-fold and 2.5-fold, respectively. This knockdown concurrently increased focal adhesion kinase (FAK) phosphorylation, upregulated the EMT marker vimentin, and increased the expression of key EMT-related transcription factors, including Snail, Slug, and Twist. Furthermore, SNPH depletion induced the phosphorylation of nuclear factor kappa B (NF-κB), a transcription factor regulating matrix metalloproteinase-9 (MMP-9), which subsequently upregulated MMP-9 mRNA expression. This cascade promotes extracellular matrix degradation, thereby increasing metastatic potential. Notably, these phenotypic and molecular changes were completely reversed upon SNPH overexpression in SNU-638 cells. Taken together, our results demonstrate that SNPH deficiency enhances the migration and metastatic potential of gastric cancer cells by driving EMT and invasion via the FAK/NF-κB/MMP-9 signaling pathway. Consequently, we propose that SNPH represents a novel biomarker and a promising therapeutic target for mitigating gastric cancer metastasis. Full article

Background/Objectives: Persicaria senticosa (Meisn.) H.Gross (PS) has anti-photoaging, anti-inflammatory, and antioxidant activities, but the anti-pigmentation potential of the PS flower absolute (PSFAb) remains largely unexplored. This study aimed to examine the chemical composition and anti-melanogenic and melanosome transport-inhibitory effects of PSFAb using B16BL6 murine melanoma cells. Methods: PSFAb was extracted with hexane and analyzed by gas chromatography–mass spectrometry (GC-MS). The biological activities in B16BL6 murine melanoma cells were evaluated using water-soluble tetrazolium salt (WST) assays, 5-bromo-2′-deoxyuridine (BrdU) incorporation, enzyme-linked immunosorbent assays, and immunoblotting methods. Results: GC-MS analysis identified eight constituents in PSFAb. Cell viability was not significantly altered in B16BL6 cells at concentrations ≤ 100 μg/mL, which were used for additional tests. PSFAb inhibited serum-induced cell proliferation and suppressed α-melanocyte-stimulating hormone (α-MSH)-induced melanin synthesis and tyrosinase activity in B16BL6 cells. PSFAb also downregulated the α-MSH-induced expression of key melanogenic regulators, including microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2. PSFAb decreased extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase phosphorylation but enhanced JNK phosphorylation in α-MSH-stimulated B16BL6 cells. Furthermore, PSFAb reduced the α-MSH-induced expression of melanosome transport-related proteins (melanophilin and Rab27a) in B16BL6 cells. Conclusions: Overall, these results suggest that PSFAb has the potential to exert anti-pigmentation effects by suppressing melanogenesis and downregulating melanosome transport-related proteins. Therefore, PSFAb may be a promising candidate for the development of natural agents targeting hyperpigmentation and skin pigmentation regulation. Full article