Updates on the Molecular Basis of Photoaging in All Skin Types.

Photoaging is a complex, ongoing process that clinically manifests as cutaneous rhytides, atrophy, laxity, dyspigmentation, telangiectasias, roughness, and mottled appearance of the skin. There is an abundance of research establishing the mechanism of ultraviolet (UV) - induced photodamage as it is a significant source of photoaging and skin cancers. While UV damage is known to induce photoaging, it is important to understand how other forms of light radiation also contribute to this process. UV only constitutes 5 to 10% of solar radiation that reaches the earth's surface. The remaining nearly 90% is evenly split between infrared and visible light radiation. Early research shows that varied skin types may elicit different photobiologic responses to light. This article presents the mechanisms and biomarkers of photodamage induced by light from across the spectrum, including UV, visible light, and infrared to better prevent and reverse the damage of photoaging in all skin types.J Drugs Dermatol. 2024;23(7):504-509.  doi:10.36849/JDD.7438.

The role of distinct APOBEC/ADAR mRNA levels in mutational signatures linked to aging and ultraviolet radiation.

The APOBEC/AID family is known for its mutator activity, and recent evidence also supports the potential impact of ADARs. Furthermore, the mutator impacts of APOBEC/ADAR mutations have not yet been investigated. Assessment of pancancer TCGA exomes identified enriched somatic variants among exomes with nonsynonymous APOBEC1, APOBEC3B, APOBEC3C, ADAR, and ADARB1 mutations, compared to exomes with synonymous ones. Principal component (PC) analysis reduced the number of potential players to eight in cancer exomes/genomes, and to five in cancer types. Multivariate regression analysis was used to assess the impact of the PCs on each COSMIC mutational signature among pancancer exomes/genomes and particular cancers, identifying several novel links, including SBS17b, SBS18, and ID7 mainly determined by APOBEC1 mRNA levels; SBS40, ID1, and ID2 by age; SBS3 and SBS16 by APOBEC3A/APOBEC3B mRNA levels; ID5 and DBS9 by DNA repair/replication (DRR) defects; and SBS7a-d, SBS38, ID4, ID8, ID13, and DBS1 by ultraviolet (UV) radiation/ADARB1 mRNA levels. APOBEC/ADAR mutations appeared to potentiate the impact of DRR defects on several mutational signatures, and some factors seemed to inversely affect certain signatures. These findings potentially implicate certain APOBEC/ADAR mutations/mRNA levels in distinct mutational signatures, particularly APOBEC1 mRNA levels in aging-related signatures and ADARB1 mRNA levels in UV radiation-related signatures.

From bedside to genetic analysis: New insights into pathophysiology of melanoma, basal cell carcinoma, and other cancers.

OBJECTIVE: Patients with myotonic muscular dystrophy (MMD) were observed to have numerous basal cell carcinoma (BCC) and abnormal dysplastic nevi (DN) on non-sun exposed skin. Simultaneously a large study published in the Journal of American Medical Association (JAMA) illustrated that patients with MMD have "overall" an increased risk for cancer development. Based on these findings, this author in 2010 postulated that dysregulation of RNA binding proteins (RBP), responsible for clinical manifestations of MMD, is also responsible for the development of BCC and melanoma. METHODS: To report new research elucidating the etiology of melanoma, BCC, MMD-induced cancers, and potentially other environmentally induced malignancies. RESULTS: Dysregulation of RBP induces aberrant mRNA splicing; recent data indicates that abnormal mRNA splicing not just plays a key role in the pathogenesis of melanoma but is a hallmark of essentially all human malignancies. CONCLUSION: The author's hypothesis is that ultraviolet (UV) radiation induces DNA damage in intronic regions of a variety of genes. Furthermore, these UV-induced abnormal DNA dimers, repeats and mutations interfere with normal mRNA splicing thus producing abnormal proteins. These abnormal proteins in turn activate oncogenic pathways such as hedgehog, MAP kinase, and WNT.

[Photochemical Processes of Cell DNA Damage by UV Radiation of Various Wavelengths: Biological Consequences].

Photochemical reactions in cell DNA are induced in various organisms by solar UV radiation and may lead to a series of biological responses to DNA damage, including apoptosis, mutagenesis, and carcinogenesis. The chemical nature and the amount of DNA lesions depend on the wavelength of UV radiation. UV type B (UVB, 290-320 nm) causes two main lesions, cyclobutane pyrimidine dimers (CPDs) and, with a lower yield, pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). Their formation is a result of direct UVB photon absorption by DNA bases. UV type A (UVA, 320-400 nm) induces only cyclobutane dimers, which most likely arise via triplet-triplet energy transfer (TTET) from cell chromophores to DNA thymine bases. UVA is much more effective than UVB in inducing sensitized oxidative DNA lesions, such as single-strand breaks and oxidized bases. Of the latter, 8-oxo-dihydroguanine (8-oxodG) is the most frequent, being produced in several oxidation processes. Many recent studies reported novel, more detailed information about the molecular mechanisms of the photochemical reactions that underlie the formation of various DNA lesions. The information is mostly summarized and analyzed in the review. Special attention is paid to the oxidation reactions that are initiated by reactive oxygen species (ROS) and radicals generated by potential endogenous photosensitizers, such as pterins, riboflavin, protoporphyrin IX, NADH, and melanin. The review discusses the role that specific DNA photoproducts play in genotoxic processes induced in living systems by UV radiation of various wavelengths, including human skin carcinogenesis.

The interferon-rich skin environment regulates Langerhans cell ADAM17 to promote photosensitivity in lupus.

The autoimmune disease lupus erythematosus (lupus) is characterized by photosensitivity, where even ambient ultraviolet radiation (UVR) exposure can lead to development of inflammatory skin lesions. We have previously shown that Langerhans cells (LCs) limit keratinocyte apoptosis and photosensitivity via a disintegrin and metalloprotease 17 (ADAM17)-mediated release of epidermal growth factor receptor (EGFR) ligands and that LC ADAM17 sheddase activity is reduced in lupus. Here, we sought to understand how the lupus skin environment contributes to LC ADAM17 dysfunction and, in the process, differentiate between effects on LC ADAM17 sheddase function, LC ADAM17 expression, and LC numbers. We show through transcriptomic analysis a shared IFN-rich environment in non-lesional skin across human lupus and three murine models: MRL/lpr, B6.Sle1yaa, and imiquimod (IMQ) mice. IFN-I inhibits LC ADAM17 sheddase activity in murine and human LCs, and IFNAR blockade in lupus model mice restores LC ADAM17 sheddase activity, all without consistent effects on LC ADAM17 protein expression or LC numbers. Anti-IFNAR-mediated LC ADAM17 sheddase function restoration is associated with reduced photosensitive responses that are dependent on EGFR signaling and LC ADAM17. Reactive oxygen species (ROS) is a known mediator of ADAM17 activity; we show that UVR-induced LC ROS production is reduced in lupus model mice, restored by anti-IFNAR, and is cytoplasmic in origin. Our findings suggest that IFN-I promotes photosensitivity at least in part by inhibiting UVR-induced LC ADAM17 sheddase function and raise the possibility that anifrolumab ameliorates lupus skin disease in part by restoring this function. This work provides insight into IFN-I-mediated disease mechanisms, LC regulation, and a potential mechanism of action for anifrolumab in lupus.

[Ultraviolet radiation in the pathogenesis of lupus erythematosus]. / UV-induzierte Pathogenese des Lupus erythematodes.

Photosensitivity represents an increased inflammatory reaction to sunlight, which can be observed particularly in the autoimmune disease lupus erythematosus. Cutaneous lupus erythematosus (CLE) can be provoked by ultraviolet (UV) radiation and can cause both acute, nonscarring and chronic, scarring skin changes. In systemic lupus erythematosus, on the other hand, provocation by UV radiation can lead to flare or progression of systemic involvement. The etiology of lupus erythematosus is multifactorial and includes genetic, epigenetic and immunologic mechanisms. In this review, we address the effect of UV radiation on healthy skin and photosensitive skin using the example of lupus erythematosus. We describe possible mechanisms of UV-triggered immune responses that could offer therapeutic approaches. Currently, photosensitivity can only be prevented by avoiding UV exposure itself. Therefore, it is important to better understand the underlying mechanisms in order to develop strategies to counteract the deleterious effects of photosensitivity.

Reduction of Campylobacter jejuni contamination by using UVA-LED and sodium hypochlorite on the surface of chicken meat.

Campylobacter jejuni causes gastroenteritis in humans and is a major concern in food safety. Commercially prepared chicken meats are frequently contaminated with C. jejuni, which is closely associated with the diffusion of intestinal contents in poultry processing plants. Sodium hypochlorite (NaClO) is commonly used during chicken processing to prevent food poisoning; however, its antimicrobial activity is not effective in the organic-rich solutions. In this study, we investigated the potential of a new photo-disinfection system, UVA-LED, for the disinfection of C. jejuni-contaminated chicken surfaces. The data indicated that UVA irradiation significantly killed C. jejuni and that its killing ability was significantly facilitated in NaClO-treated chickens. Effective inactivation of C. jejuni was achieved using a combination of UVA and NaClO, even in the organic-rich condition. The results of this study show that synergistic disinfection using a combination of UVA and NaClO has potential beneficial effects in chicken processing systems.

L-Theanine Prolongs the Lifespan by Activating Multiple Molecular Pathways in Ultraviolet C-Exposed Caenorhabditis elegans.

L-theanine, a unique non-protein amino acid, is an important bioactive component of green tea. Previous studies have shown that L-theanine has many potent health benefits, such as anti-anxiety effects, regulation of the immune response, relaxing neural tension, and reducing oxidative damage. However, little is known concerning whether L-theanine can improve the clearance of mitochondrial DNA (mtDNA) damage in organisms. Here, we reported that L-theanine treatment increased ATP production and improved mitochondrial morphology to extend the lifespan of UVC-exposed nematodes. Mechanistic investigations showed that L-theanine treatment enhanced the removal of mtDNA damage and extended lifespan by activating autophagy, mitophagy, mitochondrial dynamics, and mitochondrial unfolded protein response (UPRmt) in UVC-exposed nematodes. In addition, L-theanine treatment also upregulated the expression of genes related to mitochondrial energy metabolism in UVC-exposed nematodes. Our study provides a theoretical basis for the possibility that tea drinking may prevent mitochondrial-related diseases.

Ex Vivo Analysis of Cell Differentiation, Oxidative Stress, Inflammation, and DNA Damage on Cutaneous Field Cancerization.

Cutaneous field cancerization (CFC) refers to a skin region containing mutated cells' clones, predominantly arising from chronic exposure to ultraviolet radiation (UVR), which exhibits an elevated risk of developing precancerous and neoplastic lesions. Despite extensive research, many molecular aspects of CFC still need to be better understood. In this study, we conducted ex vivo assessment of cell differentiation, oxidative stress, inflammation, and DNA damage in CFC samples. We collected perilesional skin from 41 patients with skin cancer and non-photoexposed skin from 25 healthy control individuals. These biopsies were either paraffin-embedded for indirect immunofluorescence and immunohistochemistry stain or processed for proteins and mRNA extraction from the epidermidis. Our findings indicate a downregulation of p53 expression and an upregulation of Ki67 and p16 in CFC tissues. Additionally, there were alterations in keratinocyte differentiation markers, disrupted cell differentiation, increased expression of iNOS and proinflammatory cytokines IL-6 and IL-8, along with evidence of oxidative DNA damage. Collectively, our results suggest that despite its outwardly normal appearance, CFC tissue shows early signs of DNA damage, an active inflammatory state, oxidative stress, abnormal cell proliferation and differentiation.

Impact of double-strand breaks induced by uv radiation on neuroinflammation and neurodegenerative disorders.

Exposure to UV affects the development and growth of a wide range of organisms. Nowadays, researchers are focusing on the impact of UV radiation and its underlying molecular mechanisms, as well as devising strategies to mitigate its harmful effects. Different forms of UV radiation, their typical exposure effects, the impact of UV on DNA integrity, and the deterioration of genetic material are discussed in this review; furthermore, we also review the effects of UV radiation that affect the biological functions of the organisms. Subsequently, we address the processes that aid organisms in navigating the damage in genetic material, neuroinflammation, and neurodegeneration brought on by UV-mediated double-strand breaks. To emphasize the molecular pathways, we conclude the review by going over the animal model studies that highlight the genes and proteins that are impacted by UV radiation.

Sunscreen Practices and Preferences of Skin of Color Patients.

Sunscreen is an essential way to protect against photodamage from ultraviolet (UV) radiation. Despite the recognized benefits of sunscreen in preventing skin damage from UV light, its use varies across different patient groups. This cross-sectional, questionnaire-based study aims to uncover the sunscreen usage patterns, preferences, and barriers among non-Hispanic White (NHW) and skin of color (SOC) individuals. Our findings demonstrate that NHW individuals are more likely to wear sunscreen daily (31% NHW vs 25% SOC) and reapply sunscreen at least once a day (76% NHW vs 45% SOC) compared with SOC individuals. SOC individuals demonstrate a willingness to use sunscreen, but they face barriers such as cost (2% NHW vs 16% SOC), lack of knowledge in finding suitable products (22% NHW vs 41% SOC), and concerns about white cast (7% NHW vs 25% SOC). SOC individuals are less likely to know the difference between mineral and chemical sunscreen (49% NHW vs 29% SOC), less likely to learn about sunscreen from dermatologists (36% NHW vs 22% SOC), and more likely to prefer sunscreen from brands owned by people of color (13% NHW vs 47% SOC).  In addition to analyzing the broader categories of NHW and SOC, subgroup analysis was conducted on specific subgroups, including Black, Asian, and Hispanic groups. Herein, we highlight differences in motivations, sunscreen preferences, sources of information, and knowledge levels about sun protection between NHW and SOC individuals. By uncovering the unique needs and challenges faced by SOC individuals, we aim to improve culturally competent patient education and promote effective sun protection practices across diverse populations. J Drugs Dermatol. 2024;23(6):456-462.     doi:10.36849/JDD.8268.

Annexin A1 protects epidermal stem cells against ultraviolet-B irradiation-induced mitochondrial dysfunction.

Ultraviolet-B (UV-B) radiation overexposure causes function impairment of epidermal stem cells (ESCs). We explored the mechanism of Annexin A1 (ANXA1) ameliorating UV-B-induced ESC mitochondrial dysfunction/cell injury. ESCs were cultured in vitro and irradiated with different doses of UV-B. Cell viability/ANXA1 protein level were assessed. After oe-ANXA1 transfection, ESCs were treated with oe-ANXA1/UV-B irradiation/CCCP/CCG-1423/3-methyladenine for 12 h. Cell viability/death, and adenosine triphosphate (ATP)/reactive oxygen species (ROS) levels were determined. Mitochondrial membrane potential (MMP) changes/DNA (mtDNA) content/oxygen consumption and RhoA activation were assessed. ROCK1/p-MYPT1/MYPT1/(LC3BII/I)/Beclin-1/p62 protein levels were determined. Mitochondrial morphology was observed. Mito-Tracker Green (MTG) and LC3B levels were determined. UV-B irradiation decreased cell viability/ANXA1 expression in a dose-dependent manner. UV-B-treated ESCs exhibited reduced cell viability/ATP content/MMP level/mitochondrial respiratory control ratio/mtDNA number/RhoA activity/MYPT1 phosphorylation/MTG+LC3B+ cells/(LC3BII/I) and Beclin-1 proteins, increased cell death/ROS/p62/IL-1ß/IL-6/TNF-α expression, contracted mitochondrial, disappeared mitochondrial cristae, and increased vacuolar mitochondria, which were averted by ANXA1 overexpression, suggesting that UV-B induced ESC mitochondrial dysfunction/cell injury/inflammation by repressing mitophagy, but ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thus repressing UV-B's effects. Mitophagy activation ameliorated UV-B-caused ESC mitochondrial dysfunction/cell injury/inflammation. Mitophagy inhibition partly diminished ANXA1-ameliorated UV-B's effects. Conjointly, ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thereby improving UV-B-induced ESC mitochondrial dysfunction/cell injury.

The Skin-Brain Axis: From UV and Pigmentation to Behaviour Modulation.

The skin-brain axis has been suggested to play a role in several pathophysiological conditions, including opioid addiction, Parkinson's disease and many others. Recent evidence suggests that pathways regulating skin pigmentation may directly and indirectly regulate behaviour. Conversely, CNS-driven neural and hormonal responses have been demonstrated to regulate pigmentation, e.g., under stress. Additionally, due to the shared neuroectodermal origins of the melanocytes and neurons in the CNS, certain CNS diseases may be linked to pigmentation-related changes due to common regulators, e.g., MC1R variations. Furthermore, the HPA analogue of the skin connects skin pigmentation to the endocrine system, thereby allowing the skin to index possible hormonal abnormalities visibly. In this review, insight is provided into skin pigment production and neuromelanin synthesis in the brain and recent findings are summarised on how signalling pathways in the skin, with a particular focus on pigmentation, are interconnected with the central nervous system. Thus, this review may supply a better understanding of the mechanism of several skin-brain associations in health and disease.

Photoprotection: Current developments and controversies.

This review aimed at summarizing some of the key points that were discussed during the photoprotection session at the International Forum of Dermatology in 2022. This international conference was designed to address prominent topics of clinical dermatology in a holistic way, allowing to articulate multiple viewpoints. Therefore, this review does not claim to be exhaustive, but is instead intended to give an overview of recent developments and ongoing controversies in the field of photoprotection. Cumulative ultraviolet radiation (UVR) exposure is the major aetiological factor in the development of photoageing, photoimunosuppression and photocarcinogenesis. UVA (320-400 nm) penetrates into the dermis and damages DNA and other intracellular and acellular targets primarily by generating reactive oxygen species (ROS). It is the major contributor to photoageing, characterized by fine and coarse wrinkles, dyspigmentation and loss of elasticity. UVB (290-320 nm) is responsible for sunburns through direct damage to DNA by the formation of 6-4 cyclobutane pyrimidine dimers (CPDs) and pyrimidine 6-4 pyrimidone photoproducts. Both UVA and UVB exposure increase the risk of basal cell carcinoma, squamous cell carcinoma and melanoma. In recent years, visible light (VL; 400-700 nm) has also been implicated in the exacerbation of conditions aggravated by sun exposure such as hyperpigmentation and melasma. Photoprotection is a critical health strategy to reduce the deleterious effects of UVR and VL. Comprehensive photoprotection strategies include staying in the shade when outdoors, wearing photoprotective clothing including a wide-brimmed hat, and sunglasses, and the use of sunscreen. Due to the absorption of UV filters, the safety of sunscreens has been questioned. Newer sunscreens are becoming available with filters with absorption even beyond the UV spectrum, offering enhanced protection compared with older products. Prevention of photocarcinogenesis, sun-induced or sunlight-exacerbated hyperpigmentary conditions and drug-induced photosensitivity is an important reason for adopting comprehensive photoprotection strategies.

Antioxidant Properties of Platycladus orientalis Flavonoids for Treating UV-Induced Damage in Androgenetic Alopecia Hair.

BACKGROUND: Androgenetic alopecia (AGA) causes thinning hair, but poor hair quality in balding areas and damage from UV radiation have been overlooked. Plant extracts like Platycladus orientalis flavonoids (POFs) may improve hair quality in AGA. This study examines POFs' effectiveness in treating AGA-affected hair and repairing UV-induced damage. METHODS: Hair samples were analyzed using scanning electron microscopy (SEM) to examine surface characteristics, electron paramagnetic resonance (EPR) spectroscopy to measure free radicals in the hair, and spectrophotometry to assess changes in hair properties. RESULTS: POFs effectively removed hydroxyl radicals from keratinocytes and had antioxidant properties. They also reduced UV-induced damage to AGA hair by mitigating the production of melanin free radicals. Following POF treatment, the reduction in peroxidized lipid loss in AGA hair was notable at 59.72%, thereby effectively delaying the progression of hair color change. Moreover, protein loss decreased by 191.1 µ/g and tryptophan loss by 15.03%, ultimately enhancing hair's tensile strength. CONCLUSION: compared to healthy hair, hair damaged by AGA shows more pronounced signs of damage when exposed to UV radiation. POFs help protect balding hair by reducing oxidative damage and slowing down melanin degradation.

A prospective cohort study exploring the joint influence of sunlight exposure and tanning bed use on basal cell carcinoma, squamous cell carcinoma, and melanoma risk.

Exposure to solar ultraviolet (UV) radiation and use of UV-emitting tanning devices are known risk factors for skin cancer. Few studies have explored the interaction between these risk factors, namely how the risk of skin cancer increases among those who both have been exposed to high levels of natural sunlight and regularly use tanning beds. Nurses' Health Study II followed 116,430 women, aged 25-42, from 1991 to 2011. Cumulative average UV exposure was based on participants' residences at follow-up periods. History of severe sunburn during ages 15-20 was used as a proxy for early-life sunlight exposure. Tanning bed use in early life data was collected. Participants reported melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) diagnoses. We built multivariable Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of skin cancer associated with joint effects of sunlight exposure and tanning bed use. Participants with high sunlight exposure and tanning bed use during high school/college had an increased risk of BCC (HR = 1.53, 95% CI 1.37-1.71, Pinteraction=0.01; vs. low sun exposure and no tanning bed use). Participants with a history of severe sunburns and tanning bed use during high school/college were at increased risk of BCC (HR = 1.62, 95% CI 1.47-1.79, Pinteraction=0.02; vs. no sunburns and no tanning bed use). No significant interactions were found between sunlight exposure and tanning bed use on SCC and melanoma risk. We found significant interactions between sunlight exposure and tanning bed use on the risk of BCC.

Germicidal lamps using UV-C radiation may pose health safety issues: a biomolecular analysis of their effects on apoptosis and senescence.

The battle against the COVID-19 pandemic has spurred a heightened state of vigilance in global healthcare, leading to the proliferation of diverse sanitization methods. Among these approaches, germicidal lamps utilizing ultraviolet (UV) rays, particularly UV-C (wavelength ranging from 280 to 100 nm), have gained prominence for domestic use. These light-emitting diode (LED) lamps are designed to sanitize the air, objects, and surfaces. However, the prevailing concern is that these UV lamps are often introduced into the market without adequate accompanying information to ensure their safe utilization. Importantly, exposure to absorbed UV light can potentially trigger adverse biological responses, encompassing cell death and senescence. Our research encompassed a series of investigations aimed at comprehending the biological repercussions of UV-C radiation exposure from readily available domestic lamps. Our focus centered on epithelial retinal cells, keratinocytes, and fibroblasts, components of the skin and ocular targets frequently exposed to UV irradiation. Our findings underscore the potential harm associated with even brief exposure to UV, leading to irreversible and detrimental alterations in both skin cells and retinal cells of the eye. Notably, epithelial retinal cells exhibited heightened sensitivity, marked by substantial apoptosis. In contrast, keratinocytes demonstrated resilience to apoptosis even at elevated UV doses, though they were prone to senescence. Meanwhile, fibroblasts displayed a gradual amplification of both senescence and apoptosis as radiation doses escalated. In summary, despite the potential benefits offered by UV-C in deactivating pathogens like SARS-CoV-2, it remains evident that the concurrent risks posed by UV-C to human health cannot be ignored.

UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism.

Aquatic environments are subject to ultraviolet B (UVB) radiation incidence, and its effects on organisms are dose-dependent. Besides DNA, mitochondria are an important target of this radiation that causes structural damage and impairs its functional dynamics. Here, we hypothesize that mitophagy acts as an organelle quality control mechanism to mitigate UVB impacts in embryonic cells. Then, freshwater prawn Macrobrachium olfersii embryos was used as a model to investigate the effects of UVB on genes (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) and proteins (TOM20, PINK1, p62 and LC3B) involved in mitophagy modulation. The choice of genes and proteins was based on the identification of mitochondrial membrane (Tomm20, Opa1 and TOM20), mediation of mitophagy (Pink1, Prkn and PINK1), and recognition of mitochondria by the autophagosome membrane (Sqstm1, Map1lc3, p62 and LC3B). First, the phylogeny of all genes presented bootstrap values >80 and conserved domains among crustacean species. Gene expression was inherently modulated during development, with transcripts (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) overexpressed in the initial and final stages of development. Moreover, UVB radiation induced upregulation of Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3 genes at 6 h after exposure. Interestingly, after 12 h, the protein content of PINK1, p62, and LC3B increased, while TOM20 was not responsive. Despite UVB radiation's harmful effects on embryonic cells, the chronology of gene expression and protein content indicates rapid activation of mitophagy, serving as an organelle quality control mechanism, given the analyzed cells' integrity.