How does UV exposure affect keratinocytes and melanocytes?
Exposure to solar UVR results in direct DNA damage (such as CPDs) and oxidative lesions (such as 8-OHdG) in both keratinocytes and melanocytes. While squamous and basal cell carcinomas typically have signature DNA mutations caused by direct DNA damage, these mutations are rare in primary melanomas.
Do keratinocytes protect against UV radiation?
Keratinocytes contribute to protecting the body from ultraviolet radiation (UVR) by taking up melanosomes, vesicles containing the endogenous photoprotectant melanin, from epidermal melanocytes.
What is the melanin protecting from UV light in the keratinocyte?
A melanocyte is a type of cell that’s primarily located in the basal layer of the epidermis. Melanocytes produce melanin, a brown pigment that is responsible for skin coloration and protecting against the harmful effects of UV light. Melanocytes are also present in the hair and in the irises of the eyes.
Does UV light increase melanocytes?
UVR causes DNA damage in the epidermis and results in melanin synthesis in melanocytes and transfer to neighboring keratinocytes, leading to increased skin pigmentation within one day after exposure.
Why does UV light damage skin?
The sun’s ultraviolet light can cause major damage to the skin. The outer layer of the skin has cells that contain the pigment melanin. Melanin protects skin from the sun’s ultraviolet rays. These can burn the skin and reduce its elasticity, leading to premature aging.
What is the process that darkens skin when exposed to UV light?
Exposure to the UV rays of the sun or a tanning salon causes melanin to be manufactured and built up in keratinocytes, as sun exposure stimulates keratinocytes to secrete chemicals that stimulate melanocytes. The accumulation of melanin in keratinocytes results in the darkening of the skin, or a tan.
What happens to DNA as it absorbs UV light?
Direct DNA damage can occur when DNA directly absorbs a UVB photon, or for numerous other reasons. UVB light causes thymine base pairs next to each other in genetic sequences to bond together into pyrimidine dimers, a disruption in the strand, which reproductive enzymes cannot copy.
Is lots of melanin good?
Melanin is a natural protector against the ultraviolet (UV) rays of the sun. People who have more melanin in their skin have a lower risk of sunburn and skin cancer, according to the American Cancer Society. However, experts also link sun exposure, sunburns, and suntans to skin damage and skin cancer.
How are keratinocytes and melanocytes sensitive to UV?
They also found that both melanocytes and keratinocytes are sensitive to arsenic. However, if there is enough DNA damage generated by UVR in either cell type, then both are susceptible to arsenic-mediated DNA repair inhibition.
What is the protective role of melanin against UV damage?
The Protective Role of Melanin Against UV Damage in Human Skin 1 DNA photodamage. One of the most important acute effects of UVR is DNA photodamage. 2 Sunburn. The effectiveness of UV to induce erythema declines rapidly with longer wavelengths. 3 UV and immunosuppression. Besides its deleterious photodamaging and erythema-inducing effects,…
Where are melanocytes found in the human body?
Melanin Properties. The number of melanocytes in the skin is race-independent, but can vary at different body sites with densities between 2000 mm -2 in head or forearm skin to 1000 mm -2 elsewhere. Melanocyte density in the skin of the palms and soles is about 10-20% that in skin on the trunk ( 63 ).
How does melanin change the cellular response to arsenic?
The researchers reasoned that there must be different mechanisms at work, and that the melanin pigment present in melanocytes could be changing the cellular response to arsenic and UVR.