response to UV

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an ultraviolet radiation (UV light) stimulus. Ultraviolet radiation is electromagnetic radiation with a wavelength in the range of 10 to 380 nanometers. [GOC:hb]

Response to UV radiation is a complex biological process that involves a cascade of events, starting with the absorption of UV light by DNA and culminating in various cellular responses aimed at repairing the damage and protecting the cell from further harm. Here’s a breakdown of the key steps:

1. **UV Absorption and DNA Damage:** UV radiation, particularly UVB, can directly damage DNA by causing the formation of pyrimidine dimers. These dimers, primarily cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs), disrupt the normal structure of DNA and hinder its proper functioning.

2. **Signal Transduction Pathways:** DNA damage triggers a signaling cascade that activates various repair and protective mechanisms. Key players in this pathway include:
* **p53:** A tumor suppressor protein that acts as a crucial checkpoint for DNA damage. It can induce cell cycle arrest, allowing time for DNA repair, or activate apoptosis if the damage is too severe.
* **ATM (Ataxia Telangiectasia Mutated):** A protein kinase that senses DNA double-strand breaks, a particularly dangerous form of DNA damage. It activates downstream signaling pathways that lead to cell cycle arrest, DNA repair, or apoptosis.
* **ATR (ATM and Rad3-related):** A protein kinase involved in sensing and responding to single-strand DNA breaks and stalled replication forks. It triggers a cascade of events leading to cell cycle arrest, DNA repair, and protection against further damage.

3. **DNA Repair Mechanisms:** The cell deploys various DNA repair mechanisms to correct the damage caused by UV radiation. These include:
* **Nucleotide Excision Repair (NER):** A major pathway for removing bulky lesions like pyrimidine dimers from DNA. It involves a series of steps:
* **Recognition:** Specific proteins identify and bind to the damaged DNA.
* **Excision:** The damaged segment of DNA is excised, removing the dimer.
* **Synthesis:** DNA polymerase fills in the gap with the correct nucleotides.
* **Ligation:** DNA ligase seals the newly synthesized DNA to the original strand.
* **Base Excision Repair (BER):** This pathway primarily removes damaged or modified bases from DNA. It involves several steps:
* **Recognition:** Specific enzymes recognize and remove the damaged base.
* **Excision:** The damaged base is excised, leaving an empty spot in the DNA.
* **Synthesis:** DNA polymerase fills in the gap with the correct nucleotide.
* **Ligation:** DNA ligase seals the newly synthesized DNA to the original strand.

4. **Cellular Responses:** In addition to DNA repair, the cell also mounts various responses to protect itself from UV damage:
* **Cell Cycle Arrest:** DNA damage triggers cell cycle arrest at specific checkpoints (G1/S, G2/M) to allow time for repair before proceeding to the next phase.
* **Apoptosis:** If the damage is too severe or unrepairable, the cell may undergo programmed cell death (apoptosis) to prevent the propagation of damaged DNA.
* **Melanogenesis:** UV radiation can induce the production of melanin, a pigment that protects the skin from further UV damage by absorbing UV light.
* **Inflammation:** UV exposure can trigger inflammation, which is a complex biological process involving immune cells and signaling molecules that aim to repair the damaged tissue and protect against further harm.

5. **UV Protection:** Protecting the skin from excessive UV exposure is crucial to minimize DNA damage and its potential consequences. This can be achieved by:
* **Sunscreen:** Applying sunscreen with a high SPF (Sun Protection Factor) can block a significant portion of UV radiation.
* **Protective Clothing:** Wearing protective clothing, such as long sleeves and pants, can further reduce UV exposure.
* **Shade:** Seeking shade during peak UV hours can minimize exposure.
* **Sunglasses:** Protecting the eyes from UV radiation with sunglasses is essential.

Overall, response to UV radiation involves a complex interplay of signaling pathways, repair mechanisms, and cellular responses. The cell’s ability to respond to UV damage effectively is crucial for maintaining genomic integrity, preventing disease, and ensuring normal cellular function.'
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Proteins (17)

Compounds (658)