Activation of HIV type 1 long terminal repeat by ultraviolet light is serum and strain specific

The UV-inducible RNA-binding protein A18 (A18 hnRNP) plays a protective role in the genotoxic stress response

We have previously shown that specific RNA-binding proteins (RBP) are activated by genotoxic stress. The role and function of these stress-activated RBP are, however, poorly understood. The data presented here indicate that the RBP A18 heterogeneous ribonucleoprotein (hnRNP) is induced and translocated from the nuclei to the cytoplasm after exposure to UV radiation. Using a new in vitro system we identified potential cellular targets for A18 hnRNP. Forty-six mRNA transcripts were identified, most of which are stress- or UV-responsive genes. Two important stress-responsive transcripts, the replication protein A (RPA2) and thioredoxin, were studied in more detail. Northwestern analyses indicate that A18 hnRNP binds specifically to the 3'-untranslated region of RPA2 transcript independently of its poly(A) tail, whereas the poly(A) tail of thioredoxin mRNA reinforces binding. Overexpression of A18 hnRNP increases the mRNAs stability and consequently enhances translation in a dose-dependent manner. Moreover, cell lines expressing reduced levels of A18 hnRNP are more sensitive to UV radiation. These data suggest that A18 hnRNP plays a protective role against genotoxic stresses by translocating to the cytosol and stabilizing specific transcripts involved in cell survival.

Review of the impact on the activation of the human immunodeficiency virus type 1 of ultraviolet light

Acquired immune deficiency syndrome is a devastating disease with a high mortality rate and the failure of adequate therapy and vaccine stands in sharp contrast to the ultimate progress made in the biomedical sciences. We review the damaging effects of ultraviolet rays on the activation of the human immunodeficiency virus type-1, and theorize that human immunodeficiency virus type-1 positive individuals should minimize their exposures to prolonged and unnecessary ultraviolet radiations such as sunbaths, phototherapy or cosmetic treatments based on a risk-benefit analysis as more epidemiological studies are investigated.