VRK proteins are a group of serine-threonine kinases involved in the regulation of p53 and other transcription factors involved in cellular stress responses. Most recently, Pedro Lazo’s laboratory at the Cancer Research Center of Salamanca has identified new aspects of the biology of two members of the family. The VRK1 kinase is required to carry out the cell cycle. VRK1 gene expression when standing stop the cycle and is activated after addition of serum. VRK1 gene behaves as an early response to serum, and its expression parallels that of the oncogenes MYC and FOS.

This led to synchronized cells to determine their correlation with the sequential appearance of cyclins. VRK1 is almost parallel to that of cyclin D1 in early G1 phase. The elimination of VRK1 by RNA interference causes a stop in cell division accompanied by loss of phosphorylation of retinoblastoma and accumulating cycle inhibitors such as p27. This effect is induced because the expression of VRK1 is required for cyclin D1 is expressed and this is lost after removal of VRK1. The paper concludes that VRK1 is necessary for cell cycle progression before they reach the restriction point in G1 and its pharmacological inhibition could be useful for anticancer drug development.

In turn, the endoplasmic reticulum-associated VRK2 can modulate signaling in response to interleukin 1. VRK2 interacts with JIP1 scaffold protein complexes form very high molecular weight. By forming this complex blocks the transmission of MAP kinase signal which is detected as a release of JNK from the complex and a decrease in phosphorylation of the factor c-Jun in response to interleukin 1. These results obtained studying the cellular response to hypoxic stress indicate that signal transduction known there are other proteins that can alter the balance of the different routes in response to a stimulus, and this alteration of the balance of signals result in different biological effects. This field of signal modulators is still little known but will become significant for understanding the specificity of many biological effects, like the response to hypoxia, growth factors …