Chemistry of Life

Molecular genetics, biochemistry

nuclear speckles

New Gene Regulation Mechanism Discovered: "Dr. David Spector noticed that under standard growth conditions, a particular population of messenger RNA molecules lingered in the nucleus indefinitely--in structures they call 'nuclear speckles'--and never reached the cytoplasm.

One of Spector's graduate students developed a method for purifying speckles. That allowed the researchers to identify not only the many different protein components of speckles, but also the messenger RNAs that are the basis of the new study, published in the October 21 issue of the journal Cell. The study--spearheaded by Cold Spring Harbor Laboratory postdoctoral fellow Dr. Kannanganattu Prasanth--identified the first such messenger RNA: one transcribed from a mouse gene called mCAT2 that encodes a cell surface receptor.

The scientists learned from the work of others that the mCAT2 receptor is involved in the production of nitric oxide, and that nitric oxide production is stimulated by various stress conditions including wound healing and viral infection. " That told us that when cells are stressed, maybe the atypical messenger RNA is released from the nucleus, exported to the cytoplasm, and translated into protein, thus circumventing the time-consuming process of producing new messenger RNA and providing a rapid response to viral infection or other stresses," says Spector. To test this idea, the researchers mimicked the effect of viral infection by treating cells with interferon.

Sure enough, they discovered that the atypical mCAT2 messenger RNA in the nucleus was rapidly cleaved in response to interferon treatment, and that the protein coding portion of the molecule was then quickly exported to the cytoplasm and translated into protein. diagram. "

This 'cut and run' mechanism is a completely new paradigm of gene regulation, so studying it will keep us busy for a while. But we already suspect that there is going to be a large family of genes regulated in this way," says Spector.""

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. . . transcription begun 10/06/06