The Integral Nuclear Membrane Protein Nurim Plays a Role in the Suppression of Apoptosis

As an essential component of eukaryotic cells, the nuclear envelope (NE) plays a crucial role in many physiological processes. At present, a few membrane proteins from NE have been functionally characterized. To determine whether the inner nuclear membrane (INM) protein Nurim is expressed in cancer cells with evidence of apoptosis, we identified three isoforms of this protein that are specific for human testicular seminoma and are generated by alternative splicing. We observed that Nurim is expressed in a broad range of cancer types and that its expression level is correlated with a higher tumor grade. Biochemical analysis showed that Nurim b, like a, is tightly bound to the nuclear envelope. Furthermore, knockdown using miR-Nurim resulted in an abnormal shape change of the nuclear envelope. Notably, Nurim knockdown obviously increased apoptosis induced by ultraviolet in HeLa cells. Together, these findings implicate that the INM protein Nurim plays an important role in the suppression of apoptosis. Keywords: Apoptosis, cancer, nuclear envelope, transmembrane protein, eukaryotic cells, lipid membranes, chromatin organization, cell cycle progression, cell migration, gene expression, signal transduction, aging, Nurim, isoform, carcinoma