New LAP dog for nuclear lamins

The nuclear protein lamina-associated polypeptide 2α (LAP2α) plays a key role in chromatin organisation, cell cycle regulation and differentiation. These functions are, in part, regulated by its interactions with the A-type lamins that reside in the nuclear compartment and the tumour suppressor pRb. To investigate the mechanisms of LAP2α function in chromatin organisation and cell cycle control, Nana Naetar and co-workers (p. 737) used a yeast two-hybrid approach to identify a novel LAP2α binding partner, LAP2α-interactor-25 (LINT-25). The authors confirmed the direct interaction between LINT-25 and the LAP2α C-terminus with additional in vitro binding assays. LINT-25 protein is upregulated and relocalises to heterochromatin foci when cells exit the cell cycle, and its upregulation is tightly coupled with the downregulation and proteasomal degradation of LAP2α. Furthermore, the authors demonstrate that LINT-25 upregulation is not dependent on LAP2α but that LINT-25 acts upstream of LAP2α to regulate its cell cycle function. The authors propose a model whereby LINT-25 causes loss of LAP2α by affecting its stability, thus contributing to the proper timing of cell cycle exit.