Human polynucleotide phosphorylase, hPNPase, is localized in mitochondria

The human gene encoding a polynucleotide phosphorylase (hPNPase) has been recently identified as strongly up-regulated in two processes leading to irreversible arrest of cell division: progeroid senescence and terminal differentiation. Here, we demonstrate that the hPNPase is localized in mitochondria. Our finding suggests the involvement of mitochondrial RNA metabolism in cellular senescence. (C) 2003 Elsevier Science Ltd. All rights reserved.