Mice lacking ADPRT and poly(ADP-ribosyl)ation develop normally but are susceptible to skin disease.

Abstract

Poly(ADP-ribosyl)ation is catalyzed by NAD + :protein(ADP-ribosyl)transferase (ADPRT), a chromatinassociated enzyme which, in the presence of DNA breaks, transfers ADP-ribose from NAD + to nuclear proteins. This post-translational modification has been implicated in many fundamental processes, like DNA repair, chromatin stability, cell proliferation, and cell death. To elucidate the biological function of ADPRT and poly(ADP-ribosyl)ation in vivo the gene was inactivated in the mouse germ line. Mice homozygous for the ADPRT mutation are healthy and fertile. Analysis of mutant tissues and fibroblasts isolated from mutant fetuses revealed the absence of ADPRT enzymatic activity and poly(ADP-ribose), implying that no poly(ADP-ribosyl)ated proteins are present. Mutant embryonic fibroblasts were able to efficiently repair DNA damaged by UV and alkylating agents. However, proliferation of mutant primary fibroblasts as well as thymocytes following y-radiation in vivo was impaired. Moreover, mutant mice are susceptible to the spontaneous development of skin disease as -30% of older mice develop epidermal hyperplasia. The generation of viable ADPRT-/-mice negates an essential role for this enzyme in normal chromatin function, but the impaired proliferation and the onset of skin lesions in older mice suggest a function for ADPRT in response to environmental stress.

Regulation of the human poly(ADP-ribose) polymerase promoter by the ETS transcription factor

“…We attributed this e ect to the co-regulated inhibition of the expression of PARP, an enzyme implicated in DNA-repair (Satoh and Lindahl, 1992). This suggestion is consistent with ®ndings by others that PARP levels are not rate limiting for the proliferation of normal (undamaged) cells and that downregulation of PARP expression results in increased cell susceptibility to DNA-damaging treatments (Ding et al, 1992;Wang et al, 1995;KuÈ pper et al, 1995;Schreiber et al, 1995). Another explanation may involve the potential role of the ETS protein itself in the radiation response of EWS cells.…”

Poly(ADP-ribose) polymerase upregulates E2F-1 promoter activity and DNA pol α expression during early S phase

“…Thus, under these conditions, quiescent control cells are induced to proliferate and go through a round of the cell cycle, but not the PARP-depleted antisense cells. To determine whether depletion of PARP by gene disruption similarly blocks reentry of cells into S phase, we studied immortalized ®broblasts that were derived from wild-type (control) and PARP knockout (PARP7/7) mice (Wang et al, 1995). These PARP7/7 cells were previously con®rmed to be devoid of detectable PARP and poly(ADP-ribose) by immunoblot analysis with the corresponding antibodies (Simbulan-Rosenthal et al, 1998b).…”

“…While certain strains of PARP knockout mice are viable and fertile, primary ®broblasts derived from these animals exhibit proliferation de®ciencies in culture (de Murcia et al, 1997;Wang et al, 1995). Thus, although both DNA replication and di erentiation occur in these animals in the absence of PARP, isolated cell systems may show more profound e ects of the lack of this enzyme that are not apparent in the animals.…”

“…PARP depletion by antisense RNA expression results in a decrease in the initial rate of DNA repair in HeLa cells (Ding et al, 1992) and keratinocytes , a reduction in the survival of cells exposed to mutagenic agents, alterations in chromatin structure, an increase in gene ampli®cation (Ding and Smulson, 1994), and inhibition of the biochemical and morphological changes associated with apoptosis (SimbulanRosenthal et al, 1998b). Fibroblasts derived from PARP knockout mice exhibit proliferation de®ciencies in culture, and thymocytes from these animals show a delayed recovery after exposure to g-radiation (Wang et al, 1995). Other PARP knockout mice exhibit extreme sensitivity to ionizing radiation, and splenocytes derived from these animals undergo abnormal apoptosis (de Murcia et al, 1997).…”

An ICE‐like protease is a common mediator of apoptosis induced by diverse stimuli in human monocytic THP.1 cells

“…This data is consistent with the involvement of an ICE-like protease in PARP proteolysis. However the significance of PARP proteolysis in apoptosis is unclear as a PARP knockout mouse developed normally [35]. This suggested that apoptosis probably does not have an absolute requirement for proteolysis of PARP but rather that it may be a consequence of cell death.…”