Arabidopsis PARG1 is the key factor promoting cell survival among the enzymes regulating post-translational poly(ADP-ribosyl)ation

Abstract

Poly(ADP-ribosyl)ation is a reversible post-translational modification of proteins, characterized by the addition of poly(ADP-ribose) (PAR) to proteins by poly(ADP-ribose) polymerase (PARP), and removal of PAR by poly(ADP-ribose) glycohydrolase (PARG). Three PARPs and two PARGs have been found in Arabidopsis, but their respective roles are not fully understood. In this study, the functions of each PARP and PARG in DNA repair were analyzed based on their mutant phenotypes under genotoxic stresses. Double or triple mutant analysis revealed that PARP1 and PARP2, but not PARP3, play a similar but not critical role in DNA repair in Arabidopsis seedlings. PARG1 and PARG2 play an essential and a minor role, respectively under the same conditions. Mutation of PARG1 results in increased DNA damage level and enhanced cell death in plants after bleomycin treatment. PARG1 expression is induced primarily in root and shoot meristems by bleomycin and induction of PARG1 is dependent on ATM and ATR kinases. PARG1 also antagonistically modulates the DNA repair process by preventing the over-induction of DNA repair genes. Our study determined the contribution of each PARP and PARG member in DNA repair and indicated that PARG1 plays a critical role in this process.

MEDIATOR18 influences Arabidopsis root architecture, represses auxin signaling and is a critical factor for cell viability in root meristems

“…Although auxin by itself can lead to root phenotypic changes via cell signaling, environmental factors such as radiation, heavy metals or dehydration may result in cell death or DNA damage, thus plants need to efficiently respond to these cues to adapt and avoid accumulation of potentially harmful mutations, which occur through the socalled 'DNA damage response' (DDR) pathway (Ciccia and Elledge, 2010;Hu et al, 2016). Several Arabidopsis components involved in DNA damage repair or recovery of tissue via cell regeneration have been identified, including ATAXIA TELANGIECTASIA MUTATED (ATM), ATM-RAD3-RELATED (ATR), the heterodimeric transcription factor complex ERF115-PAT1, RETINOBLASTOMA RELATED (RBR), WEE1, METHYL METANESULFONATE SENSITIVITY GENE 21 (MMS21), DNA POLIMERASE k (POL k), MERIS-TEM DESORGANIZATION 1 (MDO1) and Poly(ADP-ribose) glycohydrolase (PARG; De Schutter et al, 2007;Hashimura and Ueguchi, 2011;Heyman et al, 2013Heyman et al, , 2016Roy et al, 2013;Xu et al, 2013;Zhang et al, 2015Zhang et al, , 2016Horvath et al, 2017). Moreover, the inability to correctly replicate or repair the DNA results in cell death of stem cells, as seen in seedlings lacking functional JIN HE SHENG 1 (JHS1), a homolog of human and yeast DNA Replication Helicase/ Nuclease 2, and TOPOISOMERASE 1 (TOP1; Jia et al, 2016;Zhang et al, 2016).…”

(ADP-ribosyl)hydrolases: structure, function, and biology

“…Beyond the immediate biochemical connection, it is our hope that future studies will use these links to elucidate the role of the hydrolases in their specific signaling pathways. In this context, it is important to note that the study of hydrolases should be extended beyond the human realm since many (ADP-ribosyl)hydrolases in plants, pathogenic organisms, and model systems among others have still unclear functions (de Souza and Aravind 2012; Perina et al 2014;Aravind et al 2015;Zhang et al 2015a;Gunn et al 2016;Haikarainen and Lehtiö 2016;Lalićet al 2016;Zapata-Pérez et al 2017).…”

Poly(ADP‐ribose) polymerases regulate cell division and development in Arabidopsis roots

“…In recent years, the functions of PARPs in Arabidopsis have been studied through mutant characterization or pharmaceutical inhibition. PARPs are involved in DNA repair, plant growth, seed germination, abiotic and biotic stress tolerance (De Block et al ; Vanderauwera et al ; Ishikawa et al ; Schulz et al ; Jia et al ; Liu et al ; Rissel et al ; Schulz et al ; Feng et al ; Pham et al ; Song et al ; Zhang et al ). So far, whether and how PARPs regulate root development has not been addressed.…”