An Mdm2 antagonist, Nutlin-3a, induces p53-dependent and proteasome-mediated poly(ADP-ribose) polymerase1 degradation in mouse fibroblasts

Matsushima, Shin; Okita, Naoyuki; Oku, Makito; Nagai, Wataru; Kobayashi, Masaki; Higami, Yoshikazu

doi:10.1016/j.bbrc.2011.03.061

Cited by 21 publications

(20 citation statements)

References 25 publications

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“…PF-8 degrades PARP-1 in a proteasome-dependent way. Several studies have reported the association of proteasome activity with PARP-1 degradation (28)(29)(30). To investigate whether PF-8 induces the degradation of PARP-1 in a proteasome-dependent manner, HEK293T cells transfected with increasing amounts of PF-8 for 18 h were treated with the 26S proteasome subunit inhibitor MG132 (1 M) (31) (Fig.…”

Section: Resultsmentioning

confidence: 99%

Downregulation of Poly(ADP-Ribose) Polymerase 1 by a Viral Processivity Factor Facilitates Lytic Replication of Gammaherpesvirus

Cheong

Park

Kang

et al. 2015

J Virol

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In Kaposi's sarcoma-associated herpesvirus (KSHV), poly(ADP-ribose) polymerase 1 (PARP-1) acts as an inhibitor of lytic replication. Here, we demonstrate that KSHV downregulated PARP-1 upon reactivation. The viral processivity factor of KSHV (PF-8) interacted with PARP-1 and was sufficient to degrade PARP-1 in a proteasome-dependent manner; this effect was conserved in murine gammaherpesvirus 68. PF-8 knockdown in KSHV-infected cells resulted in reduced lytic replication upon reactivation with increased levels of PARP-1, compared to those in control cells. PF-8 overexpression reduced the levels of the poly(ADPribosyl)ated (PARylated) replication and transcription activator (RTA) and further enhanced RTA-mediated transactivation. These results suggest a novel viral mechanism for overcoming the inhibitory effect of a host factor, PARP-1, thereby promoting the lytic replication of gammaherpesvirus. IMPORTANCEGammaherpesviruses are important human pathogens, as they are associated with various kinds of tumors and establish latency mainly in host B lymphocytes. Replication and transcription activator (RTA) of Kaposi's sarcoma-associated herpesvirus (KSHV) is a central molecular switch for lytic replication, and its expression is tightly regulated by many host and viral factors. In this study, we investigated a viral strategy to overcome the inhibitory effect of poly(ADP-ribose) polymerase 1 (PARP-1) on RTA's activity. PARP-1, an abundant multifunctional nuclear protein, was downregulated during KSHV reactivation. The viral processivity factor of KSHV (PF-8) directly interacted with PARP-1 and was sufficient and necessary to degrade PARP-1 protein in a proteasome-dependent manner. PF-8 reduced the levels of PARylated RTA and further promoted RTA-mediated transactivation. As this was also conserved in another gammaherpesvirus, murine gammaherpesvirus 68, our results suggest a conserved viral modulation of a host inhibitory factor to facilitate its lytic replication. Gammaherpesviruses, such as Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV), and murine gammaherpesvirus 68 (MHV-68), are associated with various malignancies and lymphoproliferative disorders (1, 2). Several cellular factors are known to regulate the lytic replication of gammaherpesvirus, ultimately contributing to viral pathogenesis (3, 4). Poly(ADP-ribose) polymerase 1 (PARP-1) is an abundant nuclear protein that catalyzes the poly(ADP-ribosyl)ation of target proteins acting in DNA repair, cell cycle control, apoptosis, and gene expression (5-7). In KSHV and MHV-68 infections, PARP-1 interacts with the poly(ADP-ribosyl)ate replication and transcription activator (RTA), the molecular switch of lytic replication, thereby repressing lytic viral replication (8-11). PARP-1 is also known to be a component of the viral replication complex, increasing viral genome replication (9, 12). Previously, we showed that open reading frame 49 (ORF49) of MHV-68 interacts with PARP-1, disrupting interactions between RTA and PARP-1 and furthe...

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Section: Resultsmentioning

confidence: 99%

Downregulation of Poly(ADP-Ribose) Polymerase 1 by a Viral Processivity Factor Facilitates Lytic Replication of Gammaherpesvirus

Cheong

Park

Kang

et al. 2015

J Virol

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“…3T3-L1 preadipocytes were purchased from RIKEN Bioresource Center (Ibaraki, Japan) and were maintained in Dulbecco's modified Eagle's medium (low glucose) (Wako, 041–29775) with 10% fetal bovine serum and 1% penicillin/streptomycin (Sigma) 55,56 . Differentiation of 3T3-L1 preadipocytes to adipocytes was performed as previously reported by our laboratory 55,56 …”

Section: Methodsmentioning

confidence: 99%

“…pMXs-neo-mU6 vector was constructed as previously reported 55,56 . We designed a mouse Ctsl shRNA expression vector based on target sequences for effective CTSL protein knockdown, also as previously reported 56 .…”

Section: Methodsmentioning

confidence: 99%

“…For CTSL knockdown, mock (sh Luc ) and 2 CTSL-knockdown 3T3L1 cell lines (sh Ctsl #1 and sh Ctsl #2) were generated using a retroviral system with pMXs-neo-mU6 vector, as previously reported 55,56 . For CTSB overexpression, mock and CTSB-overexpressing 3T3L1 cell lines (CTSB [OE]) were generated using a retroviral system with pMXs-Puro-AMNN vector.…”

Section: Methodsmentioning

confidence: 99%

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Involvement of lysosomal dysfunction in autophagosome accumulation and early pathologies in adipose tissue of obese mice

et al. 2017

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Whether obesity accelerates or suppresses autophagy in adipose tissue is still debatable. To clarify dysregulation of autophagy and its role in pathologies of obese adipose tissue, we focused on lysosomal function, protease maturation and activity, both in vivo and in vitro. First, we showed that autophagosome formation was accelerated, but autophagic clearance was impaired in obese adipose tissue. We also found protein and activity levels of CTSL (cathepsin L) were suppressed in obese adipose tissue, while the activity of CTSB (cathepsin B) was significantly enhanced. Moreover, cellular senescence and inflammasomes were activated in obese adipose tissue. In 3T3L1 adipocytes, downregulation of CTSL deteriorated autophagic clearance, upregulated expression of CTSB, promoted cellular senescence and activated inflammasomes. Upregulation of CTSB promoted additional activation of inflammasomes. Therefore, we suggest lysosomal dysfunction observed in obese adipose tissue leads to lower autophagic clearance, resulting in autophagosome accumulation. Simultaneously, lysosomal abnormalities, including deteriorated CTSL function and compensatory activation of CTSB, caused cellular senescence and inflammasome activation. Our findings strongly suggest lysosomal dysfunction is involved in early pathologies of obese adipose tissue.

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“…In fact, a number of MDM2-targeting compounds have been identified or designed, which accounts for the majority of the current E3-liagse-targeting molecules [134]. Nutlin is the first selective small molecule that specifically targets MDM2-p53 interaction [135]. Crystal structure analysis revealed that Nutlin interacts with a region in p53, which MDM2 also utilizes to bind with the p53 protein [136].…”

Section: Small Molecules Target the Ubiquitin-proteasome Systemmentioning

confidence: 99%

Targeting the ubiquitin pathway for cancer treatment

Liu

Shaik

Dai

et al. 2015

Biochimica et Biophysica Acta (BBA) - Reviews on Cancer

111

104

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Proteasome-mediated degradation is a common mechanism by which cells renew their intracellular proteins and maintain protein homeostasis. In this process, the E3 ubiquitin ligases are responsible for targeting specific substrates (proteins) for ubiquitin-mediated degradation. However, in cancer cells, the stability and the balance between oncoproteins and tumor suppressor proteins are disturbed in part due to deregulated proteasome-mediated degradation. This ultimately leads to either stabilization of oncoprotein(s) or increased degradation of tumor suppressor(s), contributing to tumorigenesis and cancer progression. Therefore, E3 ubiquitin ligases including the SCF types of ubiquitin ligases have recently evolved as promising therapeutic targets for the development of novel anti-cancer drugs. In this review, we highlighted the critical components along the ubiquitin pathway including E1, E2, various E3 enzymes and DUBs that could serve as potential drug targets and also described the available bioactive compounds that target the ubiquitin pathway to control various cancers.

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An Mdm2 antagonist, Nutlin-3a, induces p53-dependent and proteasome-mediated poly(ADP-ribose) polymerase1 degradation in mouse fibroblasts

Cited by 21 publications

References 25 publications

Downregulation of Poly(ADP-Ribose) Polymerase 1 by a Viral Processivity Factor Facilitates Lytic Replication of Gammaherpesvirus

Downregulation of Poly(ADP-Ribose) Polymerase 1 by a Viral Processivity Factor Facilitates Lytic Replication of Gammaherpesvirus

Involvement of lysosomal dysfunction in autophagosome accumulation and early pathologies in adipose tissue of obese mice

Targeting the ubiquitin pathway for cancer treatment

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