Amir Orian - Academia.edu (original) (raw)

Papers by Amir Orian

The transcription factor ΔNp63 is a master regulator that establishes epithelial cell identity an... more The transcription factor ΔNp63 is a master regulator that establishes epithelial cell identity and is essential for the survival of SCC of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ΔNp63 protein and maintains elevated ΔNP63 levels in SCC by counteracting its proteasome-mediated degradation. Interference with USP28 activity by genetic means abolishes the transcriptional identity of SCC cells and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered mouse models establish that both induction and maintenance of lung SCC strictly depend on endogenous USP28. Targeting ΔNp63 protein abundance in SCC via inhibition of USP28 therefore is a feasible strategy for the treatment of SCC tumours.SignificanceSCC depend on ΔNp63, and its protein abundance is tightly controlled by the ubiquitin proteasome system. Here, we demonstrate the dependence of SCC on USP28 for various human SCC in vitro and in vivo using mur...

BIO-PROTOCOL, 2019

Regulation of gene expression involves dynamic changes in chromatin organization, where in many c... more Regulation of gene expression involves dynamic changes in chromatin organization, where in many cases open chromatin structure correlates with gene activation. Several methods enable monitoring changes in chromatin accessibility, including ATAC-seq, FAIRE-seq, MNase-seq and DNAseseq methods, which involve Next-generation-sequencing (NGS). Focusing on the adult Drosophila differentiated gut enterocytes (ECs) we used a sequencing-free method that enables visualizing and semi-quantifying large-scale changes in chromatin structure using in vitro methylation assay with the bacterial CpG Methyltransferase, M. Sssl, that determine chromatin accessibility. In brief, as CpG methylation is minimal in differentiated somatic Drosophila cells, we used the bacterial M. SssI enzyme to methylate CpG dinucleotides in situ depending on their chromatin accessibility. The methylated dinucleotides are detected using 5mCytosine monoclonal antibody and nuclei are visualized microscopically. Thus, the 5mC method enables to monitor large-scale chromatin changes in heterogenic cellular tissue focusing on the cell type of interest and without the need for cell purification or NGS.

Genes & Development, 2003

The Myc/Max/Mad transcription factor network is critically involved in cell behavior; however, th... more The Myc/Max/Mad transcription factor network is critically involved in cell behavior; however, there is relatively little information on its genomic binding sites. We have employed the DamID method to carry out global genomic mapping of theDrosophilaMyc, Max, and Mad/Mnt proteins. Each protein was tethered toEscherichia coliDNA adenine-methyltransferase (Dam) permitting methylation proximal to in vivo binding sites inKccells. Microarray analyses of methylated DNA fragments reveals binding to multiple loci on all majorDrosophilachromosomes. This approach also reveals dynamic interactions among network members as we find that increased levels of dMax influence the extent of dMyc, but not dMnt, binding. Computer analysis using the REDUCE algorithm demonstrates that binding regions correlate with the presence of E-boxes, CG repeats, and other sequence motifs. The surprisingly large number of directly bound loci (∼15% of coding regions) suggests that the network interacts widely with the...

Highlights d RNF4 stabilizes and enhances the activity of short-lived oncogenes d Stabilization r... more Highlights d RNF4 stabilizes and enhances the activity of short-lived oncogenes d Stabilization requires substrate phosphorylation and atypical ubiquitylation d RNF4 is essential for cancer cell survival d High RNF4 levels are correlated with reduced survival in epithelial tumors

Cellular and Molecular Life Sciences

Regulation of the differentiated identity requires active and continued supervision. Inability to... more Regulation of the differentiated identity requires active and continued supervision. Inability to maintain the differentiated state is a hallmark of aging and aging-related disease. To maintain cellular identity, a network of nuclear regulators is devoted to silencing previous and non-relevant gene programs. This network involves transcription factors, epigenetic regulators, and the localization of silent genes to heterochromatin. Together, identity supervisors mold and maintain the unique nuclear environment of the differentiated cell. This review describes recent discoveries regarding mechanisms and regulators that supervise the differentiated identity and protect from de-differentiation, tumorigenesis, and attenuate forced somatic cell reprograming. The review focuses on mechanisms involved in H3K9me3-decorated heterochromatin and the importance of nuclear lamins in cell identity. We outline how the biophysical properties of these factors are involved in self-compartmentalization...

SummaryA hallmark of aging is the inability of differentiated cells to maintain their identity. I... more SummaryA hallmark of aging is the inability of differentiated cells to maintain their identity. In the agedDrosophilamidgut differentiated enterocytes (ECs) lose their identity, and the integrity of the midgut tissue and its homeostasis are impaired. To discover regulators of EC identity relevant to aging we performed an RNAi screen targeting 453 ubiquitin-related genes in fully differentiated ECs. Seventeen genes were identified, including the de-ubiquitinase Non-stop (Not/dUSP22; CG4166). Acute loss of Non-stop in young ECs phenotypically resembled aged ECs. Lineage tracing experiments established that Non-stop-deficient young ECs as well as wild-type aged ECs are no longer differentiated. Aging or acute loss of Non-stop also resulted in progenitor cell hyperproliferation and mis-differentiation, loss of gut integrity, and reduced organismal survival. Proteomic analysis unveiled that Non-stop maintains identity as part of a Non-stop identity complex (NIC) that contains E(y)2, Sgf1...

PLOS Pathogens

The Immune Deficiency (IMD) pathway in Drosophila melanogaster is activated upon microbial challe... more The Immune Deficiency (IMD) pathway in Drosophila melanogaster is activated upon microbial challenge with Gram-negative bacteria to trigger the innate immune response. In order to decipher this nuclear factor κB (NF-κB) signaling pathway, we undertook an in vitro RNAi screen targeting E3 ubiquitin ligases specifically and identified the HECT-type E3 ubiquitin ligase Hyperplastic discs (Hyd) as a new actor in the IMD pathway. Hyd mediated Lys 63 (K63)-linked polyubiquitination of the NF-κB cofactor Akirin was required for efficient binding of Akirin to the NF-κB transcription factor Relish. We showed that this Hyd-dependent interaction was required for the transcription of immunity-related genes that are activated by both Relish and Akirin but was dispensable for the transcription of genes that depend solely on Relish. Therefore Hyd is key in NF-κB transcriptional selectivity downstream of the IMD pathway. Drosophila depleted of Akirin or Hyd failed to express the full set of genes encoding immune-induced anti-microbial peptides and succumbed to immune challenges. We showed further that UBR5, the mammalian homolog of Hyd, was also required downstream of the NF-κB pathway for the activation of Interleukin 6 (IL6) transcription by LPS or IL-1β in cultured human cells. Our findings link the action of an E3 ubiquitin ligase to the activation of immune effector genes, deepening our understanding of the involvement of ubiquitination in inflammation and identifying a potential target for the control of inflammatory diseases.

EMBO Molecular Medicine, Apr 7, 2020

The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential fo... more The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ∆Np63 and maintains elevated ∆NP63 levels in SCC by counteracting its proteasome‐mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9‐engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ∆Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.The study reveals that squamous tumours are dependent on the expression of the deubiquitylase USP28. Inhibition of USP28 destabilises ΔNp63 protein abundance and enables therapeutic targeting of squamous tumours of various origins, such as head and neck, lung, cervix and pancreas.

Journal of Investigative Dermatology

Nature Communications

Accumulating evidence points to an important role for the gut microbiome in anti-tumor immunity. ... more Accumulating evidence points to an important role for the gut microbiome in anti-tumor immunity. Here, we show that altered intestinal microbiota contributes to anti-tumor immunity, limiting tumor expansion. Mice lacking the ubiquitin ligase RNF5 exhibit attenuated activation of the unfolded protein response (UPR) components, which coincides with increased expression of inflammasome components, recruitment and activation of dendritic cells and reduced expression of antimicrobial peptides in intestinal epithelial cells. Reduced UPR expression is also seen in murine and human melanoma tumor specimens that responded to immune checkpoint therapy. Co-housing of Rnf5 −/− and WT mice abolishes the anti-tumor immunity and tumor inhibition phenotype, whereas transfer of 11 bacterial strains, including B. rodentium, enriched in Rnf5 −/− mice, establishes anti-tumor immunity and restricts melanoma growth in germ-free WT mice. Altered UPR signaling, exemplified in Rnf5 −/− mice, coincides with altered gut microbiota composition and anti-tumor immunity to control melanoma growth.

One Sentence SummaryUpon microbial infection in Drosophila, the E3-ubiquitin ligase Hyd ubiquitin... more One Sentence SummaryUpon microbial infection in Drosophila, the E3-ubiquitin ligase Hyd ubiquitinylates the NF-κB co-factor Akirin for its efficient binding to the NF-κB factor Relish and subsequent activation of immune effectors genes.ABSTRACTThe Drosophila IMD pathway is activated upon microbial challenge with Gramnegative bacteria to trigger the innate immune response. In order to decipher this NF-κB signaling pathway, we undertook an ex-vivo RNAi screen targeting specifically E3 ubiquitin ligases and identified the HECT E3 ubiquitin ligase Hyperplastic Discs “Hyd” as a new actor of the IMD pathway. We showed that Hyd targets the NF-κB cofactor of Akirin. The K63-polyubiquitination chains deposited by Hyd decorate Akirin for its efficient binding to the NF-κB transcription factor Relish. We showed that this Hyd-mediated interaction is critical to activate immune-induced genes that depend on both Relish and Akirin, but is dispensable for those that depend solely on Relish. Therefo...

Journal of Investigative Dermatology

Current Opinion in Systems Biology

Abstract How differentiated cells maintain their identity is a fundamental question in biology. L... more Abstract How differentiated cells maintain their identity is a fundamental question in biology. Loss of identity is a hallmark of aged cells and tissues, and is associated with age-related diseases such as neurodegeneration, metabolic disorders and cancer. It is an active process that requires dedicated transcription factor networks. Recent findings suggest that another level of identity regulation involves maintenance of nuclear organization that is unique to the differentiated cell and is dependent on nuclear lamins. Here we review the current understanding of the mechanisms and regulators that maintain the differentiated identity by connecting chromatin state with large-scale organization of the nucleus. We forecast that mechanisms involved in supervising cell identity will be highly relevant to aging biology, cancer, and regenerative medicine.

Journal of developmental biology, 2018

The ubiquitin and SUMO (small ubiquitin-like modifier) pathways modify proteins that in turn regu... more The ubiquitin and SUMO (small ubiquitin-like modifier) pathways modify proteins that in turn regulate diverse cellular processes, embryonic development, and adult tissue physiology. These pathways were originally discovered biochemically in vitro, leading to a long-standing challenge of elucidating both the molecular cross-talk between these pathways and their biological importance. Recent discoveries in established that ubiquitin and SUMO pathways are interconnected via evolutionally conserved SUMO-targeted ubiquitin ligase (STUbL) proteins. STUbL are RING ubiquitin ligases that recognize SUMOylated substrates and catalyze their ubiquitination, and include Degringolade (Dgrn) in and RNF4 and RNF111 in humans. STUbL are essential for early development of both the fly and mouse embryos. In the fly embryo, Dgrn regulates early cell cycle progression, sex determination, zygotic gene transcription, segmentation, and neurogenesis, among other processes. In the fly adult, Dgrn is required...

Protein & cell, Jan 28, 2015

SUMOylation is recently found to function as a targeting signal for the degradation of substrates... more SUMOylation is recently found to function as a targeting signal for the degradation of substrates through the ubiquitin-proteasome system. RNF4 is the most studied human SUMO-targeted ubiquitin E3 ligase. However, the relationship between SUMO proteases, SENPs, and RNF4 remains obscure. There are limited examples of the SENP regulation of SUMO2/3-targeted proteolysis mediated by RNF4. The present study investigated the role of SENP3 in the global protein turnover related to SUMO2/3-targeted ubiquitination and focused in particular on the SENP3 regulation of the stability of Sp1. Our data demonstrated that SENP3 impaired the global ubiquitination profile and promoted the accumulation of many proteins. Sp1, a cancer-associated transcription factor, was among these proteins. SENP3 increased the level of Sp1 protein via antagonizing the SUMO2/3-targeted ubiquitination and the consequent proteasome-dependent degradation that was mediated by RNF4. De-conjugation of SUMO2/3 by SENP3 attenu...

The transcription factor ΔNp63 is a master regulator that establishes epithelial cell identity an... more The transcription factor ΔNp63 is a master regulator that establishes epithelial cell identity and is essential for the survival of SCC of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ΔNp63 protein and maintains elevated ΔNP63 levels in SCC by counteracting its proteasome-mediated degradation. Interference with USP28 activity by genetic means abolishes the transcriptional identity of SCC cells and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered mouse models establish that both induction and maintenance of lung SCC strictly depend on endogenous USP28. Targeting ΔNp63 protein abundance in SCC via inhibition of USP28 therefore is a feasible strategy for the treatment of SCC tumours.SignificanceSCC depend on ΔNp63, and its protein abundance is tightly controlled by the ubiquitin proteasome system. Here, we demonstrate the dependence of SCC on USP28 for various human SCC in vitro and in vivo using mur...

BIO-PROTOCOL, 2019

Regulation of gene expression involves dynamic changes in chromatin organization, where in many c... more Regulation of gene expression involves dynamic changes in chromatin organization, where in many cases open chromatin structure correlates with gene activation. Several methods enable monitoring changes in chromatin accessibility, including ATAC-seq, FAIRE-seq, MNase-seq and DNAseseq methods, which involve Next-generation-sequencing (NGS). Focusing on the adult Drosophila differentiated gut enterocytes (ECs) we used a sequencing-free method that enables visualizing and semi-quantifying large-scale changes in chromatin structure using in vitro methylation assay with the bacterial CpG Methyltransferase, M. Sssl, that determine chromatin accessibility. In brief, as CpG methylation is minimal in differentiated somatic Drosophila cells, we used the bacterial M. SssI enzyme to methylate CpG dinucleotides in situ depending on their chromatin accessibility. The methylated dinucleotides are detected using 5mCytosine monoclonal antibody and nuclei are visualized microscopically. Thus, the 5mC method enables to monitor large-scale chromatin changes in heterogenic cellular tissue focusing on the cell type of interest and without the need for cell purification or NGS.

Genes & Development, 2003

The Myc/Max/Mad transcription factor network is critically involved in cell behavior; however, th... more The Myc/Max/Mad transcription factor network is critically involved in cell behavior; however, there is relatively little information on its genomic binding sites. We have employed the DamID method to carry out global genomic mapping of theDrosophilaMyc, Max, and Mad/Mnt proteins. Each protein was tethered toEscherichia coliDNA adenine-methyltransferase (Dam) permitting methylation proximal to in vivo binding sites inKccells. Microarray analyses of methylated DNA fragments reveals binding to multiple loci on all majorDrosophilachromosomes. This approach also reveals dynamic interactions among network members as we find that increased levels of dMax influence the extent of dMyc, but not dMnt, binding. Computer analysis using the REDUCE algorithm demonstrates that binding regions correlate with the presence of E-boxes, CG repeats, and other sequence motifs. The surprisingly large number of directly bound loci (∼15% of coding regions) suggests that the network interacts widely with the...

Highlights d RNF4 stabilizes and enhances the activity of short-lived oncogenes d Stabilization r... more Highlights d RNF4 stabilizes and enhances the activity of short-lived oncogenes d Stabilization requires substrate phosphorylation and atypical ubiquitylation d RNF4 is essential for cancer cell survival d High RNF4 levels are correlated with reduced survival in epithelial tumors

Cellular and Molecular Life Sciences

Regulation of the differentiated identity requires active and continued supervision. Inability to... more Regulation of the differentiated identity requires active and continued supervision. Inability to maintain the differentiated state is a hallmark of aging and aging-related disease. To maintain cellular identity, a network of nuclear regulators is devoted to silencing previous and non-relevant gene programs. This network involves transcription factors, epigenetic regulators, and the localization of silent genes to heterochromatin. Together, identity supervisors mold and maintain the unique nuclear environment of the differentiated cell. This review describes recent discoveries regarding mechanisms and regulators that supervise the differentiated identity and protect from de-differentiation, tumorigenesis, and attenuate forced somatic cell reprograming. The review focuses on mechanisms involved in H3K9me3-decorated heterochromatin and the importance of nuclear lamins in cell identity. We outline how the biophysical properties of these factors are involved in self-compartmentalization...

SummaryA hallmark of aging is the inability of differentiated cells to maintain their identity. I... more SummaryA hallmark of aging is the inability of differentiated cells to maintain their identity. In the agedDrosophilamidgut differentiated enterocytes (ECs) lose their identity, and the integrity of the midgut tissue and its homeostasis are impaired. To discover regulators of EC identity relevant to aging we performed an RNAi screen targeting 453 ubiquitin-related genes in fully differentiated ECs. Seventeen genes were identified, including the de-ubiquitinase Non-stop (Not/dUSP22; CG4166). Acute loss of Non-stop in young ECs phenotypically resembled aged ECs. Lineage tracing experiments established that Non-stop-deficient young ECs as well as wild-type aged ECs are no longer differentiated. Aging or acute loss of Non-stop also resulted in progenitor cell hyperproliferation and mis-differentiation, loss of gut integrity, and reduced organismal survival. Proteomic analysis unveiled that Non-stop maintains identity as part of a Non-stop identity complex (NIC) that contains E(y)2, Sgf1...

PLOS Pathogens

The Immune Deficiency (IMD) pathway in Drosophila melanogaster is activated upon microbial challe... more The Immune Deficiency (IMD) pathway in Drosophila melanogaster is activated upon microbial challenge with Gram-negative bacteria to trigger the innate immune response. In order to decipher this nuclear factor κB (NF-κB) signaling pathway, we undertook an in vitro RNAi screen targeting E3 ubiquitin ligases specifically and identified the HECT-type E3 ubiquitin ligase Hyperplastic discs (Hyd) as a new actor in the IMD pathway. Hyd mediated Lys 63 (K63)-linked polyubiquitination of the NF-κB cofactor Akirin was required for efficient binding of Akirin to the NF-κB transcription factor Relish. We showed that this Hyd-dependent interaction was required for the transcription of immunity-related genes that are activated by both Relish and Akirin but was dispensable for the transcription of genes that depend solely on Relish. Therefore Hyd is key in NF-κB transcriptional selectivity downstream of the IMD pathway. Drosophila depleted of Akirin or Hyd failed to express the full set of genes encoding immune-induced anti-microbial peptides and succumbed to immune challenges. We showed further that UBR5, the mammalian homolog of Hyd, was also required downstream of the NF-κB pathway for the activation of Interleukin 6 (IL6) transcription by LPS or IL-1β in cultured human cells. Our findings link the action of an E3 ubiquitin ligase to the activation of immune effector genes, deepening our understanding of the involvement of ubiquitination in inflammation and identifying a potential target for the control of inflammatory diseases.

EMBO Molecular Medicine, Apr 7, 2020

The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential fo... more The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ∆Np63 and maintains elevated ∆NP63 levels in SCC by counteracting its proteasome‐mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9‐engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ∆Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.The study reveals that squamous tumours are dependent on the expression of the deubiquitylase USP28. Inhibition of USP28 destabilises ΔNp63 protein abundance and enables therapeutic targeting of squamous tumours of various origins, such as head and neck, lung, cervix and pancreas.

Journal of Investigative Dermatology

Nature Communications

Accumulating evidence points to an important role for the gut microbiome in anti-tumor immunity. ... more Accumulating evidence points to an important role for the gut microbiome in anti-tumor immunity. Here, we show that altered intestinal microbiota contributes to anti-tumor immunity, limiting tumor expansion. Mice lacking the ubiquitin ligase RNF5 exhibit attenuated activation of the unfolded protein response (UPR) components, which coincides with increased expression of inflammasome components, recruitment and activation of dendritic cells and reduced expression of antimicrobial peptides in intestinal epithelial cells. Reduced UPR expression is also seen in murine and human melanoma tumor specimens that responded to immune checkpoint therapy. Co-housing of Rnf5 −/− and WT mice abolishes the anti-tumor immunity and tumor inhibition phenotype, whereas transfer of 11 bacterial strains, including B. rodentium, enriched in Rnf5 −/− mice, establishes anti-tumor immunity and restricts melanoma growth in germ-free WT mice. Altered UPR signaling, exemplified in Rnf5 −/− mice, coincides with altered gut microbiota composition and anti-tumor immunity to control melanoma growth.

One Sentence SummaryUpon microbial infection in Drosophila, the E3-ubiquitin ligase Hyd ubiquitin... more One Sentence SummaryUpon microbial infection in Drosophila, the E3-ubiquitin ligase Hyd ubiquitinylates the NF-κB co-factor Akirin for its efficient binding to the NF-κB factor Relish and subsequent activation of immune effectors genes.ABSTRACTThe Drosophila IMD pathway is activated upon microbial challenge with Gramnegative bacteria to trigger the innate immune response. In order to decipher this NF-κB signaling pathway, we undertook an ex-vivo RNAi screen targeting specifically E3 ubiquitin ligases and identified the HECT E3 ubiquitin ligase Hyperplastic Discs “Hyd” as a new actor of the IMD pathway. We showed that Hyd targets the NF-κB cofactor of Akirin. The K63-polyubiquitination chains deposited by Hyd decorate Akirin for its efficient binding to the NF-κB transcription factor Relish. We showed that this Hyd-mediated interaction is critical to activate immune-induced genes that depend on both Relish and Akirin, but is dispensable for those that depend solely on Relish. Therefo...

Journal of Investigative Dermatology

Current Opinion in Systems Biology

Abstract How differentiated cells maintain their identity is a fundamental question in biology. L... more Abstract How differentiated cells maintain their identity is a fundamental question in biology. Loss of identity is a hallmark of aged cells and tissues, and is associated with age-related diseases such as neurodegeneration, metabolic disorders and cancer. It is an active process that requires dedicated transcription factor networks. Recent findings suggest that another level of identity regulation involves maintenance of nuclear organization that is unique to the differentiated cell and is dependent on nuclear lamins. Here we review the current understanding of the mechanisms and regulators that maintain the differentiated identity by connecting chromatin state with large-scale organization of the nucleus. We forecast that mechanisms involved in supervising cell identity will be highly relevant to aging biology, cancer, and regenerative medicine.

Journal of developmental biology, 2018

The ubiquitin and SUMO (small ubiquitin-like modifier) pathways modify proteins that in turn regu... more The ubiquitin and SUMO (small ubiquitin-like modifier) pathways modify proteins that in turn regulate diverse cellular processes, embryonic development, and adult tissue physiology. These pathways were originally discovered biochemically in vitro, leading to a long-standing challenge of elucidating both the molecular cross-talk between these pathways and their biological importance. Recent discoveries in established that ubiquitin and SUMO pathways are interconnected via evolutionally conserved SUMO-targeted ubiquitin ligase (STUbL) proteins. STUbL are RING ubiquitin ligases that recognize SUMOylated substrates and catalyze their ubiquitination, and include Degringolade (Dgrn) in and RNF4 and RNF111 in humans. STUbL are essential for early development of both the fly and mouse embryos. In the fly embryo, Dgrn regulates early cell cycle progression, sex determination, zygotic gene transcription, segmentation, and neurogenesis, among other processes. In the fly adult, Dgrn is required...

Protein & cell, Jan 28, 2015

SUMOylation is recently found to function as a targeting signal for the degradation of substrates... more SUMOylation is recently found to function as a targeting signal for the degradation of substrates through the ubiquitin-proteasome system. RNF4 is the most studied human SUMO-targeted ubiquitin E3 ligase. However, the relationship between SUMO proteases, SENPs, and RNF4 remains obscure. There are limited examples of the SENP regulation of SUMO2/3-targeted proteolysis mediated by RNF4. The present study investigated the role of SENP3 in the global protein turnover related to SUMO2/3-targeted ubiquitination and focused in particular on the SENP3 regulation of the stability of Sp1. Our data demonstrated that SENP3 impaired the global ubiquitination profile and promoted the accumulation of many proteins. Sp1, a cancer-associated transcription factor, was among these proteins. SENP3 increased the level of Sp1 protein via antagonizing the SUMO2/3-targeted ubiquitination and the consequent proteasome-dependent degradation that was mediated by RNF4. De-conjugation of SUMO2/3 by SENP3 attenu...