Recruitment of a ROC1–CUL1 Ubiquitin Ligase by Skp1 and HOS to Catalyze the Ubiquitination of IκBα

Tan, Peilin; Fuchs, Serge Y.; Chen, Angus; Wu, Ken; Gómez, Carlos A.; Ronai, Ze’ev A.; Pan, Zhen‐Qiang

doi:10.1016/s1097-2765(00)80481-5

Cited by 319 publications

(322 citation statements)

References 25 publications

Supporting

Mentioning

309

Contrasting

Unclassified

Order By: Relevance

“…We showed a morphological cell enlargement and a broad distribution of¯uorescence intensities with an increased DNA content in SAG knockout cells (Figure 4). Several recent ®ndings also support this notion: (1) Xenopus Cdc34, an E2 that binds to SAG/ROC/Rbx/Hrt Ohta et al, 1999;Seol et al, 1999;Skowyra et al, 1999;Tan et al, 1999;Tyers and Willems, 1999) promoted degradation of Wee1 (Michael and Newport, 1998), a key G2/M negative regulator (McGowan and Russell, 1993;Parker and Piwnica Worms, 1992); (2) SCF components, Skp1 and Cul1 were localized to the centrosome and regulated the centrosome duplication cycle in mammalian cells (Freed et al, 1999); and (3) Cdc4, an F-box protein in SCF complex was required for the onset of S phase as well as anaphase in Saccharomyces cerevisiae (Goh and Surana, 1999).…”

Section: Discussionmentioning

confidence: 88%

“…SAG is also shown to be a component of E3 ubiquitin ligase involved in the degradation of many biological important molecules including IkB Ohta et al, 1999;Skowyra et al, 1999;Tan et al, 1999). It is possible that anti-apopotosis activity of SAG/ROC/Rbx can also be achieved through ubiquitination and degradation of IkB, an inhibitor of NF-kB (Ohta et al, 1999;Tan et al, 1999), leading to activation of apoptosis inhibitor, NF-kB (Beg and Baltimore, 1996;Mayo et al, 1997;Van Antwerp et al, 1996, 1998Wang et al, 1996). This hypothesis is being tested currently in our laboratory.…”

Section: Discussionmentioning

confidence: 99%

“…While this manuscript was in its late stage of preparation, several groups have reported the cloning and characterization of ROC1 (regulator of cullins), Rbx1 (RING box) or Hrt1 that either binds to cullins or VHL tumor suppressor gene product or SCF complex to form important E3 ubiquitin ligase complex Ohta et al, 1999;Seol et al, 1999;Skowyra et al, 1999;Tan et al, 1999;Tyers and Willems, 1999). By direct sequencing comparison, SAG turns out to be the second member of this ROC/Rbx/Hrt family (ROC2/Rbx2/Hrt2).…”

Section: Like Roc1 Sag Binds To Cul1mentioning

confidence: 99%

“…Phosphorylation of PK-Ub (7 mg) (from Dr Pan (Tan et al, 1999)), was carried out in a 20 ml reaction mixture containing 20 mM Tris-HCl pH 7.4, 12 mM MgCl 2 , 2 mM NaF, 50 mM NaCl, 25 mM ATP, 5 mCi of g 32 P-ATP, 0.1 mg/ml BSA, and 1 unit of cAMP kinase (Sigma). The reaction mixture was incubated at 378C for 30 min.…”

Section: Ubiquitin Labeling and Ub Ligation Assaymentioning

confidence: 99%

See 3 more Smart Citations

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

Swaroop¹,

Wang²,

Miller³

et al. 2000

Oncogene

View full text Add to dashboard Cite

In an attempt to understand the signaling pathway mediating redox-induced apoptosis, we cloned SAG, an evolutionarily conserved zinc RING ®nger gene that, when overexpressed, protects cells from apoptosis induced by redox agents. Here we report functional characterization of SAG by the use of yeast genetics approach. Targeted disruption of ySAG, yeast homolog of human SAG, and subsequent tetrad analysis revealed that ySAG is required for yeast viability. Complementation experiment showed that the lethal phenotype induced by the ySAG deletion is fully rescued by wildtype SAG, but not by several hSAG mutants. Complementation experiment has also con®rmed that ySAG is essential for normal vegetative growth, rather than being required for sporulation. Furthermore, cell death induced by SAG deletion was accompanied by cell enlargement and abnormal cell cycle pro®ling with an increased DNA content. Importantly, SAG was found to be the second family member of Rbx (RING box protein) or ROC (Regulator of cullins) or Hrt that is a component of SCF E3 ubiquitin ligase. Indeed, like ROC1/Rbx1/Hrt1, SAG binds to Cul1 and SAG-Cul1 complex has ubiquitin ligase activity to promote poly-ubiquitination of E2/ Cdc34. This ligase activity is required for complementation of death phenotype induced by ySAG disruption. Finally, chip pro®ling of the entire yeast genome revealed induction of several G1/S as well as G2/M checkpoint control genes upon SAG withdrawal. Thus, SAG appears to control cell cycle progression in yeast by promoting ubiquitination and degradation of cell cycle regulatory proteins.

show abstract

Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Like Roc1 Sag Binds To Cul1mentioning

confidence: 99%

Section: Ubiquitin Labeling and Ub Ligation Assaymentioning

confidence: 99%

See 2 more Smart Citations

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

Swaroop¹,

Wang²,

Miller³

et al. 2000

Oncogene

View full text Add to dashboard Cite

show abstract

“…This complex associates with the ubiquitin ligase, b-TrCP (b-transducin repeat-containing protein) that recognizes the N-terminally phosphorylated forms of bcatenin and regulates its ubiquitination and degradation by the proteasome (Winston et al, 1999;Liu et al, 1999;Latres et al, 1999;Hart et al, 1999;Kitagawa et al, 1999). b-TrCP associates through its F-box with Cul1/Skp1/ROC1 forming the modular ubiquitin ligase SCF complex (Latres et al, 1999;Tan et al, 1999) and via its WD repeat motif with the phosphorylated bcatenin (Winston et al, 1999;Liu et al, 1999;Hart et al, 1999), thus forming a multimolecular complex consisting of b-TrCP/b-catenin/Axin/GSK/APC (Liu et al, 1999;Kitagawa et al, 1999). b-TrCP and its Drosophila homolog Slimb were implicated in the regulation of wnt/wg signaling (Jiang and Struhl, 1998) and the DF-b-TrCP mutant, lacking the F-box, was shown to induce axis duplication in Xenopus (Marikawa and Elinson, 1998;Liu et al, 1999), and loss of function mutations in Slimb, induce the accumulation of armadillo in Drosophila (Jiang and Struhl, 1998).…”

Section: Introductionmentioning

confidence: 99%

Differential interaction of plakoglobin and β-catenin with the ubiquitin-proteasome system

et al. 2000

View full text Add to dashboard Cite

b-Catenin and plakoglobin are closely related armadillo family proteins with shared and distinct properties; Both are associated with cadherins in actin-containing adherens junctions. Plakoglobin is also found in desmosomes where it anchors intermediate ®laments to the desmosomal plaques. b-Catenin, on the other hand, is a component of the Wnt signaling pathway, which is involved in embryonic morphogenesis and tumorigenesis. A key step in the regulation of this pathway involves modulation of b-catenin stability. A multiprotein complex, regulated by Wnt, directs the phosphorylation of bcatenin and its degradation by the ubiquitin-proteasome system. Plakoglobin can also associate with members of this complex, but inhibition of proteasomal degradation has little e ect on its levels while dramatically increasing the levels of b-catenin. b-TrCP, an F-box protein of the SCF E3 ubiquitin ligase complex, was recently shown to play a role in the turnover of b-catenin. To elucidate the basis for the apparent di erences in the turnover of bcatenin and plakoglobin we compared the handling of these two proteins by the ubiquitin-proteasome system. We show here that a deletion mutant of b-TrCP, lacking the F-box, can stabilize the endogenous b-catenin leading to its nuclear translocation and induction of b-catenin/ LEF-1-directed transcription, without a ecting the levels of plakoglobin. However, when plakoglobin was overexpressed, it readily associated with b-TrCP, e ciently competed with b-catenin for binding to b-TrCP and became polyubiquitinated. Fractionation studies revealed that about 85% of plakoglobin in 293 cells, is Triton X-100-insoluble compared to 50% of b-catenin. These results suggest that while both plakoglobin and b-catenin can comparably interact with b-TrCP and the ubiquitination system, the sequestration of plakoglobin by the membrane-cytoskeleton system renders it inaccessible to the proteolytic machinery and stabilizes it.

show abstract

Modes of regulation of ubiquitin-mediated protein degradation

2000

View full text Add to dashboard Cite

The ubiquitin-proteasome pathway is responsible for the major portion of specific cellular protein degradation. Ubiquitin-mediated degradation is involved in physiological regulation of many cellular processes, including cell cycle progression, differentiation, and signal transduction. Here, we review the basic mechanisms of the ubiquitin system and the various ways in which ubiquitin-mediated degradation can be modulated by physiological signals.

show abstract

Recruitment of a ROC1–CUL1 Ubiquitin Ligase by Skp1 and HOS to Catalyze the Ubiquitination of IκBα

Cited by 319 publications

References 25 publications

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

Yeast homolog of human SAG/ROC2/Rbx2/Hrt2 is essential for cell growth, but not for germination: chip profiling implicates its role in cell cycle regulation

Differential interaction of plakoglobin and β-catenin with the ubiquitin-proteasome system

Modes of regulation of ubiquitin-mediated protein degradation

Contact Info

Product

Resources

About