Chronic granulomatous disease is an inherited disorder in which phagocytes lack a functional NADPH oxidase and so cannot generate superoxide anions (O(2) (-)). The most common form is caused by mutations in CYBB encoding gp91 phox, the heavy chain of flavocytochrome b(558) (XCGD). We investigated 11 male patients and their families suspected of suffering from X-linked CGD. These XCGD patients were classified as having different variants (X91(0), X91(-) or X91(+)) according to their cytochrome b(558) expression and NADPH oxidase activity. Nine patients had X91(0) CGD, one had X91(-) CGD and one had X91(+) CGD. Six mutations in CYBB were novel. Of the four new X91(0) CGD cases, three were point mutations: G65A in exon 2, G387T in exon 5 and G970T in exon 9, leading to premature stop codons at positions Try18, Try125 and Glu320, respectively, in gp91 phox. One case of X91(0) CGD originated from a new 1005G deletion detected in exon 9. Surprisingly, four nonsense mutations in exon 5 led to the generation of two mRNAs, one with a normal size containing the mutation and the other in which exon 5 had been spliced. A novel X91(-) CGD case with low gp91 phox expression was diagnosed. It was caused by an 11-bp deletion in the linking region between exon 12 and intron 12, activating a new cryptic site. Finally, a new X91(+) CGD case was detected, characterized by a missense mutation Leu505Arg in the potential NADPH-binding site of gp91 phox. No clear correlation between the severity of the clinical symptoms and the sub-type of XCGD could be established.

Ubiquitin and the ubiquitin-like SUMO are covalently conjugated to thousands of proteins to modulate their function and fate. Many of the enzymes involved in their conjugation are dysregulated in cancers and involved in cancer cell response to therapies. We describe here the identification of biomarkers of the activity of these enzymes and their use to predict acute myeloid leukemias (AML) response to standard chemotherapy (daunorubicin-DNR and cytarabine-Ara-C). We compared the ability of extracts from chemosensitive and chemoresistant AML cells to conjugate ubiquitin or SUMO-1 on 9,000 proteins spotted on protein arrays. We identified 122 proteins whose conjugation by these posttranslational modifiers marks AML resistance to DNR and/or Ara-C. Based on this signature, we defined a statistical score predicting AML patient response to standard chemotherapy. We finally developed a miniaturized assay allowing for easy assessment of modification levels of the selected biomarkers and validated it in patient cell extracts. Thus, our work identifies a new type of ubiquitin-based biomarkers that could be used to predict cancer patient response to treatments.

Ubiquitin defines a family of approximately 20 peptidic post-translational modifiers collectively called the Ubiquitin-like (UbLs). They are conjugated to thousands of proteins, modifying their function and fate in many ways. Dysregulation of these modifications has been implicated in a variety of pathologies, in particular cancer. Ubiquitin, SUMO (-1 to-3) and Nedd8 are the bestcharacterized UbLs. They have been involved in the regulation of the activity and/or the stability of diverse components of various oncogenic or tumor suppressor pathways. Moreover, the dysregulation of enzymes responsible for their conjugation/deconjugation has also been associated with tumorigenesis and cancer resistance to therapies. The UbL system therefore constitutes an attractive target for developing novel anticancer therapeutic strategies. Here, we review the roles and dysregulations of Ubiquitin-, SUMO-and Nedd8 pathways in tumorigenesis, as well as recent advances in the identification of small molecules targeting their conjugating machineries for potential application in the fight against cancer. 4 most substrates being constantly modified and demodified. Deconjugation is carried out by isopeptidases, which cleave the isopeptide bonds between UbLs and target lysines. This allows UbLs, which are highly stable polypeptides, to be recycled and reconjugated to other proteins. Some isopeptidases are also involved in the proteolytic maturation of UbLs, which are synthetized in the form of precursors displaying extra amino-acids at their C-termini. Similar to E3s, isopeptidases show substrate specificity or, at least, preference for particular chain linkages [9]. Concerning the SUMO pathway, deSUMOylases, such as SENP6 and SENP7, preferentially cleave SUMO-2 chains, whilst others, such as SENP-1 and SENP-2, rather deconjugate SUMO bound to target proteins [10]. Some deSUMOylases such as SENP-3, SENP-5 and USPL1 have preference for SUMO-2 over SUMO-1 [11, 12]. The consequences of UbL conjugation are numerous. They depend on the UbL type, possibly the nature of UbL chains formed and, obviously, the substrate. As they have been reviewed extensively elsewhere [3, 13-15], only the main physiological roles of Ubiquitylation, SUMOylation and Neddylation are considered hereafter. The biological outcomes of Ubiquitin conjugation are highly dependent on the chain linkage types, which, due to their diversity and complexity, create the so-called "Ubiquitin code" [14]. The most abundant and best-characterized Ubiquitin chains are long K48-linked ones (>4 Ubiquitins). They constitute a protein degradation signal recognized by the 26S proteasome, which is the main cell proteolytic machinery [16-18]). This discovery led Avram Hershko, Irwin Rose an Aaron Ciechanover to be awarded the Nobel Prize in 2004. It is, however, important to keep in mind that K48-linked Ubiquitin chains can also be involved in signaling events and transcription regulation not involving protein destruction [19-21]. K63-linked chains are bestknown as involved in protein-protei...