STRUCTURE OF THE CYLD USP DOMAIN
[CYLD_HUMAN] Defects in CYLD are the cause of familial cylindromatosis (FCYL) [MIM:132700]; also known as Ancell-Spiegler cylindromas or turban tumor syndrome or dermal eccrine cylindromatosis. CYLD is an autosomal dominant and highly tumor type-specific disorder. The tumors (known as cylindromas because of their characteristic microscopic architecture) are believed to arise from or recapitulate the appearance of the eccrine or apocrine cells of the skin that secrete sweat and scent respectively. Cylindromas arise predominantly in hairy parts of the body with approximately 90% on the head and neck. The development of a confluent mass which may ulcerate or become infected has led to the designation 'turban tumor syndrome'. The skin tumors show differentiation in the direction of hair structures, hence the synonym trichoepithelioma.  Defects in CYLD are the cause of multiple familial trichoepithelioma type 1 (MFT1) [MIM:601606]; also known as epithelioma adenoides cysticum of Brooke (EAC) or hereditary multiple benign cystic epithelioma or Brooke-Fordyce trichoepitheliomas. MFT1 is an autosomal dominant dermatosis characterized by the presence of many skin tumors predominantly on the face. Since histologic examination shows dermal aggregates of basaloid cells with connection to or differentiation toward hair follicles, this disorder has been thought to represent a benign hamartoma of the pilosebaceous apparatus. Trichoepitheliomas can degenerate into basal cell carcinoma.   Defects in CYLD are the cause of Brooke-Spiegler syndrome (BRSS) [MIM:605041]. BRSS is an autosomal dominant disorder characterized by the appearance of multiple skin appendage tumors such as cylindroma, trichoepithelioma, and spiradenoma. These tumors are typically located in the head and neck region, appear in early adulthood, and gradually increase in size and number throughout life.   
[CYLD_HUMAN] Protease that specifically cleaves 'Lys-63'-linked polyubiquitin chains. Has endodeubiquitinase activity. Plays an important role in the regulation of pathways leading to NF-kappa-B activation. Contributes to the regulation of cell survival, proliferation and differentiation via its effects on NF-kappa-B activation. Negative regulator of Wnt signaling. Inhibits HDAC6 and thereby promotes acetylation of alpha-tubulin and stabilization of microtubules. Plays a role in the regulation of microtubule dynamics, and thereby contributes to the regulation of cell proliferation, cell polarization, cell migration, and angiogenesis. Required for normal cell cycle progress and normal cytokinesis. Inhibits nuclear translocation of NF-kappa-B. Plays a role in the regulation of inflammation and the innate immune response, via its effects on NF-kappa-B activation. Dispensable for the maturation of intrathymic natural killer cells, but required for the continued survival of immature natural killer cells. Negatively regulates TNFRSF11A signaling and osteoclastogenesis (By similarity).           
Publication Abstract from PubMed
The tumor suppressor CYLD antagonizes NF-kappaB and JNK signaling by disassembly of Lys63-linked ubiquitin chains synthesized in response to cytokine stimulation. Here we describe the crystal structure of the CYLD USP domain, revealing a distinctive architecture that provides molecular insights into its specificity toward Lys63-linked polyubiquitin. We identify regions of the USP domain responsible for this specificity and demonstrate endodeubiquitinase activity toward such chains. Pathogenic truncations of the CYLD C terminus, associated with the hypertrophic skin tumor cylindromatosis, disrupt the USP domain, accounting for loss of CYLD catalytic activity. A small zinc-binding B box domain, similar in structure to other crossbrace Zn-binding folds--including the RING domain found in E3 ubiquitin ligases--is inserted within the globular core of the USP domain. Biochemical and functional characterization of the B box suggests a role as a protein-interaction module that contributes to determining the subcellular localization of CYLD.
The structure of the CYLD USP domain explains its specificity for Lys63-linked polyubiquitin and reveals a B box module.,Komander D, Lord CJ, Scheel H, Swift S, Hofmann K, Ashworth A, Barford D Mol Cell. 2008 Feb 29;29(4):451-64. PMID:18313383
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.