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Aliases USP9X, DFFRX, FAF, FAM, MRX99, MRXS99F, ubiquitin specific peptidase 9, X-linked, ubiquitin specific peptidase 9 X-linked
External IDs MGI: 894681 HomoloGene: 3418 GeneCards: USP9X
Gene location (Human)
X chromosome (human)
Chr. X chromosome (human)[1]
X chromosome (human)
Genomic location for USP9X
Genomic location for USP9X
Band Xp11.4 Start 41,085,635 bp[1]
End 41,236,579 bp[1]
RNA expression pattern
PBB GE USP9X 201100 s at fs.png

PBB GE USP9X 201099 at fs.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr X: 41.09 – 41.24 Mb Chr X: 13.07 – 13.17 Mb
PubMed search [3] [4]
View/Edit Human View/Edit Mouse

Probable ubiquitin carboxyl-terminal hydrolase FAF-X is an enzyme that in humans is encoded by the USP9X gene.[5][6]


This gene is a member of the peptidase C19 family and encodes a protein that is similar to ubiquitin-specific proteases. Though this gene is located on the X chromosome, it escapes X-inactivation.

Depletion of USP9X from two-cell mouse embryos halts blastocyst development and results in slower blastomere cleavage rate, impaired cell adhesion and a loss of cell polarity. It has also been implicated that USP9X is likely to influence developmental processes through signaling pathways of Notch, Wnt, EGF, and mTOR. USP9X has been recognized in studies of mouse and human stem cells involving embryonic, neural and hematopoietic stem cells.[7] High expression is retained in undifferentiated progenitor and stem cells and decreases as differentiation continues. USP9X is a protein-coding gene that has been implicated either directly through mutations or indirectly in a number of neurodevelopmental and neurodegenerative disorders. Three mutations have been connected with X-linked intellectual disability and disrupt neuronal growth and cell migration. Neurodegenerative disorders, such as Alzheimer’s, Parkinson’s and Huntington’s disease, have also been linked to USP9X. Specifically, USP9X has been implicated in the regulation of the phosphorylation and expression of the microtule-associated protein tau, which forms pathological aggregates in Alzheimer’s and other tauopathies.[8] Scientists have generated a knockout model where they isolated hippocampal neurons from an USP9X-knockout male mouse, which showed a 43% reduction in axonal length and aborization compared to wildtype.[9]


USP9X has been shown to interact with:


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000124486 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000031010 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:". 
  4. ^ "Mouse PubMed Reference:". 
  5. ^ Jones MH, Furlong RA, Burkin H, Chalmers IJ, Brown GM, Khwaja O, Affara NA (1996). "The Drosophila developmental gene fat facets has a human homologue in Xp11.4 which escapes X-inactivation and has related sequences on Yq11.2". Hum. Mol. Genet. 5 (11): 1695–701. doi:10.1093/hmg/5.11.1695. PMID 8922996. 
  6. ^ "Entrez Gene: USP9X ubiquitin specific peptidase 9, X-linked". 
  7. ^ Murtaza, Mariyam; Jolly, Lachlan A.; Gecz, Jozef; Wood, Stephen A. (2015-01-01). "La FAM fatale: USP9X in development and disease". Cellular and Molecular Life Sciences. 72 (11): 2075–2089. doi:10.1007/s00018-015-1851-0. ISSN 1420-682X. PMC 4427618Freely accessible. PMID 25672900. 
  8. ^ Köglsberger, Sandra; Cordero-Maldonado, Maria L.; Antony, Paul; Forster, Julia I.; Garcia, Pierre; Buttini, Manuel; Crawford, Alex; Glaab, Enrico (2016-12-01). "Gender-Specific Expression of Ubiquitin-Specific Peptidase 9 Modulates Tau Expression and Phosphorylation: Possible Implications for Tauopathies". Molecular Neurobiology. in press: 1/15. doi:10.1007/s12035-016-0299-z. PMID 27878758. 
  9. ^ "OMIM Entry - * 300072 - UBIQUITIN-SPECIFIC PROTEASE 9, X-LINKED; USP9X". Retrieved 2016-04-12. 
  10. ^ a b Taya S, Yamamoto T, Kanai-Azuma M, Wood SA, Kaibuchi K (Dec 1999). "The deubiquitinating enzyme Fam interacts with and stabilizes beta-catenin". Genes Cells. 4 (12): 757–67. doi:10.1046/j.1365-2443.1999.00297.x. PMID 10620020. 
  11. ^ a b Al-Hakim AK, Zagorska A, Chapman L, Deak M, Peggie M, Alessi DR (Apr 2008). "Control of AMPK-related kinases by USP9X and atypical Lys(29)/Lys(33)-linked polyubiquitin chains". Biochem. J. 411 (2): 249–60. doi:10.1042/BJ20080067. PMID 18254724. 
  12. ^ Taya S, Yamamoto T, Kano K, Kawano Y, Iwamatsu A, Tsuchiya T, Tanaka K, Kanai-Azuma M, Wood SA, Mattick JS, Kaibuchi K (Aug 1998). "The Ras target AF-6 is a substrate of the fam deubiquitinating enzyme". J. Cell Biol. 142 (4): 1053–62. doi:10.1083/jcb.142.4.1053. PMC 2132865Freely accessible. PMID 9722616. 
  13. ^ Wang S, Kollipara RK, Srivastava N, Li R, Ravindranathan P, Hernandez E, Freeman E, Humphries CG, Kapur P, Lotan Y, Fazli L, Gleave ME, Plymate SR, Raj GV, Hsieh JT, Kittler R (2014). "Ablation of the oncogenic transcription factor ERG by deubiquitinase inhibition in prostate cancer". Proc. Natl. Acad. Sci. U.S.A. 111 (11): 4251–6. doi:10.1073/pnas.1322198111. PMC 3964108Freely accessible. PMID 24591637. 
  14. ^ Li, Xin; Song, Nan; Liu, Ling; Liu, Xinhua; Ding, Xiang; Song, Xin; Yang, Shangda; Shan, Lin; Zhou, Xing (2017-03-31). "USP9X regulates centrosome duplication and promotes breast carcinogenesis". Nature Communications. 8. doi:10.1038/ncomms14866. ISSN 2041-1723. 

Further reading[edit]