PMID- 20148114
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20100211
LR  - 20211020
IS  - 1755-8417 (Electronic)
IS  - 1755-8417 (Linking)
VI  - 3
DP  - 2010 Jan 5
TI  - Mutations in the nuclear localization sequence of the Aristaless related 
      homeobox; sequestration of mutant ARX with IPO13 disrupts normal subcellular 
      distribution of the transcription factor and retards cell division.
PG  - 1
LID - 10.1186/1755-8417-3-1 [doi]
AB  - BACKGROUND: Aristaless related homeobox (ARX) is a paired-type homeobox gene. ARX 
      function is frequently affected by naturally occurring mutations. Nonsense 
      mutations, polyalanine tract expansions and missense mutations in ARX cause a 
      range of intellectual disability and epilepsy phenotypes with or without 
      additional features including hand dystonia, lissencephaly, autism or dysarthria. 
      Severe malformation phenotypes, such as X-linked lissencephaly with ambiguous 
      genitalia (XLAG), are frequently observed in individuals with protein truncating 
      or missense mutations clustered in the highly conserved paired-type homeodomain. 
      RESULTS: We have identified two novel point mutations in the R379 residue of the 
      ARX homeodomain; c.1135C>A, p.R379S in a patient with infantile spasms and 
      intellectual disability and c.1136G>T, p.R379L in a patient with XLAG. We 
      investigated these and other missense mutations (R332P, R332H, R332C, T333N: 
      associated with XLAG and Proud syndrome) predicted to affect the nuclear 
      localisation sequences (NLS) flanking either end of the ARX homeodomain. The NLS 
      regions are required for correct nuclear import facilitated by Importin 13 
      (IPO13). We demonstrate that missense mutations in either the N- or C-terminal 
      NLS regions of the homeodomain cause significant disruption to nuclear 
      localisation of the ARX protein in vitro. Surprisingly, none of these mutations 
      abolished the binding of ARX to IPO13. This was confirmed by 
      co-immunoprecipitation and immmuno fluorescence studies. Instead, tagged and 
      endogenous IPO13 remained bound to the mutant ARX proteins, even in the RanGTP 
      rich nuclear environment. We also identify the microtubule protein TUBA1A as a 
      novel interacting protein for ARX and show cells expressing mutant ARX protein 
      accumulate in mitosis, indicating normal cell division may be disrupted. 
      CONCLUSIONS: We show that the most likely, common pathogenic mechanism of the 
      missense mutations in NLS regions of the ARX homeodomain is inadequate 
      accumulation and distribution of the ARX transcription factor within the nucleus 
      due to sequestration of ARX with IPO13.
FAU - Shoubridge, Cheryl
AU  - Shoubridge C
AD  - Department of Genetics and Molecular Pathology, SA Pathology at the Women's and 
      Children's Hospital, North Adelaide, South Australia 5006, Australia.
FAU - Tan, May Huey
AU  - Tan MH
FAU - Fullston, Tod
AU  - Fullston T
FAU - Cloosterman, Desiree
AU  - Cloosterman D
FAU - Coman, David
AU  - Coman D
FAU - McGillivray, George
AU  - McGillivray G
FAU - Mancini, Grazia M
AU  - Mancini GM
FAU - Kleefstra, Tjitske
AU  - Kleefstra T
FAU - Gecz, Jozef
AU  - Gecz J
LA  - eng
PT  - Journal Article
DEP - 20100105
PL  - England
TA  - Pathogenetics
JT  - PathoGenetics
JID - 101469516
PMC - PMC2819251
EDAT- 2010/02/12 06:00
MHDA- 2010/02/12 06:01
PMCR- 2010/01/05
CRDT- 2010/02/12 06:00
PHST- 2009/10/17 00:00 [received]
PHST- 2010/01/05 00:00 [accepted]
PHST- 2010/02/12 06:00 [entrez]
PHST- 2010/02/12 06:00 [pubmed]
PHST- 2010/02/12 06:01 [medline]
PHST- 2010/01/05 00:00 [pmc-release]
AID - 1755-8417-3-1 [pii]
AID - 10.1186/1755-8417-3-1 [doi]
PST - epublish
SO  - Pathogenetics. 2010 Jan 5;3:1. doi: 10.1186/1755-8417-3-1.