Genetic and functional study of the IPO5 gene in schizophrenia
, Yang Liu
, Ning Wu
, Shun-Zi Jin
, Gui-Zhi Ju
, Lin Ye
, Li-bo Liu
, Jiang Wu
Research Center for Genomic Medicine and MH Radiobiology Research Unit, Jilin University, Changchun 130021, China
Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China
Research Centre for Neuroscience and Department of Neurology, Jilin University First Hospital, Changchun 130021, China
Received 1 February 2010
Received in revised form 6 April 2010
Accepted 7 May 2010
The present work reported on a weak association of the importin 5 (IPO5) gene with schizophrenia in
combined family and case-control samples and also investigated a possible mechanism by which the IPO5
gene may contribute to the development of the disease in a Chinese population. Our results suggest that
abnormal expression and alternative splicing of the IPO5 gene may be involved in the pathophysiology of
© 2010 Elsevier Ireland Ltd. All rights reserved.
Recent studies suggest that the gene encoding karyopherin beta-3
(KPNB3), also called importin 5 (IPO5) in the current nomenclature, is
associated with schizophrenia (Hu et al., 2005; Wei and Hemmings,
2004). The major ﬁnding is that a synonymous single nucleotide
polymorphism (SNP), rs626716 present in exon 10 of the IPO5 gene,
shows disease association in family-based studies among both Chinese
and British populations. However, a case-control design failed to
replicate the initial ﬁnding among the Chinese population (Wu et al.,
2008). Data from a genome-wide association study has not been
available to conﬁrm the IPO5 association in the Chinese population.
There is a great interest in applying a combined genotyping dataset for
reanalysis of the overall association of the IPO5 gene with schizophrenia
in the Chinese population. A functional study may also be useful to
conﬁrm a role of the IPO5 gene in developing schizophrenia.
The human IPO5 gene is localized in chromosome 13q32.2 and highly
expressed in B lymphocytes. There are at least four isoforms of mRNA in
humans (http://www.bioinformatics.ucla.edu/ASAP/), including isoform
56674 spanning about 3.45 kb, isoform 56676 spanning about 3.30 kb,
isoform 56677 spanning about 1.16 kb and isoform NM_002271
spanning about 6.02 kb. The splicing events of the above four isoforms
occur only in exon 29 of the gene. The present work analyzed IPO5 mRNA
expression and alternative splicing efﬁciency in schizophrenia.
The present study combined two genotyping datasets, including 282 family trios
used for a transmission disequilibrium test (Hu et al., 2005) and 780 unrelated
schizophrenia patients and 909 unrelated control subjects (Wu et al., 2008). Detailed
information regarding these samples was provided in our previous reports (Hu et al.,
2005; Wu et al., 2008). These combined genotyping data were re-analyzed for overall
association using likelihood-based association analysis for nuclear families and
unrelated subjects with missing genotype data (Dudbridge, 2008).
To perform a functional study, we recruited 39 unrelated patients with schizophrenia
(aged 30.1±6.1 years), of whom 20 were males and 19, females. We also recruited 30
unrelated healthy controls (aged 31.9± 5.4 years) from local communities, of whom 16
weremales and14,females. All the subjectswereof Han Chinese origin from the Northeast
area of China. These 39 patients were diagnosed as having schizophrenia according to the
ICD-10 criteria. Detailed information regarding a history of illness, duration and
medication was noted. All the patients had been on medication for at least a month
before sampling. These subjects all gave written informed consent before their blood
samples were taken. A 5-ml peripheral blood sample was taken from each individual. The
total RNA was extracted from leucocytes isolated from the fresh blood samples with Trizol
(Invitrogen, Carlsbad, CA). To prepare cDNA for quantitative real-time PCR analysis, 1 μgof
DNase-treated total RNA was used for reversetranscription at 42
C for 30 min, at 99
5 min and ﬁnally at 5
C for 5 min.
Quantitative analysis was carried out by Mx3000P real-time PCR (Stratagene, USA)
with SYBR green I ﬂuorescence. The speciﬁc primers used for PCR ampliﬁcation included
5’-CTGGAGGACTGTGGACTGAG-3’ (bases 3446-3465) and 5’-GGAAAGGGTAAGCGTT-
TATTTGG-3’ (bases 3584-3562) for amplicon 1 (Amp1) corresponding to a target
sequence present only in isoform NM_002271, and 5’-AGAACTGGGAGGTATATTGAAAGC-
3’ (bases 2607-2630) and 5’-CCTCATCTTGTAGTGACTCTTCG-3’ (bases 2728-2706) for
amplicon 2 (Amp2) corresponding to a target sequence present in all four isoforms.
Human β-actin (ACTB) mRNA (accession NM_001101) was used as a reference gene,
which was ampliﬁed with a pair of primers: 5'-ATTGGTCCACCTGAGCGCAAG-3' (bases
1061-1081) and 5'-GGTGTAACGCAACTAAGTCATAG-3' (bases 1207-1229). The
Psychiatry Research 187 (2011) 460–461
⁎ Corresponding authors. Zhang is to be contacted at Research Center for Genomic
Medicine and MH Radiobiology Research Unit, School of Public Health, Jilin University,
Changchun 130021, China. Wu, Research Centre for Neuroscience and Department of
Neurology, Jilin University First Hospital, 71 Xinmin Street, Changchun 130021, China.
E-mail addresses: email@example.com (X. Zhang),
firstname.lastname@example.org (J. Wu).
These two authors contributed equally to this work.
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