Decreased proliferation and erythroid differentiation of K562 cells by siRNA-induced depression of OCTN1 (SLC22A4) transporter gene.
OBJECTIVE
Recently, it was reported that OCTN1 transporter (SLC22A4) is associated with rheumatoid arthritis (RA) and Crohn's disease. Additionally, we reported that OCTN1 is expressed in hematopoietic cells, preferentially in erythroid cells. Accordingly, we assessed the physiological role of OCTN1 by examining the effect of knockdown of OCTN1 in blood cells using siRNA method.


METHODS
Vector-based short hairpin RNA (shRNA) was used to establish K562 cell line which shows stably decreased expression of OCTN1. The characteristic of knockdown of OCTN1 in K562 cells was investigated by cell proliferation, cell differentiation, and uptake of ergothioneine that is a good substrate of OCTN1.


RESULTS
Several clones of K562 cells exhibited significantly reduced expression of OCTN1 mRNA and protein. They also showed a decreased growth rate and butyrate-dependent differentiation to erythrocytes compared with control-vector transfected cells. In addition, uptake of [(3)H]ergothioneine by K562 cells suggested that Na(+)-dependent and high-affinity transporter which is similar to the characteristics of OCTN1 is functional. Moreover, uptake of ergothioneine by K562 cells which exhibit decreased-expression of OCTN1 was decreased in comparison with wild type K562 cells.


CONCLUSIONS
It was suggested that OCTN1 is involved in the transport of physiological compounds that are important for cell proliferation and erythroid differentiation.
Nakamura
Toshimichi
T
Department of Molecular Biopharmaceutics, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamasaki, Noda, Chiba, 278-8510, Japan.
Sugiura
Shigeki
S
Kobayashi
Daisuke
D
Yoshida
Kenji
K
Yabuuchi
Hikaru
H
Aizawa
Shin
S
Maeda
Tomoji
T
Tamai
Ikumi
I
D002454:Cell Differentiation; D049109:Cell Proliferation; D004880:Ergothioneine / Q000493:pharmacokinetics; D041905:Erythroid Cells / Q000166:cytology*; D006801:Humans; D020014:K562 Cells; D027701:Organic Cation Transport Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology*; D027981:Symporters
D027701:Organic Cation Transport Proteins; D034741:RNA, Small Interfering; C109807:SLC22A4 protein, human; D027981:Symporters; D004880:Ergothioneine