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ISSN 0582-9879 Acta Biochim et Biophysica Sinica 2004, 36(4):284-289 CN 31-1300/Q

Cloning and Identification of Two Novel Splice Variants of Human PD-L2

Xian-Hui HE#*, Yi LIU&#, Li-Hui XU1, and Yao-Ying ZENG*
( Key Laboratory of Tissue Transplantation and Immunology, Ji'nan University, Ministry of Education, 601 Huangpu Road West, Guangzhou 510632, China;
1 Institute of Bioengineering, Ji'nan University, 601 Huangpu Road West, Guangzhou 510632, China)

Abstract PD-L2, a newly identified member of B7 family, plays a role in down-regulating T cell responses. The common PD-L2 mRNA (type I) is the splicing product containing all 6 exons. We report here the identification of two human PD-L2 splice variants in activated leukocytes. One splice variant (type II) is generated through splicing out exon 3 encoding Ig constant-like domain; it retains all other regions without a frame shift. The other variant (type III) is created by splicing out exon 3 to an alternative acceptor site 5 bp downstream of the canonical acceptor site, leading to a frame shift. Consequently, the translated protein should be a soluble form. Furthermore, type I isoform is expressed on the plasma surface whereas type II isoform showed a pattern of intracellular membrane distribution in the transiently transfected K562 cells. In addition, the expression patterns of PD-L2 splice variants are variable in different individuals and distinct cellular status. These results suggest that PD-L2 expression may be controlled by posttranscriptional regulation through alternative splicing, and modulation of PD-L2 isoform expression may influence the outcome of immune response.

Key words costimulatory molecules; PD-L2; splice variant; leukocytes

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Received: November 24, 2003 Accepted: February 19, 2004
This work was supported by the grants from the National Natural Science Foundation of China (No. 30230350, No. 30371651) and the Major State Basic Research Development Key Program of China (No. G2000057006)
& Present address: Department of Dermatology, the First Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China
# These two authors contributed equally to this work
*Corresponding authors:
Yao-Ying ZENG: Tel, 86-20-85220732; Fax, 86-20-85221337; E-mail, ozms@jnu.edu.cn;
Xian-Hui HE: Tel, 86-20-85220679; Fax, 86-20-85221337; E-mail, thexh@jnu.edu.cn