Advanced Search

Journal Navigation

Journal Home

Subscriptions

Archive

Contact Us

Table of Contents

SAGETRACK
Journal of the Society for Gynecologic Investigation
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to Saved Citations
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Request Reprints
Right arrow Add to My Marked Citations
Citing Articles
Right arrow Citing Articles via Google Scholar
Right arrow Citing Articles via Scopus
Google Scholar
Right arrow Articles by Chen, Z.
Right arrow Articles by Prasad, P. D.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Chen, Z.
Right arrow Articles by Huang, W.
Right arrow Articles by Srinivas, S. R.
Right arrow Articles by Jones, C. R.
Right arrow Articles by Ganapathy, V.
Right arrow Articles by Prasad, P. D.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

Serine Racemase and D-Serine Transport in Human Placenta and Evidence for a Transplacental Gradient for D-Serine in Humans

Zhong Chen, MD

Wei Huang, MS

Sonne R. Srinivas, PhD

Chandra R. Jones, MD

Vadivel Ganapathy, PhD

Departments of Biochemistry and Molecular Biology, and Obstetrics and Gynecology, Medical College of Georgia, Augusta, Georgia

Puttur D. Prasad, PhD

Departments of Biochemistry and Molecular Biology, and Obstetrics and Gynecology, Medical College of Georgia, Augusta, Georgia; pprasad{at}mail.mcg.edu

Objective: To investigate the possible role of human placenta in providing D-serine to the developing fetus.

Methods: Expression of serine racemase in placenta was determined by reverse transcriptase polymerase chain reaction and northern analysis and confirmed by subsequent cloning. The transport of D-serine by human ATB0 was characterized by expressing the cloned cDNA transiently in mammalian cells using the vaccinia virus expression system. D-serine levels in maternal and fetal blood were measured by fluorescence high-performance liquid chromatography (HPLC) after derivatization of the amino adids with o-phthaldialdehyde and N-tertiary-butyloxycarbonyl-L-cysteine.

Results: mRNA for serine racemase was detected in placenta. ATB0 was capable of D-serine transport, and the transport process is obligatorily dependent on sodium (Na+) with a Na+: substrate stoichiometry of 1:1 and saturable with a Michaelis-Menten constant of 310 ± 30 µM. Furthermore, studies have shown and ATB0 is not expressed in the maternal-facing brush border membrane of human placental syncytiotrophoblast. The circulating concentration of D-serine in maternal serum is 5.8 ± 0.5 µM, and the corresponding value in the fetal serum is 14.6 ± 1.2 µM, indicating a two- to three-fold higher concentration of D-serine in the fetus than in the mother.

Conclusion: We speculate that D-serine is synthesized in human placenta by the recemization of L-serine and that ATB0, expressed on the basal membrane of the syncytiotrophoblast, mediates the efflux of D-serine into fetal circulation in exchange for other amino acids in fetal blood.

Key Words: Trophoblast • amino acid • transport • transplacental • development

Journal of the Society for Gynecologic Investigation, Vol. 11, No. 5, 294-303 (2004)
DOI: 10.1016/j.jsgi.2004.02.003
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?