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Human-specific expression of Siglec-6 in the placenta
Els C M Brinkman-Van der Linden1, Nancy Hurtado-Ziola, Toshiyuki Hayakawa
1Glycobiology Research and Training Center, Department of Medicine, University of California at San Diego, La Jolla, CA 92093-0687, USA.
Glycobiology
|June 21, 2007
Summary
Siglec-6 (sialic acid binding immunoglobulin-like lectin 6) is expressed in the human placenta, unlike in apes. This human-specific expression may regulate human birth timing and leptin availability.
Area of Science:
- Evolutionary biology
- Immunology
- Reproductive biology
Background:
- CD33-related Siglecs are immune cell lectins that bind sialic acids and transmit inhibitory signals.
- Siglec-6/OB-BP1 binds leptin and is expressed on immune cells in humans and great apes.
- Placental expression of Siglec-6 is a unique feature of humans compared to apes.
Purpose of the Study:
- To investigate the evolutionary basis and functional significance of human-specific placental Siglec-6 expression.
- To explore the potential role of Siglec-6 in regulating human labor and parturition.
- To examine the interaction of Siglec-6 with its ligands in the human placenta and uterus.
Main Methods:
- Comparative analysis of Siglec-6 expression in human and ape placentae.
- Investigation of Siglec-6 promoter region for human-specific transcription factor binding sites.
- Detection of Siglec-6 ligands in placental, endometrial, and trophoblast/endometrial cell line tissues.
Main Results:
- Siglec-6 expression is human-specific in placental trophoblasts, with minimal expression in apes.
- Human-specific changes in the Siglec-6 promoter likely explain its unique placental expression.
- Natural ligands for Siglec-6 are present in the human placenta, endometrium, and related cell lines.
- Siglec-6 levels correlate with labor status, being highest after labor completion.
Conclusions:
- Siglec-6 was evolutionarily recruited for placental expression in humans, potentially for signaling or leptin regulation.
- Human-specific placental Siglec-6 may play a role in modulating the tempo of human birth.
- The leptin-binding capacity of Siglec-6 supports its involvement in parturition processes.
