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CD44 in human placenta: localization and binding to hyaluronic acid
S St Jacques1, H K Dadi, M Letarte
1Division of Immunology and Cancer Research, Hospital For Sick Children, Toronto, Canada.
Placenta
|January 1, 1993
Summary
CD44, a hyaluronic acid (HA) receptor, is present in the human placenta. This study identifies the specific binding region of CD44 to HA, suggesting its role in placental structural integrity.
Area of Science:
- Biochemistry
- Cell Biology
- Reproductive Biology
Background:
- CD44 is a cell surface glycoprotein known to bind hyaluronic acid (HA).
- The presence and function of CD44 in the human placenta are not fully understood.
Purpose of the Study:
- To investigate the presence and binding characteristics of CD44 in human term placenta.
- To identify the specific regions of CD44 involved in HA binding.
Main Methods:
- Isolation of CD44 glycoprotein from human term placenta using monoclonal antibody (mAb) 50B4 affinity.
- Radiolabeled CD44 binding assays to HA-coated surfaces.
- Inhibition studies using soluble HA, hyaluronidase, and specific anti-CD44 antibodies (mAb 50B4, IM7.8.1).
Main Results:
- CD44 was identified in placental stroma, primarily as M(r) 85,000 and 200,000 species.
- The M(r) 85,000 CD44 species specifically bound to HA, an interaction inhibited by soluble HA, hyaluronidase, and specific mAbs.
- Epitopes outside the B loop (residues 132-215) and within the B loop (residues 31-101) contribute to CD44-HA binding.
Conclusions:
- Functional CD44 molecules are present in the human term placenta.
- CD44 plays a role in stabilizing and orienting the HA network, crucial for placental structural integrity.