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Tissue, temporal and inducible expression pattern of haptoglobin in mice
J D'Armiento1, S S Dalal, K Chada
1Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA. jmd12@columbia.edu
Gene
|August 11, 1997
Summary
Haptoglobin (Hp) is not exclusively produced in the adult liver. This study reveals Hp expression in lung and skin, with induction in multiple tissues during acute phases, suggesting a broader role.
Area of Science:
- Biochemistry
- Immunology
- Genetics
Background:
- Haptoglobin (Hp) is an acute phase protein.
- Previously, Hp was believed to be synthesized only in the adult liver.
Purpose of the Study:
- To investigate the tissue and temporal expression of endogenous haptoglobin in mice.
- To analyze the acute phase inducibility of haptoglobin in various tissues.
- To identify regulatory elements of the haptoglobin promoter in transgenic models.
Main Methods:
- Analysis of endogenous haptoglobin expression in mouse tissues.
- Acute phase induction using bacterial lipopolysaccharide (LPS).
- Generation and analysis of transgenic mice with human haptoglobin promoter-reporter gene constructs.
Main Results:
- The liver is the primary site of haptoglobin expression, but significant levels are also found in lung and skin.
- LPS induction increased haptoglobin expression in liver, lung, skin, spleen, and kidney.
- Haptoglobin is expressed during embryogenesis and inducible throughout development.
- A 1.05-kb human haptoglobin promoter fragment drove lung-specific expression in transgenic mice.
- This promoter fragment contained elements necessary for LPS-inducible expression.
Conclusions:
- Haptoglobin is not restricted to adult liver synthesis.
- Hp plays a role in multiple tissues beyond the liver.
- The acute phase response of haptoglobin is more complex than previously understood.