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Chicken lecithin-cholesterol acyltransferase. Molecular characterization reveals unusual structure and expression
E Hengstschläger-Ottnad1, K Kuchler, W J Schneider
1Department of Molecular Genetics, University and Biocenter Vienna, Austria.
The Journal of Biological Chemistry
|November 3, 1995
Summary
This study characterizes chicken lecithin-cholesterol acyltransferase (LCAT), crucial for reverse cholesterol transport (RCT) in egg production. Unique expression patterns in female brains highlight avian oocytes as a model for studying RCT regulation.
Area of Science:
- Biochemistry
- Molecular Biology
- Reproductive Biology
Background:
- Reverse cholesterol transport (RCT) is vital in nonplacental reproduction, particularly in laying hens.
- Lecithin-cholesterol acyltransferase (LCAT) catalyzes an early, critical step in RCT.
- Understanding avian LCAT is key to elucidating RCT mechanisms in egg production.
Purpose of the Study:
- To perform molecular characterization of the first nonmammalian LCAT from chickens.
- To investigate the developmental and gender-specific expression patterns of LCAT in avian systems.
- To establish the avian oocyte/liver system as a model for studying RCT regulation.
Main Methods:
- Molecular characterization of chicken LCAT, including protein sequence analysis.
- Generation of antibodies against chicken LCAT for protein identification.
- Analysis of LCAT mRNA expression in different tissues and developmental stages in female and male chickens.
Main Results:
- High protein sequence identity (73%) between chicken and human LCAT, with notable differences in cysteine residues.
- Chicken LCAT antibodies cross-react with human LCAT, identifying a 64-kDa protein in chicken serum.
- Striking developmental and gender-specific LCAT expression: high in liver during embryogenesis/adolescence, but significantly increases in the brain of laying hens, exceeding liver levels.
Conclusions:
- Chicken LCAT shares significant homology with mammalian LCAT, but key cysteine residues differ, indicating dispensability for enzymatic activity.
- Avian LCAT exhibits unique expression dynamics, with a notable surge in brain expression in laying hens.
- The characterized chicken LCAT and its distinct expression profile provide a novel model for investigating in vivo RCT regulation in avian reproduction.