Human microglial cells synthesize albumin in brain.
Albumin, an abundant plasma protein with multifunctional properties, is mainly synthesized in the liver. Albumin has been implicated in Alzheimer's disease (AD) since it can bind to and transport amyloid beta (Abeta), the causative agent of AD; albumin is also a potent inhibitor of Abeta polymerization. Despite evidence of non-hepatic transcription of albumin in many tissues including kidney and pancreas, non-hepatic synthesis of albumin at the protein level has been rarely confirmed. In a pilot phase study of Human Brain Proteome Project, we found evidence that microglial cells in brain may synthesize albumin. Here we report, for the first time, the de novo synthesis of albumin in human microglial cells in brain. Furthermore, we demonstrate that the synthesis and secretion of albumin from microglial cells is enhanced upon microglial activation by Abeta(1-42)- or lipopolysaccharide (LPS)-treatment. These data indicate that microglial cells may play a beneficial role in AD by secreting albumin that not only inhibits Abeta polymerization but also increases its clearance.
Ahn
Sung-Min
SM
Center for Genomics and Proteomics, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, Korea.
Byun
Kyunghee
K
Cho
Kun
K
Kim
Jin Young
JY
Yoo
Jong Shin
JS
Kim
Deokhoon
D
Paek
Sun Ha
SH
Kim
Seung U
SU
Simpson
Richard J
RJ
Lee
Bonghee
B
D000418:Albumins / Q000378:metabolism*; D000544:Alzheimer Disease / Q000378:metabolism; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D002853:Chromatography, Liquid / Q000379:methods; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008070:Lipopolysaccharides / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D017628:Microglia / Q000166:cytology* / Q000378:metabolism; D008954:Models, Biological; D040901:Proteomics / Q000379:methods
D000418:Albumins; D008070:Lipopolysaccharides