Expression of basic helix-loop-helix proteins in the glomeruli.
BACKGROUND
Basic helix loop helix (bHLH) proteins play a critical role in the differentiation of not only striated muscle cells but also adipocytes, neuron cells and smooth muscle cells. Previous studies have established in vitro mouse mesangial cells (MCs) to maintain the differentiated smooth muscle phenotype.


METHODS
The purpose of the present study was to clone bHLH proteins from these MCs using the primers designed from a homologous sequence specific to bHLH, and to analyze the presence of bHLH proteins in normal kidney in vivo. From the cloning of MCs in vitro, we identified myf5 and herculin mRNA but not myoD. The expression of bHLH proteins in vivo was examined by immunohistochemistry with each specific antibody.


RESULTS
The MCs in newborn mice possessed Id but did not express either protein herculin or myoD. On the other hand, mature MCs expressed both myf5 and herculin. The Id protein disappeared in mature glomeruli.


CONCLUSIONS
These results suggest that bHLH proteins are an important factor for mature MCs in vivo.
Imabayashi
T
T
Division of Clinical Bioregulatory Science, Faculty of Medicine, Kyoto University, Japan.
Iehara
N
N
Takeoka
H
H
Uematsu-Yanagita
M
M
Kataoka
H
H
Nishikawa
S
S
Sano
H
H
Yokode
M
M
Fukatsu
A
A
Kita
T
T
Doi
T
T
D000375:Aging; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000032:analysis; D005920:Glomerular Mesangium / Q000737:chemistry; D018257:Helix-Loop-Helix Motifs; D007150:Immunohistochemistry; D051798:Inhibitor of Differentiation Protein 1; D007678:Kidney Glomerulus / Q000737:chemistry*; D051379:Mice; D009124:Muscle Proteins / Q000032:analysis* / Q000737:chemistry; D017570:MyoD Protein / Q000032:analysis; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors / Q000032:analysis; D018008:Myogenin / Q000032:analysis; D012097:Repressor Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D015534:Trans-Activators; D014157:Transcription Factors / Q000032:analysis
D004268:DNA-Binding Proteins; C497455:Idb1 protein, mouse; D051798:Inhibitor of Differentiation Protein 1; D009124:Muscle Proteins; C497418:Myf5 protein, mouse; D017570:MyoD Protein; C503801:Myog protein, mouse; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C063403:myogenic factor 6