HSF4 is required for normal cell growth and differentiation during mouse lens development.
The heat shock transcription factor (HSF) family consists of three members in mammals and regulates expression of heat shock genes via a heat shock element. HSF1 and HSF2 are required for some developmental processes, but it is unclear how they regulate these processes. To elucidate the mechanisms of developmental regulation by HSFs, we generated mice in which the HSF4 gene is mutated. HSF4-null mice had cataract with abnormal lens fiber cells containing inclusion-like structures, probably due to decreased expression of gamma-crystallin, which maintains protein stability. Furthermore, we found increased proliferation and premature differentiation of the mutant lens epithelial cells, which is associated with increased expression of growth factors, FGF-1, FGF-4, and FGF-7. Unexpectedly, HSF1 competed with HSF4 for the expression of FGFs not only in the lens but also in other tissues. These findings reveal the lens-specific role of HSF4, which activates gamma-crystallin genes, and also indicate that HSF1 and HSF4 are involved in regulating expression of growth factor genes, which are essential for cell growth and differentiation.
Fujimoto
Mitsuaki
M
Department of Biochemistry and Molecular Biology, Yamaguchi University School of Medicine, Minami-Kogushi 1-1-1, Ube 755-8505, Japan.
Izu
Hanae
H
Seki
Keisuke
K
Fukuda
Ken
K
Nishida
Teruo
T
Yamada
Shu-Ichi
S
Kato
Kanefusa
K
Yonemura
Shigenobu
S
Inouye
Sachiye
S
Nakai
Akira
A
D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation / Q000502:physiology*; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018390:Gene Targeting; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D002479:Inclusion Bodies; D007908:Lens, Crystalline / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D011485:Protein Binding; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; C490017:Hsf1 protein, mouse; C484462:Hsf4 protein, mouse; D020033:Protein Isoforms; D014157:Transcription Factors; D005346:Fibroblast Growth Factors