Inhibition of H3K27 histone trimethylation activates fibroblasts and induces fibrosis.
OBJECTIVE
Epigenetic modifications such as DNA methylation and histone acetylation have been implicated in the pathogenesis of systemic sclerosis. However, histone methylation has not been investigated so far. We therefore aimed to evaluate the role of the trimethylation of histone H3 on lysine 27 (H3K27me3) on fibroblast activation and fibrosis.


METHODS
H3K27me3 was inhibited by 3-deazaneplanocin A (DZNep) in cultured fibroblasts and in two murine models of dermal fibrosis. Fibrosis was analysed by assessment of the dermal thickening, determination of the hydroxyproline content and by quantification of the numbers of myofibroblasts. The expression of fos-related antigen 2 (fra-2) was assessed by real-time PCR, western blot and immunohistochemistry and modulated by siRNA.


RESULTS
Inhibition of H3K27me3 stimulated the release of collagen in cultured fibroblasts in a time and dose-dependent manner. Treatment with DZNep exacerbated fibrosis induced by bleomycin or by overexpression of a constitutively active transforming growth factor β receptor type I. Moreover, treatment with DZNep alone was sufficient to induce fibrosis. Inhibition of H3K27me3 induced the expression of the profibrotic transcription factor fra-2 in vitro and in vivo. Knockdown of fra-2 completely prevented the profibrotic effects of DZNep.


CONCLUSIONS
These data demonstrate a novel role of H3 Lys27 histone methylation in fibrosis. In contrast to other epigenetic modifications such as DNA methylation and histone acetylation, H3 Lys27 histone methylation acts as a negative regulator of fibroblast activation in vitro and in vivo by repressing the expression of fra-2.
Department of Internal Medicine 3 and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Ulmenweg 18, Erlangen D-91054, Germany.
Marlene
M
Krämer
Clara
C
Dees
Jingang
J
Huang
Inga
I
Schlottmann
Katrin
K
Palumbo-Zerr
Pawel
P
Zerr
Kolja
K
Gelse
Christian
C
Beyer
Alfiya
A
Distler
Victor E
VE
Marquez
Oliver
O
Distler
Georg
G
Schett
Jörg H W
JH
Distler
D000328:Adult; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001761:Bleomycin / Q000494:pharmacology; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects / Q000502:physiology; D020405:Dermis / Q000473:pathology; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D044127:Epigenesis, Genetic / Q000187:drug effects / Q000502:physiology; D005347:Fibroblasts / Q000201:enzymology* / Q000473:pathology; D005355:Fibrosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D051921:Fos-Related Antigen-2 / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D008875:Middle Aged; D045743:Scleroderma, Diffuse / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D055815:Young Adult
D000903:Antibiotics, Antineoplastic; D004791:Enzyme Inhibitors; C497872:FOSL2 protein, human; D051921:Fos-Related Antigen-2; C497873:Fosl2 protein, mouse; D006657:Histones; D001761:Bleomycin; D003094:Collagen; D056484:Jumonji Domain-Containing Histone Demethylases; C524220:KDM6B protein, human; C523761:Kdm6b protein, mouse