Expression of Runx2 transcription factor in non-skeletal tissues, sperm and brain.
Runx2 is a master transcription factor for chondrocyte and osteoblast differentiation and bone formation. However expression of Runx2 (by RT-PCR), has been reported in non-skeletal tissues such as breast, T cells and testis. To better define Runx2 activity in non-skeletal tissues, we examined transgenic (Tg) mice expressing LacZ gene under control of 3.0 kb (3 kb Tg) or 1.0 kb (1 kb Tg) of the Runx2 distal (P1) promoter, Runx2 LacZ knock-in (Runx2(+/LacZ)) and Runx2/P1 LacZ knock-in (Runx2/P1(+/LacZ)). In the Runx2 3 kb Tg mouse, beta-galactosidase (beta-gal) expression appeared in various non-skeletal tissues including testis, skin, adrenal gland and brain. beta-gal expression from both 3 kb and 1 kb Tg, reflecting activity of the Runx2 promoter, was readily detectable in seminiferous tubules of the testis and the epididymis. At the single cell level, beta-gal was detected in spermatids and mature sperms not in sertoli or Leydig cells. We also detected a positive signal from the Runx2(+/LacZ) and Runx2/P1(+/LacZ) mice. Indeed, Runx2 expression was observed in isolated mature sperms, which was confirmed by RT-PCR and Western blot analysis. Runx2, however, was not related to sex determination and sperm motility. Runx2 mediated beta-gal activity is also found robustly in the hippocampus and frontal lobe of the brain in Runx2(+/LacZ). Collectively, these results indicate that Runx2 is expressed in several non-skeletal tissues particularly sperms of testis and hippocampus of brain. It suggests that Runx2 may play an important role in male reproductive organ testis and brain.
Jeong
Jae-Hwan
JH
Department of Biochemistry and Cell Biology, School of Medicine, Cell and Matrix Research Institute, Skeletal Diseases Genome Research Center, Kyungpook National University, Daegu, Republic of Korea.
Jin
Jung-Sook
JS
Kim
Hyun-Nam
HN
Kang
Sang-Min
SM
Liu
Julie C
JC
Lengner
Christopher J
CJ
Otto
Florian
F
Mundlos
Stefan
S
Stein
Janet L
JL
van Wijnen
Andre J
AJ
Lian
Jane B
JB
Stein
Gary S
GS
Choi
Je-Yong
JY
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism; D017930:Genes, Reporter; D006624:Hippocampus / Q000378:metabolism; D007763:Lac Operon; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D010053:Ovary / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019849:Sex Determination Processes; D013081:Sperm Motility; D013091:Spermatogenesis; D013094:Spermatozoa / Q000378:metabolism*
D050659:Core Binding Factor Alpha 1 Subunit; C493716:Runx2 protein, mouse