Abstract
A view that signaling machineries for the neurotransmitter γ-aminobutyric acid (GABA) are functionally expressed by cells outside the central nervous system is now prevailing. In this study, we attempted to demonstrate functional expression of GABAergic signaling molecules by chondrocytes. In cultured murine costal chondrocytes, mRNA was constitutively expressed for metabotropic GABAB receptor subunit-1 (GABA BR1), but not for GABABR2. Immunohistochemical analysis revealed the predominant expression of GABABR1 by prehypertrophic to hypertrophic chondrocytes in tibial sections of newborn mice. The GABA BR agonist baclofen failed to significantly affect chondrocytic differentiation determined by Alcian blue staining and alkaline phosphatase activity in cultured chondrocytes, whereas newborn mice knocked out of GABA BR1 (KO) showed a decreased body size and delayed calcification in hyoid bone and forelimb and hindlimb digits. Delayed calcification was also seen in cultured metatarsals from KO mice with a marked reduction of Indian hedgehog gene (Ihh) expression. Introduction of GABABR1 led to synergistic promotion of the transcriptional activity of activating transcription factor-4 (ATF4) essential for normal chondrogenesis, in addition to facilitating ATF4-dependent Ihh promoter activation. Although immunoreactive ATF4 was negligibly detected in the nucleus of chondrocytes from KO mice, ATF4 expression was again seen in the nucleus and cytoplasm after the retroviral introduction of GABABR1 into cultured chondrocytes from KO mice. In nuclear extracts of KO chondrocytes, a marked decrease was seen in ATF4 DNA binding. These results suggest that GABABR1 positively regulates chondrogenesis through a mechanism relevant to the acceleration of nuclear translocation of ATF4 for Ihh expression in chondrocytes.
| Original language | English |
|---|---|
| Pages (from-to) | 33293-33303 |
| Number of pages | 11 |
| Journal | Journal of Biological Chemistry |
| Volume | 287 |
| Issue number | 40 |
| DOIs | |
| Publication status | Published - Sep 28 2012 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biochemistry
- Cell Biology
- Molecular Biology
Cite this
Positive regulation by γ-aminobutyric acid B receptor subunit-1 of chondrogenesis through acceleration of nuclear translocation of activating transcription factor-4. / Takahata, Yoshifumi; Hinoi, Eiichi; Takarada, Takeshi; Nakamura, Yukari; Ogawa, Shinya; Yoneda, Yukio.
In: Journal of Biological Chemistry, Vol. 287, No. 40, 28.09.2012, p. 33293-33303.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Positive regulation by γ-aminobutyric acid B receptor subunit-1 of chondrogenesis through acceleration of nuclear translocation of activating transcription factor-4
AU - Takahata, Yoshifumi
AU - Hinoi, Eiichi
AU - Takarada, Takeshi
AU - Nakamura, Yukari
AU - Ogawa, Shinya
AU - Yoneda, Yukio
PY - 2012/9/28
Y1 - 2012/9/28
N2 - A view that signaling machineries for the neurotransmitter γ-aminobutyric acid (GABA) are functionally expressed by cells outside the central nervous system is now prevailing. In this study, we attempted to demonstrate functional expression of GABAergic signaling molecules by chondrocytes. In cultured murine costal chondrocytes, mRNA was constitutively expressed for metabotropic GABAB receptor subunit-1 (GABA BR1), but not for GABABR2. Immunohistochemical analysis revealed the predominant expression of GABABR1 by prehypertrophic to hypertrophic chondrocytes in tibial sections of newborn mice. The GABA BR agonist baclofen failed to significantly affect chondrocytic differentiation determined by Alcian blue staining and alkaline phosphatase activity in cultured chondrocytes, whereas newborn mice knocked out of GABA BR1 (KO) showed a decreased body size and delayed calcification in hyoid bone and forelimb and hindlimb digits. Delayed calcification was also seen in cultured metatarsals from KO mice with a marked reduction of Indian hedgehog gene (Ihh) expression. Introduction of GABABR1 led to synergistic promotion of the transcriptional activity of activating transcription factor-4 (ATF4) essential for normal chondrogenesis, in addition to facilitating ATF4-dependent Ihh promoter activation. Although immunoreactive ATF4 was negligibly detected in the nucleus of chondrocytes from KO mice, ATF4 expression was again seen in the nucleus and cytoplasm after the retroviral introduction of GABABR1 into cultured chondrocytes from KO mice. In nuclear extracts of KO chondrocytes, a marked decrease was seen in ATF4 DNA binding. These results suggest that GABABR1 positively regulates chondrogenesis through a mechanism relevant to the acceleration of nuclear translocation of ATF4 for Ihh expression in chondrocytes.
AB - A view that signaling machineries for the neurotransmitter γ-aminobutyric acid (GABA) are functionally expressed by cells outside the central nervous system is now prevailing. In this study, we attempted to demonstrate functional expression of GABAergic signaling molecules by chondrocytes. In cultured murine costal chondrocytes, mRNA was constitutively expressed for metabotropic GABAB receptor subunit-1 (GABA BR1), but not for GABABR2. Immunohistochemical analysis revealed the predominant expression of GABABR1 by prehypertrophic to hypertrophic chondrocytes in tibial sections of newborn mice. The GABA BR agonist baclofen failed to significantly affect chondrocytic differentiation determined by Alcian blue staining and alkaline phosphatase activity in cultured chondrocytes, whereas newborn mice knocked out of GABA BR1 (KO) showed a decreased body size and delayed calcification in hyoid bone and forelimb and hindlimb digits. Delayed calcification was also seen in cultured metatarsals from KO mice with a marked reduction of Indian hedgehog gene (Ihh) expression. Introduction of GABABR1 led to synergistic promotion of the transcriptional activity of activating transcription factor-4 (ATF4) essential for normal chondrogenesis, in addition to facilitating ATF4-dependent Ihh promoter activation. Although immunoreactive ATF4 was negligibly detected in the nucleus of chondrocytes from KO mice, ATF4 expression was again seen in the nucleus and cytoplasm after the retroviral introduction of GABABR1 into cultured chondrocytes from KO mice. In nuclear extracts of KO chondrocytes, a marked decrease was seen in ATF4 DNA binding. These results suggest that GABABR1 positively regulates chondrogenesis through a mechanism relevant to the acceleration of nuclear translocation of ATF4 for Ihh expression in chondrocytes.
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U2 - 10.1074/jbc.M112.344051
DO - 10.1074/jbc.M112.344051
M3 - Article
VL - 287
SP - 33293
EP - 33303
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 40
ER -