Abstract
Rab44 is an atypical Rab GTPase that contains some additional domains such as the EF-hand and coiled-coil domains as well as Rab-GTPase domain. Although Rab44 genes have been found in mammalian genomes, no studies concerning Rab44 have been reported yet. Here, we identified Rab44 as an upregulated protein during osteoclast differentiation. Knockdown of Rab44 by small interfering RNA promotes RANKL-induced osteoclast differentiation of the murine monocytic cell line, RAW-D or of bone marrow-derived macrophages (BMMs). In contrast, overexpression of Rab44 prevents osteoclast differentiation. Rab44 was localized in the Golgi complex and lysosomes, and Rab44 overexpression caused an enlargement of early endosomes. A series of deletion mutant studies of Rab44 showed that the coiled-coil domain and lipidation sites of Rab44 is important for regulation of osteoclast differentiation. Mechanistically, Rab44 affects nuclear factor of activated T-cells c1 (NFATc1) signaling in RANKL-stimulated macrophages. Moreover, Rab44 depletion caused an elevation in intracellular Ca2+ transients upon RANKL stimulation, and particularly regulated lysosomal Ca2+ influx. Taken together, these results suggest that Rab44 negatively regulates osteoclast differentiation by modulating intracellular Ca2+ levels followed by NFATc1 activation.
| Original language | English |
|---|---|
| Pages (from-to) | 1-16 |
| Number of pages | 16 |
| Journal | Cellular and Molecular Life Sciences |
| DOIs | |
| Publication status | Accepted/In press - Aug 8 2017 |
| Externally published | Yes |
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Keywords
- Intracellular Ca levels
- NFATc1
- Osteoclast
- Rab GTPase
- Rab44
ASJC Scopus subject areas
- Molecular Medicine
- Molecular Biology
- Pharmacology
- Cellular and Molecular Neuroscience
- Cell Biology
Cite this
Rab44, a novel large Rab GTPase, negatively regulates osteoclast differentiation by modulating intracellular calcium levels followed by NFATc1 activation. / Yamaguchi, Yu; Sakai, Eiko; Okamoto, Kuniaki; Kajiya, Hiroshi; Okabe, Koji; Naito, Mariko; Kadowaki, Tomoko; Tsukuba, Takayuki.
In: Cellular and Molecular Life Sciences, 08.08.2017, p. 1-16.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Rab44, a novel large Rab GTPase, negatively regulates osteoclast differentiation by modulating intracellular calcium levels followed by NFATc1 activation
AU - Yamaguchi, Yu
AU - Sakai, Eiko
AU - Okamoto, Kuniaki
AU - Kajiya, Hiroshi
AU - Okabe, Koji
AU - Naito, Mariko
AU - Kadowaki, Tomoko
AU - Tsukuba, Takayuki
PY - 2017/8/8
Y1 - 2017/8/8
N2 - Rab44 is an atypical Rab GTPase that contains some additional domains such as the EF-hand and coiled-coil domains as well as Rab-GTPase domain. Although Rab44 genes have been found in mammalian genomes, no studies concerning Rab44 have been reported yet. Here, we identified Rab44 as an upregulated protein during osteoclast differentiation. Knockdown of Rab44 by small interfering RNA promotes RANKL-induced osteoclast differentiation of the murine monocytic cell line, RAW-D or of bone marrow-derived macrophages (BMMs). In contrast, overexpression of Rab44 prevents osteoclast differentiation. Rab44 was localized in the Golgi complex and lysosomes, and Rab44 overexpression caused an enlargement of early endosomes. A series of deletion mutant studies of Rab44 showed that the coiled-coil domain and lipidation sites of Rab44 is important for regulation of osteoclast differentiation. Mechanistically, Rab44 affects nuclear factor of activated T-cells c1 (NFATc1) signaling in RANKL-stimulated macrophages. Moreover, Rab44 depletion caused an elevation in intracellular Ca2+ transients upon RANKL stimulation, and particularly regulated lysosomal Ca2+ influx. Taken together, these results suggest that Rab44 negatively regulates osteoclast differentiation by modulating intracellular Ca2+ levels followed by NFATc1 activation.
AB - Rab44 is an atypical Rab GTPase that contains some additional domains such as the EF-hand and coiled-coil domains as well as Rab-GTPase domain. Although Rab44 genes have been found in mammalian genomes, no studies concerning Rab44 have been reported yet. Here, we identified Rab44 as an upregulated protein during osteoclast differentiation. Knockdown of Rab44 by small interfering RNA promotes RANKL-induced osteoclast differentiation of the murine monocytic cell line, RAW-D or of bone marrow-derived macrophages (BMMs). In contrast, overexpression of Rab44 prevents osteoclast differentiation. Rab44 was localized in the Golgi complex and lysosomes, and Rab44 overexpression caused an enlargement of early endosomes. A series of deletion mutant studies of Rab44 showed that the coiled-coil domain and lipidation sites of Rab44 is important for regulation of osteoclast differentiation. Mechanistically, Rab44 affects nuclear factor of activated T-cells c1 (NFATc1) signaling in RANKL-stimulated macrophages. Moreover, Rab44 depletion caused an elevation in intracellular Ca2+ transients upon RANKL stimulation, and particularly regulated lysosomal Ca2+ influx. Taken together, these results suggest that Rab44 negatively regulates osteoclast differentiation by modulating intracellular Ca2+ levels followed by NFATc1 activation.
KW - Intracellular Ca levels
KW - NFATc1
KW - Osteoclast
KW - Rab GTPase
KW - Rab44
UR - http://www.scopus.com/inward/record.url?scp=85027063277&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85027063277&partnerID=8YFLogxK
U2 - 10.1007/s00018-017-2607-9
DO - 10.1007/s00018-017-2607-9
M3 - Article
C2 - 28791425
AN - SCOPUS:85027063277
SP - 1
EP - 16
JO - Cellular and Molecular Life Sciences
JF - Cellular and Molecular Life Sciences
SN - 1420-682X
ER -