Advanced

Murine ameloblasts are immunonegative for Tcirg1, the v-H-ATPase subunit essential for the osteoclast plasma proton pump

Bronckers, Antonius L. J. J.; Lyaruu, Donacian M.; Bervoets, Theodore J.; Medina, Juan F.; DenBesten, Pamela; Richter, Johan LU and Everts, Vincent (2012) In Bone 50(4). p.901-908
Abstract
Maturation stage ameloblasts of rodents express vacuolar type-H-ATPase in the ruffled border of their plasma membrane in contact with forming dental enamel, similar to osteoclasts that resorb bone. It has been proposed that in ameloblasts this v-H-ATPase acts as proton pump to acidify the enamel space, required to complete enamel mineralization. To examine whether this v-H-ATPase in mouse ameloblasts is a proton pump, we determined whether these cells express the lysosomal, T-cell, immune regulator I (Tcirg1, v-H-Atp6v(0)a(3)), which is an essential part of the plasma membrane proton pump that is present in osteoclasts. Mutation of this subunit in Tcirg1 null (or oc/oc) mice leads to severe osteopetrosis. No immunohistochemically... (More)
Maturation stage ameloblasts of rodents express vacuolar type-H-ATPase in the ruffled border of their plasma membrane in contact with forming dental enamel, similar to osteoclasts that resorb bone. It has been proposed that in ameloblasts this v-H-ATPase acts as proton pump to acidify the enamel space, required to complete enamel mineralization. To examine whether this v-H-ATPase in mouse ameloblasts is a proton pump, we determined whether these cells express the lysosomal, T-cell, immune regulator I (Tcirg1, v-H-Atp6v(0)a(3)), which is an essential part of the plasma membrane proton pump that is present in osteoclasts. Mutation of this subunit in Tcirg1 null (or oc/oc) mice leads to severe osteopetrosis. No immunohistochemically detectable Tcirg1 was seen in mouse maturation stage ameloblasts. Strong positive staining in secretory and maturation stage ameloblasts however was found for another subunit of v-H-ATPase, subunit b, brain isoform (v-H-Atp6v(1)b(2)). Mouse osteoclasts and renal tubular epithelium stained strongly for both Tcirg1 and v-H-Atp6v(1)b(2). In Tcirg1 null mice osteoclasts and renal epithelium were negative for Tcirg1 but remained positive for v-H-Atp6v(1)b(2). The bone in these mutant mice was osteopetrotic, tooth eruption was inhibited or delayed, and teeth were often morphologically disfigured. However, enamel formation in these mutant mice was normal, ameloblasts structurally unaffected and the mineral content of enamel similar to that of wild type mice. We concluded that Tcirg1, which is essential for osteoclasts to pump protons into the bone, is not appreciably expressed in maturation stage mouse ameloblasts. Our data suggest that the reported v-H-ATPase in maturation stage ameloblasts is not the typical osteoclast-type plasma membrane associated proton pump which acidifies the extracellular space, but rather a v-H-ATPase potentially involved in intracellular acidification. (C) 2012 Elsevier Inc. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ameloblasts, v-H-Atp6v(0)a(3), v-H-Atp6v(1)b(2), Tcirg1, pH regulation
in
Bone
volume
50
issue
4
pages
901 - 908
publisher
Elsevier
external identifiers
  • wos:000301967400013
  • scopus:84858070672
ISSN
1873-2763
DOI
10.1016/j.bone.2011.12.019
language
English
LU publication?
yes
id
fa5028de-ce6f-441e-9248-7d170be36c0e (old id 2494533)
date added to LUP
2012-05-08 07:50:36
date last changed
2017-08-20 03:52:27
@article{fa5028de-ce6f-441e-9248-7d170be36c0e,
  abstract     = {Maturation stage ameloblasts of rodents express vacuolar type-H-ATPase in the ruffled border of their plasma membrane in contact with forming dental enamel, similar to osteoclasts that resorb bone. It has been proposed that in ameloblasts this v-H-ATPase acts as proton pump to acidify the enamel space, required to complete enamel mineralization. To examine whether this v-H-ATPase in mouse ameloblasts is a proton pump, we determined whether these cells express the lysosomal, T-cell, immune regulator I (Tcirg1, v-H-Atp6v(0)a(3)), which is an essential part of the plasma membrane proton pump that is present in osteoclasts. Mutation of this subunit in Tcirg1 null (or oc/oc) mice leads to severe osteopetrosis. No immunohistochemically detectable Tcirg1 was seen in mouse maturation stage ameloblasts. Strong positive staining in secretory and maturation stage ameloblasts however was found for another subunit of v-H-ATPase, subunit b, brain isoform (v-H-Atp6v(1)b(2)). Mouse osteoclasts and renal tubular epithelium stained strongly for both Tcirg1 and v-H-Atp6v(1)b(2). In Tcirg1 null mice osteoclasts and renal epithelium were negative for Tcirg1 but remained positive for v-H-Atp6v(1)b(2). The bone in these mutant mice was osteopetrotic, tooth eruption was inhibited or delayed, and teeth were often morphologically disfigured. However, enamel formation in these mutant mice was normal, ameloblasts structurally unaffected and the mineral content of enamel similar to that of wild type mice. We concluded that Tcirg1, which is essential for osteoclasts to pump protons into the bone, is not appreciably expressed in maturation stage mouse ameloblasts. Our data suggest that the reported v-H-ATPase in maturation stage ameloblasts is not the typical osteoclast-type plasma membrane associated proton pump which acidifies the extracellular space, but rather a v-H-ATPase potentially involved in intracellular acidification. (C) 2012 Elsevier Inc. All rights reserved.},
  author       = {Bronckers, Antonius L. J. J. and Lyaruu, Donacian M. and Bervoets, Theodore J. and Medina, Juan F. and DenBesten, Pamela and Richter, Johan and Everts, Vincent},
  issn         = {1873-2763},
  keyword      = {Ameloblasts,v-H-Atp6v(0)a(3),v-H-Atp6v(1)b(2),Tcirg1,pH regulation},
  language     = {eng},
  number       = {4},
  pages        = {901--908},
  publisher    = {Elsevier},
  series       = {Bone},
  title        = {Murine ameloblasts are immunonegative for Tcirg1, the v-H-ATPase subunit essential for the osteoclast plasma proton pump},
  url          = {http://dx.doi.org/10.1016/j.bone.2011.12.019},
  volume       = {50},
  year         = {2012},
}