Cellular distribution and regulation of NHE-1 isoform of the NA-H exchanger in the avian osteoclast

Bone. 1996 Feb;18(2):87-95. doi: 10.1016/8756-3282(95)00455-6.


The sodium-hydrogen exchanger (NHE) has been implicated in bone resorption by osteoclasts. We have studied expression of NHE-1, an isoform of the NHE, in chicken bone marrow mononuclear phagocyte precursors during differentiation into the osteoclast phenotype in culture. A monoclonal anti-body raised against the carboxy-terminus of NHE-1 detected the presence of a 100 kDa protein (similar to the mammalian form of NHE-1) in the osteoclasts. Laser scanning confocal microscopy revealed association with the alpha(v)beta(3) integrin and focal adhesion kinase (pp(125)FAK) at the basolateral membrane (BLM) of the osteoclast in addition to a more generalized cellular distribution. A fragment of avian NHE-1 cDNA was obtained by polymerase chain reaction cloning, and it was used to characterize expression of NHE-1 transcripts in cultured chicken osteoclast precursors. The avian NHE-1 message was a 3.9 kB band on Northern analysis, which differed from the mammalian message. Retinoic acid (RA) elicited an increase in the steady-state intracellular pH (pH(1)) from 6.87 to 7.10 in the absence of bicarbonate and was inhibited by ethylisopropylamiloride, an inhibitor of Na-H exchange. Using ribonuclease protection assays, we found that NHE-1 transcripts are induced as cells differentiate in vitro and in response to 13-cis-RA. Western blot analysis indicated that protein levels also increased in response to 13-cis-RA. Our results demonstrate expression of NHE-1 in avian osteoclasts with a complex cellular distribution in culture, and NHE-1 expression is induced as cells differentiate into mature osteoclasts in response to 13-cis-RA.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bone Marrow / metabolism*
  • Bone Marrow Cells
  • Calcium / physiology*
  • Cell Differentiation / physiology
  • Cells, Cultured
  • Chickens
  • Gene Expression Regulation / physiology*
  • Hydrogen-Ion Concentration
  • Immunohistochemistry
  • Isotretinoin / pharmacology
  • Molecular Sequence Data
  • Osteoclasts / drug effects
  • Osteoclasts / metabolism*
  • RNA, Messenger / analysis
  • Sodium-Hydrogen Exchangers / genetics
  • Sodium-Hydrogen Exchangers / metabolism*
  • Subcellular Fractions / metabolism*


  • RNA, Messenger
  • Sodium-Hydrogen Exchangers
  • growth factor-activatable Na-H exchanger NHE-1
  • Isotretinoin
  • Calcium