Regulation of spontaneous glutamate release activity in osteoblastic cells and its role in differentiation and survival: evidence for intrinsic glutamatergic signaling in bone

P G Genever; T M Skerry

doi:10.1096/fj.00-0594fje

Regulation of spontaneous glutamate release activity in osteoblastic cells and its role in differentiation and survival: evidence for intrinsic glutamatergic signaling in bone

P G Genever, T M Skerry

Biology

Research output: Contribution to journal › Article › peer-review

Abstract

Maintenance of bone mass depends on numerous osteoblast-derived autocrine and paracrine signaling factors that ensure the coupled resorptive and formative activity of osteoclasts and osteoblasts. Here, we provide the first evidence that osteoblasts actively secrete glutamate, an amino acid neurotransmitter found at excitatory synapses in the central nervous system, complementing previous reports of functional glutamate receptor expression by bone cells, Several osteoblastic cell-types spontaneously released between 2-7 nmoles glutamate per mg protein, equivalent to or greater than reported levels of glutamate release from depolarized neurons. Osteoblastic glutamate exocytosis appeared dependent on an AMPA-type glutamate autoreceptor, and addition of depolarizing concentrations of KCl caused significant calcium-dependent inhibition of glutamate release. Levels of exocytosed and intracellular free glutamate, and susceptibility to depolarization-induced inhibition of glutamate release, increased during osteoblastic differentiation of MC3T3-E1 cells. Pharmacological inhibition of glutamate release with riluzole (1-25 muM) significantly inhibited differentiation and induced morphological and biochemical characteristics of apoptosis in osteoblastic cells. Exogenous glutamate application increased survival rates of osteoblasts grown in serum-free medium, and proinflammatory cytokines (tumor necrosis factor-alpha and interferon-gamma) significantly inhibited osteoblastic glutamate release. These findings provide evidence for an intrinsic synaptic-like glutamatergic signaling network in bone that is essential for in vitro osteoblast differentiation and survival.

Original language	English
Pages (from-to)	1586-+
Number of pages	29
Journal	The FASEB Journal
Volume	15
Issue number	7
DOIs	https://doi.org/10.1096/fj.00-0594fje
Publication status	Published - 29 May 2001

Keywords

intercellular communication
osteoblasts
osteoclasts
SODIUM-CHANNEL EXPRESSION
IN-VITRO
NONNEURONAL CELLS
RAT OSTEOBLASTS
NITRIC-OXIDE
RECEPTORS
RESORPTION
RILUZOLE
DEATH
NEUROTOXICITY

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10.1096/fj.00-0594fje

Cite this

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title = "Regulation of spontaneous glutamate release activity in osteoblastic cells and its role in differentiation and survival: evidence for intrinsic glutamatergic signaling in bone",

abstract = "Maintenance of bone mass depends on numerous osteoblast-derived autocrine and paracrine signaling factors that ensure the coupled resorptive and formative activity of osteoclasts and osteoblasts. Here, we provide the first evidence that osteoblasts actively secrete glutamate, an amino acid neurotransmitter found at excitatory synapses in the central nervous system, complementing previous reports of functional glutamate receptor expression by bone cells, Several osteoblastic cell-types spontaneously released between 2-7 nmoles glutamate per mg protein, equivalent to or greater than reported levels of glutamate release from depolarized neurons. Osteoblastic glutamate exocytosis appeared dependent on an AMPA-type glutamate autoreceptor, and addition of depolarizing concentrations of KCl caused significant calcium-dependent inhibition of glutamate release. Levels of exocytosed and intracellular free glutamate, and susceptibility to depolarization-induced inhibition of glutamate release, increased during osteoblastic differentiation of MC3T3-E1 cells. Pharmacological inhibition of glutamate release with riluzole (1-25 muM) significantly inhibited differentiation and induced morphological and biochemical characteristics of apoptosis in osteoblastic cells. Exogenous glutamate application increased survival rates of osteoblasts grown in serum-free medium, and proinflammatory cytokines (tumor necrosis factor-alpha and interferon-gamma) significantly inhibited osteoblastic glutamate release. These findings provide evidence for an intrinsic synaptic-like glutamatergic signaling network in bone that is essential for in vitro osteoblast differentiation and survival.",

keywords = "intercellular communication, osteoblasts, osteoclasts, SODIUM-CHANNEL EXPRESSION, IN-VITRO, NONNEURONAL CELLS, RAT OSTEOBLASTS, NITRIC-OXIDE, RECEPTORS, RESORPTION, RILUZOLE, DEATH, NEUROTOXICITY",

author = "Genever, {P G} and Skerry, {T M}",

year = "2001",

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doi = "10.1096/fj.00-0594fje",

language = "English",

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T1 - Regulation of spontaneous glutamate release activity in osteoblastic cells and its role in differentiation and survival: evidence for intrinsic glutamatergic signaling in bone

AU - Genever, P G

AU - Skerry, T M

PY - 2001/5/29

Y1 - 2001/5/29

N2 - Maintenance of bone mass depends on numerous osteoblast-derived autocrine and paracrine signaling factors that ensure the coupled resorptive and formative activity of osteoclasts and osteoblasts. Here, we provide the first evidence that osteoblasts actively secrete glutamate, an amino acid neurotransmitter found at excitatory synapses in the central nervous system, complementing previous reports of functional glutamate receptor expression by bone cells, Several osteoblastic cell-types spontaneously released between 2-7 nmoles glutamate per mg protein, equivalent to or greater than reported levels of glutamate release from depolarized neurons. Osteoblastic glutamate exocytosis appeared dependent on an AMPA-type glutamate autoreceptor, and addition of depolarizing concentrations of KCl caused significant calcium-dependent inhibition of glutamate release. Levels of exocytosed and intracellular free glutamate, and susceptibility to depolarization-induced inhibition of glutamate release, increased during osteoblastic differentiation of MC3T3-E1 cells. Pharmacological inhibition of glutamate release with riluzole (1-25 muM) significantly inhibited differentiation and induced morphological and biochemical characteristics of apoptosis in osteoblastic cells. Exogenous glutamate application increased survival rates of osteoblasts grown in serum-free medium, and proinflammatory cytokines (tumor necrosis factor-alpha and interferon-gamma) significantly inhibited osteoblastic glutamate release. These findings provide evidence for an intrinsic synaptic-like glutamatergic signaling network in bone that is essential for in vitro osteoblast differentiation and survival.

AB - Maintenance of bone mass depends on numerous osteoblast-derived autocrine and paracrine signaling factors that ensure the coupled resorptive and formative activity of osteoclasts and osteoblasts. Here, we provide the first evidence that osteoblasts actively secrete glutamate, an amino acid neurotransmitter found at excitatory synapses in the central nervous system, complementing previous reports of functional glutamate receptor expression by bone cells, Several osteoblastic cell-types spontaneously released between 2-7 nmoles glutamate per mg protein, equivalent to or greater than reported levels of glutamate release from depolarized neurons. Osteoblastic glutamate exocytosis appeared dependent on an AMPA-type glutamate autoreceptor, and addition of depolarizing concentrations of KCl caused significant calcium-dependent inhibition of glutamate release. Levels of exocytosed and intracellular free glutamate, and susceptibility to depolarization-induced inhibition of glutamate release, increased during osteoblastic differentiation of MC3T3-E1 cells. Pharmacological inhibition of glutamate release with riluzole (1-25 muM) significantly inhibited differentiation and induced morphological and biochemical characteristics of apoptosis in osteoblastic cells. Exogenous glutamate application increased survival rates of osteoblasts grown in serum-free medium, and proinflammatory cytokines (tumor necrosis factor-alpha and interferon-gamma) significantly inhibited osteoblastic glutamate release. These findings provide evidence for an intrinsic synaptic-like glutamatergic signaling network in bone that is essential for in vitro osteoblast differentiation and survival.

KW - intercellular communication

KW - osteoblasts

KW - osteoclasts

KW - SODIUM-CHANNEL EXPRESSION

KW - IN-VITRO

KW - NONNEURONAL CELLS

KW - RAT OSTEOBLASTS

KW - NITRIC-OXIDE

KW - RECEPTORS

KW - RESORPTION

KW - RILUZOLE

KW - DEATH

KW - NEUROTOXICITY

U2 - 10.1096/fj.00-0594fje

DO - 10.1096/fj.00-0594fje

M3 - Article

SN - 0892-6638

VL - 15

SP - 1586-+

JO - The FASEB Journal

JF - The FASEB Journal

IS - 7

ER -