Hyperosmotic modulation of the cytosolic calcium concentration in a rat osteoblast‐like cell line.

Dascalu, Avi; Oron, Yoram; Nevo, Zvi; Korenstein, Rafi

doi:10.1113/jphysiol.1995.sp020793

Cited by 16 publications

(14 citation statements)

References 28 publications

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“…Duncan and Hruska (5) demonstrated that the whole cell conductance increase with hypotonic challenge was blocked by gadolinium (20 M) in osteoblast-like osteosar- 20). Taken together, the Ca 2ϩ influx through the SAC channels first triggers the mechanotransduction in osteobalsts in consistent with previous reports (3,5,26).…”

Section: Discussionsupporting

confidence: 78%

Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system

Asada

Okihara

Horiguchi

et al. 2012

American Journal of Physiology-Cell Physiology

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Asada K, Obata K, Horiguchi K, Takaki M. Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system. Am J Physiol Cell Physiol 302: C757-C765, 2012. First published November 16, 2011 doi:10.1152/ajpcell.00362.2011.-Bone homeostasis is regulated by mechanical stimulation (MS). The sensory mechanism of bone tissue for MS remains unknown in the maintenance of bone homeostasis. We aimed to investigate the sensory mechanism from osteoblasts to sensory neurons in a coculture system by MS of osteoblasts. Primary sensory neurons isolated from dorsal root ganglia (DRG) of neonatal, juvenile, and adult mice and osteoblasts isolated from calvaria of neonatal mice were cocultured for 24 h. The responses in DRG neurons elicited by MS of osteoblasts with a glass micropipette were detected by increases in intracellular Ca 2ϩ concentration ([Ca 2ϩ ]i) with fluo 3-AM. In all developmental stages mice, [Ca 2ϩ ]i-increasing responses in osteoblasts were promptly elicited by MS. After a short delay, [Ca 2ϩ ]i-increasing responses were observed in neurites of DRG neurons. The osteoblastic response to second MS was largely attenuated by a stretch-activated Ca 2ϩ channel blocker, gadolinium. The increases of [Ca 2ϩ ]i in DRG neurons were abolished by a P2 receptor antagonist; suramin, a P2X receptor antagonist, pyridoxal-phosphate-6-azophenyl-2=,4=-disulfonate; and an ATP-hydrolyzing enzyme, apyrase. Satellite cells were found around DRG neurons in cocultured cells of only neonatal and juvenile mice. After satellite cells were removed, excessive abnormal responses to MS of osteoblasts were observed in neonatal neurites with unchanged osteoblast responses. The present study indicated that MS of bone tissue elicited afferent P2X receptor-mediated purinergic transmission to sensory neurons in all stages mice. This transmission is modulated by satellite cells, which may have protective actions on sensory neurons. dorsal root ganglia; calcium imaging; satellite cell; 5=-triphosphate; bone formation BONE HAS IMPORTANT ROLES IN supporting the body to maintain motor functions against the gravity and in storing minerals such as calcium and phosphate, resulting in an essential role player maintaining life. In the maintenance of bone homeostasis, mechanical stimulation (MS) to the bone plays critical roles. Mechanically unloading by prolonged bed rest, immobilization, or microgravity in space causes a marked loss of bone (28, 34). The atrophic changes in bone or heterotopic bone formations are observed in patients with neurological disorder (7, 10). It would be beneficial in treatments for the patients with neurological disorder and for aged patients with bone loss (24) to reveal the transduction mechanism of MS into bone homeostasis.Such studies (17) have been initiated from the molecular mechanism in bone underlying transduction of MS into a cellular response, although the benefits of MS have been well demonstrated in clinical settings. Activation of a variety of factors s...

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Section: Discussionsupporting

confidence: 78%

Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system

Asada

Okihara

Horiguchi

et al. 2012

American Journal of Physiology-Cell Physiology

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“…However, actin disassembly has been implicated in hyperosmotically stimulated increases in [Ca 2+ ] i in osteoblasts [3]. Using similar protocols to those described previously [21,39], results from the present study indicate that disruption of the actin and microtubule components of the cytoskeleton within mammary epithelial cells does not prevent hypo-osmotically induced stimulation of [Ca 2+ ] i .…”

Section: Discussionsupporting

confidence: 68%

“…Others have reported that hypo-osmotically induced increases in [Ca 2+ ] i that can be inhibited by trivalent ions such as Gd 3+ or lanthium, but not by nifedipine or other dihydropyridines, are indicative of Ca 2+ influx through stretch-activated, non-selective cation channels [3,26,28,29]. In experiments described here, a short pre-incubation with micromolar concentrations of Gd 3+ partially inhibited hypo-osmotically induced stimulation of [Ca 2+ ] i .…”

Section: Discussionmentioning

confidence: 56%

A hypo-osmotically induced increase in intracellular Ca 2+ in lactating mouse mammary epithelial cells involving Ca 2+ influx

Sudlow

Burgoyne

1997

Pfl�gers Archiv European Journal of Physiology

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Using a fluorescent Ca2+-sensitive dye, we studied the effect of hypo-osmotic stress on the intracellular free Ca2+ concentration ([Ca2+]i) in acini freshly isolated from lactating mouse mammary gland. The basal [Ca2+]i of mammary acini was unaffected by a 50% (v/v) dilution of suspensions with isotonic or hypertonic buffer, or after ionic (iso-osmotic) dilution (external Ca2+ was 3 mM). Hypo-osmotic dilution (50%) elicited a rapid increase in [Ca2+]i comprising a large, transient elevation, followed by a maintained plateau phase. No hypo-osmotically induced rise in [Ca2+]i was observed in the absence of extracellular Ca2+. Neither microtubule disassembly using nocodazole nor actin disruption with cytochalasin D prevented hypo-osmotically evoked stimulation of [Ca2+]i. Pre-incubation of acini with nifedipine did not prevent hypo-osmotically induced stimulation of [Ca2+]i, whereas a non-specific cation channel blocker, gadolinium, partially inhibited the increases in [Ca2+]i induced by hypo-osmotic stress. Furthermore, the transient component was still apparent, and not diminished in magnitude, after [Ca2+]i had been elevated by mobilisation of Ca2+ from intracellular stores using thapsigargin. The results demonstrate that hypo-osmotic stress generates an increase in [Ca2+]i in lactating mammary epithelial cells, the major, transient component of which appears to be due to influx of extracellular Ca2+.

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“…Since different apoptotic stimuli activate different signaling pathways and differentially effect intracellular calcium levels, it can be postulated that increases in the levels of calcium in certain cellular compartments in response to a specific stressor is one of the factors that determines the effects of tTG on the apoptotic process. Indeed, tTG potentiated apoptosis in response to osmotic stress, a stimulus that significantly increases in situ TG activity (15), most likely due to an increase in intracellular calcium (62,63). In contrast tTG protected against heat shock induced apoptosis, a stressor that did not increase tTG activity (15).…”

Section: Fig 6 the Interaction Of Ttg With Rb In The Nucleus Did Nomentioning

confidence: 99%

Intracellular Localization and Activity State of Tissue Transglutaminase Differentially Impacts Cell Death

Milaković

Tucholski

McCoy

et al. 2004

Journal of Biological Chemistry

118

141

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Tissue transglutaminase (tTG) is a unique member of the transglutaminase family as it is both a transamidating enzyme and a GTPase. In the cell tTG is mostly cytosolic, however it is also found in the nucleus and associated with the plasma membrane. tTG can be proapoptotic, however anti-apoptotic activities of the enzyme have also been reported. To determine how the intracellular localization and transamidating activity of tTG modulates its effects on apoptosis, HEK293 cells were transiently transfected with tTG or [C277S]tTG (which lacks transamidating activity) constructs that were targeted to different intracellular compartments. Apoptosis was induced by thapsigargin treatment, which results in increased intracellular calcium concentrations. Cytosolic tTG was pro-apoptotic, while nuclear localization of [C277S]tTG attenuated apoptosis. Membrane-targeted tTG had neither pro-nor anti-apoptotic functions. This finding indicates for the first time that intracellular localization is an important determinant of the effect of tTG on apoptosis. Previous studies have suggested that tTG may modulate retinoblastoma (Rb) protein, an important suppressor of apoptosis. tTG interacted with Rb and after induction of apoptosis, the interaction of nuclear-targeted [C277S]tTG with Rb was increased significantly concomitant with an attenuation of apoptosis. In contrast, the interaction of nucleartargeted tTG with Rb was significantly decreased and apoptosis was not attenuated. These data suggest that tTG protects cells against apoptosis in response to stimuli that do not result in increased transamidating activity by translocating to the nucleus, and that complexing with Rb may be an important aspect of the protective effects of tTG.

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Hyperosmotic modulation of the cytosolic calcium concentration in a rat osteoblast‐like cell line.

Abstract: 1. The effects of hyperosmotic stress on cytosolic calcium concentration ([Ca2+]

Cited by 16 publications

References 28 publications

Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system

Age-related changes in afferent responses in sensory neurons to mechanical stimulation of osteoblasts in coculture system

A hypo-osmotically induced increase in intracellular Ca 2+ in lactating mouse mammary epithelial cells involving Ca 2+ influx

Intracellular Localization and Activity State of Tissue Transglutaminase Differentially Impacts Cell Death

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