Importance of melastatin-like transient receptor potential 7 and magnesium in the stimulation of osteoblast proliferation and migration by platelet-derived growth factor

2009 ◽  
Vol 297 (2) ◽  
pp. C360-C368 ◽  
Author(s):  
Elie Abed ◽  
Robert Moreau

Bone is a dynamic tissue that is continuously being remodeled throughout life. Specialized cells called osteoclasts transiently break down old bone (resorption process) at multiple sites as other cells known as osteoblasts are replacing it with new tissue (bone formation). Usually, both resorption and formation processes are in balance and thereby maintain skeletal strength and integrity. This equilibrium is assured by the coordination of proliferation, migration, differentiation, and secretory functions of the osteoblasts, which are essential for adequate formation and resorption processes. Disturbances of this equilibrium may lead to decreased bone mass (osteoporosis), increased bone fragility, and susceptibility to fractures. Epidemiological studies have linked insufficient dietary magnesium (Mg2+) intake in humans with low bone mass and osteoporosis. Here, we investigated the roles of Mg2+ and melastatin-like transient receptor potential 7 (TRPM7), known as Mg2+ channels, in human osteoblast cell proliferation and migration induced by platelet-derived growth factor (PDGF), which has been involved in the bone remodeling process. PDGF promoted an influx of Mg2+, enhanced cell migration, and stimulated the gene expression of TRPM7 channels in human osteoblast MG-63 cells. The stimulation of osteoblast proliferation and migration by PDGF was significantly reduced under culture conditions of low extracellular Mg2+ concentrations. Silencing TRPM7 expression in osteoblasts by specific small interfering RNA prevented the induction by PDGF of Mg2+ influx, proliferation, and migration. Our results indicate that extracellular Mg2+ and TRPM7 are important for PDGF-induced proliferation and migration of human osteoblasts. Thus Mg2+ deficiency, a common condition among the general population, may be associated with altered osteoblast functions leading to inadequate bone formation and the development of osteoporosis.

2016 ◽  
Vol 67 (4) ◽  
pp. 497-505 ◽  
Author(s):  
Kayoko Oda ◽  
Masanari Umemura ◽  
Rina Nakakaji ◽  
Ryo Tanaka ◽  
Itaru Sato ◽  
...  

2020 ◽  
Vol 10 ◽  
Author(s):  
Yuan Huang ◽  
Shi Li ◽  
Zhenhua Jia ◽  
Weiwei Zhao ◽  
Cefan Zhou ◽  
...  

The calcium-permeable cation channel TRPM8 (transient receptor potential melastatin 8) is a member of the TRP superfamily of cation channels that is upregulated in various types of cancer with high levels of autophagy, including prostate, pancreatic, breast, lung, and colon cancers. Autophagy is closely regulated by AMP-activated protein kinase (AMPK) and plays an important role in tumor growth by generating nutrients through degradation of intracellular structures. Additionally, AMPK activity is regulated by intracellular Ca2+ concentration. Considering that TRPM8 is a non-selective Ca2+-permeable cation channel and plays a key role in calcium homoeostasis, we hypothesized that TRPM8 may control AMPK activity thus modulating cellular autophagy to regulate the proliferation and migration of breast cancer cells. In this study, overexpression of TRPM8 enhanced the level of basal autophagy, whereas TRPM8 knockdown reduced the level of basal autophagy in several types of mammalian cancer cells. Moreover, the activity of the TRPM8 channel modulated the level of basal autophagy. The mechanism of regulation of autophagy by TRPM8 involves autophagy-associated signaling pathways for activation of AMPK and ULK1 and phagophore formation. Impaired AMPK abolished TRPM8-dependent regulation of autophagy. TRPM8 interacts with AMPK in a protein complex, and cytoplasmic C-terminus of TRPM8 mediates the TRPM8–AMPK interaction. Finally, basal autophagy mediates the regulatory effects of TRPM8 on the proliferation and migration of breast cancer cells. Thus, this study identifies TRPM8 as a novel regulator of basal autophagy in cancer cells acting by interacting with AMPK, which in turn activates AMPK to activate ULK1 in a coordinated cascade of TRPM8-mediated breast cancer progression.


2012 ◽  
Vol 303 (3) ◽  
pp. C308-C317 ◽  
Author(s):  
Jaladanki N. Rao ◽  
Navneeta Rathor ◽  
Ran Zhuang ◽  
Tongtong Zou ◽  
Lan Liu ◽  
...  

Early epithelial restitution occurs as a consequence of intestinal epithelial cell (IEC) migration after wounding, and its defective regulation is implicated in various critical pathological conditions. Polyamines stimulate intestinal epithelial restitution, but their exact mechanism remains unclear. Canonical transient receptor potential-1 (TRPC1)-mediated Ca2+ signaling is crucial for stimulation of IEC migration after wounding, and induced translocation of stromal interaction molecule 1 (STIM1) to the plasma membrane activates TRPC1-mediated Ca2+ influx and thus enhanced restitution. Here, we show that polyamines regulate intestinal epithelial restitution through TRPC1-mediated Ca2+ signaling by altering the ratio of STIM1 to STIM2. Increasing cellular polyamines by ectopic overexpression of the ornithine decarboxylase (ODC) gene stimulated STIM1 but inhibited STIM2 expression, whereas depletion of cellular polyamines by inhibiting ODC activity decreased STIM1 but increased STIM2 levels. Induced STIM1/TRPC1 association by increasing polyamines enhanced Ca2+ influx and stimulated epithelial restitution, while decreased formation of the STIM1/TRPC1 complex by polyamine depletion decreased Ca2+ influx and repressed cell migration. Induced STIM1/STIM2 heteromers by polyamine depletion or STIM2 overexpression suppressed STIM1 membrane translocation and inhibited Ca2+ influx and epithelial restitution. These results indicate that polyamines differentially modulate cellular STIM1 and STIM2 levels in IECs, in turn controlling TRPC1-mediated Ca2+ signaling and influencing cell migration after wounding.


2018 ◽  
Vol 315 (6) ◽  
pp. C793-C802 ◽  
Author(s):  
Mohammad Shahidullah ◽  
Amritlal Mandal ◽  
Nicholas A. Delamere

Lens ion homeostasis is crucial in maintaining water content and, in turn, refractive index and transparency of the multicellular syncytium-like structure. New information is emerging on the regulation of ion transport in the lens by mechanisms that rely on transient receptor potential vanilloid (TRPV) ion channels. We found recently that TRPV1 activation leads to Ca2+/PKC-dependent ERK1/2 signaling. Here, we show that the TRPV1 agonist capsaicin (100 nM) and hyperosmotic solution (350 vs. 300 mosM) each caused an increase of bumetanide-inhibitable Rb uptake by intact porcine lenses and Na-K-2Cl cotransporter 1 (NKCC1) phosphorylation in the lens epithelium. The TRPV1 antagonist A889425 (1 µM) abolished the increases of Rb uptake and NKCC1 phosphorylation in response to hyperosmotic solution. Exposing lenses to hyperosmotic solution in the presence of MEK/ERK inhibitor U0126 (10 µM) or the with-no-lysine kinase (WNK) inhibitor WNK463 (1 µM) also prevented NKCC1 phosphorylation and the Rb uptake responses to hyperosmotic solution. WNK463 did not prevent the increase in ERK1/2 phosphorylation that occurs in response to capsaicin or hyperosmotic solution, suggesting that ERK1/2 activation occurs before WNK activation in the sequence of signaling events. Taken together, the evidence indicates that activation of TRPV1 is a critical early step in a signaling mechanism that responds to a hyperosmotic stimulus, possibly lens shrinkage. By activating ERK1/2 and WNK, TRPV1 activation leads to NKCC1 phosphorylation and stimulation of NKCC1-mediated ion transport.


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