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Simulated microgravity inhibits L-type calcium channel currents partially by the up-regulation of miR-103 in MC3T3-E1 osteoblasts.

Sun Z, Cao X, Zhang Z, Hu Z, Zhang L, Wang H, Zhou H, Li D, Zhang S, Xie M - Sci Rep (2015)

Bottom Line: In addition, reduced Cav1.2 protein levels decreased LTCC currents in MC3T3-E1 cells.Cav1.2 expression and LTCC current densities both significantly increased in cells that were transfected with a miR-103 inhibitor under mechanical unloading conditions.These results suggest that simulated microgravity substantially inhibits LTCC currents in osteoblasts by suppressing Cav1.2 expression.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Aerospace Medicine, Ministry of Education, The Fourth Military Medical University, 710032, Xi'an, Shaanxi, China.

ABSTRACT
L-type voltage-sensitive calcium channels (LTCCs), particularly Cav1.2 LTCCs, play fundamental roles in cellular responses to mechanical stimuli in osteoblasts. Numerous studies have shown that mechanical loading promotes bone formation, whereas the removal of this stimulus under microgravity conditions results in a reduction in bone mass. However, whether microgravity exerts an influence on LTCCs in osteoblasts and whether this influence is a possible mechanism underlying the observed bone loss remain unclear. In the present study, we demonstrated that simulated microgravity substantially inhibited LTCC currents and suppressed Cav1.2 at the protein level in MC3T3-E1 osteoblast-like cells. In addition, reduced Cav1.2 protein levels decreased LTCC currents in MC3T3-E1 cells. Moreover, simulated microgravity increased miR-103 expression. Cav1.2 expression and LTCC current densities both significantly increased in cells that were transfected with a miR-103 inhibitor under mechanical unloading conditions. These results suggest that simulated microgravity substantially inhibits LTCC currents in osteoblasts by suppressing Cav1.2 expression. Furthermore, the down-regulation of Cav1.2 expression and the inhibition of LTCCs caused by mechanical unloading in osteoblasts are partially due to miR-103 up-regulation. Our study provides a novel mechanism for microgravity-induced detrimental effects on osteoblasts, offering a new avenue to further investigate the bone loss induced by microgravity.

No MeSH data available.


Related in: MedlinePlus

Effects of miR-103 knockdown on Cav1.2 subunit expression under simulated microgravity conditions.(a) Knockdown of endogenous miR-103 by a miR-103 inhibitor in MC3T3-E1 cells (n = 4, α = 0.05, *P = 0.016). (b) Western blot analysis of the role of miR-103 in regulating the expression of the Cav1.2 subunit under simulated microgravity conditions (n = 4, α = 0.05, *P = 0.022, #P = 0.017, &P = 0.016). Bars represent the mean ± s.d. with two-tailed Student's t-test against control samples.
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f7: Effects of miR-103 knockdown on Cav1.2 subunit expression under simulated microgravity conditions.(a) Knockdown of endogenous miR-103 by a miR-103 inhibitor in MC3T3-E1 cells (n = 4, α = 0.05, *P = 0.016). (b) Western blot analysis of the role of miR-103 in regulating the expression of the Cav1.2 subunit under simulated microgravity conditions (n = 4, α = 0.05, *P = 0.022, #P = 0.017, &P = 0.016). Bars represent the mean ± s.d. with two-tailed Student's t-test against control samples.

Mentions: To confirm the effect of miR-103 on Cav1.2 expression under simulated microgravity conditions, a miR-103 inhibitor was transfected into MC3T3-E1 cells, and western blot analyses were performed to test for Cav1.2 expression. miR-103 expression was significantly down-regulated (P < 0.05, Figure 7a) in miR-103 inhibitor-transfected cells. Under simulated microgravity conditions, Cav1.2 expression significantly increased in miR-103 inhibitor-transfected cells compared with that of miR-103 negative control-transfected cells (P < 0.05, Figure 7b); however, Cav1.2 expression was not restored to control levels. In addition, the miR-103 inhibitor had no effects on Cav1.2 expression in cells under normal gravity conditions (P < 0.05, Figure 7b). These data suggest that miR-103 partially regulates Cav1.2 expression in MC3T3-E1 cells under simulated microgravity conditions.


Simulated microgravity inhibits L-type calcium channel currents partially by the up-regulation of miR-103 in MC3T3-E1 osteoblasts.

Sun Z, Cao X, Zhang Z, Hu Z, Zhang L, Wang H, Zhou H, Li D, Zhang S, Xie M - Sci Rep (2015)

Effects of miR-103 knockdown on Cav1.2 subunit expression under simulated microgravity conditions.(a) Knockdown of endogenous miR-103 by a miR-103 inhibitor in MC3T3-E1 cells (n = 4, α = 0.05, *P = 0.016). (b) Western blot analysis of the role of miR-103 in regulating the expression of the Cav1.2 subunit under simulated microgravity conditions (n = 4, α = 0.05, *P = 0.022, #P = 0.017, &P = 0.016). Bars represent the mean ± s.d. with two-tailed Student's t-test against control samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308706&req=5

f7: Effects of miR-103 knockdown on Cav1.2 subunit expression under simulated microgravity conditions.(a) Knockdown of endogenous miR-103 by a miR-103 inhibitor in MC3T3-E1 cells (n = 4, α = 0.05, *P = 0.016). (b) Western blot analysis of the role of miR-103 in regulating the expression of the Cav1.2 subunit under simulated microgravity conditions (n = 4, α = 0.05, *P = 0.022, #P = 0.017, &P = 0.016). Bars represent the mean ± s.d. with two-tailed Student's t-test against control samples.
Mentions: To confirm the effect of miR-103 on Cav1.2 expression under simulated microgravity conditions, a miR-103 inhibitor was transfected into MC3T3-E1 cells, and western blot analyses were performed to test for Cav1.2 expression. miR-103 expression was significantly down-regulated (P < 0.05, Figure 7a) in miR-103 inhibitor-transfected cells. Under simulated microgravity conditions, Cav1.2 expression significantly increased in miR-103 inhibitor-transfected cells compared with that of miR-103 negative control-transfected cells (P < 0.05, Figure 7b); however, Cav1.2 expression was not restored to control levels. In addition, the miR-103 inhibitor had no effects on Cav1.2 expression in cells under normal gravity conditions (P < 0.05, Figure 7b). These data suggest that miR-103 partially regulates Cav1.2 expression in MC3T3-E1 cells under simulated microgravity conditions.

Bottom Line: In addition, reduced Cav1.2 protein levels decreased LTCC currents in MC3T3-E1 cells.Cav1.2 expression and LTCC current densities both significantly increased in cells that were transfected with a miR-103 inhibitor under mechanical unloading conditions.These results suggest that simulated microgravity substantially inhibits LTCC currents in osteoblasts by suppressing Cav1.2 expression.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Aerospace Medicine, Ministry of Education, The Fourth Military Medical University, 710032, Xi'an, Shaanxi, China.

ABSTRACT
L-type voltage-sensitive calcium channels (LTCCs), particularly Cav1.2 LTCCs, play fundamental roles in cellular responses to mechanical stimuli in osteoblasts. Numerous studies have shown that mechanical loading promotes bone formation, whereas the removal of this stimulus under microgravity conditions results in a reduction in bone mass. However, whether microgravity exerts an influence on LTCCs in osteoblasts and whether this influence is a possible mechanism underlying the observed bone loss remain unclear. In the present study, we demonstrated that simulated microgravity substantially inhibited LTCC currents and suppressed Cav1.2 at the protein level in MC3T3-E1 osteoblast-like cells. In addition, reduced Cav1.2 protein levels decreased LTCC currents in MC3T3-E1 cells. Moreover, simulated microgravity increased miR-103 expression. Cav1.2 expression and LTCC current densities both significantly increased in cells that were transfected with a miR-103 inhibitor under mechanical unloading conditions. These results suggest that simulated microgravity substantially inhibits LTCC currents in osteoblasts by suppressing Cav1.2 expression. Furthermore, the down-regulation of Cav1.2 expression and the inhibition of LTCCs caused by mechanical unloading in osteoblasts are partially due to miR-103 up-regulation. Our study provides a novel mechanism for microgravity-induced detrimental effects on osteoblasts, offering a new avenue to further investigate the bone loss induced by microgravity.

No MeSH data available.


Related in: MedlinePlus