Limits...
Overexpression of tau downregulated the mRNA levels of Kv channels and improved proliferation in N2A cells.

Li X, Hu X, Li X, Hao X - PLoS ONE (2015)

Bottom Line: Furthermore, the macroscopic currents through Kv channels were reduced by 36.5% at +60 mV in tau-transfected N2A cells.Following the cotransfection with tau in HEK293 cells, the mRNA levels and corresponding currents of Kv2.1 were significantly declined compared with single Kv2.1 transfection.Our data indicated that overexpression of tau declined the mRNA levels of Kv channels and related currents.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China.

ABSTRACT
Microtubule binding protein tau has a crucial function in promoting the assembly and stabilization of microtubule. Besides tuning the action potentials, voltage-gated K+ channels (Kv) are important for cell proliferation and appear to play a role in the development of cancer. However, little is known about the possible interaction of tau with Kv channels in various tissues. In the present study, tau plasmids were transiently transfected into mouse neuroblastoma N2A cells to explore the possible linkages between tau and Kv channels. This treatment led to a downregulation of mRNA levels of several Kv channels, including Kv2.1, Kv3.1, Kv4.1, Kv9.2, and KCNH4, but no significant alteration was observed for Kv5.1 and KCNQ4. Furthermore, the macroscopic currents through Kv channels were reduced by 36.5% at +60 mV in tau-transfected N2A cells. The proliferation rates of N2A cells were also improved by the induction of tau expression and the incubation of TEA (tetraethylammonium) for 48 h by 120.9% and 149.3%, respectively. Following the cotransfection with tau in HEK293 cells, the mRNA levels and corresponding currents of Kv2.1 were significantly declined compared with single Kv2.1 transfection. Our data indicated that overexpression of tau declined the mRNA levels of Kv channels and related currents. The effects of tau overexpression on Kv channels provided an alternative explanation for low sensitivity to anti-cancer chemicals in some specific cancer tissues.

Show MeSH

Related in: MedlinePlus

Effects of cotransfection with tau and Kv2.1 in HEK293 cells.(A) QPCR data showed that the induction of tau downregulated the mRNA level of Kv2.1. But no change was produced after the transfection of an empty vector (mock) of tau (n = 8). The * denoted p<0.05 compared with control Kv2.1 (B) The representative current traces of Kv2.1 before and after tau transfection. Currents were evoked by a 500 ms long voltage pulse to potentials from -80 mV to +60 mV at a holding potential of -80 mV. (C) Current–voltage (I-V) relations of Kv2.1 currents in the absence and presence of tau. (D) The statistic analysis of effects of tau transfection on macroscopic Kv2.1 currents in HEK293 cells (n = 8). The * denoted p<0.05 compared with Kv2.1 currents.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4295873&req=5

pone.0116628.g006: Effects of cotransfection with tau and Kv2.1 in HEK293 cells.(A) QPCR data showed that the induction of tau downregulated the mRNA level of Kv2.1. But no change was produced after the transfection of an empty vector (mock) of tau (n = 8). The * denoted p<0.05 compared with control Kv2.1 (B) The representative current traces of Kv2.1 before and after tau transfection. Currents were evoked by a 500 ms long voltage pulse to potentials from -80 mV to +60 mV at a holding potential of -80 mV. (C) Current–voltage (I-V) relations of Kv2.1 currents in the absence and presence of tau. (D) The statistic analysis of effects of tau transfection on macroscopic Kv2.1 currents in HEK293 cells (n = 8). The * denoted p<0.05 compared with Kv2.1 currents.

Mentions: To obtain the direct evidence about the effects of tau overexpression on Kv channels, we conducted the cotransfection of tau and Kv2.1, one of the Kv members with the highest inhibitory percentage following induction of tau in N2A cells (see Fig. 3), into HEK293 cells without the expression of both tau and Kv2.1. At 48 h after cotransfection with tau, the mRNA levels of Kv2.1 were significantly declined by 49.7% compared with single Kv2.1 transfection, whereas no effect was observed for cotransfection with empty vector (mock) of tau (Fig. 6A). Accordingly, whole-cell currents of Kv2.1 in HEK293 cells cotransfected with tau were potentially reduced with respect to the single Kv2.1 transfection. At +60 mV, overexpression of tau declined Kv2.1 currents from 11.2 ± 0.9 nA to 5.7 ± 0.5 nA (Fig. 6D). The representative Kv2.1 current traces and current–voltage (I–V) curves were presented in Fig. 6B and 6C, respectively. We next measured the effects of interaction of tau and Kv2.1 on the growth of HEK293 using a method described above. As shown in Fig. 7, transfection with tau leaded to a weak and significant increase in proliferation of HEK293 cells in comparison to single Kv2.1 transfection, but no alteration was visible after mock transfection.


Overexpression of tau downregulated the mRNA levels of Kv channels and improved proliferation in N2A cells.

Li X, Hu X, Li X, Hao X - PLoS ONE (2015)

Effects of cotransfection with tau and Kv2.1 in HEK293 cells.(A) QPCR data showed that the induction of tau downregulated the mRNA level of Kv2.1. But no change was produced after the transfection of an empty vector (mock) of tau (n = 8). The * denoted p<0.05 compared with control Kv2.1 (B) The representative current traces of Kv2.1 before and after tau transfection. Currents were evoked by a 500 ms long voltage pulse to potentials from -80 mV to +60 mV at a holding potential of -80 mV. (C) Current–voltage (I-V) relations of Kv2.1 currents in the absence and presence of tau. (D) The statistic analysis of effects of tau transfection on macroscopic Kv2.1 currents in HEK293 cells (n = 8). The * denoted p<0.05 compared with Kv2.1 currents.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4295873&req=5

pone.0116628.g006: Effects of cotransfection with tau and Kv2.1 in HEK293 cells.(A) QPCR data showed that the induction of tau downregulated the mRNA level of Kv2.1. But no change was produced after the transfection of an empty vector (mock) of tau (n = 8). The * denoted p<0.05 compared with control Kv2.1 (B) The representative current traces of Kv2.1 before and after tau transfection. Currents were evoked by a 500 ms long voltage pulse to potentials from -80 mV to +60 mV at a holding potential of -80 mV. (C) Current–voltage (I-V) relations of Kv2.1 currents in the absence and presence of tau. (D) The statistic analysis of effects of tau transfection on macroscopic Kv2.1 currents in HEK293 cells (n = 8). The * denoted p<0.05 compared with Kv2.1 currents.
Mentions: To obtain the direct evidence about the effects of tau overexpression on Kv channels, we conducted the cotransfection of tau and Kv2.1, one of the Kv members with the highest inhibitory percentage following induction of tau in N2A cells (see Fig. 3), into HEK293 cells without the expression of both tau and Kv2.1. At 48 h after cotransfection with tau, the mRNA levels of Kv2.1 were significantly declined by 49.7% compared with single Kv2.1 transfection, whereas no effect was observed for cotransfection with empty vector (mock) of tau (Fig. 6A). Accordingly, whole-cell currents of Kv2.1 in HEK293 cells cotransfected with tau were potentially reduced with respect to the single Kv2.1 transfection. At +60 mV, overexpression of tau declined Kv2.1 currents from 11.2 ± 0.9 nA to 5.7 ± 0.5 nA (Fig. 6D). The representative Kv2.1 current traces and current–voltage (I–V) curves were presented in Fig. 6B and 6C, respectively. We next measured the effects of interaction of tau and Kv2.1 on the growth of HEK293 using a method described above. As shown in Fig. 7, transfection with tau leaded to a weak and significant increase in proliferation of HEK293 cells in comparison to single Kv2.1 transfection, but no alteration was visible after mock transfection.

Bottom Line: Furthermore, the macroscopic currents through Kv channels were reduced by 36.5% at +60 mV in tau-transfected N2A cells.Following the cotransfection with tau in HEK293 cells, the mRNA levels and corresponding currents of Kv2.1 were significantly declined compared with single Kv2.1 transfection.Our data indicated that overexpression of tau declined the mRNA levels of Kv channels and related currents.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, College of Life Sciences, South-Central University for Nationalities, Wuhan, 430074, China.

ABSTRACT
Microtubule binding protein tau has a crucial function in promoting the assembly and stabilization of microtubule. Besides tuning the action potentials, voltage-gated K+ channels (Kv) are important for cell proliferation and appear to play a role in the development of cancer. However, little is known about the possible interaction of tau with Kv channels in various tissues. In the present study, tau plasmids were transiently transfected into mouse neuroblastoma N2A cells to explore the possible linkages between tau and Kv channels. This treatment led to a downregulation of mRNA levels of several Kv channels, including Kv2.1, Kv3.1, Kv4.1, Kv9.2, and KCNH4, but no significant alteration was observed for Kv5.1 and KCNQ4. Furthermore, the macroscopic currents through Kv channels were reduced by 36.5% at +60 mV in tau-transfected N2A cells. The proliferation rates of N2A cells were also improved by the induction of tau expression and the incubation of TEA (tetraethylammonium) for 48 h by 120.9% and 149.3%, respectively. Following the cotransfection with tau in HEK293 cells, the mRNA levels and corresponding currents of Kv2.1 were significantly declined compared with single Kv2.1 transfection. Our data indicated that overexpression of tau declined the mRNA levels of Kv channels and related currents. The effects of tau overexpression on Kv channels provided an alternative explanation for low sensitivity to anti-cancer chemicals in some specific cancer tissues.

Show MeSH
Related in: MedlinePlus