Limits...
Modulation of Kv channel expression and function by TCR and costimulatory signals during peripheral CD4(+) lymphocyte differentiation.

Liu QH, Fleischmann BK, Hondowicz B, Maier CC, Turka LA, Yui K, Kotlikoff MI, Wells AD, Freedman BD - J. Exp. Med. (2002)

Bottom Line: However, how Kv channels cooperate with other signaling pathways involved in T cell activation and differentiation is unknown.Effector CD4(+) cells generated by optimal TCR and costimulation exhibit only Kv1.3 current, but at approximately sixfold higher levels than naive cells.To determine if Kv channels contribute to the distinct functions of naive, effector, and anergized T cells, we tested their role in immunoregulatory cytokine production.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA.

ABSTRACT
Ionic signaling pathways, including voltage-dependent potassium (Kv) channels, are instrumental in antigen-mediated responses of peripheral T cells. However, how Kv channels cooperate with other signaling pathways involved in T cell activation and differentiation is unknown. We report that multiple Kv channels are expressed by naive CD4(+) lymphocytes, and that the current amplitude and kinetics are modulated by antigen receptor-mediated stimulation and costimulatory signals. Currents expressed in naive CD4(+) lymphocytes are consistent with Kv1.1, Kv1.2, Kv1.3, and Kv1.6. Effector CD4(+) cells generated by optimal TCR and costimulation exhibit only Kv1.3 current, but at approximately sixfold higher levels than naive cells. CD4(+) lymphocytes anergized through partial stimulation exhibit similar Kv1.1, Kv1.2, and/or Kv1.6 currents, but approximately threefold more Kv1.3 current than naive cells. To determine if Kv channels contribute to the distinct functions of naive, effector, and anergized T cells, we tested their role in immunoregulatory cytokine production. Each Kv channel is required for maximal IL-2 production by naive CD4(+) lymphocytes, whereas none appears to play a role in IL-2, IL-4, or IFN-gamma production by effector cells. Interestingly, Kv channels in anergized lymphocytes actively suppress IL-4 production, and these functions are consistent with a role in regulating the membrane potential and calcium signaling.

Show MeSH
Kv current density in naive, effector, and anergic lymphocytes. Whole cell potassium currents were normalized to the cell surface area (density) for multiple separate experiments (at least 10 measurements for each condition) to determine whether the increase in Kv current is proportional to the increased cell surface area in stimulated lymphocytes. Effector and anergic lymphocytes were produced in vivo by inoculation of Vβ8.1 TCR Tg mice with Mls-disparate splenocytes and T cells were isolated as described in Materials and Methods. The current density of proliferating (day 3, 3G11−) lymphocytes (97 ± 15 pA/pF) was ∼2.5-fold greater than the aggregate current density of resting cells, that represents a 6–7-fold increase in CTX-sensitive current density. The CTX-resistant current density for resting and day 14 lymphocytes is similar, whereas the CTX-sensitive current density is about twofold greater in day 14 than naive cells. The current in proliferating cells was significantly larger than any other subpopulation. *, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2194034&req=5

fig3: Kv current density in naive, effector, and anergic lymphocytes. Whole cell potassium currents were normalized to the cell surface area (density) for multiple separate experiments (at least 10 measurements for each condition) to determine whether the increase in Kv current is proportional to the increased cell surface area in stimulated lymphocytes. Effector and anergic lymphocytes were produced in vivo by inoculation of Vβ8.1 TCR Tg mice with Mls-disparate splenocytes and T cells were isolated as described in Materials and Methods. The current density of proliferating (day 3, 3G11−) lymphocytes (97 ± 15 pA/pF) was ∼2.5-fold greater than the aggregate current density of resting cells, that represents a 6–7-fold increase in CTX-sensitive current density. The CTX-resistant current density for resting and day 14 lymphocytes is similar, whereas the CTX-sensitive current density is about twofold greater in day 14 than naive cells. The current in proliferating cells was significantly larger than any other subpopulation. *, P < 0.05.

Mentions: Capacitance (surface area) normalized toxin-defined current values (Kv current density) were found to be significantly (P < 0.05) higher in productively primed effector and anergic lymphocytes than in naive cells (∼2.3 times and 1.4-fold respectively; Fig. 3) . The observed differences in total current primarily reflects an increase in CTX-sensitive current density (28.9 ± 2.7 pA/pF, 112.4 ± 18.5 pA/pF, and 42.7 ± 10.6 pA/pF for naive, effector, and anergic cells, respectively). By contrast, the CTX-resistant DTX-I–sensitive current density is essentially identical for resting and anergic CD4+ lymphocytes (20.9 ± 4.3 pA/pF and 21.7 ± 3.9 pA/pF, respectively). Importantly, the increase in Kv current density is about fourfold greater (455 ± 197 pA/pF, n = 4) for CD4+ Vβ8.1 TCR transgenic lymphocytes that are inoculated into CBA/J mice compared with those stimulated in Vβ8.1 TCR transgenic mice by injection of superantigen. Consequently, the larger Kv currents in productively primed and anergic lymphocytes are not simply a function of increased cell size or membrane surface area.


Modulation of Kv channel expression and function by TCR and costimulatory signals during peripheral CD4(+) lymphocyte differentiation.

Liu QH, Fleischmann BK, Hondowicz B, Maier CC, Turka LA, Yui K, Kotlikoff MI, Wells AD, Freedman BD - J. Exp. Med. (2002)

Kv current density in naive, effector, and anergic lymphocytes. Whole cell potassium currents were normalized to the cell surface area (density) for multiple separate experiments (at least 10 measurements for each condition) to determine whether the increase in Kv current is proportional to the increased cell surface area in stimulated lymphocytes. Effector and anergic lymphocytes were produced in vivo by inoculation of Vβ8.1 TCR Tg mice with Mls-disparate splenocytes and T cells were isolated as described in Materials and Methods. The current density of proliferating (day 3, 3G11−) lymphocytes (97 ± 15 pA/pF) was ∼2.5-fold greater than the aggregate current density of resting cells, that represents a 6–7-fold increase in CTX-sensitive current density. The CTX-resistant current density for resting and day 14 lymphocytes is similar, whereas the CTX-sensitive current density is about twofold greater in day 14 than naive cells. The current in proliferating cells was significantly larger than any other subpopulation. *, P < 0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2194034&req=5

fig3: Kv current density in naive, effector, and anergic lymphocytes. Whole cell potassium currents were normalized to the cell surface area (density) for multiple separate experiments (at least 10 measurements for each condition) to determine whether the increase in Kv current is proportional to the increased cell surface area in stimulated lymphocytes. Effector and anergic lymphocytes were produced in vivo by inoculation of Vβ8.1 TCR Tg mice with Mls-disparate splenocytes and T cells were isolated as described in Materials and Methods. The current density of proliferating (day 3, 3G11−) lymphocytes (97 ± 15 pA/pF) was ∼2.5-fold greater than the aggregate current density of resting cells, that represents a 6–7-fold increase in CTX-sensitive current density. The CTX-resistant current density for resting and day 14 lymphocytes is similar, whereas the CTX-sensitive current density is about twofold greater in day 14 than naive cells. The current in proliferating cells was significantly larger than any other subpopulation. *, P < 0.05.
Mentions: Capacitance (surface area) normalized toxin-defined current values (Kv current density) were found to be significantly (P < 0.05) higher in productively primed effector and anergic lymphocytes than in naive cells (∼2.3 times and 1.4-fold respectively; Fig. 3) . The observed differences in total current primarily reflects an increase in CTX-sensitive current density (28.9 ± 2.7 pA/pF, 112.4 ± 18.5 pA/pF, and 42.7 ± 10.6 pA/pF for naive, effector, and anergic cells, respectively). By contrast, the CTX-resistant DTX-I–sensitive current density is essentially identical for resting and anergic CD4+ lymphocytes (20.9 ± 4.3 pA/pF and 21.7 ± 3.9 pA/pF, respectively). Importantly, the increase in Kv current density is about fourfold greater (455 ± 197 pA/pF, n = 4) for CD4+ Vβ8.1 TCR transgenic lymphocytes that are inoculated into CBA/J mice compared with those stimulated in Vβ8.1 TCR transgenic mice by injection of superantigen. Consequently, the larger Kv currents in productively primed and anergic lymphocytes are not simply a function of increased cell size or membrane surface area.

Bottom Line: However, how Kv channels cooperate with other signaling pathways involved in T cell activation and differentiation is unknown.Effector CD4(+) cells generated by optimal TCR and costimulation exhibit only Kv1.3 current, but at approximately sixfold higher levels than naive cells.To determine if Kv channels contribute to the distinct functions of naive, effector, and anergized T cells, we tested their role in immunoregulatory cytokine production.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104, USA.

ABSTRACT
Ionic signaling pathways, including voltage-dependent potassium (Kv) channels, are instrumental in antigen-mediated responses of peripheral T cells. However, how Kv channels cooperate with other signaling pathways involved in T cell activation and differentiation is unknown. We report that multiple Kv channels are expressed by naive CD4(+) lymphocytes, and that the current amplitude and kinetics are modulated by antigen receptor-mediated stimulation and costimulatory signals. Currents expressed in naive CD4(+) lymphocytes are consistent with Kv1.1, Kv1.2, Kv1.3, and Kv1.6. Effector CD4(+) cells generated by optimal TCR and costimulation exhibit only Kv1.3 current, but at approximately sixfold higher levels than naive cells. CD4(+) lymphocytes anergized through partial stimulation exhibit similar Kv1.1, Kv1.2, and/or Kv1.6 currents, but approximately threefold more Kv1.3 current than naive cells. To determine if Kv channels contribute to the distinct functions of naive, effector, and anergized T cells, we tested their role in immunoregulatory cytokine production. Each Kv channel is required for maximal IL-2 production by naive CD4(+) lymphocytes, whereas none appears to play a role in IL-2, IL-4, or IFN-gamma production by effector cells. Interestingly, Kv channels in anergized lymphocytes actively suppress IL-4 production, and these functions are consistent with a role in regulating the membrane potential and calcium signaling.

Show MeSH