PT-1 selectively activates AMPK-γ1 complexes in mouse skeletal muscle, but activates all three γ subunit complexes in cultured human cells by inhibiting the respiratory chain
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PT-1 selectively activates AMPK-γ1 complexes in mouse skeletal muscle, but activates all three γ subunit complexes in cultured human cells by inhibiting the respiratory chain. / Jensen, Thomas Elbenhardt; Ross, Fiona A; Kleinert, Maximilian; Sylow, Lykke; Knudsen, Jonas Roland; Gowans, Graeme J; Hardie, D Grahame; Richter, Erik A.
I: Biochemical Journal, Bind 467, Nr. 3, 2015, s. 461-472.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › fagfællebedømt
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T1 - PT-1 selectively activates AMPK-γ1 complexes in mouse skeletal muscle, but activates all three γ subunit complexes in cultured human cells by inhibiting the respiratory chain
AU - Jensen, Thomas Elbenhardt
AU - Ross, Fiona A
AU - Kleinert, Maximilian
AU - Sylow, Lykke
AU - Knudsen, Jonas Roland
AU - Gowans, Graeme J
AU - Hardie, D Grahame
AU - Richter, Erik A.
N1 - CURIS 2015 NEXS 138
PY - 2015
Y1 - 2015
N2 - AMP-activated protein kinase (AMPK) occurs as heterotrimeric complexes in which a catalytic subunit (α1/α2) is bound to one of two b subunits (β1/β2) and one of three γ subunits (γ1/γ2/γ3). The ability to selectively activate specific isoforms would be a useful research tool, and a promising strategy to combat diseases such as cancer and type 2 diabetes. We report that the AMPK activator PT-1 selectively increased the activity of γ1- but not γ3-containing complexes in incubated mouse muscle. PT-1 increased the AMPK-dependent phosphorylation of the autophagy-regulating kinase ULK1 on Ser555, but not proposed AMPK-γ3 substrates such as Ser231 on TBC1D1 or Ser212 on ACC2, nor did it stimulate glucose transport. Surprisingly, however, in HEK-293 cells expressing human γ1, γ2 or γ3, PT-1 activated all three complexes equally. We were unable to reproduce previous findings suggesting that PT-1 activates AMPK by direct binding between the kinase and auto-inhibitory domains of the α subunit. We show instead that PT-1 activates AMPK indirectly by inhibiting the respiratory chain and increasing cellular AMP:ATP and/or ADP:ATP ratios. Consistent with this mechanism, PT-1 failed to activate AMPK in HEK-293 cells expressing an AMP-insensitive R299G mutant of AMPK-γ1. We propose that the failure of PT-1 to activate γ3-containing complexes in muscle is not an intrinsic feature of such complexes, but is because PT-1 does not increase cellular AMP:ATP ratios in the specific subcellular compartment(s) in which γ3 complexes are located.
AB - AMP-activated protein kinase (AMPK) occurs as heterotrimeric complexes in which a catalytic subunit (α1/α2) is bound to one of two b subunits (β1/β2) and one of three γ subunits (γ1/γ2/γ3). The ability to selectively activate specific isoforms would be a useful research tool, and a promising strategy to combat diseases such as cancer and type 2 diabetes. We report that the AMPK activator PT-1 selectively increased the activity of γ1- but not γ3-containing complexes in incubated mouse muscle. PT-1 increased the AMPK-dependent phosphorylation of the autophagy-regulating kinase ULK1 on Ser555, but not proposed AMPK-γ3 substrates such as Ser231 on TBC1D1 or Ser212 on ACC2, nor did it stimulate glucose transport. Surprisingly, however, in HEK-293 cells expressing human γ1, γ2 or γ3, PT-1 activated all three complexes equally. We were unable to reproduce previous findings suggesting that PT-1 activates AMPK by direct binding between the kinase and auto-inhibitory domains of the α subunit. We show instead that PT-1 activates AMPK indirectly by inhibiting the respiratory chain and increasing cellular AMP:ATP and/or ADP:ATP ratios. Consistent with this mechanism, PT-1 failed to activate AMPK in HEK-293 cells expressing an AMP-insensitive R299G mutant of AMPK-γ1. We propose that the failure of PT-1 to activate γ3-containing complexes in muscle is not an intrinsic feature of such complexes, but is because PT-1 does not increase cellular AMP:ATP ratios in the specific subcellular compartment(s) in which γ3 complexes are located.
U2 - 10.1042/BJ20141142
DO - 10.1042/BJ20141142
M3 - Journal article
C2 - 25695398
VL - 467
SP - 461
EP - 472
JO - Biochemical Journal
JF - Biochemical Journal
SN - 0264-6021
IS - 3
ER -
ID: 131739473