Leukemia inhibitory factor activates cardiac L-Type Ca2+ channels via phosphorylation of serine 1829 in the rabbit Cav1.2 subunit.
We have previously reported that leukemia inhibitory factor (LIF) gradually increased cardiac L-type Ca2+ channel current (I(CaL)), which peaked at 15 minutes in both adult and neonatal rat cardiomyocytes, and this increase was blocked by the mitogen-activated protein kinase kinase inhibitor PD98059. This study investigated the molecular basis of LIF-induced augmentation of I(CaL) in rodent cardiomyocytes. LIF induced phosphorylation of a serine residue in the alpha(1c) subunit (Ca(v)1.2) of L-type Ca2+ channels in cultured rat cardiomyocytes, and this phosphorylation was inhibited by PD98059. When constructs encoding either a wild-type or a carboxyl-terminal-truncated rabbit Ca(v)1.2 subunit were transfected into HEK293 cells, LIF induced phosphorylation of the resultant wild-type protein but not the mutant protein. Cotransfection of constitutively active mitogen-activated protein kinase kinase also resulted in phosphorylation of the Ca(v)1.2 subunit in the absence of LIF stimulation. In in-gel kinase assays, extracellular signal-regulated kinase phosphorylated a glutathione S-transferase fusion protein of the carboxyl-terminal region of Ca(v)1.2 (residues 1700 through 1923), which contains the consensus sequence Pro-Leu-Ser-Pro. A point mutation within this consensus sequence, which results in a substitution of alanine for serine at residue 1829 (S1829A), was sufficient to abolish the LIF-induced phosphorylation. LIF increased I(CaL) in HEK cells transfected with wild-type Ca(v)1.2 but not with the mutated version. These results provide direct evidence that LIF phosphorylates the serine residue at position 1829 of the Ca(v)1.2 subunit via the actions of extracellular signal-regulated kinase and that this phosphorylation increases I(CaL) in cardiomyocytes.
Takahashi
Eiichi
E
Institute for Advanced Cardiac Therapeutics, Shinanomachi Research Park, Keio University School of Medicine, Tokyo, Japan.
Fukuda
Keiichi
K
Miyoshi
Shunichiro
S
Murata
Mitsushige
M
Kato
Takahiro
T
Ita
Makoto
M
Tanabe
Tsutomu
T
Ogawa
Satoshi
S
D019943:Amino Acid Substitution; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001011:Aorta; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D016384:Consensus Sequence; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology / Q000502:physiology*; D007668:Kidney; D053605:Leukemia Inhibitory Factor; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000032:analysis; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D017384:Sequence Deletion; D013045:Species Specificity; D014162:Transfection
D020746:Calcium Channels, L-Type; D005419:Flavonoids; D015850:Interleukin-6; C419385:L-type calcium channel alpha(1C); C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D011994:Recombinant Proteins; D000804:Angiotensin II; D010768:Phosphoserine; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium