Protein kinase-mediated regulation of calcineurin through the phosphorylation of modulatory calcineurin-interacting protein 1.
Calcineurin is a serine/threonine protein phosphatase that plays a critical role in many physiologic processes such as T-cell activation, skeletal myocyte differentiation, and cardiac hypertrophy. We previously showed that active MEKK3 is capable of stimulating calcineurin/nuclear factor of activated T-cells (NFAT) signaling in cardiac myocytes through phosphorylation of modulatory calcineurin-interacting protein 1 (MCIP1). However, the protein kinases that function downstream of MEKK3 to mediate MCIP1 phosphorylation and the mechanism of MCIP1-mediated calcineurin regulation have not been defined. Here, we show that MEK5 and big MAP kinase 1 (BMK1) function downstream of MEKK3 in a signaling cascade that induces calcineurin activity through phosphorylation of MCIP1. Genetic studies showed that BMK1-deficient mouse lung fibroblasts failed to mediate MCIP1 phosphorylation and activate calcineurin/NFAT in response to angiotensin II, a potent NFAT activator. Conversely, restoring BMK1 to the deficient cells restored angiotensin II-mediated calcineurin/NFAT activation. Thus, using BMK1-deficient mouse lung fibroblast cells, we provided the genetic evidence that BMK1 is required for angiotensin II-mediated calcineurin/NFAT activation through MICP1 phosphorylation. Finally, we discovered that phosphorylated MCIP1 dissociates from calcineurin and binds with 14-3-3, thereby relieving its inhibitory effect on calcineurin activity. In summary, our findings reveal a previously unrecognized essential regulatory role of mitogen-activated protein kinase signaling in calcineurin activation through the reversible phosphorylation of a calcineurin-interacting protein, MCIP1.
Abbasi
Shahrzad
S
Department of Biochemistry and Molecular Biology, The University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Lee
Jiing-Dwan
JD
Su
Bing
B
Chen
Xiang
X
Alcon
Joseph L
JL
Yang
JianHua
J
Kellems
Rodney E
RE
Xia
Yang
Y
D048948:14-3-3 Proteins / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000469:Alkaline Phosphatase / Q000378:metabolism; D000804:Angiotensin II / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D019703:Calcineurin / Q000737:chemistry* / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D004268:DNA-Binding Proteins; D017930:Genes, Reporter; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism; D048671:MAP Kinase Kinase 5 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D051379:Mice; D008822:Mice, Transgenic; D048054:Mitogen-Activated Protein Kinase 7 / Q000378:metabolism; D009124:Muscle Proteins / Q000737:chemistry* / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D014162:Transfection
D048948:14-3-3 Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009124:Muscle Proteins; D050778:NFATC Transcription Factors; C108612:RCAN1 protein, human; D034741:RNA, Small Interfering; D000804:Angiotensin II; D012694:Serine; D048054:Mitogen-Activated Protein Kinase 7; D048671:MAP Kinase Kinase 5; C482565:Map2k5 protein, rat; D000469:Alkaline Phosphatase; D019703:Calcineurin