PI3K pathway is involved in ERK signaling cascade activation by histamine H2R agonist in HEK293T cells.
Histamine, through histamine H2 receptor (H2R), modulates different biological processes, involving the modulation of PI3K/AKT/mTOR and RAS/RAF/MEK/ERK pathways. Many evidences have demonstrated the existence and importance of the crossregulation between these two signaling pathways. The aim of the present work was to determine the molecular mechanisms leading to PI3K and ERK pathways modulation induced by the H2R agonist amthamine and to evaluate the possible interplay between them.



Phosphorylation levels of ERK and Akt were examined by Western blot in HEK293T cells expressing the human H2R, in the presence of H2R agonist and dominant negative mutants or pharmacological inhibitors of different proteins/pathways. Transcriptional activity assays were assessed to determine SRE activity. Amthamine-mediated cellular proliferation was investigated in MA-10A cells in the presence of PI3K inhibitor.



H2R agonist inhibits PI3K/Akt/mTOR and stimulates Ras/MEK/ERK pathways. Moreover, PI3K/Akt/mTOR signaling inhibition is necessary to achieve H2R mediated ERK activation. In the presence of a constitutive active mutant of Akt, amthamine is not able to mediate ERK activation. This crosstalk affects classical ERK downstream targets such as Elk1 phosphorylation and the transcriptional activity of the SRE, classically associated to proliferation. We further demonstrate that amthamine-induced proliferation in Leydig MA-10 tumor cells, is enhanced by LY294002, a PI3K inhibitor.



These results describe a crosstalk between PI3K/AKT/mTOR and Ras/MEK/ERK pathways induced by H2R stimulation with implications in cell proliferation.



This work indicates that the modulation of PI3K/AKT/mTOR pathway by H2R in turn regulates Ras/MEK/ERK activation conditioning the proliferative capacity of the cells.
IBYME, Instituto de Biología y Medicina Experimental, Laboratorio de Patología y Farmacología Molecular, CONICET, Ciudad Autónoma de Buenos Aires, Argentina.
Natalia
N
Alonso
IBYME, Instituto de Biología y Medicina Experimental, Laboratorio de Patología y Farmacología Molecular, CONICET, Ciudad Autónoma de Buenos Aires, Argentina.
Antonela
A
Diaz Nebreda
Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina; ININFA, Instituto de Investigaciones Farmacológicas, UBA-CONICET, Facultad de Farmacia y Bioquímica, Junin 956, Ciudad Autónoma de Buenos Aires, Argentina.
Federico
F
Monczor
Oral and Pharyngeal Cancer Branch, National Institute of Dental Research, NIH, Bethesda, MD, USA.
J Silvio
JS
Gutkind
Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina; ININFA, Instituto de Investigaciones Farmacológicas, UBA-CONICET, Facultad de Farmacia y Bioquímica, Junin 956, Ciudad Autónoma de Buenos Aires, Argentina.
Carlos
C
Davio
Cátedra de Química Medicinal, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina; ININFA, Instituto de Investigaciones Farmacológicas, UBA-CONICET, Facultad de Farmacia y Bioquímica, Junin 956, Ciudad Autónoma de Buenos Aires, Argentina.
Natalia
N
Fernandez
IBYME, Instituto de Biología y Medicina Experimental, Laboratorio de Patología y Farmacología Molecular, CONICET, Ciudad Autónoma de Buenos Aires, Argentina. Electronic address: carinashayo@hotmail.com.
Carina
C
Shayo
D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D057809:HEK293 Cells; D006632:Histamine / Q000378:metabolism*; D017442:Histamine Agonists / Q000494:pharmacology*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology
D048049:Extracellular Signal-Regulated MAP Kinases; D006632:Histamine; D017442:Histamine Agonists; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D013844:Thiazoles; C076207:amthamine; C546842:MTOR protein, human
Cell proliferation; Cell signaling; ERK; Histamine H2 receptor; PI3K