title: Direct antiapoptotic effects of growth hormone are mediated by PI3K/Akt pathway in the chicken bursa of Fabricius.
abstract: Growth hormone (GH) is expressed in several extra-pituitary tissues, including the primary and secondary lymphoid organs of the immune system. In birds, GH mRNA and protein expression show a specific developmental distribution pattern in the bursa of Fabricius (BF), particularly in epithelial and B cells. Changes in the bursal concentration and distribution of locally produced GH during ontogeny suggest it is involved in B cell differentiation and maturation, as well as in a functional survival role in this organ, which may be mediated by paracrine/autocrine mechanisms. Here, we analyzed the anti-apoptotic effect of GH in BF and the intracellular signaling pathways involved in this activity. Also, we studied if this effect was exerted directly by GH or mediated indirectly by IGF-I. Bursal cell cultures showed an important loss of their viability after 4h of incubation and a significant increase in apoptosis. However, treatment with 10nM GH or 40 nM IGF-I significantly increased B cell viability (16.7 ± 0.67% and 13.4 ± 1.12%, respectively) when compared with the untreated controls. In addition, the presence of apoptotic bodies (TUNEL) dramatically decreased (5.5-fold) after GH and IGF-I treatments, whereas co-incubation with anti-GH or anti-IGF-I, respectively, blocked their anti-apoptotic effect. Likewise, both GH and IGF-I significantly inhibited caspase-3 activity (by 40 ± 2.0%) in these cultures. However, the use of anti-IGF-I could not reverse the GH anti-apoptotic effects, thus indicating that these were exerted directly. The addition of 100 nM wortmannin (a PI3K/Akt inhibitor) blocked the GH protective effects. Also, GH stimulated (3-fold) the phosphorylation of Akt in bursal cells, and adding wortmannin or an anti-GH antibody inhibited this effect. Furthermore, GH was capable to stimulate (7-fold) the expression of Bcl-2. Taken together, these results indicate that the direct anti-apoptotic activity of GH observed in the chicken bursal B cell cultures might be mediated through the PI3K/Akt pathway.
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Luna-Acosta
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico; Departamento de Farmacia, Universidad de Guanajuato, Guanajuato 36050, Mexico.
authors.forename: Clara
authors.initials: C
authors.lastname: Alba-Betancourt
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors.forename: Carlos G
authors.initials: CG
authors.lastname: Martínez-Moreno
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors.forename: Candy
authors.initials: C
authors.lastname: Ramírez
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors.forename: Martha
authors.initials: M
authors.lastname: Carranza
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
authors.forename: Maricela
authors.initials: M
authors.lastname: Luna
authors.affiliation: Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico. Electronic address: aramburo@unam.mx.
authors.forename: Carlos
authors.initials: C
authors.lastname: Arámburo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D002060:Bursa of Fabricius / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D002645:Chickens / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D013006:Growth Hormone / Q000494:pharmacology*; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D019869:Phosphatidylinositol 3-Kinases; D053148:Caspase 3
keywords: Apoptosis; Bursa of Fabricius; Growth hormone; IGF-I; PI3K/Akt pathway; Wortmannin