ICIVET-LITORAL   24728
INSTITUTO DE CIENCIAS VETERINARIAS DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Heat Stress reduces phosphorylation activity of the mTOR signaling cascade in bovine mammary cells
Autor/es:
KAUFMAN, J. D; KASSUBE, K. R; BARAVALLE C; RÍUS A
Lugar:
Orlando -Florida - EEUU
Reunión:
Jornada; American Dairy Science Association- American Society of Animal Science (ADSA-ASAS) 2015 Joint Annual Meeting (JAM); 2015
Institución organizadora:
American Dairy Science Association- American Society of Animal Science (ADSA-ASAS)
Resumen:
Heat stress reducesthe phosphorylation activity of mTOR signaling cascade in bovine mammary cellsJ. D. Kaufman*1, K. R.Kassube1, C. Baravalle2, and A. G. Ríus11Dept. of Animal Science, University of Tennessee, Knoxville, 2Facultadde Cs. Veterinarias, Universidad Nacionaldel Litoral Santa Fe, ArgentinaHeat stress (HS) altersmetabolism of amino acids and reduces synthesis of caseins in bovine mammaryglands.  The mammalian target ofrapamycin (mTOR) cascade regulates the initiation of the translation of proteinsynthesis and is mediated by protein factors that are activated or inhibitedupon phosphorylation.  It has beenreported that essential amino acids increased protein synthesis by activatingthe mTOR cascade.  Our objective was to determinethe effect of HS in phosphorylating mTOR protein factors in immortalized bovinemammary cells line (MAC-T).  It washypothesized that the phosphorylation activity of mTOR signaling factors wouldbe altered in MAC-T cells exposed to HS.  Cells were cultured in 15 mL of Dulbecco?sModified Eagle Medium with 10% fetal bovine serum at 37°C and 5% CO2.  Cells were subjected to one of two treatments:1) 37°C (control) and 2) 41.5°C (HS) for 12 hours.  The treatments were repeated 5 times in 5 differentdays.  Cell proteins were harvested and separatedby gel electrophoresis and transferred to a polyvinylidene fluoride membrane.  Western blotting was conducted to identifytotal and site-specific phosphorylated forms of protein kinase B (Akt; Thr308/Ser473),P70 S6 kinase (S6K1; Thr389), ribosomal protein S6 (rpS6; Ser235/236), andeukaryotic elongation factor 2 (eEF2; Thr56). Relative densities for phosphorylated and total forms of Akt, S6K1, rpS6and eEF2 were quantified and expressed as phosphorylated to total ratio.  Analysis of variance was conducted using a mixedmodel.  Compared with control, cells exposedto HS decreased phosphorylation to total ratio of Akt (0.41 vs. 0.29; P<0.001),S6K1 (1.65 vs. 0.97; P=0.042), and rpS6 (1.45 vs. 1.07; P<0.001).  However, preliminary results indicated that HSdid not affect the ratio of eEF2.  Theseresults indicate that HS impaired the translation of protein by altering the phosphorylationactivity of mTOR signaling factors in MAC-T cells.Key Words: heat stress, mammary cells, translation of protein