ABSTRACT
A previous study in the bovine mammary epithelial cell line BME-UV1 demonstrated that suppression of the phosphatidylinositol-4,5-biphosphate 3 kinase (PI3K)/AKT (somatotropic) signaling pathway was required for transforming growth factor ß1 (TGFß1)-induced programmed cell death (PCD). To investigate whether this is a universal mechanism for TGFß1 to induce PCD in bovine mammary epithelium, we compared TGFß1 modulation of PI3K/AKT and its role in PCD in 2 bovine mammary epithelial cell lines: MAC-T and BME-UV1. In MAC-T cells, TGFß1 promoted cell survival, and this paralleled a reduction in PI3K/AKT activity, rather than an increase. In BME-UV1 cells, TGFß1 induced PCD, and this was accompanied by a time-dependent effect on PI3K/AKT activity, including an initial significant increase in the phosphorylation of AKT at 3 h, followed by a reduction between 12 and 24 h, and then an increase at 48 h. Inhibition of AKT activity enhanced TGFß1-induced PCD in BME-UV1 cells but had no effect on MAC-T cells, suggesting that TGFß1 mediates PCD in BME-UV1 cells through suppression of AKT activity. Inhibition of TGFß receptor type I (TßRI) kinase activity completely abrogated TGFß1-induced PCD in BME-UV1 cells but had no effect on TGFß1-induced suppression of PCD in MAC-T cells, demonstrating that TGFß1-induced PCD in BME-UV1 cells is dependent on TßRI/SMAD signaling. These and previous observations suggest that the different effects of TGFß1 on PCD in these cell lines might involve noncanonical signaling pathways other than PI3K/AKT, and may reflect their different lineages. Future studies should address this finding, taking into consideration the effect that different culture conditions might have on cell phenotype.
Subject(s)
Apoptosis , Cattle/physiology , Signal Transduction , Transforming Growth Factor beta1/metabolism , Animals , Cell Line , Cell Survival , Epithelial Cells/metabolism , Female , Mammary Glands, Animal/metabolism , Phosphatidylinositol 3-Kinases/metabolism , PhosphorylationABSTRACT
A reference staging series of 18 morphological stages of laboratory reared lake whitefish Coregonus clupeaformis is provided. The developmental processes of blastulation, gastrulation, neurulation as well as development of the eye, circulatory system, chromatophores and mouth are included and accompanied by detailed descriptions and live imaging. Quantitative measurements of embryo size and mass were taken at each developmental stage. Eggs were 3·19 ± 0·16 mm (mean ± s.d.) in diameter at fertilization and embryos reached a total length (LT ) of 14·25 ± 0·41 mm at hatch. Separated yolk and embryo dry mass were 0·25 ± 0·08 mg and 1·39 ± 0·17 mg, respectively, at hatch. The effects of two common preservatives (formalin and ethanol) were examined throughout development and post hatch. Embryo LT significantly decreased following fixation at all points in development. A correction factor to estimate live LT from corresponding fixed LT was determined as live LT = (fixed LT )(1·025) . Eye diameter and yolk area measurements significantly increased in fixed compared with live embryos up to 85-90% development for both measurements. The described developmental stages can be generalized to teleost species, and is particularly relevant for the study of coregonid development due to additionally shared developmental characteristics. The results of this study and staging series are therefore applicable across various research streams encompassing numerous species that require accurate staging of embryos and descriptions of morphological development.