ABSTRACT
The expression of apoptosis regulators (proapoptotic protein Bad and anti-apoptotic protein Bcl-2) was analyzed and Bcl-2/Bad ratio in the follicular apparatus of the rat ovary was determined on day 3 after hyperthermia (rectal temperature 43.5°C). Hyperthermia in the catabolic phase leads to different degrees of activation of the molecular "switches" of apoptosis in cells of ovarian follicular epithelium. This was seen from increased intensity of immunohistochemical staining for Bad protein against the background of more pronounced expression of Bcl-2 protein. On day 3 after exposure to hyperthermia, Bcl-2/Bad ratio increased, which reflects antiapoptotic protection of cells and conditions for blockade of mitochondrial pathway of apoptosis in the follicular apparatus of the ovaries during the acute period after hyperthermia.
Subject(s)
Hyperthermia, Induced/methods , Ovarian Follicle/metabolism , Proto-Oncogene Proteins c-bcl-2/genetics , bcl-2-Associated X Protein/genetics , bcl-Associated Death Protein/genetics , Animals , Apoptosis/genetics , Diestrus/physiology , Female , Gene Expression Regulation , Mitochondria/metabolism , Mitochondria/pathology , Ovarian Follicle/cytology , Proto-Oncogene Proteins c-bcl-2/agonists , Proto-Oncogene Proteins c-bcl-2/metabolism , Rats , Rats, Wistar , Signal Transduction , bcl-2-Associated X Protein/metabolism , bcl-Associated Death Protein/agonists , bcl-Associated Death Protein/metabolismABSTRACT
Nerve growth factor is a neurotrophin that promotes cell growth, differentiation, survival and death through two different receptors: TrkA(NTR) and p75(NTR). Nerve growth factor serum concentrations increase during many inflammatory and autoimmune diseases, glomerulonephritis, chronic kidney disease, end-stage renal disease and, particularly, in renal transplant. Considering that nerve growth factor exerts beneficial effects in the treatment of major central and peripheral neurodegenerative diseases, skin and corneal ulcers, we asked whether nerve growth factor could also exert a role in Cyclosporine A-induced graft nephrotoxicity. Our hypothesis was raised from basic evidence indicating that Cyclosporine A-inhibition of calcineurin-NFAT pathway increases nerve growth factor expression levels. Therefore, we investigated the involvement of nerve growth factor and its receptors in the damage exerted by Cyclosporine A in tubular renal cells, HK-2. Our results showed that in HK-2 cells combined treatment with Cyclosporine A + nerve growth factor induced a significant reduction in cell vitality concomitant with a down-regulation of Cyclin D1 and up-regulation of p21 levels respect to cells treated with Cyclosporine A alone. Moreover functional experiments showed that the co-treatment significantly up-regulated human p21promoter activity by involvement of the Sp1 transcription factor, whose nuclear content was negatively regulated by activated NFATc1. In addition we observed that the combined exposure to Cyclosporine A + nerve growth factor promoted an up-regulation of p75 (NTR) and its target genes, p53 and BAD leading to the activation of intrinsic apoptosis. Finally, the chemical inhibition of p75(NTR) down-regulated the intrinsic apoptotic signal. We describe two new mechanisms by which nerve growth factor promotes growth arrest and apoptosis in tubular renal cells exposed to Cyclosporine A.
