Normal regulation of the supernumerary p53 animals [37].Retinal Astrocytes in “Super p53” MiceFigure 4. Mean GFAP+ area occupied by one astrocyte. In “super p53” retinas the mean GFAP+ area occupied by one astrocyte was significantly higher (*P,0.05; Student’s t-test) than in WT retinas. Columns represent mean 6 SDM of GFAP+ area. [WT: wild type p53 age-matched control; “super p53” : mice with two extra copies of p53]. doi:10.1371/journal.pone.0065446.gFigure 5. Astrocyte quantification in the entire retinal wholemount. Total number of astrocytes in “super p53” retinas were significantly more numerous than in WT retinas (**p,0.01; Student’s ttest). Columns represent the mean number 6 SDM of GFAP+ astrocytes [WT: wild type p53 age-matched control; “super p53” : mice with two extra copies of p53]. doi:10.1371/journal.pone.0065446.gThe “super p53” retinas showed more astrocytes, which also had more evident secondary processes to interact with neighbouring Title Loaded From File neuronal cells. This could be a factor to increase the neurosupporting role of astrocytes. In the human retina, astroglial processes join together by means of desmosomes [64,65] and gap junctions [65] to form a mesh that reinforces the capillary network and supports the neurons present in the glial network. These kinds of junctions between processes have also been reported in rats [66] as well in other animal species [67,68]. It is known that astrocytes play a decisive role in the metabolism of neurotransmitters and CO2. Moreover, ions, most sugars, amino acids, nucleotides, vitamins, hormones, and cyclic AMC pass through gap junctions. Apart from coordinating the Title Loaded From File metabolic activity of cell populations, gap junctions may also participate in electrical activities or amplify the consequences of signal transduction [69]. Recently another kind of cell-cell communication, i.e. tunneling-nanotubes (TNTs), has been described [70]. TNTs are thin membranous extensions that form channels between cells for intercellular communication and trafficking and are found in numerous cell types, including neurons and astrocytes [71,72]. The p53 gene is involved in TNT development. Cell insults activate p53 and induce M-Sec overexpression, which can trigger F-actin polymerization and contribute to TNT development from the initiating cell membrane [73,74]. The apparent increment of astrocyte secondary processes found in this study could mean an increase of their gap junctions and TNTs and, consequently, an improvement in cell-cell interactions and neural function. There is clear evidence for a role of p53 in the regulation of oxidative stress [75]. Although the apoptotic activity of p53 is mediated, at least partly, by rising ROS levels [76,77], a number of studies have shown a survival function for p53 in lowering intracellular ROS levels, involving the activity of p53-inducible genes such as TIGAR, sestrins [78,79], aldehyde dehydrogenase-4 (ALDH4) [80], and others [81]. Most notably, this antioxidantfunction of p53 is important in the absence of acute stress, preventing the accumulation of DNA damage on a day-to-day basis [24]. An increased p53 gene dosage confers the retina with noticeable resistance to OS, presumably by boosting antioxidant activity and opening anti-apoptotic pathways [82]. We have recently reported an increase in the 1676428 total antioxidant activity in the optic nerve and retina of “super p53” with respect to WT animals [83,84]. This higher antioxidant activity could indicate tha.Normal regulation of the supernumerary p53 animals [37].Retinal Astrocytes in “Super p53” MiceFigure 4. Mean GFAP+ area occupied by one astrocyte. In “super p53” retinas the mean GFAP+ area occupied by one astrocyte was significantly higher (*P,0.05; Student’s t-test) than in WT retinas. Columns represent mean 6 SDM of GFAP+ area. [WT: wild type p53 age-matched control; “super p53” : mice with two extra copies of p53]. doi:10.1371/journal.pone.0065446.gFigure 5. Astrocyte quantification in the entire retinal wholemount. Total number of astrocytes in “super p53” retinas were significantly more numerous than in WT retinas (**p,0.01; Student’s ttest). Columns represent the mean number 6 SDM of GFAP+ astrocytes [WT: wild type p53 age-matched control; “super p53” : mice with two extra copies of p53]. doi:10.1371/journal.pone.0065446.gThe “super p53” retinas showed more astrocytes, which also had more evident secondary processes to interact with neighbouring neuronal cells. This could be a factor to increase the neurosupporting role of astrocytes. In the human retina, astroglial processes join together by means of desmosomes [64,65] and gap junctions [65] to form a mesh that reinforces the capillary network and supports the neurons present in the glial network. These kinds of junctions between processes have also been reported in rats [66] as well in other animal species [67,68]. It is known that astrocytes play a decisive role in the metabolism of neurotransmitters and CO2. Moreover, ions, most sugars, amino acids, nucleotides, vitamins, hormones, and cyclic AMC pass through gap junctions. Apart from coordinating the metabolic activity of cell populations, gap junctions may also participate in electrical activities or amplify the consequences of signal transduction [69]. Recently another kind of cell-cell communication, i.e. tunneling-nanotubes (TNTs), has been described [70]. TNTs are thin membranous extensions that form channels between cells for intercellular communication and trafficking and are found in numerous cell types, including neurons and astrocytes [71,72]. The p53 gene is involved in TNT development. Cell insults activate p53 and induce M-Sec overexpression, which can trigger F-actin polymerization and contribute to TNT development from the initiating cell membrane [73,74]. The apparent increment of astrocyte secondary processes found in this study could mean an increase of their gap junctions and TNTs and, consequently, an improvement in cell-cell interactions and neural function. There is clear evidence for a role of p53 in the regulation of oxidative stress [75]. Although the apoptotic activity of p53 is mediated, at least partly, by rising ROS levels [76,77], a number of studies have shown a survival function for p53 in lowering intracellular ROS levels, involving the activity of p53-inducible genes such as TIGAR, sestrins [78,79], aldehyde dehydrogenase-4 (ALDH4) [80], and others [81]. Most notably, this antioxidantfunction of p53 is important in the absence of acute stress, preventing the accumulation of DNA damage on a day-to-day basis [24]. An increased p53 gene dosage confers the retina with noticeable resistance to OS, presumably by boosting antioxidant activity and opening anti-apoptotic pathways [82]. We have recently reported an increase in the 1676428 total antioxidant activity in the optic nerve and retina of “super p53” with respect to WT animals [83,84]. This higher antioxidant activity could indicate tha.