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  • Interleukin-4 activates div...
    da Silva, Gustavo Mataruna; de Figueiredo, Camila Saggioro; da Rocha Oliveira, Amanda Cândida; Raony, Ícaro; de Araújo Miranda, Raphael Amorim; de Mello Silva, Eliezer; Guilarducci, Carla Valéria Vieira; dos Santos, Aline Araujo; Giestal-de-Araujo, Elizabeth

    Molecular and cellular neuroscience, December 2022, 2022-12-00, 20221201, Letnik: 123
    Journal Article

    In the developing retina, precise coordination of cell proliferation, differentiation, and survival is essential for proper retinal maturation and function. We have previously reported evidence that interleukin-4 (IL-4) plays critical roles in neuronal differentiation and survival during retinal development. However, little is known about the role of IL-4 on retinal cell proliferation. In the current study, we investigated if IL-4 regulates cell proliferation induced by epidermal growth factor (EGF) and by fibroblast growth factor 2 (FGF2) in primary retinal cell cultures obtained from newborn rats. First, we show that EGF and FGF2 act as mitogens for glial cells, increasing proliferation of these cells in the retina. EGF- and FGF2-induced mitogenesis requires activation of distinct cell-intrinsic signals. In retinal cells exposed to FGF2, IL-4 downregulates p53 levels (a protein whose activation induces cell-cycle arrest) and increases mitogenic responsiveness to FGF2 through activation of protein kinase A (PKA) pathway. Conversely, in retinal cells exposed to EGF, IL-4 downregulates cyclin D1 levels (a protein required for cell-cycle progression), upregulates p53 levels, and decreases mitogenic responsiveness to EGF. The inhibitory effect induced by IL-4 on retinal cells exposed to EGF requires activation of Janus kinase 3 (JAK3), but not activation of PKA. Based on previous and current findings, we propose that IL-4 serves as a node of signal divergence, modulating multiple cell-intrinsic signals (e.g., cyclin D1, p53, JAK3, and PKA) and mitogenic responsiveness to cell-extrinsic signals (e.g., FGF2 and EGF) to control cell proliferation, differentiation, and survival during retinal development. •EGF and FGF2 increase cell proliferation, acting as mitogens for retinal glial cells.•EGF- and FGF2-induced retinal cell proliferation requires distinct cell-intrinsic signals.•IL-4 ensures homeostatic proliferation by controlling mitogenic responsiveness to EGF and FGF2.•IL-4 increases mitogenic responsiveness to FGF2 through PKA activation and p53 downregulation.•IL-4 decreases mitogenic responsiveness to EGF through JAK3 activation, p53 upregulation, and cyclin D1 downregulation.