Differential enhancement of neural and photoreceptor cell differentiation of cultured pineal cells by FGF‐1, IGF‐1, and EGF

Abstract

There are several common features between the pineal organ and the lateral eye in their developmental and evolutionary aspects. The avian pineal is a photoendocrine organ that originates from the diencephalon roof and represents a transitional type between the photosensory organ of lower vertebrates and the endocrine gland of mammals. Previous cell culture studies have shown that embryonic avian pineal cells retain a wide spectrum of differentiative capacities, although little is known about the mechanisms involved in their fate determination. In the present study, we investigated the effects of various cell growth factors on the differentiation of photoreceptor and neural cell types using pineal cell cultures from quail embryos. The results show that IGF-1 promotes differentiation of rhodopsin-immunoreactive cells, but had no effect on neural cell differentiation. Simultaneous administration of EGF and IGF-1 further enhanced differentiation of rhodopsin-immunoreactive cells, although the mechanism of the synergistic effect is unknown. FGF-1 did not stimulate proliferation of neural progenitor cells, but intensively promoted and maintained expression of a neural cell phenotype. FGF-1 appeared to lead to the conversion from an epithelial (endocrinal) to a neuronal type. It also enhanced phenotypic expression of retinal ganglion cell markers but rather suppressed expression of an amacrine cell marker. These results indicate that growth factors are important regulatory cues for pineal cell differentiation and suggest that they play roles in determining the fate of the pineal organ and the eye. It can be speculated that the differences in environmental cues between the retina and pineal may result in the transition of the pineal primordium from a potentially ocular (retinal) organ to a photoendocrine organ.

RETRACTED: Comparison of the effects of EGF, FGF-b, and NGF on the proliferation, migration, and reprogramming of primary rat Müller cells

“…Lawrence et al ( Lawrence et al, 2007 ) and Das et al ( Das et al, 2006 ) attempted to cultivate mammalian Müller cells using FGF2, retinoic acid (RA), and brain-derived neurotrophic factor (BDNF), which seemed to promote the regeneration of ganglia, bipolar cells, and photoreceptors. Some studies ( Araki et al, 2007 ) suggest that EGF can enhance the possibility of pineal cells differentiating into photoreceptor cells. However, the mechanisms that control the differentiation of mammalian Müller cell-derived progenitors in adult retina are still poorly understood.…”

MicroRNAs in the Pineal Gland

“…The role of Igf1r in the pineal gland has not been fully established; however, it has been suggested that cross-talk may exist between insulin and noradrenergic signaling (52). Also, Igf1 may influence differentiation of pineal cells (53). miRNAs may influence these process through effects on Igf1.…”