Localization of acetylcholine-related molecules in the retina: Implication of the communication from photoreceptor to retinal pigment epithelium

Hidetaka Matsumoto, Koji Shibasaki, Motokazu Uchigashima, Amane Koizumi, Masashi Kurachi, Yasuhiro Moriwaki, Hidemi Misawa, Koichiro Kawashima, Masahiko Watanabe, Shoji Kishi, Yasuki Ishizaki

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Abstract

It has been long speculated that specific signals are transmitted from photoreceptors to the retinal pigment epithelium (RPE). However, such signals have not been identified. In this study, we examined the retinal expression and localization of acetylcholine-related molecules as putative candidates for these signals. Previous reports revealed that α7 nicotinic acetylcholine receptors (nAChRs) are present in the microvilli of RPE cells that envelope the tips of photoreceptor outer segments (OS). Secreted mammalian leukocyte antigen 6/urokinase-type plasminogen activator receptor-related protein-1 (SLURP-1) is a positive allosteric modulator of the α7 nAChR. Therefore, we first focused on the expression of SLURP-1. SLURP-1 mRNA was expressed in the outer nuclear layer, which is comprised of photoreceptor cell bodies. SLURP-1 immunoreactivity co-localized with rhodopsin and S-opsin in photoreceptor OS, while choline acetyltransferase (ChAT) and high affinity choline transporter (CHT-1) were also expressed in photoreceptor OS. Immunoelectron microscopy identified that the majority of SLURP-1 was localized to the plasma membranes of photoreceptor OS. These results provide evidence that SLURP-1 is synthesized in photoreceptor cell bodies and transported to photoreceptor OS, where SLURP-1 may also be secreted. Our findings suggest that photoreceptor OS communicate via neurotransmitters such as ACh and SLURP-1, while RPE cells might receive these signals through α7 nAChRs in their microvilli.

Original languageEnglish
Article numbere42841
JournalPLoS One
Volume7
Issue number8
DOIs
Publication statusPublished - 2012 Aug 3

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ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Matsumoto, H., Shibasaki, K., Uchigashima, M., Koizumi, A., Kurachi, M., Moriwaki, Y., Misawa, H., Kawashima, K., Watanabe, M., Kishi, S., & Ishizaki, Y. (2012). Localization of acetylcholine-related molecules in the retina: Implication of the communication from photoreceptor to retinal pigment epithelium. PLoS One, 7(8), [e42841]. https://doi.org/10.1371/journal.pone.0042841