Distribution of Smoothened at hippocampal mossy fiber synapses

Abstract

The seven-transmembrane receptor Smoothened is essential for hedgehog signal transduction. In adulthood, the highest density of Smoothened mRNA is found in the granule cell layer of the dentate gyrus. There, Smoothened expression is regulated by the synaptic activity involving the glutamatergic transmission. The precise localization of Smoothened proteins, however, has not yet been reported. Here, we describe Smoothened protein distribution in the hippocampal mossy fibers using specific Smoothened antibodies. We provide evidences for their presynaptic localization, and using electron microscopy, show that Smoothened is located in close association with synaptic vesicles and rarely with the plasma membrane. These findings demonstrate that Smoothened is localized presynaptically and suggest that Smoothened signal transduction may be implicated in the complex aspects of mossy fiber function.

A role for primary cilia in glutamatergic synaptic integration of adult-born neurons

“…Since there is no significant increase before cilia formation, Kif3a or Ift88 likely modulates this pathway through its ciliary function rather than both ciliary and non-ciliary functions, as previously reported 19 . Furthermore, the lack of Smoothened expression in the granule cell and molecular layers in the dentate gyrus makes it unlikely that hedgehog signaling is involved in dendritic refinement during this period 43–44 . With regard to the second question, the data (Fig.…”

Subcellular localization of patched and smoothened, the receptors for sonic hedgehog signaling, in the hippocampal neuron

“…One previous study reported Smo’s “exclusively” presynaptic expression in the hippocampal mossy terminal (Masdeu et al, 2007; reviewed in Traiffort et al, 2010). However, we find that Ptch and Smo are present predominately in the spines and dendrites of hippocampal neurons; this pattern is seen in vitro of cultured neurons and in vivo of different types of synapses in several regions of the hippocampus (Figs.…”

Identification and Mechanism of Action of the Acylguanidine MRT-83, a Novel Potent Smoothened Antagonist

“…Antibodies. A previously described polyclonal rabbit antiserum against rat Smo was used (Masdeu et al, 2007). The mouse antiacetylated tubulin antibody and the mouse monoclonal anti-c-myc antibody were obtained from Sigma; the goat anti-mouse Alexa Fluor 546 antibody was obtained from Invitrogen (Leiden, The Nederlands); and the goat anti-rabbit fluorescein isothiocyanate antibody from Millipore Bioscience Research Reagents (Temecula, CA).…”