Active zone proteins are dynamically associated with synaptic ribbons in rat pinealocytes

Abstract

Synaptic ribbons (SRs) are prominent organelles that are abundant in the ribbon synapses of sensory neurons where they represent a specialization of the cytomatrix at the active zone (CAZ). SRs occur not only in neurons, but also in neuroendocrine pinealocytes where their function is still obscure. In this study, we report that pinealocyte SRs are associated with CAZ proteins such as Bassoon, Piccolo, CtBP1, Munc13-1, and the motorprotein KIF3A and, therefore, consist of a protein complex that resembles the ribbon complex of retinal and other sensory ribbon synapses. The pinealocyte ribbon complex is biochemically dynamic. Its protein composition changes in favor of Bassoon, Piccolo, and Munc13-1 at night and in favor of KIF3A during the day, whereas CtBP1 is equally present during the night and day. The diurnal dynamics of the ribbon complex persist under constant darkness and decrease after stimulus deprivation of the pineal gland by constant light. Our findings indicate that neuroendocrine pinealocytes possess a protein complex that resembles the CAZ of ribbon synapses in sensory organs and whose dynamics are under circadian regulation.

Circadian rhythms in the morphology of neurons in Drosophila

“…Circadian changes in synapse numbers among brain neurons have additionally been shown in vertebrates (Gupta et al 1992;Spiwoks-Becker et al 2008;Girardet et al 2010) and are likely also to occur in motor neurons. Furthermore, synapses are plastic and can form within hours in Drosophila (Zito et al 1999;Ataman et al 2008) and then disassembled rapidly (Eaton et al 2002).…”

Phosphodiesterase 10A in the Rat Pineal Gland: Localization, Daily and Seasonal Regulation of Expression and Influence on Signal Transduction

“…This was performed using double labeling immunohistochemical analysis for PDE10A and RIBEYE/CtBP2. Consistent with the presence of CtBP2 in the cell nuclei [33], the RIBEYE/CtBP2 antibody labeled the cell nuclei of pinealocytes (sections a and d in fig. 1B).…”

“…Labeling was performed using an indirect fluorescence method (for details, see Spiwoks-Becker et al [33]) with the mouse anti-PDE10A monoclonal antibody (1:500) (1:250; clone 24F3.F11 directed against rat PDE10A [26,33]) and the rabbit anti-RIBEYE/CtBP2 (1:1,000; BD Biosciences, Heidelberg, Germany) as primary antibodies. The binding sites of the primary antisera were revealed by goat anti-mouse (Alexa 488; 1:500) or goat anti-rabbit (Alexa 594; 1:500; both from Molecular Probes, Eugene, Oreg., USA) as secondary antisera.…”

‘TRPing’ Synaptic Ribbon Function in the Rat Pineal Gland: Neuroendocrine Regulation Involves the Capsaicin Receptor TRPV1

“…It was recently demonstrated by means of light and electron microscopy that the kinesin motor KIF3A, a component of the microtubule motor KIN, is part of the presynaptic ribbon in retina and pineal gland [12,13,36]. The same antibody was used in the present study.…”

“…The kinesin motor KIF3A – a component of the microtubule motor kinesin II (KIN) – is part of presynaptic ribbons in the retina and pineal [11,12,13]. An interesting aspect of possible SR function came up by the demonstration that KIF3A is colocalized to the transient receptor potential channel of the vanilloid receptor family, subtype 1 (TRPV1, formerly known as the vanilloid receptor, VR1) [14] at the photoreceptor SR [15].…”