Active zone proteins are dynamically associated with synaptic ribbons in rat pinealocytes.
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.
Spiwoks-Becker
Isabella
I
Department of Anatomy and Cell Biology, Johannes Gutenberg University, Becherweg 13, Mainz, Germany. spiwoks@uni-mainz.de
Maus
Christian
C
tom Dieck
Susanne
S
Fejtová
Anna
A
Engel
Lydia
L
Wolloscheck
Tanja
T
Wolfrum
Uwe
U
Vollrath
Lutz
L
Spessert
Rainer
R
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D003624:Darkness; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D016547:Kinesins / Q000235:genetics / Q000378:metabolism; D008027:Light; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology; D010870:Pineal Gland / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000737:chemistry / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology
C113688:Bsn protein, rat; C486016:Ctbp2 protein, rat; D003598:Cytoskeletal Proteins; D005136:Eye Proteins; C490201:Kif3a protein, rat; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; C405514:Pclo protein, rat; C103912:Unc13a protein, rat; D016547:Kinesins