Modulation of 5-HT3 receptor desensitization by the light chain of microtubule-associated protein 1B expressed in HEK 293 cells.
Regulation of ligand-gated ion channel (LGIC) function and trafficking by cytoskeleton proteins has been the topic of recent research. Here, we report that the light chain (LC1) of microtubule-associated protein 1B (MAP1B) specifically interacted with the 5-HT(3A) receptor, a predominant serotonin-gated ion channel in the brain. LC1 and 5-HT(3A) receptors were colocalized in central neurons and in HEK 293 cells expressing 5-HT(3A) receptors. LC1 reduced the steady-state density of 5-HT(3A) receptors at the membrane surface of HEK 293 cells and significantly accelerated receptor desensitization time constants from 3.8 +/- 0.3 s to 0.8 +/- 0.1 s. However, LC1 did not significantly alter agonist binding affinity and single-channel conductance of 5-HT(3A) receptors. On the other hand, application of specific LC1 antisense oligonucleotides and nocodazole, a microtubule disruptor, significantly prolonged the desensitization time of the recombinant and native neuronal 5-HT(3) receptors by 3- to 6-fold. This kinetic change induced by nocodazole was completely rescued by addition of LC1 but not GABA(A) receptor-associated protein (GABARAP), suggesting that LC1 can specifically interact with 5-HT(3A) receptors. These observations suggest that the LC1-5-HT(3A) receptor interaction contributes to a mechanism that regulates receptor desensitization kinetics. Such dynamic regulation may play a role in reshaping the efficacy of 5-HT(3) receptor-mediated synaptic transmission.
Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, TS24, Bethesda, MD 20892, USA.
Hui
H
Sun
Xiang-Qun
XQ
Hu
Michel B
MB
Emerit
Jeffrey C
JC
Schoenebeck
Cassin E
CE
Kimmel
Robert W
RW
Peoples
Angela
A
Miko
Li
L
Zhang
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D006624:Hippocampus / Q000166:cytology; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044406:Receptors, Serotonin, 5-HT3 / Q000187:drug effects / Q000378:metabolism*; D050257:Tubulin Modulators / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C116741:GABARAP protein, human; C475491:MAP1B protein, human; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; D044406:Receptors, Serotonin, 5-HT3; D050257:Tubulin Modulators; C085284:microtubule-associated protein 1B; D015739:Nocodazole