Dominant role of the cytosolic C-terminal domain of the rat 5-HT1B receptor in axonal-apical targeting.
The 5-HT(1A) and 5-HT(1B) receptors for serotonin exhibit a different membrane localization to either soma and dendrites (5-HT(1A)R) or axons and terminals (5-HT(1B)R) of neurons in the CNS. The mechanisms responsible for their differential targeting were investigated previously by transfecting various 5-HT(1A)R/5-HT(1B)R chimeras in the epithelial Lilly pork kidney (LLC-PK1) cell line. This first study suggested that a specific targeting signal is located in the C-terminal portion (comprising the last two transmembrane and the cytoplasmic C-terminal domains) of the 5-HT(1A)and/or 5-HT(1B) receptors. In the present study, the role of the cytosolic C-terminal tail of the receptors was further investigated by transfecting truncated receptors and 5-HT(1A)R/5-HT(1B)R chimeras in both the epithelial LLC-PK1 cells and rat hippocampal neurons in primary culture. Confocal microscopic analysis of immunofluorescence with specific anti-5-HTR antibodies and anti-microtubule-associated protein 2 or anti-neurofilament 200k antibodies showed that substitution of the cytosolic C-terminal tail of the 5-HT(1B)R in the 5-HT(1A)R addressed the resulting chimera to the axon of neurons and to the apical domain of LLC-PK1 cells. Therefore, the short tail of the 5-HT(1B)R presents an apical targeting signal that can also act as an axonal targeting signal. In addition, a domain within the third intracytoplasmic loop of the 5-HT(1B)R, responsible for its Golgi sequestration in LLC-PK1 cells, appeared to act as another axonal targeting signal in hippocampal neurons.
Jolimay
N
N
Institut National de la Santé et de la Recherche Médicale U288, Faculté de Médecine Pitié-Salpêtrière, 75013 Paris, France.
Franck
L
L
Langlois
X
X
Hamon
M
M
Darmon
M
M
D020816:Amino Acid Motifs / Q000235:genetics / Q000502:physiology; D000818:Animals; D001369:Axons / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D003600:Cytosol / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006056:Golgi Apparatus / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D018374:LLC-PK1 Cells; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D016900:Neurofilament Proteins / Q000378:metabolism; D009457:Neuroglia / Q000166:cytology; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000235:genetics / Q000502:physiology; D051381:Rats; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin / Q000235:genetics / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D013552:Swine; D014162:Transfection
D008869:Microtubule-Associated Proteins; D016900:Neurofilament Proteins; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D011993:Recombinant Fusion Proteins