Molecular characterization of a transport vesicle protein Neurensin-2, a homologue of Neurensin-1, expressed in neural cells.
We have isolated and characterized a novel cDNA encoding a small neuronal membrane protein showing high sequence homology to Neuro-p24/Neurensin-1, a protein containing a microtubule-associated domain at the carboxyl-terminus and exclusively localized to small vesicles of neurons. The newly identified Neurensin-2 constitutes two-membrane spanning domains but not the microtubule-binding domain, with a molecular mass of 28 kDa. Neurensin-2 mRNA is expressed only in brain, whereas the protein expressed in various neurons including those of the thalamus/hypothalamus and hippocampus, of postnatally developing mice. While the levels of Neurensin-1 mRNA and protein in retinoic acid-exposed mouse neuroblastoma Neuro2a cells increased, those of Neurensin-2 mRNA and protein remained unchanged. When the Neurensin-2 cDNA was transfected into Neuro2a cells, Neurensin-2 was expressed in small vesicles including lysosomes in the perinuclear region. On the cotransfection of Neurensin-1 and -2 cDNA into Neuro2a cells, Neurensin-2 was mainly found in small vesicles of the cell body and Neurensin-1 in those of growth cones. In nerve growth factor-stimulated PC12 cells, the intracellular localization of these proteins also differed. Furthermore, immunochemical staining of mouse brain revealed that Neurensin-1 and -2 had a similar distribution in many regions such as the Diagonal band, hippocampus, amygdaloid nucleus, and habenula nucleus, but differed in the intracellular localization as follows: Neurensin-1 was found mainly in neuritic processes, while Neurensin-2 was found in cell bodies. Thus, both Neurensin-1, and -2 are localized in small vesicles in neural cells, but their localizations of the vesicles are not always the same by each other, suggesting that they are under separate regulation.
Nakanishi
Katsuyuki
K
Department of Biotechnology, Kyoto Institute of Technology, Kyoto 606-8585, Japan.
Ida
Mizuho
M
Suzuki
Haruno
H
Kitano
Chiaki
C
Yamamoto
Akitsugu
A
Mori
Nozomu
N
Araki
Masasuke
M
Taketani
Shigeru
S
D000818:Animals; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular / Q000379:methods; D053938:DNA Fragmentation / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D020932:Nerve Growth Factor / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016415:Sequence Alignment / Q000379:methods; D017386:Sequence Homology, Amino Acid; D014162:Transfection / Q000379:methods; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
D009419:Nerve Tissue Proteins; C481124:Neuro-p24 protein, mouse; D033921:Vesicular Transport Proteins; D020932:Nerve Growth Factor