Cellular and subcellular localization of Marlin-1 in the brain.
BACKGROUND
Marlin-1 is a microtubule binding protein that associates specifically with the GABAB1 subunit in neurons and with members of the Janus kinase family in lymphoid cells. In addition, it binds the molecular motor kinesin-I and nucleic acids, preferentially single stranded RNA. Marlin-1 is expressed mainly in the central nervous system but little is known regarding its cellular and subcellular distribution in the brain.


RESULTS
Here we have studied the localization of Marlin-1 in the rodent brain and cultured neurons combining immunohistochemistry, immunofluorescence and pre-embedding electron microscopy. We demonstrate that Marlin-1 is enriched in restricted areas of the brain including olfactory bulb, cerebral cortex, hippocampus and cerebellum. Marlin-1 is abundant in dendrites and axons of GABAergic and non-GABAergic hippocampal neurons. At the ultrastructural level, Marlin-1 is present in the cytoplasm and the nucleus of CA1 neurons in the hippocampus. In the cytoplasm it associates to microtubules in the dendritic shaft and occasionally with the Golgi apparatus, the endoplasmic reticulum (ER) and dendritic spines. In the nucleus, clusters of Marlin-1 associate to euchromatin.


CONCLUSIONS
Our results demonstrate that Marlin-1 is expressed in discrete areas of the brain. They also confirm the microtubule association at the ultrastructural level in neurons. Together with the abundance of the protein in dendrites and axons they are consistent with the emerging role of Marlin-1 as an intracellular protein linking the cytoskeleton and transport. Our study constitutes the first detailed description of the cellular and subcellular distribution of Marlin-1 in the brain. As such, it will set the basis for future studies on the functional implications of Marlin-1 in protein trafficking.
Vidal
René L
RL
Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Independencia, Santiago, Chile. renevidalg@gmail.com
Valenzuela
José I
JI
Luján
Rafael
R
Couve
Andrés
A
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D006624:Hippocampus / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D008807:Mice, Inbred BALB C; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D009830:Olfactory Bulb / Q000378:metabolism / Q000648:ultrastructure; D016601:RNA-Binding Proteins / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
C484853:Jakmip1 protein, rat; C484852:Marlin-1 protein, mouse; D016601:RNA-Binding Proteins