title: The related neuronal endosomal proteins NEEP21 (Nsg1) and P19 (Nsg2) have divergent expression profiles in vivo.
abstract: Endosomal maturation and transport constitutes a complex trafficking system present in all cell types. Neurons have adapted their endosomal system to meet their unique and complex needs. These adaptations include repurposing existing proteins to diversify endocytosis and trafficking, as well as preferential expression of certain regulators more highly in neurons than other cell types. These neuronal regulators include the family of Neuron-Specific Gene family members (Nsg), NEEP21 (Nsg1), and P19 (Nsg2). NEEP21/Nsg1 plays a role in the trafficking of multiple receptors, including the cell adhesion molecule L1/NgCAM, the neurotransmitter receptor GluA2, and β-APP. Recently, we showed that NEEP2/Nsg1 and P19/Nsg2 are not expressed in all neuronal cell types in vitro. However, it is not known where and when NEEP21/Nsg1 and P19/Nsg2 are expressed in vivo, and whether both proteins are always coexpressed. Here, we show that NEEP21/Nsg1 and P19/Nsg2 are present in both overlapping and distinct cell populations in the hippocampus, neocortex, and cerebellum during development. NEEP21/Nsg1 and P19/Nsg2 levels are highest during embryonic development, and expression persists in the juvenile mouse brain. In particular, a subset of layer V cortical neurons retains relatively high expression of both NEEP21/Nsg1 and P19/Nsg2 at postnatal day 16 as well as in the CA1-3 regions of the hippocampus. In the cerebellum, NEEP21/Nsg1 expression becomes largely restricted to Purkinje neurons in adulthood whereas P19/Nsg2 expression strikingly disappears from the cerebellum with age. This divergent and restricted expression likely reflects differential needs for this class of trafficking regulators in different neurons during different stages of maturation.
authors.affiliation: Department of Cell Biology, University of Virginia, Charlottesville, Virginia.
authors.forename: Kelly
authors.identifier: http://orcid.org/0000-0002-8999-9580
authors.initials: K
authors.lastname: Barford
authors.affiliation: Department of Cell Biology, University of Virginia, Charlottesville, Virginia.
authors.forename: Chan Choo
authors.initials: CC
authors.lastname: Yap
authors.affiliation: Department of Cell Biology, University of Virginia, Charlottesville, Virginia.
authors.forename: Noelle D
authors.initials: ND
authors.lastname: Dwyer
authors.affiliation: Department of Cell Biology, University of Virginia, Charlottesville, Virginia.
authors.forename: Bettina
authors.initials: B
authors.lastname: Winckler
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis*; D011992:Endosomes / Q000378:metabolism; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology*; D059467:Transcriptome
chemical_list: D002352:Carrier Proteins; D009419:Nerve Tissue Proteins; C000600524:Nsg2 protein, mouse
keywords: KEYWORDS endosome; Purkinje neuron; RRID: AB_10896795; RRID: AB_11205592; RRID: AB_2138173; RRID: AB_2286684; RRID: AB_2314065; RRID: AB_2340462; RRID: AB_2340686; RRID: AB_2534017; RRID: AB_2534102; RRID: AB_2535788; RRID: AB_2536181; RRID: AB_2571866; RRID: AB_477329; RRID: AB_882455; RRID: RGD_737891; RRID: SCR_007318; neural-specific gene; neurodevelopment