Subpopulations of proliferating cells of the adult hippocampus respond differently to physiologic neurogenic stimuli.
To study how adult hippocampal neurogenesis might originate from the proliferation of stem or progenitor cells in vivo, we have used transgenic mice expressing green fluorescent protein (GFP) under the nestin promoter to identify these cells. Having described an astrocyte-like type 1 cell with low proliferative activity, a characteristic morphology, vascular end feet, and passive electrophysiological properties, we focused here on the large population of nestin-GFP-expressing type 2 cells, which lack all these features. Type 2 cells were highly proliferative and showed signs suggestive of their involvement in the neuronal lineage. They could be subclassified by the absence (type 2a) or presence (type 2b) of a coexpression of the early neuronal marker doublecortin. A third type of proliferating cells was doublecortin positive but nestin-GFP negative (type 3). We believe that type 2a, 2b, and 3 cells mirror a marker progression during earliest neuronal development. This view is supported by the increasing coexpression of the early granule cell-specific marker Prox-1. The low proliferative activity of type 1 cells showed little change over time or under "neurogenic interventions," such as a challenge by environmental complexity (ENR) or voluntary physical activity (RUN). However, RUN led to a significant increase of type 2 cells labeled with the proliferation marker bromodeoxyuridine (BrdU). ENR did not cause increased cell proliferation or an increased number of BrdU-labeled type 2 cells, but both ENR and RUN resulted in more newly generated cells lacking nestin-GFP immunoreactivity and expressing Prox-1. These findings allow us to break down what was broadly perceived as "proliferation" in earlier experiments into the relative contribution of several cell types, representing the earliest steps of neuronal development.
Kronenberg
Golo
G
Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch, 13125 Berlin, Germany.
Reuter
Katja
K
Steiner
Barbara
B
Brandt
Moritz D
MD
Jessberger
Sebastian
S
Yamaguchi
Masahiro
M
Kempermann
Gerd
G
D000818:Animals; D001522:Behavior, Animal; D001973:Bromodeoxyuridine / Q000493:pharmacokinetics; D002455:Cell Division; D000089622:Doublecortin Domain Proteins; D004777:Environment; D049452:Green Fluorescent Proteins; D006624:Hippocampus / Q000166:cytology* / Q000254:growth & development; D018398:Homeodomain Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000235:genetics / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins; D009043:Motor Activity / Q000502:physiology; D009419:Nerve Tissue Proteins; D064231:Nestin; D039842:Neural Cell Adhesion Molecule L1 / Q000378:metabolism; D009474:Neurons / Q000145:classification / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism; D011897:Random Allocation; D012794:Sialic Acids / Q000378:metabolism; D013997:Time Factors; D025521:Tumor Suppressor Proteins; D000098551:Prospero-Related Homeobox 1 Protein
D000089622:Doublecortin Domain Proteins; D018398:Homeodomain Proteins; D007381:Intermediate Filament Proteins; D019394:Ki-67 Antigen; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D039842:Neural Cell Adhesion Molecule L1; D009479:Neuropeptides; D012794:Sialic Acids; D025521:Tumor Suppressor Proteins; C103469:polysialyl neural cell adhesion molecule; D000098551:Prospero-Related Homeobox 1 Protein; D049452:Green Fluorescent Proteins; D001973:Bromodeoxyuridine