title: Reliable Genetic Labeling of Adult-Born Dentate Granule Cells Using Ascl1 CreERT2 and Glast CreERT2 Murine Lines.
abstract: Newly generated dentate granule cells (GCs) are relevant for input discrimination in the adult hippocampus. Yet, their precise contribution to information processing remains unclear. To address this question, it is essential to develop approaches to precisely label entire cohorts of adult-born GCs. In this work, we used genetically modified mice to allow conditional expression of tdTomato (Tom) in adult-born GCs and characterized their development and functional integration. Ascl1(CreERT2);CAG(floxStopTom) and Glast(CreERT2);CAG(floxStopTom) mice resulted in indelible expression of Tom in adult neural stem cells and their lineage upon tamoxifen induction. Whole-cell recordings were performed to measure intrinsic excitability, firing behavior, and afferent excitatory connectivity. Developing GCs were also staged by the expression of early and late neuronal markers. The slow development of adult-born GCs characterized here is consistent with previous reports using retroviral approaches that have revealed that a mature phenotype is typically achieved after 6-8 weeks. Our findings demonstrate that Ascl1(CreERT2) and Glast(CreERT2) mouse lines enable simple and reliable labeling of adult-born GC lineages within restricted time windows. Therefore, these mice greatly facilitate tagging new neurons and manipulating their activity, required for understanding adult neurogenesis in the context of network remodeling, learning, and behavior.
  
  
  CONCLUSIONS
  Our study shows that Ascl1(CreERT2) and Glast(CreERT2) mice lines can be used to label large cohorts of adult-born dentate granule cells with excellent time resolution. Neurons labeled in this manner display developmental and functional profiles that are in full agreement with previous findings using thymidine analogs and retroviral labeling, thus providing an alternative approach to tackle fundamental questions on circuit remodeling. Because of the massive neuronal targeting and the simplicity of this method, genetic labeling will contribute to expand research on adult neurogenesis.
authors.affiliation: Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, C1405BWE, Argentina.
authors.forename: Sung M
authors.initials: SM
authors.lastname: Yang
authors.affiliation: Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, C1405BWE, Argentina.
authors.forename: Diego D
authors.initials: DD
authors.lastname: Alvarez
authors.affiliation: Laboratorio de Plasticidad Neuronal, Fundación Instituto Leloir-Instituto de Investigaciones Bioquímicas de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, C1405BWE, Argentina aschinder@leloir.org.ar.
authors.forename: Alejandro F
authors.identifier: http://orcid.org/0000-0003-4863-8348
authors.initials: AF
authors.lastname: Schinder
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D064092:Calbindin 1 / Q000378:metabolism; D003198:Computer Simulation; D018891:Dentate Gyrus / Q000166:cytology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D027341:Excitatory Amino Acid Transporter 1 / Q000172:deficiency / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000235:genetics; D005260:Female; D066298:In Vitro Techniques; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008959:Models, Neurological; D009419:Nerve Tissue Proteins / Q000378:metabolism; D055495:Neurogenesis / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D064092:Calbindin 1; D004965:Estrogen Antagonists; D027341:Excitatory Amino Acid Transporter 1; D019426:Integrases; D009419:Nerve Tissue Proteins; D022661:RNA, Untranslated; D013629:Tamoxifen; C499317:Ascl1 protein, mouse; C110853:Gt(ROSA)26Sor non-coding RNA, mouse; C493393:Slc1a3 protein, mouse; C045073:Cre recombinase
keywords: adult neurogenesis; electrophysiology; hippocampus; neural circuits; synaptogenesis; transgenic mice