Functional Differentiation of Cholecystokinin-Containing Interneurons Destined for the Cerebral Cortex.
Although extensively studied postnatally, the functional differentiation of cholecystokinin (CCK)-containing interneurons en route towards the cerebral cortex during fetal development is incompletely understood. Here, we used CCKBAC/DsRed mice encoding a CCK promoter-driven red fluorescent protein to analyze the temporal dynamics of DsRed expression, neuronal identity, and positioning through high-resolution developmental neuroanatomy. Additionally, we developed a dual reporter mouse line (CCKBAC/DsRed::GAD67gfp/+) to differentiate CCK-containing interneurons from DsRed+ principal cells during prenatal development. We show that DsRed is upregulated in interneurons once they exit their proliferative niche in the ganglionic eminence and remains stably expressed throughout their long-distance migration towards the cerebrum, particularly in the hippocampus. DsRed+ interneurons, including a cohort coexpressing calretinin, accumulated at the palliosubpallial boundary by embryonic day 12.5. Pioneer DsRed+ interneurons already reached deep hippocampal layers by embryonic day 14.5 and were morphologically differentiated by birth. Furthermore, we probed migrating interneurons entering and traversing the cortical plate, as well as stationary cells in the hippocampus by patch-clamp electrophysiology to show the first signs of Na+ and K+ channel activity by embryonic day 12.5 and reliable adult-like excitability by embryonic day 18.5. Cumulatively, this study defines key positional, molecular, and biophysical properties of CCK+ interneurons in the prenatal brain.
Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Scheeles väg 1.|Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Daniela
D
Calvigioni
Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, H-1083 Budapest, Hungary.
Zoltán
Z
Máté
Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
János
J
Fuzik
Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Fatima
F
Girach
Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Scheeles väg 1.|Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-17177 Stockholm, Sweden.
Ming-Dong
MD
Zhang
Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown Street, L69 3BX Liverpool, UK.
Andrea
A
Varro
Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Johannes
J
Beiersdorf
Microscopy Labs Munich, Global Sales Support-Life Sciences, Carl Zeiss Microscopy GmbH, Kistlerhofstrasse 75, D-81379 Munich, Germany.
Christian
C
Schwindling
Department of Genetic and Behavioral Neuroscience, Gunma University School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
Yuchio
Y
Yanagawa
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-17177 Stockholm, Sweden.
Graham J
GJ
Dockray
Program in Developmental Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Chris J
CJ
McBain
Department of Neuroscience, Karolinska Institutet, Retzius väg 8, SE-17177 Stockholm, Sweden.
Tomas
T
Hökfelt
Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, H-1083 Budapest, Hungary.
Gábor
G
Szabó
Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Erik
E
Keimpema
Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Scheeles väg 1.|Department of Molecular Neurosciences, Center for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria.
Tibor
T
Harkany
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology / Q000378:metabolism; D002766:Cholecystokinin / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007395:Interneurons / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D055495:Neurogenesis / Q000502:physiology*; D018408:Patch-Clamp Techniques
D002766:Cholecystokinin
cortical plate; light sheet microscopy; migration; specification; synaptogenesis; transgene reporter