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chemical–genetic study of EphB signaling identifies kinase-ependent developmental processes

. Soskis 1,∗, H. Ho 1, B. Ataman 1, C. Zhang 2, K. Shokat 2, M.reenberg 1

Harvard Medical School, USAUCSF, USA

-mail address: msoskis@fas.harvard.edu (M. Soskis).EphB receptor tyrosine kinases regulate cell–cell contacts in a

ariety of processes ranging from axon guidance and topographicapping to neuronal migration and synapse formation. EphBs

ind to a group of ligands, ephrin-Bs, which span the plasmaembrane, thus allowing for bidirectional signaling between cells.

his complexity combined with the pleiotropic functions of EphBshroughout development has obscured the exact nature of endoge-ous EphB signaling. To refine our understanding of how EphBsignal, we used a chemical–genetic approach to reversibly inhibitphB receptors in vitro and in vivo. By mutating a residue inhe receptor’s ATP-binding pocket, its kinase activity is renderedensitive to reversible inhibition by allele-specific PP1 derivatives.his approach blocks the kinase activity of EphBs while leavingheir scaffolding and reverse signaling capabilities intact and canircumvent the developmental compensation that may occur afterenetic lesions. Using this approach we generated knockin miceith mutations in EphB1, EphB2, and EphB3. We demonstrate that

phB kinase activity is required for several distinct processes inervous system development. Further studies with these allele-pecific kinase mice may be especially valuable in exploring theature of EphB signaling in the adult brain.

oi:10.1016/j.ijdevneu.2012.03.329

omparative gene expression in developing cognitive circuits inommon marmoset brain

iromi Mashiko ∗, Aya C. Yoshida, Satomi S. Kikuchi, Kimie Niimi,iki Takahashi, Jun Aruga, Hideyuki Okano, Tomomi Shimogori

Lab for Molecular Mechanisms of Thalamus Development, RIKEN BSI,apan

-mail address: h-mashiko@brain.riken.jp (H. Mashiko).The developmental mechanisms by which the cerebral cortex

ncreased in size and complexity during primate evolution aressentially unknown. To understand the molecular mechanismsf how animals evolved higher brain functions such as cognition,elf-awareness, and language ability, precise gene expression pro-les are required. In particular, studies of gene expression duringarly developmental stages are important to reveal homologousnd analogous structures. Here, we report gene expression anal-sis in the neonatal common marmoset (Callithrix jacchus) brain.sing in situ hybridization, we focused especially on areas known

o control cognition and their connective areas, including therefrontal cortex, pulvinar nuclei in the thalamus, hippocampus,rimary and secondary visual cortices, and dorsal lateral geniculateucleus in the thalamus. To directly compare gene expression, weelected marker genes whose expression patterns and functionsave been studied in developing mouse brain. We found thatany, but not all, cortical markers tested showed similar patterns

etween mouse and marmoset prefrontal cortex, supporting thedea that regional identity is conserved at a molecular level across

ammalian super orders. However, some genes showed very

ifferent expression patterns in marmoset brain, providing insight

nto the combination of conserved and novel genes that resultedn the evolution of new areas and functions. Our results establish

uroscience 30 (2012) 640–671 669

a powerful tool kit to advance understanding of primate-specificcognitive circuit development.

doi:10.1016/j.ijdevneu.2012.03.331

Norepinephrine stimulates a distinct precursor population inthe adult hippocampus

Dhanisha Jhaveri a,∗, Estella Newcombe a, Virginia Nink a, GeoffreyOsborne a, Vidita Vaidya b, Perry Bartlett a

a The Queensland Brain Institute, The University of Queensland, Bris-bane, Queensland 4072, Australiab Department of Biological Sciences, Tata Institute of FundamentalResearch, Mumbai 400005, India

E-mail address: dhanisha@uq.edu.au (D. Jhaveri).New neurons are continuously generated from a resident pop-

ulation of stem and precursor cells in the adult hippocampus.Accumulating evidence points to a direct role of newborn neuronsin the functional hippocampal circuitry that leads to enhancementof mood, cognition and memory. The current thinking is that thereis a homogenous pool of precursors in the hippocampus that gen-erates these new neurons, all of which contribute equally to thehippocampal functions. Recent studies from our laboratory haveshown that the majority of the precursor cells are latent and canbe activated by either high levels of K+ (mimicking neural exci-tation) or by the monoamine neurotransmitter norepinephrine.Using selective pharmacological blockers, we have shown that�3 adrenergic receptors mediate this norepinephrine-dependentactivation. Interestingly, we have found that norepinephrine acti-vates a separate precursor population than KCl and that �3adrenergic receptor antagonist fails to block KCl-mediated activa-tion of hippocampal precursors. Together, these findings suggestthat distinct precursor populations exist in the adult hippocampus,which are regulated by different molecular mechanisms. We arecurrently phenotyping the different precursor populations using apanel (∼87) of monoclonal antibodies to CD antigens. We believethat this knowledge will significantly enhance our understandingof heterogeneity amongst precursor populations in the adult hip-pocampus and guide the next generation of therapeutic strategiesinvolving the use of adult-born neurons for the treatment of neuro-psychiatric disorders.

doi:10.1016/j.ijdevneu.2012.03.332

Role of neural EGF-like like protein 2 (NELL2) in neuronal dif-ferentiation of P19 cells

B.J. Lee a,∗, D.H. Kim a, S.G. Kang b

a University of Ulsan, South Koreab Inje University, South Korea

E-mail address: bjlee@ulsan.ac.kr (B.J. Lee).NELL2 was first identified as a mammalian homolog of chick

NEL (neural EGF-like) protein. It was almost exclusively expressedin neurons of rat brain and has been suggested to play a role in neu-roprotection and neural differentiation. However, no clear evidencehas yet been available for detailed function of NELL2. In this studywe tried to identify NELL2 function during neural differentiationof mouse embryonic carcinoma P19 cells. Endogenous expressionof NELL2 in P19 cells increased in parallel with neural differentia-tion process induced by retinoic acid (RA). We found that rat NELL2

promoter contains RA response element (RARE) and that treatmentof RA increased NELL2 promoter activity. Transfection of P19 cellswith NELL2 expression vectors induced a dramatic increase in cellaggregation, which in turn, resulting in an increase of neurosphere