Volume 16, Number 9,
Issue of May 1, 1996
pp. 2972-2982
Copyright ©1996 Society for Neuroscience
The Divergent Homeobox Gene PBX1 Is Expressed in the
Postnatal Subventricular Zone and Interneurons of the Olfactory
Bulb
Received Aug. 30, 1995; revised Feb. 2, 1996; accepted Feb. 12, 1996.
Lori Redmond1,
Susan Hockfield1, and
Maria A. Morabito2
1 Section of Neurobiology, and 2 Department
of Pharmacology, Yale University School of Medicine, New Haven,
Connecticut 06520-8066
In the mammalian brain, an important phase of neurogenesis occurs
postnatally in the subventricular zone (SVZ). This region consists of a
heterogeneous population of cells, some mitotically active, others
postmitotic. A subset of mitotically active SVZ precursor cells gives
rise to a population of neurons that migrates over a long distance to
their final destination, the olfactory bulb. Other SVZ precursor cells
continue to proliferate or undergo cell death. The combination of genes
that regulates proliferation and cell fate determination of SVZ
precursor cells remains to be identified. We have used the rat homolog
of the human homeobox gene PBX1 in Northern analysis and
in situ hybridization studies to determine the temporal and
regional localization of PBX1 expression during embryonic
and postnatal rat brain development. PBX1 is expressed
embryonically in the telencephalon. In addition, it is expressed at
high levels postnatally in the SVZ, in the migratory pathway to the
olfactory bulb, and in the layers of the olfactory bulb that are the
targets of these migratory neurons. Combining in situ
hybridization for PBX1 with immunostaining for markers of
cell proliferation (PCNA), postmitotic neurons (class III
-tubulin),
and glia (GFAP), we show that SVZ proliferating cells and their
neuronal progeny express rat PBX1 mRNA, whereas glial cells
do not express detectable levels of PBX1. The expression of
PBX1 in SVZ precursor cells and postmitotic neurons suggests
a role for PBX1 in the generation of olfactory bulb
interneurons and in mammalian neurogenesis.
Key words:
development;
differentiation;
PBX1;
homeobox gene;
transcription factor;
neurogenesis;
precursor cell;
subventricular zone;
forebrain;
olfactory bulb