Disruption of early events in thalamocortical tract formation in mice lacking the transcription factors Pax6 or Foxg1

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Abstract

Early events in the formation of the thalamocortical tract remain poorly understood. Recent work has suggested that thalamocortical axons follow a path pioneered by transient thalamic afferents originating from the medial part of the ventral telencephalon. We studied the development of these transient afferents and the thalamocortical tract in mutant mice lacking transcription factors normally expressed in the dorsal thalamus or ventral telencephalon. Pax6 is expressed in the dorsal thalamus, but not in the medial part of the ventral telencephalon, and the thalamocortical tract fails to form inPax6−/− embryos. We found that transient thalamic afferents from the ventral telencephalon do not form in Pax6−/− embryos; this may contribute to the failure of their thalamocortical development. The distribution ofPax6−/− cells inPax6−/− ↔Pax6+/+ chimeras supports conclusions drawn from forebrain marker gene expression that Pax6 is not required for the normal development of the medial part of the ventral telencephalon but is required in the dorsal thalamus. Failure of the transient afferent pathway to develop is therefore likely a cell nonautonomous defect reflecting primary defects in the thalamus. We then examined the formation of thalamic afferents and efferents inFoxg1−/− embryos, which lack recognizable ventral telencephalic structures. In these embryos thalamic efferents navigate correctly through the thalamus but fail to turn laterally into the telencephalon, whereas other axons are able to cross the diencephalic/telencephalic boundary. Our results support a role for the ventral telencephalon in guiding the early development of the thalamocortical tract and identify a new role for the transcription factor Pax6 in regulating the ability of the thalamus to attract ventral telencephalic afferents.
Original languageEnglish
Pages (from-to)8523-8531
Number of pages9
JournalJournal of Neuroscience
Volume22
Issue number19
DOIs
Publication statusPublished - 2002

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Telencephalon
Transcription Factors
Thalamus
Embryonic Structures
Axons
Afferent Pathways
Prosencephalon
Gene Expression

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@article{b6c665350512459ca3cd425eb85084c3,
title = "Disruption of early events in thalamocortical tract formation in mice lacking the transcription factors Pax6 or Foxg1",
abstract = "Early events in the formation of the thalamocortical tract remain poorly understood. Recent work has suggested that thalamocortical axons follow a path pioneered by transient thalamic afferents originating from the medial part of the ventral telencephalon. We studied the development of these transient afferents and the thalamocortical tract in mutant mice lacking transcription factors normally expressed in the dorsal thalamus or ventral telencephalon. Pax6 is expressed in the dorsal thalamus, but not in the medial part of the ventral telencephalon, and the thalamocortical tract fails to form inPax6−/− embryos. We found that transient thalamic afferents from the ventral telencephalon do not form in Pax6−/− embryos; this may contribute to the failure of their thalamocortical development. The distribution ofPax6−/− cells inPax6−/− ↔Pax6+/+ chimeras supports conclusions drawn from forebrain marker gene expression that Pax6 is not required for the normal development of the medial part of the ventral telencephalon but is required in the dorsal thalamus. Failure of the transient afferent pathway to develop is therefore likely a cell nonautonomous defect reflecting primary defects in the thalamus. We then examined the formation of thalamic afferents and efferents inFoxg1−/− embryos, which lack recognizable ventral telencephalic structures. In these embryos thalamic efferents navigate correctly through the thalamus but fail to turn laterally into the telencephalon, whereas other axons are able to cross the diencephalic/telencephalic boundary. Our results support a role for the ventral telencephalon in guiding the early development of the thalamocortical tract and identify a new role for the transcription factor Pax6 in regulating the ability of the thalamus to attract ventral telencephalic afferents.",
keywords = "thalamocortical tract, diencephalon, ventral telencephalon, Pax6, Foxg1, transciption factor, axon guidance, chimera, optic tract, mouse, transient thalamic afferents, tract tracing",
author = "Jane Quinn",
year = "2002",
doi = "10.1523/JNEUROSCI.22-19-08523.2002",
language = "English",
volume = "22",
pages = "8523--8531",
journal = "Journal of Neuroscience",
issn = "0270-6474",
publisher = "Society for Neuroscience",
number = "19",

}

TY - JOUR

T1 - Disruption of early events in thalamocortical tract formation in mice lacking the transcription factors Pax6 or Foxg1

AU - Quinn, Jane

PY - 2002

Y1 - 2002

N2 - Early events in the formation of the thalamocortical tract remain poorly understood. Recent work has suggested that thalamocortical axons follow a path pioneered by transient thalamic afferents originating from the medial part of the ventral telencephalon. We studied the development of these transient afferents and the thalamocortical tract in mutant mice lacking transcription factors normally expressed in the dorsal thalamus or ventral telencephalon. Pax6 is expressed in the dorsal thalamus, but not in the medial part of the ventral telencephalon, and the thalamocortical tract fails to form inPax6−/− embryos. We found that transient thalamic afferents from the ventral telencephalon do not form in Pax6−/− embryos; this may contribute to the failure of their thalamocortical development. The distribution ofPax6−/− cells inPax6−/− ↔Pax6+/+ chimeras supports conclusions drawn from forebrain marker gene expression that Pax6 is not required for the normal development of the medial part of the ventral telencephalon but is required in the dorsal thalamus. Failure of the transient afferent pathway to develop is therefore likely a cell nonautonomous defect reflecting primary defects in the thalamus. We then examined the formation of thalamic afferents and efferents inFoxg1−/− embryos, which lack recognizable ventral telencephalic structures. In these embryos thalamic efferents navigate correctly through the thalamus but fail to turn laterally into the telencephalon, whereas other axons are able to cross the diencephalic/telencephalic boundary. Our results support a role for the ventral telencephalon in guiding the early development of the thalamocortical tract and identify a new role for the transcription factor Pax6 in regulating the ability of the thalamus to attract ventral telencephalic afferents.

AB - Early events in the formation of the thalamocortical tract remain poorly understood. Recent work has suggested that thalamocortical axons follow a path pioneered by transient thalamic afferents originating from the medial part of the ventral telencephalon. We studied the development of these transient afferents and the thalamocortical tract in mutant mice lacking transcription factors normally expressed in the dorsal thalamus or ventral telencephalon. Pax6 is expressed in the dorsal thalamus, but not in the medial part of the ventral telencephalon, and the thalamocortical tract fails to form inPax6−/− embryos. We found that transient thalamic afferents from the ventral telencephalon do not form in Pax6−/− embryos; this may contribute to the failure of their thalamocortical development. The distribution ofPax6−/− cells inPax6−/− ↔Pax6+/+ chimeras supports conclusions drawn from forebrain marker gene expression that Pax6 is not required for the normal development of the medial part of the ventral telencephalon but is required in the dorsal thalamus. Failure of the transient afferent pathway to develop is therefore likely a cell nonautonomous defect reflecting primary defects in the thalamus. We then examined the formation of thalamic afferents and efferents inFoxg1−/− embryos, which lack recognizable ventral telencephalic structures. In these embryos thalamic efferents navigate correctly through the thalamus but fail to turn laterally into the telencephalon, whereas other axons are able to cross the diencephalic/telencephalic boundary. Our results support a role for the ventral telencephalon in guiding the early development of the thalamocortical tract and identify a new role for the transcription factor Pax6 in regulating the ability of the thalamus to attract ventral telencephalic afferents.

KW - thalamocortical tract

KW - diencephalon

KW - ventral telencephalon

KW - Pax6

KW - Foxg1

KW - transciption factor

KW - axon guidance

KW - chimera

KW - optic tract

KW - mouse

KW - transient thalamic afferents

KW - tract tracing

U2 - 10.1523/JNEUROSCI.22-19-08523.2002

DO - 10.1523/JNEUROSCI.22-19-08523.2002

M3 - Article

VL - 22

SP - 8523

EP - 8531

JO - Journal of Neuroscience

JF - Journal of Neuroscience

SN - 0270-6474

IS - 19

ER -