Analysis of hindbrain patterning defects caused by the kreisler enu mutation reveals multiple roles of Kreisler in hindbrain segmentation
Abstract The embryonic hindbrain is subdivided into eight subunits, termed rhombomeres (r1–r8). The Kreisler ( Krml1/MafB/val ) transcription factor is expressed in and essential for patterning rhombomeres 5 and 6. Here, we have shown that in the chemically induced kreisler enu ( kr enu ) allele, a...
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Published in | Developmental dynamics Vol. 227; no. 1; pp. 134 - 142 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
01.05.2003
|
Online Access | Get full text |
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Summary: | Abstract
The embryonic hindbrain is subdivided into eight subunits, termed rhombomeres (r1–r8). The
Kreisler
(
Krml1/MafB/val
) transcription factor is expressed in and essential for patterning rhombomeres 5 and 6. Here, we have shown that in the chemically induced
kreisler
enu
(
kr
enu
) allele, a point mutation in the DNA binding domain abolishes or severely reduces Kreisler‐dependent transcription. Comparison of
kr
enu
/kr
enu
embryos with those homozygous for the classic
kreisler
(
kr
) mutation has reconciled past discrepancies and revealed multiple roles of
Kreisler
in hindbrain segmentation. These analyses demonstrate that
Kreisler
is required for maintenance and expansion but not initiation of the
Krox20
expressing r5 domain. The differences in the “r5‐like” phenotype of
kr
enu
/kr
enu
and
kr/kr
mouse embryos, and zebrafish carrying mutations in the Kreisler orthologue
valentino
(
val
) suggest that Kreisler performs many of its r5‐specific functions by associating with other proteins. By contrast,
kr/kr
and
kr
enu
/kr
enu
mouse and
val‐/‐
zebrafish embryos all exhibit indistinguishable defects in r6 specification. Thus, transcriptionally active Kreisler is required for r6 specification. Unlike mouse
kr
enu
/kr
enu
and zebrafish
val‐/‐
embryos,
kr/kr
embryos exhibited anterior defects. We determined that the
kr
chromosomal inversion caused ectopic
Kreisler
expression in r3 of
kr/kr
and
kr
/+ embryos. Hence,
Kreisler
regulates maintenance and expansion of r5 and specification of r6 but is not required for r3 development. Developmental Dynamics 227:134–142, 2003. © 2003 Wiley‐Liss, Inc. |
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ISSN: | 1058-8388 1097-0177 |
DOI: | 10.1002/dvdy.10279 |