References of "Steel, K. P"
     in
Bookmark and Share    
Peer Reviewed
See detailThe Notch ligand Jagged1 is required for inner ear sensory development.
Kiernan, A. E.; Ahituv, N.; Fuchs, H. et al

in Proceedings of the National Academy of Sciences of the United States of America (2001), 98(7), 3873-8

Within the mammalian inner ear there are six separate sensory regions that subserve the functions of hearing and balance, although how these sensory regions become specified remains unknown. Each sensory ... [more ▼]

Within the mammalian inner ear there are six separate sensory regions that subserve the functions of hearing and balance, although how these sensory regions become specified remains unknown. Each sensory region is populated by two cell types, the mechanosensory hair cell and the supporting cell, which are arranged in a mosaic in which each hair cell is surrounded by supporting cells. The proposed mechanism for creating the sensory mosaic is lateral inhibition mediated by the Notch signaling pathway. However, one of the Notch ligands, Jagged1 (Jag1), does not show an expression pattern wholly consistent with a role in lateral inhibition, as it marks the sensory patches from very early in their development--presumably long before cells make their final fate decisions. It has been proposed that Jag1 has a role in specifying sensory versus nonsensory epithelium within the ear [Adam, J., Myat, A., Roux, I. L., Eddison, M., Henrique, D., Ish-Horowicz, D. & Lewis, J. (1998) Development (Cambridge, U.K.) 125, 4645--4654]. Here we provide experimental evidence that Notch signaling may be involved in specifying sensory regions by showing that a dominant mouse mutant headturner (Htu) contains a missense mutation in the Jag1 gene and displays missing posterior and sometimes anterior ampullae, structures that house the sensory cristae. Htu/+ mutants also demonstrate a significant reduction in the numbers of outer hair cells in the organ of Corti. Because lateral inhibition mediated by Notch predicts that disruptions in this pathway would lead to an increase in hair cells, we believe these data indicate an earlier role for Notch within the inner ear. [less ▲]

Detailed reference viewed: 94 (0 UL)
Peer Reviewed
See detailTailchaser (Tlc): a new mouse mutation affecting hair bundle differentiation and hair cell survival.
Kiernan, A. E.; Zalzman, M.; Fuchs, H. et al

in Journal of Neurocytology (1999), 28(10-11), 969-85

We have undertaken a phenotypic approach in the mouse to identifying molecules involved in inner ear function by N-ethyl-N-nitrosourea mutagenesis followed by screening for new dominant mutations ... [more ▼]

We have undertaken a phenotypic approach in the mouse to identifying molecules involved in inner ear function by N-ethyl-N-nitrosourea mutagenesis followed by screening for new dominant mutations affecting hearing or balance. The pathology and genetic mapping of the first of these new mutants, tailchaser (Tlc), is described here. Tlc/+ mutants display classic behavioural symptoms of a vestibular dysfunction, including head-shaking and circling. Behavioural testing of ageing mice revealed a gradual deterioration of both hearing and balance function, indicating that the pathology caused by the Tlc mutation is progressive, similar to many dominant nonsyndromic deafnesses in humans. Based on scanning electron microscopy (SEM) studies, Tlc clearly plays a developmental role in the hair cells of the cochlea since the stereocilia bundles fail to form the characteristic V-shape pattern around the time of birth. By young adult stages, Tlc/+ outer hair bundles are grossly disorganised although inner hair bundles appear relatively normal by SEM. Increased compound action potential thresholds revealed that the Tlc/+ cochlear hair cells were not functioning normally in young adults. Similar to inner hair cells, the hair bundles of the vestibular hair cells also do not appear grossly disordered. However, all types of hair cells in the Tlc/+ inner ear eventually degenerate, apparently regardless of the degree of organisation of their hair bundles. We have mapped the Tlc mutation to a 12 cM region of chromosome 2, between D2Mit164 and D2Mit423. Based on the mode of inheritance and map location, Tlc appears to be a novel mouse mutation affecting both hair cell survival and stereocilia bundle development. [less ▲]

Detailed reference viewed: 62 (0 UL)
Peer Reviewed
See detailAnalysis of the Pax-3 gene in the mouse mutant splotch.
Goulding, M.; Sterrer, S.; Fleming, J. et al

in Genomics (1993), 17(2), 355-63

In a linkage analysis of Pax-3 and splotch no recombinations were found in 117 backcross mice. Molecular analysis of Pax-3 in three alleles of splotch shows a number of significant alterations to the Pax ... [more ▼]

In a linkage analysis of Pax-3 and splotch no recombinations were found in 117 backcross mice. Molecular analysis of Pax-3 in three alleles of splotch shows a number of significant alterations to the Pax-3 gene. In Sp/Sp embryos, cDNA PCR analysis reveals a shortened transcript in which exon 4 of Pax-3 is deleted due to mutation of the splice acceptor site of intron 3. In the Sp4H allele, the Pax-3 gene is deleted and in Spd embryos, Pax-3 expression is significantly lower than that in normal littermate embryos. The linkage analysis, shortened Pax-3 transcript in Sp, and deletion of Pax-3 in Sp4H described here, together with the previous report of an intragenic deletion in Pax-3 in Sp2H mice and the deletion of Pax-3 in Spr mice, provide strong evidence for the allelic identity of Pax-3 and Sp. [less ▲]

Detailed reference viewed: 107 (0 UL)