The objective of this proposal is to provide a deeper molecular understanding of certain key processes in mammalian development and embryology. A clearer understanding of normal development will, of course, impact greatly on our ability to comprehend and deal with the abnormal events resulting in birth defects and proliferative diseases. The main premise of this proposal is that the study of mammalian development can benefit greatly from a combined approach that employs the tools of embryology, genetics and recombinant DNA methodology. In particular, analysis of genes of central importance in development may be quite enlightening. This laboratory has been extremely fortunate in its recent identification of a transgenic line of mice in which such a gene, of key significance in development, has been disrupted. Mice with two copies of the interrupted gene are born with hindlimbs that truncate abruptly at the femur, with no distal structures present. Forelimbs are missing anterior digits and while one bone of the forearm, the ulna, is always normal, the bone beside it, the radius, is often dramatically reduced or absent. The brains are also malformed, with missing olfactory lobes and necrotic lesions in the anterior cerebrum. Embryological analysis is beginning to shed light on the nature of the defect at the cellular level. An abnormal wave of mesenchymal cell death is observed during early hindlimb development. Furthermore because this gene, named legless, carries the foreign transgene """"""""tag"""""""" within it, it can readily be cloned and studied to better understand its role in development. The timing and positional specificity of gene expression can be determined. The encoded protein can be made, analyzed and localized within the developing embryo. Moreover, the gene can be systematically altered in vitro and then functionally dissected by re-introducing it into mutant mice and observing the partial or complete rescue of normal development. The proposed embryological, genetic and molecular study is only possible because of the presence of the transgenic line, which allows continual production of abnormal mice for embryological study, as well as molecular isolation and characterization of the altered gene. Each aspect of analysis complements the others, providing a more complete understanding of the developmental process.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD024517-03
Application #
3325173
Study Section
Human Embryology and Development Subcommittee 1 (HED)
Project Start
1988-08-01
Project End
1993-04-30
Budget Start
1990-05-01
Budget End
1991-04-30
Support Year
3
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Cincinnati Children's Hospital Medical Center
Department
Type
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
Bell, Sheila M; Schreiner, Claire M; Wert, Susan E et al. (2008) R-spondin 2 is required for normal laryngeal-tracheal, lung and limb morphogenesis. Development 135:1049-58
Bell, Sheila M; Schreiner, Claire M; Waclaw, Ronald R et al. (2003) Sp8 is crucial for limb outgrowth and neuropore closure. Proc Natl Acad Sci U S A 100:12195-200
Valerius, M Todd; Patterson, Larry T; Feng, Yuxin et al. (2002) Hoxa 11 is upstream of Integrin alpha8 expression in the developing kidney. Proc Natl Acad Sci U S A 99:8090-5
Supp, D M; Brueckner, M; Kuehn, M R et al. (1999) Targeted deletion of the ATP binding domain of left-right dynein confirms its role in specifying development of left-right asymmetries. Development 126:5495-504
Bell, S M; Lan, Y; Jiang, R et al. (1998) Exclusion of Jagged2 as a candidate for the legless gene. Mamm Genome 9:778-9
Bell, S M; Schreiner, C M; Scott, W J (1998) The loss of ventral ectoderm identity correlates with the inability to form an AER in the legless hindlimb bud. Mech Dev 74:41-50
Supp, D M; Witte, D P; Potter, S S et al. (1997) Mutation of an axonemal dynein affects left-right asymmetry in inversus viscerum mice. Nature 389:963-6
Supp, D M; Witte, D P; Branford, W W et al. (1996) Sp4, a member of the Sp1-family of zinc finger transcription factors, is required for normal murine growth, viability, and male fertility. Dev Biol 176:284-99
Scott, W J; Collins, M D; Ernst, A N et al. (1994) Enhanced expression of limb malformations and axial skeleton alterations in legless mutants by transplacental exposure to retinoic acid. Dev Biol 164:277-89
Schreiner, C M; Scott Jr, W J; Supp, D M et al. (1993) Correlation of forelimb malformation asymmetries with visceral organ situs in the transgenic mouse insertional mutation, legless. Dev Biol 158:560-2

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