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New Insights into Limb Formation
August 13, 2009Investigators at Burnham Institute for Medical Research (Burnham) and the University of Connecticut Health Center (U.C.H.C.) have gained new understanding of the role hyaluronic acid (HA) plays in skeletal growth, chondrocyte maturation and joint formation in developing limbs. Significantly, these discoveries were made using a novel mouse model in which the production of HA is blocked in a tissue-specific manner. The Yamaguchi laboratory genetically modified the Has2 gene, which is a critical enzyme for HA synthesis, so that the gene can be "conditionally" disrupted in mice. This is the first time a conditional Has2 knockout mouse has been created, a breakthrough that opens vast possibilities for future research. The paper was published online in the journal Development on July 24.
HA is a large sugar molecule that is produced by every cell in the body and has been thought to play a role in joint disease, heart disease and invasive cancers. Yu Yamaguchi, M.D., Ph.D., a professor in the Sanford Children's Health Research Center at Burnham and Robert Kosher, Ph.D., a professor in the Center for Regenerative Medicine and Skeletal Development at U.C.H.C. and colleagues showed that transgenic mice, in which Has2 was inactivated in the limb bud mesoderm, had shortened limbs, abnormal growth plates and duplicated bones in the fingers and toes.
"Because hyaluronic acid is so prevalent in the body, it has been difficult to study," said Dr. Yamaguchi. "Systemic Has2 knockout mice died mid-gestation and could not be used to study the role of HA in adults. By inactivating Has2 in specific tissues, we give ourselves the opportunity to study the many roles HA plays in biology. This mouse model will be useful to study the role of HA in various age-related diseases and conditions, such as arthritis and skin aging, as well as cancer."
To create the conditional knockout mice, the Yamaguchi laboratory genetically engineered the Has2 gene to create the Has2flox allele. The team then added the Prxl1-Cre transgene, which is associated with early limb bud mesenchyme to produce the conditional Has2 knockout mice.
The research was funded by grants from the National Institutes of Health.
About Burnham Institute for Medical Research
Burnham Institute for Medical Research is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. Burnham, with operations in California and Florida, is one of the fastest-growing research institutes in the country. The institute ranks among the top four institutions nationally for NIH grant funding and among the top 25 organizations worldwide for its research impact. For the past decade (1999-2009), Burnham ranked first worldwide in the fields of biology and biochemistry for the impact of its research publications (defined by citations per publication), according to the Institute for Scientific Information.
Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Burnham is a nonprofit public benefit corporation.
Burnham Institute for Medical Research
To create the conditional knockout mice, the Yamaguchi laboratory genetically engineered the Has2 gene to create the Has2flox allele. The team then added the Prxl1-Cre transgene, which is associated with early limb bud mesenchyme to produce the conditional Has2 knockout mice.
The research was funded by grants from the National Institutes of Health.
About Burnham Institute for Medical Research
Burnham Institute for Medical Research is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. Burnham, with operations in California and Florida, is one of the fastest-growing research institutes in the country. The institute ranks among the top four institutions nationally for NIH grant funding and among the top 25 organizations worldwide for its research impact. For the past decade (1999-2009), Burnham ranked first worldwide in the fields of biology and biochemistry for the impact of its research publications (defined by citations per publication), according to the Institute for Scientific Information.
Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Burnham is a nonprofit public benefit corporation.
Burnham Institute for Medical Research
Discovery of a molecular mechanism underlying limb architecture
A genetic study performed by Dr. Marie Kmita, a researcher at the Institut de Recherches Cliniques de Montréal (IRCM), in collaboration with Drs Basile Tarchini and Denis Duboule of the University of Geneva in Switzerland, sheds light on the origins of the architecture of arms and legs.
Causative gene for human "lobster claw" syndrome identified
A new study using mouse "knockouts" shows that genes that control limb formation in insects have similar functions in mammals. Split hand/foot malformation (SHFM) or ectrodactyly (the "lobster claw" anomaly), is a severe congenital malformation syndrome characterised by a profound median cleft of the hands and/or feet, typically associated with absence or fusion of the remaining fingers. This condition is quite frequent as about 6 cases of SHFM are observed for every 10,000 human births. Several forms of SHFM are each associated with a different genetic mutation. One of the most frequent forms called Type I is associated with a specific region of human chromosome 7 that contains two homeobo
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