Höfundar:
Abbi Smith, Eiríkur Steingrímsson, Sara Sigurbjörnsdóttir
Introduction: Limb patterning and anatomical arrangement during development is governed by the Hedgehog signaling pathway. Pathological activation of hedgehog signaling can be found in diseases like cancer and osteoarthritis. The protein Smoothened (SMO) is a gatekeeper of downstream hedgehog signaling, and recent work has shown that cholesterol binding of Smoothened is necessary for downstream activation. A recently discovered SMO mutation in the cholesterol binding domain was found to be highly associated with hip osteoarthritis. Our lab studies the role of cholesterol binding of Smoothened on the development of osteoarthritis.
Methods and Data: Chondrogenic mouse Smo-/- ATDC5 cells overexpressing human SMO harboring mutations to the cholesterol binding pocket are used to study the effect of the mutations of interest on downstream hedgehog signaling in vitro. Additionally, zebrafish harboring a presumed null Smo mutation are used to characterize the Smo-deficient phenotype and assess the ability Smo mRNA (wildtype or mutant) to alter the phenotype.
Results: The experiments are still in progress. The ATDC5 cells overexpressing human SMO mutants show changes in the downstream activation of HH signaling. The Smo-deficient zebrafish have altered morphology and reduced survival, as anticipated.
Conclusions: We used cell culture and zebrafish embryos to model the effect of Smoothened cholesterol binding capability on downstream hedgehog signaling activity. We have assessed the phenotype of Smo-deficient embryos and confirmed that hedgehog signaling is reduced, resulting in severe morphological defects.