@article {967, title = {Biallelic mutations in LAMA5 disrupts a skeletal noncanonical focal adhesion pathway and produces a distinct bent bone dysplasia.}, journal = {EBioMedicine}, volume = {62}, year = {2020}, month = {2020 Dec}, pages = {103075}, abstract = {

BACKGROUND: Beyond its structural role in the skeleton, the extracellular matrix (ECM), particularly basement membrane proteins, facilitates communication with intracellular signaling pathways and cell to cell interactions to control differentiation, proliferation, migration and survival. Alterations in extracellular proteins cause a number of skeletal disorders, yet the consequences of an abnormal ECM on cellular communication remains less well understood METHODS: Clinical and radiographic examinations defined the phenotype in this unappreciated bent bone skeletal disorder. Exome analysis identified the genetic alteration, confirmed by Sanger sequencing. Quantitative PCR, western blot analyses, immunohistochemistry, luciferase assay for WNT signaling were employed to determine RNA, proteins levels and localization, and dissect out the underlying cell signaling abnormalities.~ Migration and wound healing assays examined cell migration properties.

FINDINGS: This bent bone dysplasia resulted from biallelic mutations in LAMA5, the gene encoding the alpha-5 laminin basement membrane protein. This finding uncovered a mechanism of disease driven by ECM-cell interactions between alpha-5-containing laminins, and integrin-mediated focal adhesion signaling, particularly in cartilage. Loss of LAMA5 altered β1 integrin signaling through the non-canonical kinase PYK2 and the skeletal enriched SRC kinase, FYN. Loss of LAMA5 negatively impacted the actin cytoskeleton, vinculin localization, and WNT signaling.

INTERPRETATION: This newly described mechanism revealed a LAMA5-β1 Integrin-PYK2-FYN focal adhesion complex that regulates skeletogenesis, impacted WNT signaling and, when dysregulated, produced a distinct skeletal disorder.

FUNDING: Supported by NIH awards R01 AR066124, R01 DE019567, R01 HD070394, and U54HG006493, and Czech Republic grants INTER-ACTION LTAUSA19030, V18-08-00567 and GA19-20123S.

}, issn = {2352-3964}, doi = {10.1016/j.ebiom.2020.103075}, author = {Barad, Maya and Csukasi, Fabiana and Bosakova, Michaela and Martin, Jorge H and Zhang, Wenjuan and Paige Taylor, S and Lachman, Ralph S and Zieba, Jennifer and Bamshad, Michael and Nickerson, Deborah and Chong, Jessica X and Cohn, Daniel H and Krejci, Pavel and Krakow, Deborah and Duran, Ivan} } @article {931, title = {Mutations in GRK2 cause Jeune syndrome by impairing Hedgehog and canonical Wnt signaling.}, journal = {EMBO Mol Med}, volume = {12}, year = {2020}, month = {2020 11 06}, pages = {e11739}, abstract = {

Mutations in genes affecting primary cilia cause ciliopathies, a diverse group of disorders often affecting skeletal development. This includes Jeune syndrome or asphyxiating thoracic dystrophy (ATD), an autosomal recessive skeletal disorder. Unraveling the responsible molecular pathology helps illuminate mechanisms responsible for functional primary cilia. We identified two families with ATD caused by loss-of-function mutations in the gene encoding adrenergic receptor kinase 1 (ADRBK1 or GRK2). GRK2 cells from an affected individual homozygous for the p.R158* mutation resulted in loss of GRK2, and disrupted chondrocyte growth and differentiation in the cartilage growth plate. GRK2 null cells displayed normal cilia morphology, yet loss of GRK2 compromised cilia-based signaling of Hedgehog (Hh) pathway. Canonical Wnt signaling was also impaired, manifested as a failure to respond to Wnt ligand due to impaired phosphorylation of the Wnt co-receptor LRP6. We have identified GRK2 as an essential regulator of skeletogenesis and demonstrate how both Hh and Wnt signaling mechanistically contribute to skeletal ciliopathies.

}, issn = {1757-4684}, doi = {10.15252/emmm.201911739}, author = {Bosakova, Michaela and AbrAHm, Sara P and Nita, Alexandru and Hruba, Eva and Buchtova, Marcela and Taylor, S Paige and Duran, Ivan and Martin, Jorge and Svozilova, Katerina and Barta, Tomas and Varecha, Miroslav and Balek, Lukas and Kohoutek, Jiri and Radaszkiewicz, Tomasz and Pusapati, Ganesh V and Bryja, Vitezslav and Rush, Eric T and Thiffault, Isabelle and Nickerson, Deborah A and Bamshad, Michael J and Rohatgi, Rajat and Cohn, Daniel H and Krakow, Deborah and Krejci, Pavel} }