RESUMO
Mutations in actin-bundling protein plastin 3 (PLS3) emerged as a cause of congenital osteoporosis, but neither the role of PLS3 in bone development nor the mechanisms underlying PLS3-dependent osteoporosis are understood. Of the over 20 identified osteoporosis-linked PLS3 mutations, we investigated all five that are expected to produce full-length protein. One of the mutations distorted an actin-binding loop in the second actin-binding domain of PLS3 and abolished F-actin bundling as revealed by cryo-EM reconstruction and protein interaction assays. Surprisingly, the remaining four mutants fully retained F-actin bundling ability. However, they displayed defects in Ca2+ sensitivity: two of the mutants lost the ability to be inhibited by Ca2+, while the other two became hypersensitive to Ca2+. Each group of the mutants with similar biochemical properties showed highly characteristic cellular behavior. Wild-type PLS3 was distributed between lamellipodia and focal adhesions. In striking contrast, the Ca2+-hyposensitive mutants were not found at the leading edge but localized exclusively at focal adhesions/stress fibers, which displayed reinforced morphology. Consistently, the Ca2+-hypersensitive PLS3 mutants were restricted to lamellipodia, while chelation of Ca2+ caused their redistribution to focal adhesions. Finally, the bundling-deficient mutant failed to co-localize with any F-actin structures in cells despite a preserved F-actin binding through a non-mutation-bearing actin-binding domain. Our findings revealed that severe osteoporosis can be caused by a mutational disruption of the Ca2+-controlled PLS3's cycling between adhesion complexes and the leading edge. Integration of the structural, biochemical, and cell biology insights enabled us to propose a molecular mechanism of plastin activity regulation by Ca2+.
RESUMO
BACKGROUND: Families of children at the worst end of the congenital heart disease endure a significant burden which is often not clearly delineated in the clinical literature. We examined the greatest concerns of parents whose children have a Fontan circulation. METHODS: Parents (Nâ¯=â¯107) of children in the Australian and New Zealand Fontan Registry completed online surveys with open-ended and closed questions. A qualitative method approach incorporating thematic analyses was used. RESULTS: The greatest concerns for parents of a child with a Fontan circulation were centered on fear of death for their child and psychosocial well-being, followed by lesser themes around anti-coagulation use, pregnancy and financial burdens. CONCLUSIONS: Fear of death and the psychological well-being of their children were the main parental concerns. It highlights the need to clearly communicate information on outcomes to families, and the need for family-focused psychological interventions to improve the psychosocial functioning of both parents and young people.
RESUMO
BACKGROUND: Little is known about adults living with a Fontan circulation's concerns outside the scope of their clinical outcomes. We examined adults with a Fontan circulations' greatest concerns, as well as their concerns around anti-coagulation, pregnancy and finances. METHODS: Adults with a Fontan circulation in the Australian and New Zealand Fontan Registry were invited to complete an anonymous online survey, of which 57 participated. A qualitative method approach using thematic analyses was used. RESULTS: The greatest concerns for adults living with a Fontan circulation were fear of death/uncertainty around life expectancy which for many individuals colored their concerns around physical health, pregnancy and having children, quality of life and finances. Improving information about outcomes to patients with a Fontan circulation might alleviate uncertainties about their future. CONCLUSIONS: Fear of death is the primary concern of adults with a Fontan circulation. It may require improved communication and targeted psychological interventions. Physical exercise incorporated as part of their lifestyle should be encouraged to alleviate physical concerns and also improve psychological well-being.
