The Vinculin-ΔIn20/21 Mouse: Characteristics of a Constitutive, Actin-Binding Deficient Splice Variant of Vinculin

BACKGROUND: The cytoskeletal adaptor protein vinculin plays a fundamental role in cell contact regulation and affects central aspects of cell motility, which are essential to both embryonal development and tissue homeostasis. Functional regulation of this evolutionarily conserved and ubiquitously expressed protein is dominated by a high-affinity, autoinhibitory head-to-tail interaction that spatially restricts ligand interactions to cell adhesion sites and, furthermore, limits the residency time of vinculin at these sites. To date, no mutants of the vinculin protein have been characterized in animal models. METHODOLOGY/PRINCIPAL FINDINGS: Here, we investigate vinculin-DeltaEx20, a splice variant of the protein lacking the 68 amino acids encoded by exon 20 of the vinculin gene VCL. Vinculin-DeltaEx20 was found to be expressed alongside with wild type protein in a knock-in mouse model with a deletion of introns 20 and 21 (VCL-DeltaIn20/21 allele) and shows defective head-to-tail interaction. Homozygous VCL-DeltaIn20/21 embryos die around embryonal day E12.5 showing cranial neural tube defects and exencephaly. In mouse embryonic fibroblasts and upon ectopic expression, vinculin-DeltaEx20 reveals characteristics of constitutive head binding activity. Interestingly, the impact of vinculin-DeltaEx20 on cell contact induction and stabilization, a hallmark of the vinculin head domain, is only moderate, thus allowing invasion and motility of cells in three-dimensional collagen matrices. Lacking both F-actin interaction sites of the tail, the vinculin-DeltaEx20 variant unveils vinculin's dynamic binding to cell adhesions independent of a cytoskeletal association, and thus differs from head-to-tail binding deficient mutants such as vinculin-T12, in which activated F-actin binding locks the protein variant to cell contact sites. CONCLUSIONS/SIGNIFICANCE: Vinculin-DeltaEx20 is an active variant supporting adhesion site stabilization without an enhanced mechanical coupling. Its presence in a transgenic animal reveals the potential of splice variants in the vinculin gene to alter vinculin function in vivo. Correct control of vinculin is necessary for embryonic development

Relationships between type of pain and work participation in people with long-standing spinal cord injury: results from a cross-sectional study

STUDY DESIGN: Multicentre, cross-sectional study. OBJECTIVES: To describe the relationships between the presence of (different types of) pain and participation in paid work in people with long-standing spinal cord injury (SCI). Furthermore, the associations of pain-related work limitations, age, gender, relationship, education, lesion level, and time since injury (TSI) with work participation (WP) were investigated. SETTING: The Netherlands. METHODS: Individuals (n = 265) with SCI for ≥ 10 years were included. Data were collected through a structured consultation with a rehabilitation physician and self-report questionnaire. Descriptive statistics and logistic regression analysis were performed. RESULTS: Median age of participants was 47.9 years, median time since injury was 22 years, 73% were male, 69% had complete SCI and 59% had paraplegia, 50% had paid work, 63% reported musculoskeletal pain, 49% reported neuropathic pain, and 31% reported other pain. Self-reported pain-related work limitations were significantly (V = 0.26 and V = 0.27) related to WP. In bivariable logistic regression analyses, no statistically significant relationships between type of pain and WP were observed. Younger age (OR=0.96), male gender (OR=0.52), a stable relationship (OR = 1.70), and shorter time since SCI (OR = 0.97) were significantly associated with a higher chance of being employed. Multivariable analysis confirmed these findings and in addition showed a higher level of education to be positively related with WP. CONCLUSION: Age, gender, relationship, education, TSI and self-reported work limitations showed a relationship with WP. Different types of pain were unrelated to WP. SPONSORSHIP: Fonds NutsOHRA through the Dutch Organization for Health Research and Development (ZonMw), Project number 89000006