Mutations in Lamin and How It Causes Multiple Tissue-Specific Disorders

Lamins are the major components of the nuclear lamina where they provide a platform for the binding of proteins to the chromatin and confer mechanical stability (Dittmer and Misteli.,2011). Mutations in the human LMNA gene result in at least 15 distinct disorders ranging from muscular dystrophies to neurological disorders to lipodystrophies (Vytopil et al.,2003). Interestingly, some mutant forms of lamin protein aggregate, which may be toxic to the cells. However, it is unknown how specific mutations in lamin give rise to tissue-specific disease. I hypothesize that certain tissues are susceptible to specific lamin mutations due to the inability of tissue-specific quality control mechanisms to degrade those mutant forms, leading to protein aggregation and cellular toxicity. I will be testing if tissue-specific disease mutations in Lam Dm0, one of the fly homologs of LMNA (Gene that codes for Lamin), cause the protein to aggregate in muscles and neurons. Lamin can be post-translationally modified by the addition of a farnesyl group that helps anchor Lamin into the nuclear envelop. We find that the unfarnesylated form (the predominant form) and the farnesylated form of the different Lam Dm0mutant proteins have different expression patterns in the muscle. In addition, we find that the p38 MAPK (p38Kb) interacts with the CASA (Chaperone Assisted Selective Autophagy) complex to regulate the degradation of Lam Dm0. Future experiments will characterize how these mutant forms of Dm0 affect the functionality of the muscles and neurons in flies and if these forms can be targeted for degradation by p38Kb and the CASA complex

MUTATIONS IN LAMIN GENE AND HOW IT CAUSES MULTIPLE TISSUE-SPECIFIC DISORDERS

Mutations in the LMNA gene result in at least 15 distinct disorders ranging from muscular dystrophies to neurological disorders to lipodystrophies. These disorders are collectively called laminopathies. Lamins are fibrous proteins in type V intermediate filaments, providing structural function and transcriptional regulation in the cell nucleus. One outstanding question is how mutations in the Lamin genes result in such different disorders, as these proteins play a critical role in nuclear shape and are expressed in most cell types. Interestingly, mutant forms of lamin proteins aggregate, which may be toxic to the cells. Studies on the fruit fly Drosophila melanogaster has been instrumental in our understanding of la min functions. Flies have two lamin genes, LamC and Lam Dm0, that evolved from a single ancestral gene and are homologous to both the LamA/C and LamB genes in humans. Many of the disease causing mutations in LMNA are conserved in both LamC and Lam Dm0. Fur thermore, while LamC is not expressed in neurons, Lam Dm0 is expressed in both muscle and neurons suggesting that Lam Dm0 in muscles and neurons has both Aand Btype lamin activities. Therefore, we hypothesize that certain tissues are susceptible to spe cific lamin mutations due to the inability of tissue specific quality control mechanisms to degrade those mutant forms, leading to protein aggregation and cellular toxicity. We have found that the p38Kb interacts with the CASA complex in flies to regulate the degradation of Lam Dm0. However, we will be testing if different lamin mutations aggregates in muscles and neurons

Adaptation of the Wound Healing Questionnaire universal-reporter outcome measure for use in global surgery trials (TALON-1 study): mixed-methods study and Rasch analysis

BackgroundThe Bluebelle Wound Healing Questionnaire (WHQ) is a universal-reporter outcome measure developed in the UK for remote detection of surgical-site infection after abdominal surgery. This study aimed to explore cross-cultural equivalence, acceptability, and content validity of the WHQ for use across low- and middle-income countries, and to make recommendations for its adaptation.MethodsThis was a mixed-methods study within a trial (SWAT) embedded in an international randomized trial, conducted according to best practice guidelines, and co-produced with community and patient partners (TALON-1). Structured interviews and focus groups were used to gather data regarding cross-cultural, cross-contextual equivalence of the individual items and scale, and conduct a translatability assessment. Translation was completed into five languages in accordance with Mapi recommendations. Next, data from a prospective cohort (SWAT) were interpreted using Rasch analysis to explore scaling and measurement properties of the WHQ. Finally, qualitative and quantitative data were triangulated using a modified, exploratory, instrumental design model.ResultsIn the qualitative phase, 10 structured interviews and six focus groups took place with a total of 47 investigators across six countries. Themes related to comprehension, response mapping, retrieval, and judgement were identified with rich cross-cultural insights. In the quantitative phase, an exploratory Rasch model was fitted to data from 537 patients (369 excluding extremes). Owing to the number of extreme (floor) values, the overall level of power was low. The single WHQ scale satisfied tests of unidimensionality, indicating validity of the ordinal total WHQ score. There was significant overall model misfit of five items (5, 9, 14, 15, 16) and local dependency in 11 item pairs. The person separation index was estimated as 0.48 suggesting weak discrimination between classes, whereas Cronbach's α was high at 0.86. Triangulation of qualitative data with the Rasch analysis supported recommendations for cross-cultural adaptation of the WHQ items 1 (redness), 3 (clear fluid), 7 (deep wound opening), 10 (pain), 11 (fever), 15 (antibiotics), 16 (debridement), 18 (drainage), and 19 (reoperation). Changes to three item response categories (1, not at all; 2, a little; 3, a lot) were adopted for symptom items 1 to 10, and two categories (0, no; 1, yes) for item 11 (fever).ConclusionThis study made recommendations for cross-cultural adaptation of the WHQ for use in global surgical research and practice, using co-produced mixed-methods data from three continents. Translations are now available for implementation into remote wound assessment pathways