Biology subjects

Willis, A. B.

Publications and source records attributed to Willis, A. B..

3 recordsLinked to original sources

bioRxiv2023

The super-healing MRL strain promotes muscle growth in muscular dystrophy through a regenerative extracellular matrix

Genetic background shifts the severity of muscular dystrophy. In mice, the DBA/2J strain confers a more severe muscular dystrophy phenotype, whereas the Murphys Roth Large (MRL) strain has "super-healing" properties that reduce fibrosis. A comparative analysis of the Sgcg null model of Limb Girdle Muscular Dystrophy in the DBA/2J versus MRL strain showed the MRL background was associated with greater myofiber regeneration and reduced structural degradation of muscle. Transcriptomic profiling of dystrophic muscle in the DBA/2J and MRL strains indicated strain-dependent expression of the extracellular matrix (ECM) and TGF-{beta} signaling genes. To investigate the MRL ECM, cellular components were removed from dystrophic muscle sections to generate decellularized "myoscaffolds". Decellularized myoscaffolds from dystrophic mice in the protective MRL strain had significantly less deposition of collagen and matrix-bound TGF-{beta}1 and TGF-{beta}3 throughout the matrix, and dystrophic myoscaffolds from the MRL background were enriched in myokines. C2C12 myoblasts were seeded onto decellularized matrices from Sgcg-/- MRL and Sgcg-/- DBA/2J matrices. Acellular myoscaffolds from the dystrophic MRL background induced myoblast differentiation and growth compared to dystrophic myoscaffolds from the DBA/2J matrices. These studies establish that the MRL background also generates its effect through a highly regenerative ECM, which is active even in muscular dystrophy. Brief SummaryThe extracellular matrix of the super-healing MRL mouse strain harbors regenerative myokines that improve skeletal muscle growth and function in muscular dystrophy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/547098v1_ufig1.gif" ALT="Figure 1"> View larger version (49K): org.highwire.dtl.DTLVardef@18543eborg.highwire.dtl.DTLVardef@2e3386org.highwire.dtl.DTLVardef@138d5ccorg.highwire.dtl.DTLVardef@5c4ef6_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Nucleoli and the nucleoli-centromere association are dynamic during normal development and in cancer

Centromeres are known to cluster around nucleoli in drosophila and mammalian cells. However, the functional significance of nucleoli-centromere interaction remains underexplored. We hypothesize that if this conserved interaction is functionally important, it should be dynamic under different physiological and pathological conditions. We examined the nucleolar structure and centromeres at various differentiation stages using cell culture models. The results show dynamic changes of nucleolar number, area, and nucleoli-centromere interactions at differentiation stages and in cancer cells. Embryonic stem cells usually have a single large nucleolus, which associates with a high percentage of centromeres. As cells differentiate into intermediate states, the nucleolar number increases and the association with centromeres decreases. In terminally differentiated cells, including myotubes, neurons and keratinocytes, the number of nucleoli and their association with centromeres are at the lowest. Cancer cells demonstrate the pattern of nucleoli number and nucleoli-centromere association that is akin to proliferative less differentiated cell types, suggesting that nucleolar reorganization and changes in nucleoli-centromere interactions may help facilitate malignant transformation. This idea is supported in a case of pediatric rhabdomyosarcoma, in which induced differentiation inhibits cell proliferation and reduces nucleolar number and centromere association. These findings suggest active roles of nucleolar structure in centromere function and genome organization critical for cellular function in both normal development and cancer.

cell biology↗

bioRxiv2022

Recombinant annexin A6 promotes membrane repair in a stem cell derived-cardiomyocyte model of dystrophic cardiomyopathy

Heart failure is a major source of mortality in Duchenne muscular dystrophy (DMD). DMD arises from mutations that ablate expression of the protein dystrophin, which render the plasma membrane unusually fragile and prone to disruption. In DMD patients, repeated mechanical stress leads to membrane damage and cardiomyocyte loss. Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) offer the opportunity to study specific mutations in the context of a human cell, but these models can be improved by adding physiologic stressors. We modeled the primary defect underlying DMD by applying equibiaxial mechanical strain to DMD iPSC-CMs. DMD iPSC-CMs demonstrated an increased susceptibility to equibiaxial strain after 2 hours at 10% strain relative to healthy control cells, measured as increased lactate dehydrogenase (LDH) release. After 24 hours, both DMD and healthy control iPSC-CMs showed evidence of injury with release of LDH and cardiac troponin T. We exposed iPSC-CMs to recombinant annexin A6, a protein resealing agent, and found reduced LDH and troponin release in DMD and control iPSC-CMs that had been subjected to 24 hour strain at 10%. We used aptamer protein profiling of media collected from DMD and control iPSC-CMs and compared these results to serum protein profiling from DMD patients. We found a strong correlation between the proteins in DMD patient serum and media from DMD iPSC-CMs subjected to mechanical stress. By developing an injury assay that specifically targets an underlying mechanism of injury seen in DMD-related cardiomyopathy, we demonstrated the potential therapeutic efficacy of the protein membrane resealer, recombinant annexin A6, for the treatment of DMD-related cardiomyopathy and general cardiac injury.

bioengineering↗