Limb girdle muscular dystrophies (LGMDs) are a clinically and genetically heterogeneous group of myopathies characterized by weakness and wasting of the proximal musculature. There are currently seventeen loci associated with different LGMDs, seven with an autosomal dominant mode of inheritance (LGMD1A–1G) and 10 with an autosomal recessive mode of inheritance (LGMD2A– 2J). The cumulative worldwide prevalence of LGMD is thought to be ~1/15,000. In the Hutterite population of North America there is an over-representation of autosomal recessive LGMD with a prevalence estimated to be >1/400. The objective of this work was to delineate the genetic basis of LGMD in this large genetically isolated population. A genome-wide scan was performed on Hutterite LGMD patients and their families in order to locate the mutant gene. This allowed us to identify a novel locus at chromosome region 9q31-33 that was named LGMD2H. Extensive haplotyping and mutation screening led to the discovery of c.1459G>A in TRIM32 as the causative mutation of LGMD2H. We then found that this same mutation was the cause of another previously described myopathy in the Hutterites, sarcotubular myopathy (STM)[reference awaiting publishers decision]. Analysis of the TRIM32 gene product revealed that it is a potential E3-ubiquitin ligase, is expressed in many human tissues including muscle and brain, and has a punctate cytoplasmic distribution. During the analysis of the LGMD2H region, it became apparent that there were Hutterite LGMD patients not linked to the LGMD2H locus. In order to identify the causative gene(s) in the remaining families, we performed a genome-wide scan. A locus at chromosome 19q13 was found to correspond to disease inheritance, the site of a previously described LGMD locus, LGMD2I. No causative gene had yet been identified at this locus so haplotyping and mutation screening was performed. We were able to identify c.826C>A in FKRP as the causative mutation in our remaining cohort of LGMD patients. The same mutation has since been found in many other populations, and is apparently a relatively common cause of LGMD. We obtained DNA from 19 non-Hutterite LGMD2I patients of diverse origins with c.826C>A and determined that it is an old founder mutation. There is no further evidence of any other loci causing autosomal recessive myopathy in the Hutterites. With the identification of c.1459G>A in TRIM32 and c.826C>A in FKRP we appear to have delineated the genetic cause of all myopathies of increased prevalence in the Hutterite population. To date, we have been able to provide accurate, non-invasive, diagnosis to over 70 patients and have provided carrier testing to approximately 120 at-risk family members. This kind DNA-based approach is not feasible in the general population due the enormous amount of locus, allelic, and clinical heterogeneity among myopathy patients.

No description available.

Limb girdle muscular dystrophies (LGMDs) are a clinically and genetically heterogeneous group of myopathies characterized by weakness and wasting of the proximal musculature. There are currently seventeen loci associated with different LGMDs, seven with an autosomal dominant mode of inheritance (LGMD1A–1G) and 10 with an autosomal recessive mode of inheritance (LGMD2A– 2J). The cumulative worldwide prevalence of LGMD is thought to be ~1/15,000. In the Hutterite population of North America there is an over-representation of autosomal recessive LGMD with a prevalence estimated to be >1/400. The objective of this work was to delineate the genetic basis of LGMD in this large genetically isolated population. A genome-wide scan was performed on Hutterite LGMD patients and their families in order to locate the mutant gene. This allowed us to identify a novel locus at chromosome region 9q31-33 that was named LGMD2H. Extensive haplotyping and mutation screening led to the discovery of c.1459G>A in TRIM32 as the causative mutation of LGMD2H. We then found that this same mutation was the cause of another previously described myopathy in the Hutterites, sarcotubular myopathy (STM)[reference awaiting publishers decision]. Analysis of the TRIM32 gene product revealed that it is a potential E3-ubiquitin ligase, is expressed in many human tissues including muscle and brain, and has a punctate cytoplasmic distribution. During the analysis of the LGMD2H region, it became apparent that there were Hutterite LGMD patients not linked to the LGMD2H locus. In order to identify the causative gene(s) in the remaining families, we performed a genome-wide scan. A locus at chromosome 19q13 was found to correspond to disease inheritance, the site of a previously described LGMD locus, LGMD2I. No causative gene had yet been identified at this locus so haplotyping and mutation screening was performed. We were able to identify c.826C>A in FKRP as the causative mutation in our remaining cohort of LGMD patients. The same mutation has since been found in many other populations, and is apparently a relatively common cause of LGMD. We obtained DNA from 19 non-Hutterite LGMD2I patients of diverse origins with c.826C>A and determined that it is an old founder mutation. There is no further evidence of any other loci causing autosomal recessive myopathy in the Hutterites. With the identification of c.1459G>A in TRIM32 and c.826C>A in FKRP we appear to have delineated the genetic cause of all myopathies of increased prevalence in the Hutterite population. To date, we have been able to provide accurate, non-invasive, diagnosis to over 70 patients and have provided carrier testing to approximately 120 at-risk family members. This kind DNA-based approach is not feasible in the general population due the enormous amount of locus, allelic, and clinical heterogeneity among myopathy patients.

[Abstract]: Duchenne Muscular Dystrophy (DMD) is a fatal recessive genetic human disease affecting one in 3500 live male births. DMD is progressive, there is no cure, and patients typically die of respiratory or cardiac failure intheir second decade of life. Clinical disease symptoms are exacerbated at the onset of puberty and the physiological basis of this is unknown. The mdx mouse is the preferred experimental animal model of DMD, although aspectsof the model remain poorly understood. This dissertation characterises physiological and histological features of the dystrophic mdx mouse in response to manipulations of hormonal status including testosterone treatment, surgical castration, and oestrogen treatment. Sex-specificdifferences in the mdx were also examined. Furthermore, physiological and histological features of the dystrophic mdx mouse model throughout the mdx lifespan were evaluated. Cardiac muscle contractility, left atrial response to exogenous calcium, and the contractile properties of both fast-twitch (EDL)and slow-twitch (SOL) skeletal muscles were examined in male mdx miceranging from 14 to 330 days of age. Testosterone treatment produced a nonsignificant trend towards a dose-dependent decrease in both basal and maximal left atrial contractility in the mdx. Surgical castration produced nosignificant cardiac effects within mouse strains. The mdx castrates had a 45% lower maximum atrial force of contraction than control castrates (p<0.05). Conversely, oestrogen treatment significantly improved cardiaccontractility in the mdx. An increase in basal left atrial contractility was evident at doses of 0.08 mg/kg/day (p<0.05) and 0.16 mg/kg/day (p<0.01)and in maximum left atrial contractility at a dose of 0.16 mg/kg/day (p<0.01). Gender studies showed cardiac forces in mdx were not different between males and females at any age tested and that both sexes in mdx had adampened cardiac responsiveness to exogenous calcium. Skeletal muscle function studies showed that castration produced a 25% increase in mdx EDL specific force generation (p<0.01) and no increase in SOL forces.Oestrogen treatment produced a non-significant trend towards increased EDL forces and a 29% increase in SOL specific force at a dose of 0.16mg/kg/day (p<0.05). Gender studies revealed no differences between male and female mdx in terms of skeletal muscle force production. Further to the hormonal investigations, lifespan characterisation studies revealed that themdx mouse showed reduced basal and maximal left atrial contractility specifically at ages 14 and 90 days (p<0.05). Skeletal muscle studies showed that specific tetanic force production was significantly lower thancontrols at 19 (p<0.05), 21, 23, 27, and 330 days of age (p<0.01) for EDL muscles and at 19, 21, and 23 days of age in SOL muscles (p<0.01). These studies further improve our understanding of the mdx mouse as an experimental model of DMD and emphasises that the model is most appropriate a specific ages for specific muscles. These studies furtherillustrate that testosterone does not improve cardiac contractility in the mdx mouse but that oestrogen improves both cardiac and skeletal muscle function. Further research is warranted into the potential of oestrogen as atherapeutic agent in the treatment of both cardiac and skeletal musclemanifestations of DMD.

Thesis (Ph. D.)--State University of New York at Binghamton, Philosophy Department, 2007. / Short stories. "A compilation of creative writing that utilizes life narrative to examine living with a physical disability."--Abstract.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 107-120).

Thesis (Doctoral)--Göteborg University, 2006. / "1101-718X"--T.p. verso. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 147-167).

Our laboratory has identified two secreted proteins, Wnt7a and Sonic hedgehog (Shh), that regulate satellite cell (SC) fate, during muscle differentiation. While Wnt7a stimulates symmetric SC division through the planar cell polarity (PCP) pathway, Shh activates Myf5 expression in the committed SC following asymmetric division through cilia-mediated Hedgehog (Hh) signaling. Crosstalk between these pathways has been well characterized during development, and is likely to be conserved in muscle regeneration. Indeed, accumulating evidence suggests the PCP pathway influences primary cilia formation, an organelle required for proper Hh signal transduction. Here we show that Wnt7a treatment in primary myoblasts increases the presence of primary cilia. Additionally, using myofiber culture, we demonstrate that Wnt7a increases myogenin (MyoG) expression. Removal of primary cilia through a small interfering RNA (siRNA) targeted towards IFT88 impedes Wnt7a mediated MyoG expression, suggesting crosstalk between the PCP and Hh pathways facilitates muscle differentiation. Furthermore, through siRNA knockdown we have identified the downstream PCP effectors, Inturned and Fuzzy as the main candidates responsible for this crosstalk. Knockdown of either Inturned or Fuzzy impedes Wnt7a-mediated MyoG expression. Taken together our data demonstrates crosstalk between the PCP pathway and Hh signaling regulates the differentiation of SCs.

Many tissue-restricted diseases are linked to mutations in lamins and nuclear envelope transmembrane proteins (NETs). How these mutations in ubiquitously expressed proteins cause such defined diseases is still unknown. It is hypothesized that tissue restricted NETs that are partners of the nuclear lamins/existing linked proteins mediate tissue-specific disease pathologies. Proteomic studies have identified many tissue restricted NETs with effects on the cytoskeleton, gene positioning and regulation. This study investigates potential roles of candidate NETs in mediating tissue restricted disease pathology and their interactions with known factors such as emerin and lamins, mutations in which have been linked to a variety of tissue-specific dystrophies. This study looks into candidate tissue-specific NETs distribution in human tissues and in vitro using a solid phase binding assay to study candidate NETs interactions. I confirmed the tissue-specificity of the candidate NETs in human and mouse tissue sections but did not find clear reproducible distribution of these NETs in patient tissue biopsy. One postulate is that NETs bind WT lamin for localisation and/or function and disruption of this interaction leads to disease. Using a solid phase binding assay approach to study NETs/lamin interactions, we demonstrate that Tmem120a, an adipocyte-specific NET binds WT lamin but has a reduced Bmax when tested for binding against a lipodstrophy causing lamin mutant (R482Q and G465D). This is consistent with the hypothesis that tissue-specific NET partners might mediate tissue-specific disease pathology in lamin-linked nuclearenvelopathies.