BS, Kent State University, 2014, College of Arts and Sciences / Department of Chemistry and Biochemistry

Biomaterials must adequately facilitate tissue fixation while maintaining mechanical properties. Surface rigidity and roughness have been shown to modulate soft tissue response. In order to improve soft tissue adhesion on rigid substrates, phase separation of organosilanes was employed to create self-assembled monolayers (SAMs) of tunable wettability by creating nano-size hydrophobic and hydrophilic domains capable of eliciting phenotypic response in skeletal myoblast cells. P-aminophenyltrimethoxysilane (APhMS) and octadecyltrichlorosilane (OTS) was varied in a binary solution in order to achieve SAMs with nanoislands. C2C12 skeletal myoblast cells were seeded onto prepared SAMs in order to investigate changes in cell behavior due to surface interactions. Hydrophilic SAMs were observed to enhance cell spreading, viability, and myotube formation on glass surfaces. Furthermore, 5:5 APhMS: OTS was found to increase myoblast differentiation and anisotropy through cell mechanosensing of nanoislands. Virtual roughness of 5:5 APhMS:OTS was created by nanosized methyl-terminated pillars in an amine-terminated matrix.

Committee: Christopher Malcuit Ph.D. (Advisor); Grant McGimpsey Ph.D. (Committee Member); Edgar Kooijman Ph.D. (Committee Member); Paul Sampson Ph.D. (Committee Member) Subjects: Cellular Biology; Chemistry

Master of Science, The Ohio State University, 2013, Animal Sciences

Myogenic satellite cells are heterogeneous multipotential stem cells required for muscle repair, maintenance, and growth. The membrane-associated heparan sulfate proteoglycans syndecan-4 and glypican-1 differentially regulate satellite cell proliferation, differentiation, fibroblast growth factor 2 (FGF2) signal transduction, and expression of myogenic regulatory factors. The objective of Specific Aims 1 and 2 was to determine the effect of age on satellite cell proliferation and differentiation using cells isolated from the pectoralis major muscle of 1 d, 7 wk and 16 wk old turkeys. Proliferation was significantly reduced in the 16 wk satellite cells, while differentiation was decreased in the 7 wk and the 16 wk cells beginning at 48 h of differentiation. Fibroblast growth factor 2 responsiveness was highest in the 1 d and 7 wk cells during proliferation; during differentiation there was an age-dependent response to FGF2. Syndecan-4 and glypican-1 expressing satellite cell populations decreased with age. These data demonstrate that declining syndecan-4 and glypican-1 satellite cell subpopulations which may be associated with age-related changes in satellite cell proliferation, differentiation, and FGF2 responsiveness. In specific aim 3, the effect of overexpressing syndecan-4 and glypican-1 was investigated. Syndecan-4 and glypican-1 overexpression did not have a significant effect on proliferation and differentiation in 1 d, 7 wk and 16 wk satellite cells. Overexpression of syndecan-4 and glypican-1 did not affect FGF2 responsiveness during proliferation. During differentiation, overexpression of syndecan-4 and glypican-1 increased differentiation at 48 h of differentiation in 1 d, 7 wk and 16 wk cells treated with FGF2 and decreased differentiation in 16 wk cells not treated with FGF2. Expression of myogenic regulatory factors MyoD, myogenin, and MRF4 were also affected by overexpression of syndecan-4 and glypican-1. These data demonstrate that syde (open full item for complete abstract)

Committee: Sandra Velleman (Advisor); Kristy Daniels (Committee Member); Ramesh Selvaraj (Committee Member) Subjects: Aging; Agriculture; Animal Sciences; Cellular Biology; Nutrition

Doctor of Philosophy, Miami University, 2008, Zoology

The larval muscles of Drosophila have served as a useful system for the study of muscle development due to the vast repertoire of experimental genetic tools available in this model organism. However, the larval muscles differ significantly from vertebrate muscles. The Indirect Flight Muscles (IFMs) of the adult Drosophila are formed during metamorphosis of the larva, and their development more closely resembles vertebrate myogenesis in complexity and dependence on innervation. This thesis addresses some aspects of IFM development.In the prevalent model of myoblast fusion, which is based on Drosophila embryonic myogenesis, the small GTPase Rac is believed to play a late role, after contact between the myoblasts has been established. Rac activity is also required for IFM development (Chapter 2), but is crucial prior to the process of fusion and may be required for myoblast movement towards organizers (Chapter 2 supplement). During insect myogenesis, myoblasts are organized into a prepattern by specialized organizer cells called Founder Cells (FCs). The FCs specify muscle identity and play important roles in myoblast fusion. Targeted ablation of the IFM FCs results in the formation of supernumerary muscle fibers, suggesting that FCs normally inhibit cells of the myoblast pool from seeding fiber formation (Chapter 3). Targeted expression of constitutively active RasV12 also results in the appearance of supernumerary fibers (Chapter 3). Taken together, these data suggest that DVM myoblasts are able to respond to cues over and above those originating from the FCs, whose role is to generate the correct number of fibers. The FCs are also shown to mediate motor neuronal regulation of myoblast proliferation during fusion, as a means of fine-tuning the number of myoblasts available for fiber formation (Chapter 4). Finally, disruption of fusion also results in the formation of supernumerary fibers, which suggests that some myoblasts have the ability to seed fiber formation inde (open full item for complete abstract)

Committee: Joyce Fernandes PhD (Committee Chair); Phyllis Callahan PhD (Committee Member); Katia Del Rio-Tsonis PhD (Committee Member); Thomas Dockendorff PhD (Committee Member); Qingshun Li PhD (Committee Member) Subjects: Biology; Cellular Biology; Zoology

Doctor of Philosophy in Regulatory Biology, Cleveland State University, 2011, College of Sciences and Health Professions

Differentiation and apoptosis are coordinately regulated in skeletal myoblasts. During the process of skeletal myoblast differentiation, our lab has determined that roughly 30% of myoblasts undergo apoptosis rather than differentiation. Further, we have reported that cytochrome C is released, and that the expression level of the pro-apoptotic Bcl2 family member PUMA is elevated, when 23A2 myoblasts are cultured in DM. Our long-term goal is to identify targets for manipulation that would abrogate this apoptosis without affecting differentiation. These findings could be significant to the study of myoblast transfer as a therapeutic approach. The goals of this dissertation are to: 1- determine the significance of PUMA in apoptosis associated with skeletal myoblast differentaion 2- determine the mechanism responsible for the increased expression of PUMA

Committee: Crystal Weyman PhD (Advisor); Anton Komar (Committee Member); Dennis Stacey (Committee Member); Martha Cathcart (Committee Member); Xioxia Li (Committee Member); Barshan Mazumder (Committee Member) Subjects: Cellular Biology

Doctor of Philosophy, Case Western Reserve University, 2009, Biochemistry

Ski is the most studied member of a family of proteins all sharing a conserved Dachshund homology domain. It has been implicated in oncogenic transformation, myogenic conversion of avian embryo fibroblasts and also many aspects of vertebrate development, especially myogenesis. Ski-/- mice exhibit severe defects in skeletal muscle and die at birth, yet little is know about either the underlying mechanisms or the role of Ski in adult muscle regeneration. In these studies, I used Ski knockout mice and C2C12 myoblast cultures to address these issues, respectively. Detailed analysis of Ski-/- embryos revealed dramatically reduced hypaxial muscles but less affected epaxial muscles. The reduced number of myogenic regulatory factor positive cells in Ski-/- mice suggested an insufficient myogenic cell pool to support muscle formation. However, both the dermomyotomal hypaxial progenitors and myotomal epaxial progenitors formed and committed to myogenic fate appropriately. The hypaxial muscle defect in Ski-/- mice was not caused by abnormal proliferation, terminal differentiation or apoptosis of the myogenic cells either, but due to impaired migration of embryonic hypaxial progenitors. Surprisingly, the normal distribution of fetal/postnatal myogenic progenitors in Ski-/- mice suggested different effects of Ski on the behaviors of embryonic and fetal/postnatal myogenic progenitors. In addition, although not affecting the terminal differentiation of embryonic myogenic cells, Ski was necessary for that of adult satellite-cell derived C2C12 myoblasts as evidenced by impaired myotube formation and reduced induction of genes essential for myogenic differentiation in the absence of Ski. This function was mainly mediated by Ski's ability to form a complex with Six1 and Eya3 and activate Myog transcription through a MEF3 site. It is important in the future to further study mechanisms underlying the contrasting effects of Ski on embryonic, fetal and adult muscle development, to investi (open full item for complete abstract)

Committee: David Samols PhD (Committee Chair); Ed Stavnezer PhD (Advisor); Clemencia Colmenares PhD (Committee Member); Nikki Harter PhD (Committee Member); Lynn Landmesser PhD (Committee Member) Subjects: Biomedical Research