Adrenocortical carcinoma (ACC) is a rare and deadly disease that affects 0.5-2 people per million per year in the US. Currently, the first line clinical management includes surgical resection, followed by treatment with the chemotherapeutic agent mitotane. These interventions, however, have limited effectiveness, as the overall five-year survival rate of patients with ACC is less than 35%. Therefore, further scientific investigation underlying the molecular mechanisms and biomarkers of this disease is of high importance. The aim of this project was to identify potential biomarkers that may be used as prognosticators as well as candidate genes that might be targeted to develop new therapies for patients with ACC. An analysis of publicly-available datasets revealed PDZ-binding kinase (PBK) as being upregulated roughly 9-fold in ACC tissue compared to normal adrenal tissue. PBK has been implicated as an oncogene in several other systems, and its expression has been shown to negatively impact patient survival. Initial experiments have confirmed the upregulation of PBK in H295R cells, a human ACC cell line. We effectively silenced PBK (>95% reduction in protein content) in H295R cells using lentiviral shRNA constructs. Using high and low PBK expressing cells, we performed soft agar assays for colony formation, and found that the PBK-silenced cells produced two-fold fewer colonies than the vector control (p<0.05). This indicates that PBK likely plays a role in tumorigenicity. We further conducted functional studies for apoptosis and proliferation to elucidate the mechanism by which PBK increases tumorigenicity. Preliminary results from MTS assays showed that after 9 days, PBK-silenced cells proliferated significantly less than the vector control, so PBK likely increases proliferation. Together these data identify PBK as a kinase implicated in ACC tumorigenesis. Further in vitro and in vivo studies will be conducted to evaluate PBK as a potential therapeutic target in adrenocortical carcinoma.

Schizophrenia risk is influenced by both genetic and environmental factors. The immediate early gene early growth response 3 (Egr3), is regulated downstream of several schizophrenia risk genes and encodes a zinc-finger transcription factor protein. Previous studies from our lab indicate that Egr3 deficient (Egr3 -/-) mice exhibit schizophrenia-like phenotypes. We also discovered decreased serotonin 2a receptors (5-HT2AR) in the Egr3 -/- mice, similar to studies that reported decreased 5-HT2ARs in schizophrenia patients. We previously reported that sleep deprivation, a mild stress, causes the over expression of Egr3 and the serotonin 2a gene (Htr2a) in the cortex. To determine whether EGR3, a transcription factor, regulates Htr2a in the prefrontal cortex after sleep deprivation, Egr3 -/-and Egr3 +/+ mice were sleep deprived for eight hours. Transgenic mice were used that expressed enhanced green fluorescent protein (EGFP) under control of the Htr2a promoter via a bacterial artificial chromosome (BAC). Immunohistochemistry was performed to identify EGFP containing cells. Data analysis revealed no significant interaction between genotype and sleep deprivation in 5-HT2AR/EGFP containing cells within the prefrontal cortex. Based on the findings of this study, more data is needed to better determine the relationship between sleep deprivation and its effect on the regulation of Htr2a through in an EGR3 dependent manner.

Numb is a gene that encodes an adaptor protein which has been characterized for its role cell migration, cell adhesion, endocytosis, and cell fate determination through asymmetrical division in various embryonic and adult tissues. In vertebrates, several Numb isoforms are produced via alternative splicing. In the Mus musculus genome, one Numb gene on chromosome 12 is alternatively spliced to produce four distinct protein isoforms, characterized by an 11 amino acid insert in the phosphotyrosine binding domain and a 49 amino acid insert in the proline rich region. Two poly adenylation sites in the currently published Numb 3' UTR exist, thus, the possibility that various 3' UTRs containing different miRNA seed sites is a possible posttranscriptional mechanism by which differential expression is observed. In an attempt to elucidate this hypothesis, PCR was performed to amplify the 3' UTR of murine neural tube cells, the products of which were subsequently cloned and sequenced. Multiple fragment sizes were consistently observed in the PCR data, however, sequencing demonstrated that these bands did not reveal an association with Numb.

Sarcopenia, a disease defined by age-related muscle loss and function, impacts each and every one of us as we age. Medical research over the past 40 years has identified dozens of factors that contribute to Sarcopenia, including, hormonal changes, deficiencies in nutrition, denervation, changes in physical activity and diseases. Developing effective therapeutic treatments for Sarcopenia is dependent on identifying the mechanisms by which these factors affect muscle loss and understanding the interrelationship of these mechanisms. I conducted my research by compiling and analyzing several previous studies on many different mechanisms that contribute to Sarcopenia. Of these mechanisms, I determined the most significant mechanisms and mapped them out on a visual presentation. In addition to the contributing factors listed above, I found that dysregulated cell signaling, mitochondrial abnormalities, impaired autophagy/protein regulation, altered nitric oxide production, and systemic inflammation all contribute to Sarcopenia. Their impact on skeletal muscle is manifested by reduced satellite function, reduced regenerative capacity, loss of muscle mass, accumulation of damaged products, and fibrosis. My research clearly demonstrated that there was not a one-to-one correlation between factors and specific pathological characteristics of Sarcopenia. Instead, factors funneled into a discrete number of cellular processes, including cell proliferation, protein synthesis, and autophagy and apoptosis. Based on my findings, the overall cause of Sarcopenia appears to be a loss of balance between these pathways. The results of my thesis indicate that Sarcopenia is a multifactorial disorder, and therefore, effective therapy should consist of those that prevent necrosis associated with autophagy and apoptosis.

Multiple myeloma is a genetically heterogeneous disease, which can be divided into several genetic subtypes based upon gene expression profiles and chromosomal abnormalities. Unlike older techniques employed in myeloma research, such as cytogenetics, FISH, and microarray technologies, RNA sequencing offers a unique approach to examine the aforementioned genetic characteristics in that it allows for gene expression profiling and the detection of novel fusion transcripts arising from chromosomal rearrangements. This study utilized RNA sequencing to analyze the transcriptomes of 84 multiple myeloma patients and 69 human myeloma cell lines. FCHSD2 was found to be involved in five novel fusion events along with known oncogenes, MMSET and MYC, as well as three previously unreported genes in myeloma, including CHMP4B, NCF2, and CARNS1. An analysis of FCHSD2 expression within myeloma cell lines indicated that it is highly expressed in comparison to other tissues, suggesting that FCHSD2 translocations could lead to promoter replacement events in which the expression of partnering genes is dysregulated. The presence of the five FCHSD2 hybrid transcripts was confirmed by reverse transcription-PCR and Sanger sequencing. Overexpression of the FCHSD2 fusion transcripts in HEK293 cells resulted in the production of N-terminally truncated fusion partner proteins and a novel FCHSD2-CARNS1 fusion protein.

While a number of vertebrates, including fishes, salamanders, frogs, and lizards, display regenerative capacity, the process is not necessarily the same. It has been proposed that regeneration, while evolutionarily conserved, has diverged during evolution. However, the extent to which the mechanisms of regeneration have changed between taxa still remains elusive. In the salamander limb, cells dedifferentiate to a more plastic state and aggregate in the distal portion of the appendage to form a blastema, which is responsible for outgrowth and tissue development. In contrast, no such mechanism has been identified in lizards, and it is unclear to what extent evolutionary divergence between amniotes and anamniotes has altered this mechanism. Anolis carolinensis lizards are capable of regenerating their tails after stress-induced autotomy or self-amputation. In this investigation, the distribution of proliferating cells in early A. carolinensis tail regeneration was visualized by immunohistochemistry to examine the location and quantity of proliferating cells. An aggregate of proliferating cells at the distal region of the regenerate is considered indicative of blastema formation. Proliferating cell nuclear antigen (PCNA) and minichromosome maintenance complex component 2 (MCM2) were utilized as proliferation markers. Positive cells were counted for each tail (n=9, n=8 respectively). The percent of proliferating cells at the tip and base of the regenerating tail were compared with a one-way ANOVA statistical test. Both markers showed no significant difference (P=0.585, P=0.603 respectively) indicating absence of a blastema-like structure. These results suggest an alternative mechanism of regeneration in lizards and potentially other amniotes.

The development of skeletal muscle during embryogenesis and repair in adults is dependent on the intricate balance between the proliferation of myogenic progenitor cells and the differentiation of those cells into functional muscle fibers. Recent studies demonstrate that the Drosophila melanogaster transcription factor CG9650 is expressed in muscle progenitor cells, where it maintains myoblast numbers. We are interested in the Mus musculus orthologs Bcl11a and Bcl11b (C2H2 zinc finger transcription factors), and understanding their role as molecular switches that control proliferation/differentiation decisions in muscle progenitor cells. Expression analysis revealed that Bcl11b, but not Bcl11a, is expressed in the region of the mouse embryo populated with myogenic progenitor cells; gene expression studies in muscle cell culture confirmed Bcl11b is also selectively transcribed in muscle. Furthermore, Bcl11b is down-regulated with differentiation, which is consistent with the belief that the gene plays a role in cell proliferation.

The development of the vertebrate musculoskeletal system is a highly dynamic process, requiring tight control of the specification and patterning of myogenic, chondrogenic and tenogenic cell types. Development of the diverse musculoskeletal lineages from a common embryonic origin in the paraxial mesoderm indicates the presence of a regulatory network of transcription factors that direct lineage decisions. The basic helix-loop-helix transcription factor, PARAXIS, is expressed in the paraxial mesoderm during vertebrate somitogenesis, where it has been shown to play a critical role in the mesenchymal-to-epithelial transition associated with somitogenesis, and the development of the hypaxial skeletal musculature and axial skeleton. In an effort to elucidate the underlying genetic mechanism by which PARAXIS regulates the musculoskeletal system, I performed a microarray-based, genome-wide analysis comparing transcription levels in the somites of Paraxis-/- and Paraxis+/+ embryos. This study revealed targets of PARAXIS involved in multiple aspects of mesenchymal-to-epithelial transition, including Fap and Dmrt2, which modulate cell-extracellular matrix adhesion. Additionally, in the epaxial dermomyotome, PARAXIS activates the expression of the integrin subunits a4 and a6, which bind fibronectin and laminin, respectively, and help organize the patterning of trunk skeletal muscle. Finally, PARAXIS activates the expression of genes required for the epithelial-to-mesenchymal transition and migration of hypaxial myoblasts into the limb, including Lbx1 and Met. Together, these data point to a role for PARAXIS in the morphogenetic control of musculoskeletal patterning.

Skeletal muscles arise from the myotome compartment of the somites that form during vertebrate embryonic development. Somites are transient structures serve as the anlagen for the axial skeleton, skeletal muscle, tendons, and dermis, as well as imposing the metameric patterning of the axial musculoskeletal system, peripheral nerves, and vasculature. Classic studies have described the role of Notch, Wnt, and FGF signaling pathways in controlling somite formation and muscle formation. However, little is known about the transformation of myotome compartments into identifiable post-natal muscle groups. Using a mouse model, I have undertaken an evaluation of morphological events, including hypertrophy and hyperplasia, related to the formation of several muscles positioned along the dorsal surface of the vertebrae and ribs. Lunatic fringe (Lfng) deficient embryos and neonates were also examined to further understand the role of the Notch pathway in these processes as it is a modulator of the Notch receptor and plays an important role in defining somite borders and anterior-posterior patterning in many vertebrates. Lunatic fringe deficient embryos showed defects in muscle fiber hyperplasia and hypertrophy in the iliocostalis and longissimus muscles of the erector spinae group. This novel data suggests an additional role for Lfng and the Notch signaling pathway in embryonic and fetal muscle development.