Biology subjects

Hillman, T.

Publications and source records attributed to Hillman, T..

3 recordsLinked to original sources

bioRxiv2021

Shared and distinct genetic features in human and canine B-cell lymphomas

Animal models of human cancers are an important tool for the development and preclinical evaluation of therapeutics. Canine B-cell lymphoma (cBCL) is an appealing model for human mature B-cell neoplasms due to the high sequence similarity in cancer genes to humans and inactive telomerase in adult tissues. We performed targeted sequencing on 86 canine patients from the Canine Comparative Oncology Genomic Consortium, with 61 confirmed as B-cell lymphomas. We confirmed a high frequency of mutations in TRAF3 (45%) and FBXW7 (20%) as has been reported by our group and others. We also note a higher frequency of DDX3X (20%) and MYC (13%) mutations in our canine cohort. We compared the pattern and incidence of mutations in cBCL to human diffuse large B-cell lymphoma (hDLBCL) and human Burkitt lymphoma (hBL). Canine MYC mutations displayed a focal pattern with 80% of mutations affecting the conserved phosphodegron sequence in MYC box 1, which are known to stabilize MYC protein. We also note that MYC and FBXW7 mutations do not co-occur in our cBCL cohort, leading to the hypothesis that these mutations represent alternative approaches to stabilize MYC in canine lymphoma. We observed striking differences in the pattern of DDX3X mutations in canine lymphoma as compared to hBL and uncovered a sex-specific pattern of DDX3X mutations in hBL that is not consistent with those identified in canine lymphomas. In sum, we describe key differences between cBCL and human mature B-cell lymphomas which may indicate differences in the biology of these cancers. This should be considered in future studies of cBCL as a model of human lymphomas.

cancer biology↗

bioRxiv2021

Quantifying the antimicrobial activity of CRISPR-Cas9-accA modified ΔB. subtilis mutants against V. harveyi and E. Coli

Probiotics are increasingly popular, currently. Probiotics have been described with the ability to treat many disorders of the gastrointestinal tract (GIT) such as irritable bowel syndrome (IBS) and Crohns disease. Types of probiotics include bacterial strains from Lactobacillus and Bifidobacterium. Probiotics can restore balance to gut microbiota by outcompeting pathogenic bacteria for nutrients and secrete antimicrobials to eliminate these bacterial pathogens. However, the viability of most advertised probiotics lose their potency due to being freeze dried into powders during storage or for consuming. Many probiotics become ineffective and produce lower CFUs while traversing through the gastric acids of the digestive system. For these reasons, this study sought to enhance the antimicrobial response of a highly potent probiotic known as Bacillus subtilis. B. subtilis has been used to treat many disorders of the gut and secrete many antimicrobials lethal for pathogenic microbes. B. subtilis was genetically modified to express CRISPR-Cas9 nuclease deletion of the accA gene ({Delta}B.subtilis mutants), which inhibits expression of an essential accA gene a part of the fatty acid synthesis (FAS) metabolic pathway. The CRISPR-Cas9-accA {Delta}B.subtilis mutants were co-cultured with V. harveyi and E. Coli. Bacterial growth, biofilm formation, antimicrobial activity, and antibiotic resistance were quantified. It was found that{Delta} B.subtilis mutants co-cultured with V. harveyi and E. Coli lessened bacterial growth, amplified biofilm with V. harveyi, reduced biofilm formation of E. Coli, the co-cultures with the mutants lacked antimicrobial activity, and increased the antibiotic resistance of V. harveyi and E. Coli. It can be concluded that there is an immense potential for using genetically engineered probiotic strains to enhance the antimicrobial activity of B. subtilis, which can amplify the reduction of pathogenic bacteria. However, the safety and frugality of using B. subtilis as a probiotic requires further consideration.

synthetic biology↗

bioRxiv2019

Integrating the metabolic processes of Escherichia coli with virulence by decreasing glucose availability, inhibiting the acetyl-CoA carboxylase subunit accA with asRNA, and through the quantification of the Lux-S gene

Bacterial multiple drug resistance is a significant issue for the medical community. Gram-negative bacteria exhibit higher rates of multi-drug resistance, partly due to the impermeability of the Gram-negative bacterial cell wall and double-membrane cell envelope, which limits the internal accumulation of antibiotic agents. The outer lipopolysaccharide membrane regulates the transport of hydrophobic molecules, while the inner phospholipid membrane controls influx of hydrophilic particles. In Escherichia coli, the gene accA produces the acetyl-CoA carboxylase transferase enzyme required for catalyzing synthesis of fatty acids and phospholipids that compose the inner membrane. To increase antibiotic susceptibility and decrease growth, this study interrupted fatty acid synthesis and disrupted the composition of the inner membrane through inhibiting the gene accA with antisense RNA. This inhibition suppressed expression of luxS, a vital virulence factor that regulates cell growth, transfers intercellular quorum-sensing signals mediated by autoinducer-2, and is necessary for biofilm formation. Bacterial cells in which accA was inhibited also displayed a greater magnitude of antibiotic susceptibility. These findings confirm accA as a potent target for developing novel antibiotics such as antimicrobial gene therapies.

microbiology↗