Gregg Morin

 
Prospective Graduate Students / Postdocs

This faculty member is currently not actively recruiting graduate students or Postdoctoral Fellows, but might consider co-supervision together with another faculty member.

Associate Professor

Research Interests

Proteomics
mass spectrometry
RNA processing
Ribonucleoproteins
Splicing
Cancer
RNA sequencing

Relevant Thesis-Based Degree Programs

Affiliations to Research Centres, Institutes & Clusters

Research Options

I am available and interested in collaborations (e.g. clusters, grants).
I am interested in and conduct interdisciplinary research.
I am interested in working with undergraduate students on research projects.
 
 

Research Methodology

Mass Spectrometry
chromatography
RNA sequencing

Graduate Student Supervision

Doctoral Student Supervision

Dissertations completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest dissertations.

Method development for improving the performance of bottom-up proteomics (2023)

The full abstract for this thesis is available in the body of the thesis, and will be available when the embargo expires.

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Characterization of a small molecule inhibitor of disulfide reductases that induces oxidative stress and lethality in lung cancer cells (2022)

High-throughput phenotype-based screening of large libraries of compounds without known targets can identify small molecules that elicit a desired cellular response, but additional approaches are required to find and characterize their targets and mechanisms of action. Through such a screen, the novel compound LCS3 was previously identified that selectively kills lung adenocarcinoma (LUAD) cells, but its mechanism of action remained unknown. This thesis used gene expression profiling to elucidate the cellular responses of LUAD cells to LCS3. I demonstrated that LCS3 induces NRF2 pathway activation and oxidative stress through the generation of reactive oxygen species in sensitive LUAD cell lines. I then developed and applied a thermal proteome profiling (TPP) approach and identified the disulfide reductases GSR and TXNRD1 as LCS3 targets. Through enzymatic assays using purified protein, I confirmed that LCS3 inhibits disulfide reductase activity through a reversible and uncompetitive mechanism. The results demonstrated that LCS3-sensitive LUAD cells are correspondingly sensitive to the synergistic inhibition of glutathione and thioredoxin pathways, suggesting a mechanistic overlap in cell death induced by LCS3 and lethality arising from disulfide reductase inhibition. I established that challenging resistant cells with oxidative stress increases reliance on the glutathione and thioredoxin pathways and sensitizes cells to LCS3 and dual disulfide reductase inhibition. Finally, a genome-wide CRISPR-Cas9 knockout screen identified the loss of NQO1 as a mechanism of LCS3 resistance. Together, this work shines light on the mechanism of action of LCS3 and demonstrates the potential utility of disulfide reductase inhibition in lung cancer. This work also highlights the ability of TPP to uncover novel targets of novel small molecules identified by high-throughput screens.

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Quantitative analysis of small-molecule biomarkers by capillary electrophoresis-mass spectrometry (2021)

Coupling the capillary electrophoresis (CE) to mass spectrometry (MS) provides an attractive analytical platform with minimal sample consumption, short analysis time, and high separation efficiency. Small-molecule biomarkers are metabolites associated with biological or pathogenic processes. The comprehensive study of small molecules found within the biological system is known as metabolomics. The work presented herein aimed to fulfill the advantage of CE-MS in analytical efficiency and fill the gaps of current methods by achieving the nonaqueous-CE-MS analysis of isomeric prostaglandins and enabling the peak alignment in CE-based metabolomics with inconsistent flow velocities.Urinary creatinine is commonly measured to normalize urinary metabolite concentrations or to assess renal function. In Chapter 2, multisegment injection-CE-MS was combined with a dilute-and-shoot strategy to analyze urinary creatinine. The diluted urines can be directly analyzed with a total analysis time of
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Method development and proteomics applications of nonaqueous capillary electrophoresis - mass spectrometry (2020)

Capillary electrophoresis (CE) is known for its low sample consumption, high-resolution efficiency as a separation technique, while mass spectrometry (MS) provides unprecedented selectivity and sensitivity as a detector, while adding another dimension in separation. The development of a robust CE-MS interface makes it possible to combine these two technologies for the analysis of many types of compounds. However, the coupling of CE to MS reduces its usable electrolyte ingredients substantially, and many of the popular buffer systems based on phosphate or borate, the MEKC methods dependent on the use of non-volatile surfactants, have to be excluded. As a result, formic acid and acetate buffers are the most widely used background electrolytes (BGEs) in CE-MS. In this work, we used mainly organic solvent systems to expand the choices of BGEs for CE-MS. In chapters 2 and 3, we presented two quantitative 100 % nonaqueous CE-MS methods for the separation and determination of small hydrophobic molecules. Two different BGEs were developed in this part: a basic buffer system for the analysis of negatively charged compounds and an acidic buffer system for the analysis of positively charged compounds. The compounds studied are three anthraquinones extracted from traditional Chinese medicine (TCM), Rhubarb, and six synthesized hydrophobic peptides, respectively. A high-organic-content CE-MS (HOCE) method was developed for the proteomics analysis of envelope proteins. A field amplified sample stacking technique was optimized to improve the concentration sensitivity of CE-MS for samples containing a large number of different analytes. The introduction of methanol into the buffer increased the performance of CE-MS for the detection of hydrophobic peptides in complex proteins digest. A half organic CE-MS method was used for the sequencing of novel mAbs. It was demonstrated that CE-MS/MS provided highly complementary information to LC-MS/MS with much less sample consumption. The last part of this thesis describes the application of a new generation mass spectrometry, timsTOF Pro connected with LC for the site-specific O-glycomics. In TIMS, charged compounds were separated based on their differential sizes and charges, similar to CE. The results suggest that combining CE-MS for PTMs analysis can be even more productive in the future.

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Investigation of Novel Schizophrenia Candidate Genes through Biochemical and Computational Methods (2010)

No abstract available.

Master's Student Supervision

Theses completed in 2010 or later are listed below. Please note that there is a 6-12 month delay to add the latest theses.

Peptide detectability algorithm and mass tag labeling, fractionation, and ion acquisition methods in mass spectrometry-based proteomics (2023)

Proteins are responsible for facilitating and regulating nearly all cellular processes, and the collection of all proteins in a biological system is referred to as the proteome. The field of proteomics then aims to both comprehensively and quantitatively understand the dynamics of the proteome, thus providing molecular insights to the functions of biology. This has largely been enabled by mass spectrometry (MS), a technique used to measure gas phase ions of peptides yielded from protein digestion. When designing experiments in proteomics, compromises are typically made between quantitative accuracy and proteome coverage, making it challenging to select experimental strategies and parameters given a diversity of both goals and options. For example, certain targeted strategies rely on synthetic peptides either for use as quantitative standards or for boosting the signal of corresponding endogenous peptides. However, most proteins contain a plethora of theoretical peptide sequences, many of which are not detectable by MS due to non-conducive physiochemical properties. Consequently, the selection of peptides to represent proteins targeted by these strategies is not straightforward. Experimental options are also plentiful when utilizing tandem mass tags (TMT), a labeling strategy that enables multiple samples to be combined into a single MS run. While this is an appealing technique for increasing sample throughput in global experiments, use of TMT introduces significant challenges to data analysis and the impact of mitigation strategies is not trivial to predict. Mitigation strategies include reduction of sample complexity through liquid chromatography and variations to mass spectrometry acquisition methods that dictate how the instrument gathers data from the ions. In chapter 2, we present a random forest model that predicts peptide detectability in mass spectrometry for application to synthetic peptide selection. This includes an R package containing tools for convenient prioritization of peptides for desired proteins and re-training of the model. In chapter 3, we evaluate the impact of alternate sample preparation strategies and instrument acquisition methods on TMT-based global proteomics. Such options include the depth of liquid chromatography, the type of TMT tag, and the MS acquisition methods used.

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Identification and Validation of CDK13 Interacting Proteins (2012)

Cyclin dependent kinases (CDKs) are components of signal transduction pathways that regulate cellular functions by phosphorylation of substrate proteins in response to upstream signals. The kinase domains of CDK12 and CDK13 are most similar to CDK9; CDK9 phosphorylates the C terminal domain (CTD) of RNA Polymerase II in order to stimulate processive transcription elongation. However, while most human CDKs consist of little more than a kinase domain, CDK12 and CDK13 are much larger and have several protein-protein interaction domains suggesting that they could participate within regulatory cascades. They also have a RS domain found in the SR protein family of splicing factors. Consistent with these features CDK12 and CDK13 co-localize with splicing factors and RNA Polymerase II in nuclear speckles. Based on these features CDK12 and CDK13 have been proposed to coordinately regulate splicing and transcription. Consistent with this hypothesis, both kinases phosphorylate the CTD of RNA polymerase II and regulate the alternative splicing of the Adenovirus E1a mini-gene model substrate. CDK12 has been found to interact with the splicing factors PRP19, CDC5L, RBM25, FBP11 and SRP55. Due to the similarity of CDK13 to CDK12, I investigated the interacting partners of CDK13 by immunoprecipitation and mass spectrometry and determined that CDK13 interacts with same splicing factors as CDK12. These interactions were validated by immunoprecipitation – western blot analysis. My results also indicated that PRP19 and CDC5L interact as a complex with CDK13. Therefore, the protein interaction partners of CDK13 and CDK12 suggest functional mechanisms for their ability to regulate splicing. In parallel projects, to begin investigating the functional roles of the kinase domain of CDK12 I constructed and expressed different CDK12 mutants in insect cells and in mammalian cells. Also to investigate the role of the CDK12 mutants and the protein-protein interactions of CDK13 in alternative splicing, I also developed a PCR based E1A mini-gene splicing assay.

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Publications

 
 

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