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Associate Professor
The goal of the Andrews lab is to elucidate the mechanisms of decision making in cells. Most of the time a single cell acts as the perfect CEO, using multitudes of data to make decisions, manage resources, and grow. Cells make decisions using a deep learning network, by having an input layer (biological signals), one or more hidden or interconnected layers, and finally, biological output. Our goal is to understand how these networks function when making correct and incorrect decisions. To do this, we need to map the interconnectedness of these hidden networks and mathematically model their relationships. To accomplish this goal, we combined classical enzymology with modern proteomics. This approach allows for the study of complex multi-substrate/product systems that can’t be understood using classical approaches.
There are >100 lysine residues within the nucleosome and greater than 90% have been shown to have post-translational modifications (PTMs) (Figure 1). If you considered PTMs as a chemical indexing system and each PTM creates a unique nucleosome you could make >1018 distinct nucleosomes. Not all of these modifications are observed and coordinated mechanisms of crosstalk suggest the potential that they may make up a learning network.
Mass spectrometry coupled enzyme kinetics in multiproduct systems (Figure 2). We were the first group to use validated quantitative and targeted mass spectrometry (UPLC-QqQ) to study lysine acetyltransferases (KATs) under steady state conditions, allowing us to monitor one substrate turning over into multiple products or acetylation states. This was a technical challenge due to the 100’s of samples that have to be quantitated for this analysis (typically 300 samples for one steady-state curve). We also needed to develop a new theoretical framework for the analysis of one substrate to multiple product turnover.
Specificity and selectivity of p300 and CBP are different and regulated by acetyl-CoA concentration. These two KATs share ~90% identity in their functional domains but are often correlated with different diseases and developmental responses. Thus, understanding their unique, site-specific activity has provided insight into how the function of the two proteins differ. The findings of our initial study were highlighted in F1000 for its importance in identifying unique differences in these two homologous enzymes. From this starting point we were then able to link acetyl-CoA concentration with the residue preferences of these enzymes (Figure 2). We proposed these enzymes potentially function through a monomeric cooperative model (manifesting as hysteresis), which predicts that at certain concentrations competitive inhibitors could activate the enzyme, resulting in a paradoxical activity. We were able to demonstrate this effect both in vitro and in vivo.
Histone chaperones can recognize histone PTMs, and direct crosstalk (Figure 3). Histone chaperones both interact with KATs and assemble and disassemble nucleosomes, strongly suggesting that they could regulate which histone residue could be modified. Rtt109 is a yeast KAT which is an active site structural homolog of human p300 and CBP and forms a complex with the histone chaperone Vps75 (Nap1 family). In vivo, Rtt109 functions with a second histone chaperone Asf1, to facilitate the acetylation of H3K56, which is critical for DNA damage in yeast. Early biochemical data was able to show that Asf1 could increase the activity of Rtt109-Vps75 but did not result in a change in selectivity. One of the major goals was to determine the mechanism of this change in selectivity observed in vivo. To test our hypothesis that pre-existing acetylation influences the selectivity of Rtt109-Vps75 we made a library of singly acetylated histones using a strain of E. coli containing an orthogonal Nε-acetyllysyl-tRNA synthetase/tRNACUA pair. Using this library with Rtt109-Vps75 under steady-state conditions in the presence and absence of Asf1 we found that only the combination of Asf1 and H3K14ac/H4 could completely change the selectivity of Rtt109-Vps75. The ability of Asf1 to alter the selectivity of Rtt109-Vps75 only in the presence of H3K14ac, suggest that Asf1 was not only a histone chaperone but an acetyl reader. We identified an acidic patch on the backside of Asf1, which we propose ‘reads’ the acetylation state of the H3 tail (Figure 3) and from these data we proposed a new model that reconciles previously conflicting genetic and biochemical data.
The regulation of hydroxylated estrogens in cancer. The oxidative metabolite of estrogen, 4-hydroxyestrogen, could be oncogenic, while 2-hydroxyestrogen is suggested to be anti-proliferative. Both of these products could be further broken down by the P450 enzymes CYP1A1 and 1B1 to produce semiquinones and/or quinones causing DNA damage. Preventing the formation of quinones or semiquinones is the enzyme catechol-O-methyltransferase (COMT) can convert the catechol estrogens to methoxyestrogens. To begin to understand the role of these enzymes in oncogenesis we recently developed a UPLC-QqQ based assay for estrogens and their derivatives. Our assay improves on the sensitivity and speed of existing assays allowing for both in vivo (human urine and cell culture) and in vitro quantitation (Figure 4).
The Andrews laboratory is seeking a self-motivated and organized individual with interest in cancer epigenetics and translational biology to join a research team focused on understanding the molecular determinants of post-translation modifications and their consequences in terms of the epigenetic state of the cell in health and disease.
Our lab implements a variety of biophysical and analytical techniques to develop unique models to achieve lab goals. Our lab offers a dynamic and interdisciplinary environment in close interaction with laboratory- and computational-focused researchers as well as world class scientist and clinicians. Team members will gain experience and develop skill sets for next career stages. Also, team members will be involved in developing innovative methods and protocols for research and assist with the development of other research projects in the lab.
Individuals with strong expertise in enzymology, proteomics, biophysics or cell culture (chromatin/CRISPR) will be preferred. Computational skills will be an advantage. The postdoctoral individual will be expected to lead independent research projects, foster collaborations, present and communicate research findings at meetings and conferences. Qualified candidates must be dedicated and prepared to work the necessary hours required to develop a productive research career. The candidate will receive guidance in the development of independent research interests and grant proposals. Individuals must have a PhD or equivalent degree.
Learn more about research in the Andrews laboratory.
As one of the four original cancer centers to receive comprehensive designation from the National Cancer Institute, Fox Chase Cancer Center has been at the forefront of cancer research for almost 90 years. We are home to excellent research facilities, top clinicians and scientists, and outstanding patient care. Our singular focus on cancer, which couples discovery science with state of the art clinical care and population health, remains the foundation of our work.
The scientist training programs at Fox Chase Cancer Center provide professional development opportunities in four core areas identified as crucial for successful careers in science, research, and health care including communication, leadership, teaching, and mentorship. Upon joining the program, graduate students and postdocs develop individual development plans to help guide their growth. Training throughout the year is supplemented with free professional development opportunities, including a robust ‘How To’ series, writing courses, networking, mentorship, and teaching opportunities, a trainee-led seminar series, a trainee-led annual Research Conference, and more. Postdocs at Fox Chase Cancer Center are supported by the Temple University Postdoc Association and the Office of Academic Affairs at Fox Chase, and are compensated with competitive pay and benefits.
In addition to the robust training program, scientists at Fox Chase Cancer Center benefit from being part of the rich scientific and biotech environment in the Philadelphia region. Many of our former trainees are now employees (and contacts) at nearby institutions and companies, including The Wistar Institute, Merk, GSK, AACR, and numerous others.
Interested candidates who share a passion for innovation and believe our lab is suited for you, please send 1) your CV, 2) a brief cover letter describing your expertise and scientific interests, and 3) name and contact information of three references to Andrew Andrews, PhD at Andrew.Andrews@fccc.edu. Qualified candidates will then be invited to complete a job application.
Andrew.Andrews@fccc.edu
Office Phone: 215-728-5321
Fax: 215-728-3616
Lab Phone: 215-728-3558
Office: P3133
Lab: P3117
Andrew.Andrews@fccc.edu
Office Phone: 215-728-5321
Fax: 215-728-3616
Lab Phone: 215-728-3558
Office: P3133
Lab: P3117
Associate Professor
The goal of the Andrews lab is to elucidate the mechanisms of decision making in cells. Most of the time a single cell acts as the perfect CEO, using multitudes of data to make decisions, manage resources, and grow. Cells make decisions using a deep learning network, by having an input layer (biological signals), one or more hidden or interconnected layers, and finally, biological output. Our goal is to understand how these networks function when making correct and incorrect decisions. To do this, we need to map the interconnectedness of these hidden networks and mathematically model their relationships. To accomplish this goal, we combined classical enzymology with modern proteomics. This approach allows for the study of complex multi-substrate/product systems that can’t be understood using classical approaches.
There are >100 lysine residues within the nucleosome and greater than 90% have been shown to have post-translational modifications (PTMs) (Figure 1). If you considered PTMs as a chemical indexing system and each PTM creates a unique nucleosome you could make >1018 distinct nucleosomes. Not all of these modifications are observed and coordinated mechanisms of crosstalk suggest the potential that they may make up a learning network.
Mass spectrometry coupled enzyme kinetics in multiproduct systems (Figure 2). We were the first group to use validated quantitative and targeted mass spectrometry (UPLC-QqQ) to study lysine acetyltransferases (KATs) under steady state conditions, allowing us to monitor one substrate turning over into multiple products or acetylation states. This was a technical challenge due to the 100’s of samples that have to be quantitated for this analysis (typically 300 samples for one steady-state curve). We also needed to develop a new theoretical framework for the analysis of one substrate to multiple product turnover.
Specificity and selectivity of p300 and CBP are different and regulated by acetyl-CoA concentration. These two KATs share ~90% identity in their functional domains but are often correlated with different diseases and developmental responses. Thus, understanding their unique, site-specific activity has provided insight into how the function of the two proteins differ. The findings of our initial study were highlighted in F1000 for its importance in identifying unique differences in these two homologous enzymes. From this starting point we were then able to link acetyl-CoA concentration with the residue preferences of these enzymes (Figure 2). We proposed these enzymes potentially function through a monomeric cooperative model (manifesting as hysteresis), which predicts that at certain concentrations competitive inhibitors could activate the enzyme, resulting in a paradoxical activity. We were able to demonstrate this effect both in vitro and in vivo.
Histone chaperones can recognize histone PTMs, and direct crosstalk (Figure 3). Histone chaperones both interact with KATs and assemble and disassemble nucleosomes, strongly suggesting that they could regulate which histone residue could be modified. Rtt109 is a yeast KAT which is an active site structural homolog of human p300 and CBP and forms a complex with the histone chaperone Vps75 (Nap1 family). In vivo, Rtt109 functions with a second histone chaperone Asf1, to facilitate the acetylation of H3K56, which is critical for DNA damage in yeast. Early biochemical data was able to show that Asf1 could increase the activity of Rtt109-Vps75 but did not result in a change in selectivity. One of the major goals was to determine the mechanism of this change in selectivity observed in vivo. To test our hypothesis that pre-existing acetylation influences the selectivity of Rtt109-Vps75 we made a library of singly acetylated histones using a strain of E. coli containing an orthogonal Nε-acetyllysyl-tRNA synthetase/tRNACUA pair. Using this library with Rtt109-Vps75 under steady-state conditions in the presence and absence of Asf1 we found that only the combination of Asf1 and H3K14ac/H4 could completely change the selectivity of Rtt109-Vps75. The ability of Asf1 to alter the selectivity of Rtt109-Vps75 only in the presence of H3K14ac, suggest that Asf1 was not only a histone chaperone but an acetyl reader. We identified an acidic patch on the backside of Asf1, which we propose ‘reads’ the acetylation state of the H3 tail (Figure 3) and from these data we proposed a new model that reconciles previously conflicting genetic and biochemical data.
The regulation of hydroxylated estrogens in cancer. The oxidative metabolite of estrogen, 4-hydroxyestrogen, could be oncogenic, while 2-hydroxyestrogen is suggested to be anti-proliferative. Both of these products could be further broken down by the P450 enzymes CYP1A1 and 1B1 to produce semiquinones and/or quinones causing DNA damage. Preventing the formation of quinones or semiquinones is the enzyme catechol-O-methyltransferase (COMT) can convert the catechol estrogens to methoxyestrogens. To begin to understand the role of these enzymes in oncogenesis we recently developed a UPLC-QqQ based assay for estrogens and their derivatives. Our assay improves on the sensitivity and speed of existing assays allowing for both in vivo (human urine and cell culture) and in vitro quantitation (Figure 4).
This Fox Chase professor participates in the Undergraduate Summer Research Fellowship.
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