Graduate Students

PhD Students

Yanaira Alonso (Neuroscience), Ferrario Lab

yanairaa@umich.edu

Currently working on the role of the reproductive cycle in modulating approach to food cues in female obesity-prone and obesity-resistant rats.

Rachel Altshuler, Jutkiewicz/Gnegy Lab

altshr@umich.edu

The selective protein Kinase Cβ inhibitor, enzastaurin, decreases amphetamine stimulated locomotion and self-administration in rats.

Extracellular dopamine levels are regulated by the dopamine transporter (DAT), a transmembrane protein that takes up dopamine from the synapse into the cell. Amphetamines are substrates of DAT and reverse DAT function to release dopamine into the synapse. Amphetamines elicit their stimulating and reinforcing effects by increasing extracellular dopamine levels in the brain. Protein Kinase Cβ (PKCβ) is important for amphetamine’s effects on outward transport without altering basic DAT function. Inhibition of PKCβ reduces amphetamine-stimulated dopamine efflux through the transporter in vitro and in vivo. The purpose of this study was to examine if PKCβ inhibition would decrease key amphetamine-stimulated behaviors: locomotion and self-administration. The selective PKCβ inhibitor, enzastaurin (1-10 pmol), was administered to male Sprague-Dawley rats by intracerebroventricular (icv) injections 18 hours before behavioral evaluation. Locomotor activity was measured in infrared beam break boxes following administration of single doses (0.32-3.2 mg/kg) of amphetamine. In self-administration studies, rats earned infusions of amphetamine (0.032 mg/kg/infusion) or sucrose pellets under a fixed ratio 5 schedule of reinforcement for 60- or 20-minute sessions, respectively. Pretreatment with 10 pmol enzastaurin reduced locomotion following injections of 0.32 and 1 mg/kg amphetamine but the effect was surmountable at 3.2 mg/kg amphetamine, demonstrating a rightward shift in the amphetamine dose-effect curve. 1 pmol enzastaurin was not sufficient to decrease locomotor activity. Enzastaurin decreased the number of amphetamine infusions earned by 60% but did not alter the number of sucrose pellets earned, suggesting that enzastaurin altered the reinforcing effects of amphetamine but not natural rewards. The data demonstrate that low doses of a specific PKCβ inhibitor attenuate amphetamine-mediated behaviors in a surmountable manner without non-selectively altering behavior. This study demonstrates that inhibition of PKCβ serves to reduce amphetamine reinforcement and could have therapeutic utility against amphetamine abuse.

Veronica Beck (Neuroscience), Isom Lab

vcbeck@umich.edu

I am interested in studying intestinal and metabolic dysfunction in a Dravet model of epilepsy, as well as potential therapeutic effects of a ketogenic diet in this model.

Amanda Davis (Bolles), Osawa Lab

abolles@umich.edu

Protein Quality Control by the Hsp70/Hsp90 Chaperone System and Deubiquitinating Enzymes

Protein quality control is an essential process for the maintenance of cellular function. Proteins can be damaged as a result of disease or exposure to exogenous toxins. Damaged proteins must be selectively degraded to prevent their accumulation that, if left unchecked, can lead to cellular dysfunction. The Osawa lab has utilized mechanism based inactivators to damage neuronal nitric oxide synthase (nNOS) in order to study how the cell selectively culls damaged proteins for degradation. We have found that the heat shock protein 70 and 90 (Hsp70/90) chaperones recognize damaged nNOS and selectively triage the damaged protein for ubiquitination and proteasomal degradation. Through a series of studies investigating the role of the Hsp70/90 chaperones in the regulation of nNOS ubiquitination we have demonstrated that Hsp70 and Hsp90 play opposing roles in the regulation of client protein degradation. Hsp70 and its co-chaperone CHIP (c-terminus of Hsp70 interacting protein) ubiquitinates damaged protein and tags it for proteasomal degradation whereas Hsp90 stabilizes damaged protein and prevents degradation. We have applied the knowledge gained in these studies to develop new therapeutic strategies in neurodegenerative disease by enhancing the degradation of misfolded Hsp70/90 client proteins. In collaboration with the lab of Dr. Andrew Lieberman we demonstrated that activation of Hsp70 reduces neurotoxicity in a Drosophila model of spinal bulbar muscular atrophy. As part of these studies I am currently working to identify the role of deubiquitinating enzymes (DUBs) in the regulation of nNOS ubiquitination. Inhibition of DUBs responsible for nNOS deubiquitination may offer a new therapeutic strategy to enhance the selective degradation of nNOS. Preliminary studies have demonstrated that inhibition of DUBs by WP1130 increases nNOS ubiquitination in HEK293T cells. In order to identify DUBs capable of cleaving nNOS ubiquitin conjugates an in vitro purified protein DUB screen was utilized. Eleven DUBs capable of deubiquitinating nNOS were identified the majority of which were members of the ubiquitin specific protease subclass. These results suggest that DUBs play a role in the regulation nNOS ubiquitination.

Allie Bouza, Isom Lab

Gwendolyn Burgess, Jutkiewicz lab

Neikelyn Burgos, Rotating: Auchus Lab

Naincy Chandan, Smrcka Lab

Song Chen, Parent Lab

Stephanie Crilly (Cellular & Molec Biology), Puthenveedu Lab

Cara D'Amico, Kennedy Lab

Nick Denomme, Isom Lab

Rebecca Derman (Neuroscience), Ferrario Lab

rderman@umich.edu

I study the contribution of glutamatergic circuits in the expression of cue-triggered food seeking behaviors in pre-clinical models of obesity-vulnerable individuals.

Jean Rodriguez Diaz (Neuroscience), Jones Lab

jcrd@umich.edu

Our research is focused on determining the role of NMDA receptors in network activity. In particular we are studying how NMDA receptor antagonism influences chemical induced oscillations.

Nnamdi Edokobi, Isom Lab

Dana Felker (Toxicology), Osawa Lab

Nicholas Griggs, Traynor Lab

nwgriggs@umich.edu

In the Traynor lab I study opioid receptor signaling and perform radioligand binding and second messenger assays to evaluate the affinity and functional activity of opioid ligands. In collaboration with the lab of Dr. Henry Mosberg in Medicinal Chemistry, we have characterized the SAR for hundreds of novel multifunctional ligands in pursuit of developing opioid compounds that demonstrate reduced tolerance and dependence liabilities. With this library of pharmacological tools, my objective is to elucidate how delta opioid receptor antagonism/inhibition modulates mu opioid receptor signaling.

Mirella Hernandez (Neuroscience), Jones Lab

Jacob Hull (Neuroscience), Isom Lab

Nichelle Jackson, Jones Lab

Jenny Kunselman (Cell & Molecular Biology), Puthenveedu Lab

Eli Lavender, Rotating: Ginsburg Lab

Zesen "Jason" Lin, Khoriaty/Shayman Lab

zesenlin@umich.edu

Investigation of the function and importance of Syt-7 in exocytosis by FTIR microscopy and patch clamping.

Joshua Lott, Puthenveedu Lab

Joel Maust, Leopold Lab

joeldm@umich.edu

Co-targeting MEK and CDK4/6 to Treat Pancreatic Cancer.

Hyperactivation of KRAS and inactivation of CDKN2A [p16] play a prominent role in tumor initiation and progression in a broad spectrum of human cancers. In pancreatic adenocarcinoma, KRAS mutation occurs in 90-95% of cases and is often coupled with inactivation of CDKN2A (>90% incidence), typically by homozygous deletion. Based on the high incidence of these genomic events, the present study addresses the hypothesis that dual targeting of MEK and CDK4/6 represents a viable therapeutic strategy for the treatment of pancreatic adenocarcinoma. A panel of primary and high passage xenograft models was screened for in vitro synergy to the antiproliferative effects of the MEK inhibitor trametinib and the CDK4/6 inhibitor palbociclib. Two models that emerged as highly sensitive to this combination treatment strategy, L3.6pl and UM59, both exhibited G1 cell cycle arrest that was significantly more pronounced in response to the combination compared to either single agent. In vivo studies were subsequently carried out to evaluate the efficacy of this combination in tumor-bearing mice. Mice implanted subcutaneously with L3.6pl or UM59 cells were treated daily by oral gavage for ten days with trametinib (3 mg/kg), palbociclib (100 mg/kg), or the combination of these two agents at these doses. Consistent with in vitro synergy observations, both models proved to be exceptional responders in vivo to this combination treatment strategy, showing a robust response to the combination not seen with either single agent. These results suggest that the combined inhibition of MEK and CDK4/6 may offer a valuable therapeutic strategy for the treatment of pancreatic adenocarcinoma. Studies are ongoing to identify molecular determinants of response in pancreatic tumors that are highly sensitive to this combination approach to guide future patient enrichment strategies.

Nicole Michmerhuizen, Brenner/Carey Lab

nmich@umich.edu

Head and neck squamous cell carcinoma (HNSCC) is a common form of cancer that is often debilitating, disfiguring and difficult to treat. Genes in the phosphatidylinositol 3-kinase (PI3K) pathway are often altered in HNSCC, contributing to tumor development and progression. My thesis project seeks to better understand how to use drugs that inhibit PI3K signaling to stop cancer growth and improve HNSCC patient prognosis.

Alina Morales, Anantharam Lab

Andrew Nelson, Jenkins Lab

Andrea Pesch, Speers/Rae Lab

Julie Philippe, Jenkins Lab

Jaquelyn Sanchez, Cohen Lab

jaquesan@umich.edu

My project focuses on inhibiting function of Hsp90 — a molecular chaperone responsible for the proteostasis of over 400 “client” proteins in eukaryotic cells — to overcome difficult-to-treat drug resistant melanomas. Our novel inhibitors target the carboxy terminus (C-terminal) of the chaperone decreasing adverse effects that plague all other Hsp90 inhibitors tested in clinical trials. We hypothesize that C-terminal inhibition of Hsp90 will simultaneously inhibit resistance pathways to rescue these drug resistant melanomas.

Bryan Sears, Jutkiewicz Lab

Alex Stanczyk, Traynor Lab

mastan@umich.edu

Probing Allosteric Modulation of Opioid Receptors. Focus on downstream signaling bias and in-vivo implications. Ultimate aim is elucidating novel mechanisms for analgesics with reduced side effect profiles.

Ben Thompson, Satin Lab

Kaylin White, Isom Lab

Jiuling Yang, Wang Lab

jiulingy@umich.edu

Targeting MDM2 degradation for new cancer therapy

The murine double minute 2 (MDM2) is an oncogenic protein and is the most important negative regulator of tumor suppressor p53. MDM2 is amplified and/or overexpressed in many different types of human cancers and is considered as an attractive cancer therapeutic target. A number of small-molecule inhibitors designed to target the MDM2-p53 interaction, such as RG7112 (Hoffmann-La Roche), MI-773 (U Michigan/Sanofi) and DS-3032b (Daiichi Sankyo), have been advanced into human clinical trials for cancer treatment. In addition to target the MDM2-p53 interaction, we have recently discovered a class of small-molecule inhibitors that can potently and effectively induce MDM2 degradation. In my seminar, I will present my initial investigation for their mechanism of action (MOA) and therapeutic potential for the treatment of human cancers.

XiaoXue Zhang, Satin Lab

xiaoxue@umich.edu

INVESTIGATING THE ROLE OF ER STRESS ON BETA CELL FUNCTION IN MOUSE PANCREATIC ISLETS

Type 2 diabetes mellitus (T2DM) is characterized by impaired glucose-stimulated insulin secretion and insulin resistance. Insulin is secreted from pancreatic beta-cells in response to a rise in plasma glucose in a pulsatile manner that is driven by Ca2+ oscillations. The endoplasmic reticulum (ER) is known to be one of the important Ca2+ sequestering and releasing organelle in the beta cell. Although it is well accepted that maintaining ER homeostasis is critical to proper beta cell function, the specific effects of ER stress and dysfunction on beta cell function are not completely understood. To determine the interrelationship between ER stress and intracellular free Ca2+ in pancreatic beta cells, we treated insulin-secreting INS-1 cells or isolated mouse islets with tunicamycin (TM; 10μg/ml) or DMSO as a control. Cytosolic Ca2+ was measured by loading islets with the Ca2+ sensing dye FURA2 and imaging its fluorescence using spectrofluorimetry. ER Ca2+ was measured using a novel, genetically-encoded FRET probe (D4ER). Treating islets for 16 hours with TM reduced ER Ca2+. To measure ER stress, levels of xbp1 mRNA splicing and BiP protein were measured by qPCR and immunoblotting. XBP1s and BiP levels started to increase after 6 hours and 12hours of TM treatment, respectively. Furthermore, PARP cleavage, a marker of initiation of apoptotic death, was observed after 12 hours of TM treatment by immunoblotting. We are continuing to fully delineate the effects of ER stress on insulin exocytosis and investigate the mechanism which ER stress occurs prior to ER Ca2+ reduction.

 

Master Students

Samara Attalla

Hao Chen

Haiying Dai

Rebecca Gorney

Paphitchaya Kewcharoenvong

Nicholas Kolbman

Michaela Kus

Ashleigh Matthews

Emily Ridge

Jiayu Wang

Yang Xu

Mohammed Zalmout

Yating Zheng