Dr. Stephens receives R01 award from the National Institute of Diabetes and Digestion and Kidney Diseases, 2024
Our proposed studies are designed to define the molecular mediators of β-cell ER redox control and address how ER hyperoxidation develops in Type 2 diabetes.

"A metabolic redox relay supports ER proinsulin export in pancreatic islet β-cells", published in JCI Insight, 2024
This study builds upon our previous work demonstrating that ER redox capacity is compromised in diabetes models of β-cell dysfunction. This new study demonstrates that β-cell ER redox capacity is maintained via active glucose metabolism to ensure ER folding capacity meets the biosynthetic demands of glucose-stimulated insulin production.

Dr. Stephens receives Breakthrough Type 1 Diabetes (formerly JDRF) award, 2024
These studies will explore how Golgi structural changes lead to remodeling the β-cell surface in the development of T1D.

Palin Narsian receives OUR fellowship, 2024
Palin is an undergraduate research assistant in the lab who was awarded an Office of Undergraduate Research (OUR) fellowship. He will continue his project examining the islet β-cell adaptive response to chronic hyperglycemia.
Congratulations Palin!

Cierra Boyer defends her doctoral dissertation, 2024
Cierra successfully passed her doctoral defense and will graduate with a Ph.D. from the Department of Neuroscience and Pharmacology in May. Her dissertation is titled "β-cell secretory capacity as an adaptive mechanism during the development of Type 2 diabetes"
Congratulations Dr. Cierra Boyer!

Kristen Rohli defends her doctoral dissertation, 2024
Kristen successfully passed her doctoral defense and will graduate with a Ph.D. from the Interdisciplinary Graduate Program in Genetics in May. Her dissertation is titled "Metabolic regulation of ER redox homeostasis maintains insulin granule formation in pancreatic β-cells"
Congratulations Dr. Kristen Rohli!

Kristen Rohli featured in U Iowa Graduate College newsletter, 2024
Kristen was interviewed for a recent article entitled "Genetics student unlocking the mystery of Type 2 diabetes" featured in the March newsletter from the Graduate College.
Congratulations Kristen!

Sandra Blom awarded F31 NIH pre-doctoral fellowship, 2024
Sandra's project, entitled "GRASP55 Regulates Pancreatic Beta-cell Golgi Structure and Function During Cytokine Stress" will explore how Golgi structural changes develop in response to inflammatory signals early in development of T1D.
Congratulations Sandra!

"Loss of the Golgi-localized v-ATPase subunit does not alter insulin granule formation or pancreatic islet β-cell function" published in American Journal of Physiology- Endocrinology and Metabolism, 2024
This study is based on our previous work identifying Golgi structural defects and Golgi export delays in diabetes models. This new study shows that loss of the Golgi-localized subunit of the v-ATPase pump, v0a2, results in modest perturbations to Golgi lumenal pH and structure, but does not impact beta-cell function or the beta-cell's ability to respond to diet-induced obesity and insulin resistance.

Kimberly Jackson joins the Stephens lab, 2023
Kimberly joins the Stephens lab as an undergraduate research assistant. She is currently pursuing her major in Math at the University of Iowa.
Welcome Kimberly!

Kristen Rohli and Cierra Boyer both awarded the Ballard and Seashore Dissertation Fellowship, 2023
Congratulations Kristen and Cierra for this great achievement!

Palin Narsian receives ICRU fellowship, 2023
Palin is an undergraduate research assistant in the lab who was awarded an Iowa Center for Research by Undergraduates (ICRU) fellowship. He will be examining the islet β-cell adaptive response to chronic hyperglycemia.
Congratulations Palin!

Dr. Stephens promoted to Associate Professor with tenure, 2023
Thanks to past and present trainees for your help making this possible!

Kristen Rohli wins poster competition at the Midwest Islet Club Meeting, 2023
Kristen's poster titled, "Nutrient metabolism regulates insulin granule formation in the pancreatic islet β-cell via ER redox homeostasis" was awarded a cash prize as the "Best Poster Presentation".
Congratulations Kristen!

"Synchronized proinsulin trafficking reveals delayed Golgi export accompanies β-cell secretory dysfunction in rodent models of hyperglycemia" published in Scientific Reports, 2023
This work highlights the utility of the proCpepRUSH reporter in studying proinsulin trafficking dynamics and suggests that altered Golgi export function contributes to β-cell secretory defects in the pathogenesis of Type 2 diabetes.

Palin Narsian joins the Stephens lab, 2023
Palin joins the Stephens lab as an undergraduate research assistant. He is currently pursuing his major in Biomedical Engineering at the University of Iowa.
Welcome Palin!

Cierra Boyer's proinsulin trafficking system on display in Medicine Iowa, 2022
Cierra Boyer has been developing a reporter system based on the RUSH technology to visualize proinsulin trafficking. Images of β-cells using this system were featured in Medicine Iowa.
Congratulations Cierra!

Ethan Miera joins the Stephens lab, 2022
Ethan joins the Stephens lab as an undergraduate research assistant. He is currently pursuing his major in Biomedical Engineering at the University of Iowa.
Welcome Ethan!

"ER redox homeostasis regulates proinsulin trafficking and insulin granule formation in the pancreatic islet β-cell" published in Function, 2022
This study demonstrates that proinsulin exit from the ER is delayed in models of Type 2 diabetes as a result of hyperoxidation of the ER lumen. We further demonstrate that restoration of ER redox can restore proinsulin trafficking and partially rescue β-cell function in diabetes models.

Dr. Stephens receives a catalyst award from the Fraternal Order of Eagles Diabetes Research Center, 2022
Our studies will use animal models and human β-cells to understand how metabolism supplies antioxidants to the insulin production machinery and more importantly, how this process is lost in the development of T2D.

Cierra Boyer wins poster competition at the Pharmacology and Neuroscience Annual Retreat, 2022
Cierra's poster titled, "Creb3 regulates increased β-cell secretory capacity as an adaptive mechanism during β-cell compensation" was awarded 1st place and a cash prize as the "Best Poster Presentation".
Congratulations Cierra!

Sandra Blom passes her comprehensive exam, 2022
Sandra passed her comprehensive exam for the Molecular Medicine Graduate Program and has moved forward to the next stage of her Ph.D. dissertation work.
Congratulations Sandra!

Kristen Rohli receives 2nd year of T32 Fellowship in Genetics, 2022
Kristen’s work has uncovered a novel observation that chronic hyperglycemia associated with Type 2 diabetes results in hyperoxidation of the ER, which leads to a deficit in the production of mature insulin. To further study this process, Kristen was awarded a fellowship on the Genetic Program NIH T32 Training Grant.
Congratulations Kristen!

Cierra Boyer wins oral presentation at the Midwest Islet Club meeting, 2022
Cierra presented her research entitled “Creb3 Regulates Increased β-Cell Secretory Capacity as an Adaptive Mechanism During β-Cell Compensation" at the 14th Annual Midwest Islet Club meeting. Cierra was voted the Best Oral Presentation.
Congratulations Cierra!

Nicole Stubbe receives ICRU fellowship, 2022
Nicole is an undergraduate research assistant in the lab who was awarded an Iowa Center for Research by Undergraduates (ICRU) fellowship.  She will be examining how metabolic activity contributes to proinsuiln trafficking and insulin granule formation in the islet β-cell.
Congratulations Nicole!

"Nutrient Regulation of Pancreatic Islet β-Cell Secretory Capacity and Insulin Production" published in Biomolecules, 2022
This review article is part of a special edition on the pancreatic islet β-cell and summarizes current knowledge and our thoughts on the regulation of ER and Golgi functions necessary to support insulin production in response to changes in nutrient status.

Kristen Rohli presents at the ADA Islet Biology Webinar, 2022
Kristen will present her research titled, "Nutrient metabolism regulates insulin granule formation in the pancreatic islet β-cell via ER redox homeostasis" for the American Diabetes Association Islet Biology, Development, and Function Webinar on Jan. 26 at 5:00 CST.  Registration for the webinar can be found here.
Congratulations Kristen!

Cierra Boyer wins poster competition at Internal Medicine Research Day, 2021
Cierra's poster titled, "Creb3 regulates increased β-cell secretory capacity as an adaptive mechanism during β-cell compensation" was awarded 1st place and a cash prize as the "Best Trainee Poster" at the annual Internal Medicine Research Day poster competition.
Congratulations Cierra!

Kristen Rohli passes her comprehensive exam, 2021
Kristen passed her comprehensive exam for the Interdisciplinary Graduate Program in Genetics and has moved forward to the next stage of her Ph.D. dissertation work.
Congratulations Kristen!

Kristen Rohli wins the ADA Islet Biology Thesis competition, 2021
Kristen competed in a 3-minute poster presentation hosted by the American Diabetes Association Islet Biology, Development and Function Interest Group.  Despite stiff competition from other outstanding graduate students around the nation, Kristen was selected as the winner.  As part of Kristen's prize, she will present her work on "Nutrient metabolism regulates insulin granule formation in the pancreatic islet β-cell via ER redox homeostasis" in an upcoming ADA webinar.
Congratulations Kristen!

Nicole Stubbe joins the Stephens lab, 2021
Nicole joins the Stephens lab as an undergraduate research assistant. She is currently pursuing her major in Biomedical Engineering at the University of Iowa.
Welcome Nicole!

Kristen Rohli wins 2nd place in Genetics Retreat Poster contest, 2021
Kristen's poster presentation entitled "Hyperglycemia delays ER export of proinsulin via altered ER redox homeostasis" was awarded 2nd place at the Annual Genetics Retreat.
Congratulations Kristen!

Cierra Boyer passes her comprehensive exam, 2021
Cierra passed her comprehensive exam for the Department of Pharmacology and has moved forward to the next stage of her Ph.D. dissertation work.
Congratulations Cierra!

"Mitochondrial efflux of citrate and isocitrate is fully dispensable for glucose-stimulated insulin secretion and pancreatic islet β-cell function" selected for cover art in Diabetes, 2021
Images taken for our recent study on the mitochondrial citrate-isocitrate carrier were selected for the cover art of the August edition of Diabetes.

Kristen Rohli receives T32 Fellowship in Genetics, 2021
Kristen’s work has uncovered a novel observation that chronic hyperglycemia associated with Type 2 diabetes results in early defects in the trafficking of the insulin precursor, proinsulin, from the ER to Golgi, leading to impairments in the production of mature insulin. To further study this process, Kristen was awarded a fellowship on the Genetic Program NIH T32 Training Grant.
Congratulations Kristen!

"Mitochondrial efflux of citrate and isocitrate is fully dispensable for glucose-stimulated insulin secretion and pancreatic islet β-cell function" published in Diabetes, 2021
This study opposes current dogma in the β-cell field by demonstrating that the mitochondrial citrate-isocitrate carrier is not required for glucose-stimulated insulin secretion. Furthermore, we highlight disconnects in our understanding of the roles of Idh1, NADPH, and glutathione in the regulation of β-cell function.

Ashleigh Machado receives ICRU fellowship for 2nd year, 2021
Ashleigh is an undergraduate research assistant in the lab who was once again awarded an Iowa Center for Research by Undergraduates (ICRU) fellowship.  She will be examining how Golgi sorting enzymes contribute to insulin granule formation and trafficking during early stages in the development of Type 2 diabetes.
Congratulations Ashleigh!

Sandra Blom joins the Stephens lab, 2021
Sandra joins the Stephens lab from the Molecular Medicine graduate program for her Ph.D. training.
Welcome Sandra!

Kristen Rohli's digital poster is on display, 2021
Kristen's poster entitled "Hyperglycemia delays ER export of proinsulin via altered ER redox homeostasis" is on display in the MERF-PBDB skyway connector (2nd floor).  This work details the observation that proinsulin export from the ER is delayed in beta-cells cultured with elevated glucose and fatty acid.  Included in this work are some stunning images of proinsulin trafficking using our SNAPtag model system and identification of proinsulin interactions by proximity labeling with APEX2 performed in collaboration with the Proteomics Core Facility.
Great job Kristen!

Ashleigh Machado receives ICRU fellowship, 2020
Ashleigh is an undergraduate research assistant in the lab who was awarded an Iowa Center for Research by Undergraduates (ICRU) fellowship.  She will be developing genetically encoded sensors to explore the role of organelle pH in the regulation of insulin granule trafficking.
Congratulations Ashleigh!

Casey Bauchle departs for Ph.D. training at the University of Virginia, 2020
Casey has been a research technician in the lab since 2018 and has been an outstanding member of our group. He has made numerous contributions to the research, which thus far have proven to be instrumental in many of the initiatives we are now following.  Casey is now embarking on the next steps in his training at the University of Virginia where I have no doubt that he will excel. We will genuinely miss him.
Best of luck Casey!

Kristen Rohli joins the Stephens lab, 2020
Kristen joins the Stephens lab from the Interdisciplinary Graduate Program in Genetics for her Ph.D. training
Welcome Kristen!

Cierra Boyer joins the Stephens lab, 2020
Cierra joins the Stephens lab from the Pharmacology graduate program for her Ph.D. training
Welcome Cierra!

Dr. Stephens receives an American Diabetes Association Individual Basic Science Award, 2020
The major goal of this proposal is to address a significant gap in our understanding of insulin granule assembly and trafficking, provide mechanistic insight into how VGF and CgB regulate β-cell function, and define how VGF and CgB contribute to β-cell secretory capacity in T2D.

Dr. Stephens receives Carver College of Medicine Innovator award, 2020
This project aims to investigate the contribution of metabolism to changes in β-cell secretory function.

Dr. Stephens receives Department of Defense award, 2020
These studies will explore secretory trafficking dysfunction as a central mechanism in the progressive decline of β-cell function in the pathogenesis of Type 2 diabetes.

Marshall Moyer earns a research track distinction with his MD, 2020
Marshall Moyer received his MD degree from the University of Iowa and was awarded the research track distinction for his work in the lab on developing a system to study proinsulin interactions in models of β-cell dysfunction.
Congratulations Marshall!

McKenzie Becker receives her B.S. in Chemistry, 2019,
McKenzie Becker has been an undergraduate research assistant in the lab for the past 2 years and has been instrumental in cloning many of the reporters and plasmid backbones we will use for years to come.
Congratulations McKenzie!

Weston Elison joins us for a summer research fellowship from BYU, 2019
Weston is a rising junior from BYU who was awarded a fellowship through the BYU Inspiring Learning Fellowship program.  Weston will work on developing a cell culture model of the diabetic β-cell using exposure to elevated glucose and lipids to mimic hyperglycemia and hyperlipidemia present in human Type 2 diabetes.
Welcome Weston!

Marshall Moyer joins us again for a summer research fellowship, 2019
Marshall's research project will be to map out novel protein interactions necessary for insulin trafficking within the pancreatic islet β-cell.  To do this, we are using a proximity labeling system (APEX) to enzymatically tag proteins interacting with proinsulin.  This approach will provide us with both spatial and temporal resolution of key mediators regulating insulin trafficking and allow us to investigate how these interactions are altered in pathological states of β-cell dysfunction such as Type 2 diabetes.
Welcome back Marshall!

Shelby Bearrows is featured in an interview for her recent publication in the Journal of Cell Science, 2019
Shelby was selected for an interview as an opportunity to promote early-stage career researchers for first author trainees. Congratulations Shelby!

"Chromogranin B regulates early stage insulin granule trafficking from the Golgi in pancreatic islet β-cells" published in Journal of Cell Science, 2019
This study highlights a specific role for chromogranin B (CgB) in the regulation of insulin granule formation at the trans-Golgi network utilizing a novel in situ fluorescent pulse-chase imaging technique to study insulin trafficking. Images from this work were selected for cover art for the July edition of JCS.

Visit our image of β-cells on display in the CBRB hallway, 2018
A confocal image generated by Shelby Bearrows from immunostained β-cells and spatially rendered using Imaris software was selected for display on the lower level hallway of the Pappajohn Biomedical Research Building.
Congratulations Shelby!

Shelby Bearrows wins oral presentation at the Midwest Islet Club meeting, 2018
Shelby presented her research entitled “Chromogranin B regulates early stage granule trafficking from the trans-Golgi network in pancreatic islet β-cells” at the 11th annual Midwest Islet Club meeting in St. Louis, MO.  Shelby was selected for the Best Oral Presentation Award.
Congratulations Shelby!

Dr. Stephens receives Central Microscopy Research Facility Pilot Grant, 2018
This project aims to develop a novel fluorescent pulse-chase reporter for evaluating proinsulin trafficking.

"The prohormone VGF regulates β-cell function via insulin secretory granule biogenesis" published in Cell Reports, 2017
The paper describes a novel role of the prohormone and granin-like protein VGF in the regulation of secretory granule formation and insulin secretion in pancreatic islet beta-cells.  

Marshall Moyer receives a summer research fellowship, 2017
Marshall will examine the insulinotropic actions of a novel peptide, TLQP-21, using mouse models lacking the putative TLQP-21 receptor, C3aR1.
Welcome Marshall!

"Delayed apoptosis allows islet β-cells to implement an autophagic mechanism to promote cell survival" published in PLoS One, 2017
This paper describes a novel feature of primary islet β-cells to be highly resistant to ER stress and DNA damage-induced apoptosis, which has garnered little attention in the literature.  While β-cell survival and death pathways are commonly modeled in insulinoma cell lines, we demonstrate these events to be quite distinct between isolated islets and insulinoma cells.