Nicole Krentz

All Publications

• Insights into pancreatic islet cell dysfunction from type 2 diabetes mellitus genetics. Nature reviews. Endocrinology Krentz, N. A., Gloyn, A. L. 2020

  Abstract

  Type 2 diabetes mellitus (T2DM) is an increasingly prevalent multifactorial disease that has both genetic and environmental risk factors, resulting in impaired glucose homeostasis. Genome-wide association studies (GWAS) have identified over 400 genetic signals that are associated with altered risk of T2DM. Human physiology and epigenomic data support a central role for the pancreatic islet in the pathogenesis of T2DM. This Review focuses on the promises and challenges of moving from genetic associations to molecular mechanisms and highlights efforts to identify the causal variant and effector transcripts at T2DM GWAS susceptibility loci. In addition, we examine current human models that are used to study both beta-cell development and function, including EndoC-beta cell lines and human induced pluripotent stem cell-derived beta-like cells. We use examples of four T2DM susceptibility loci (CDKAL1, MTNR1B, SLC30A8 and PAM) to emphasize how a holistic approach involving genetics, physiology, and cellular and developmental biology can disentangle disease mechanisms at T2DM GWAS signals.

  View details for DOI 10.1038/s41574-020-0325-0

  View details for PubMedID 32099086

• Loss of ZnT8 function protects against diabetes by enhanced insulin secretion. Nature genetics Dwivedi, O. P., Lehtovirta, M., Hastoy, B., Chandra, V., Krentz, N. A., Kleiner, S., Jain, D., Richard, A. M., Abaitua, F., Beer, N. L., Grotz, A., Prasad, R. B., Hansson, O., Ahlqvist, E., Krus, U., Artner, I., Suoranta, A., Gomez, D., Baras, A., Champon, B., Payne, A. J., Moralli, D., Thomsen, S. K., Kramer, P., Spiliotis, I., Ramracheya, R., Chabosseau, P., Theodoulou, A., Cheung, R., van de Bunt, M., Flannick, J., Trombetta, M., Bonora, E., Wolheim, C. B., Sarelin, L., Bonadonna, R. C., Rorsman, P., Davies, B., Brosnan, J., McCarthy, M. I., Otonkoski, T., Lagerstedt, J. O., Rutter, G. A., Gromada, J., Gloyn, A. L., Tuomi, T., Groop, L. 2019; 51 (11): 1596?1606

  Abstract

  A rare loss-of-function allele p.Arg138* in SLC30A8 encoding the zinc transporter 8 (ZnT8), which is enriched in Western Finland, protects against type 2 diabetes (T2D). We recruited relatives of the identified carriers and showed that protection was associated with better insulin secretion due to enhanced glucose responsiveness and proinsulin conversion, particularly when compared with individuals matched for the genotype of a common T2D-risk allele in SLC30A8, p.Arg325. In genome-edited human induced pluripotent stem cell (iPSC)-derived ?-like cells, we establish that the p.Arg138* allele results in reduced SLC30A8 expression due to haploinsufficiency. In human ? cells, loss of SLC30A8 leads to increased glucose responsiveness and reduced KATP channel function similar to isolated islets from carriers of the T2D-protective allele p.Trp325. These data position ZnT8 as an appealing target for treatment aimed at maintaining insulin secretion capacity in T2D.

  View details for DOI 10.1038/s41588-019-0513-9

  View details for PubMedID 31676859

  View details for PubMedCentralID PMC6858874

• TrxG Complex Catalytic and Non-catalytic Activity Play Distinct Roles in Pancreas Progenitor Specification and Differentiation. Cell reports Campbell, S. A., McDonald, C. L., Krentz, N. A., Lynn, F. C., Hoffman, B. G. 2019; 28 (7): 1830?44.e6

  Abstract

  Appropriate regulation of genes that coordinate pancreas progenitor proliferation and differentiation is required for pancreas development. Here, we explore the role of H3K4 methylation and the Trithorax group (TrxG) complexes in mediating gene expression during pancreas development. Disruption of TrxG complex assembly, but not catalytic activity, prevented endocrine cell differentiation in pancreas progenitor spheroids. In vivo loss of TrxG catalytic activity in PDX1+ cells increased apoptosis and the fraction of progenitors in the G1 phase of the cell cycle. Pancreas progenitors were reallocated to the acinar lineage, primarily at the expense of NEUROG3+ endocrine progenitors. Later in development, acinar and endocrine cell numbers were decreased, and increased gene expression variance and reduced terminal marker activation in acinar cells led to their incomplete differentiation. These findings demonstrate that TrxG co-activator activity is required for gene induction, whereas TrxG catalytic activity and H3K4 methylation help maintain transcriptional stability.

  View details for DOI 10.1016/j.celrep.2019.07.035

  View details for PubMedID 31412250

• Single-Cell Transcriptome Profiling of Mouse and hESC-Derived Pancreatic Progenitors. Stem cell reports Krentz, N. A., Lee, M. Y., Xu, E. E., Sproul, S. L., Maslova, A., Sasaki, S., Lynn, F. C. 2018; 11 (6): 1551?64

  Abstract

  Human embryonic stem cells (hESCs) are a potential unlimited source of insulin-producing ? cells for diabetes treatment. A greater understanding of how ? cells form during embryonic development will improve current hESC differentiation protocols. All pancreatic endocrine cells, including ? cells, are derived from Neurog3-expressing endocrine progenitors. This study characterizes the single-cell transcriptomes of 6,905 mouse embryonic day (E) 15.5 and 6,626 E18.5 pancreatic cells isolated from Neurog3-Cre; Rosa26mT/mG embryos, allowing for enrichment of endocrine progenitors (yellow; tdTomato + EGFP) and endocrine cells (green; EGFP). Using a NEUROG3-2A-eGFP CyT49 hESC reporter line (N5-5), 4,462 hESC-derived GFP+ cells were sequenced. Differential expression analysis revealed enrichment of markers that are consistent with progenitor, endocrine, or previously undescribed cell-state populations. This study characterizes the single-cell transcriptomes of mouse and hESC-derived endocrine progenitors and serves as a resource (https://lynnlab.shinyapps.io/embryonic_pancreas) for improving the formation of functional ?-like cells from hESCs.

  View details for DOI 10.1016/j.stemcr.2018.11.008

  View details for PubMedID 30540962

  View details for PubMedCentralID PMC6294286

• Phosphorylation of NEUROG3 Links Endocrine Differentiation to the Cell Cycle in Pancreatic Progenitors. Developmental cell Krentz, N. A., van Hoof, D., Li, Z., Watanabe, A., Tang, M., Nian, C., German, M. S., Lynn, F. C. 2017; 41 (2): 129?42.e6

  Abstract

  During pancreatic development, proliferating pancreatic progenitors activate the proendocrine transcription factor neurogenin 3 (NEUROG3), exit the cell cycle, and differentiate into islet cells. The mechanisms that direct robust NEUROG3 expression within a subset of progenitor cells control the size of the endocrine population. Here we demonstrate that NEUROG3 is phosphorylated within the nucleus on serine 183, which catalyzes its hyperphosphorylation and proteosomal degradation. During progression through the progenitor cell cycle, NEUROG3 phosphorylation is driven by the actions of cyclin-dependent kinases 2 and 4/6 at G1/S cell-cycle checkpoint. Using models of mouse and human pancreas development, we show that lengthening of the G1 phase of the pancreatic progenitor cell cycle is essential for proper induction of NEUROG3 and initiation of endocrine cell differentiation. In sum, these studies demonstrate that progenitor cell-cycle G1 lengthening, through its actions on stabilization of NEUROG3, is an essential variable in normal endocrine cell genesis.

  View details for DOI 10.1016/j.devcel.2017.02.006

  View details for PubMedID 28441528

  View details for PubMedCentralID PMC5517315

• SOX4 cooperates with neurogenin 3 to regulate endocrine pancreas formation in mouse models. Diabetologia Xu, E. E., Krentz, N. A., Tan, S., Chow, S. Z., Tang, M., Nian, C., Lynn, F. C. 2015; 58 (5): 1013?23

  Abstract

  The sex-determining region Y (SRY)-related high mobility group (HMG) box (SOX) family of transcription factors is essential for normal organismal development. Despite the longstanding knowledge that many SOX family members are expressed during pancreas development, a role for many of these factors in the establishment of insulin-producing beta cell fate remains to be determined. The aim of this study is to elucidate the role of SOX4 during beta cell development.We used pancreas and endocrine progenitor mouse knockouts of Sox4 to uncover the roles of SOX4 during pancreas development. Lineage tracing and in vitro models were used to determine how SOX4 regulates beta cell formation and understand the fate of Sox4-null endocrine lineage cells.This study demonstrates a progenitor cell-autonomous role for SOX4 in regulating the genesis of beta cells and shows that it is required at multiple stages of the process. SOX4 deletion in the multipotent pancreatic progenitors resulted in impaired endocrine progenitor cell differentiation. Deletion of SOX4 later in the Neurog3-expressing cells also caused reductions in beta cells. Lineage studies showed loss of Sox4 in endocrine progenitors resulted in a block in terminal islet cell differentiation that was attributed to reduction in the production of key beta cell specification factors.These results demonstrate that SOX4 is essential for normal endocrine pancreas development both concomitant with, and downstream of, the endocrine fate decision. In conclusion, these studies position Sox4 temporally in the endocrine differentiation programme and provide a new target for improving in vitro differentiation of glucose-responsive pancreatic beta cells.

  View details for DOI 10.1007/s00125-015-3507-x

  View details for PubMedID 25652387

• TALEN/CRISPR-mediated eGFP knock-in add-on at the OCT4 locus does not impact differentiation of human embryonic stem cells towards endoderm. PloS one Krentz, N. A., Nian, C., Lynn, F. C. 2014; 9 (12): e114275

  Abstract

  Human embryonic stem cells (hESCs) have great promise as a source of unlimited transplantable cells for regenerative medicine. However, current progress on producing the desired cell type for disease treatment has been limited due to an insufficient understanding of the developmental processes that govern their differentiation, as well as a paucity of tools to systematically study differentiation in the lab. In order to overcome these limitations, cell-type reporter hESC lines will be required. Here we outline two strategies using Transcription Activator Like Effector Nucleases (TALENs) and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-Associated protein (Cas) to create OCT4-eGFP knock-in add-on hESC lines. Thirty-one and forty-seven percent of clones were correctly modified using the TALEN and CRISPR-Cas9 systems, respectively. Further analysis of three correctly targeted clones demonstrated that the insertion of eGFP in-frame with OCT4 neither significantly impacted expression from the wild type allele nor did the fusion protein have a dramatically different biological stability. Importantly, the OCT4-eGFP fusion was easily detected using microscopy, flow cytometry and western blotting. The OCT4 reporter lines remained equally competent at producing CXCR4+ definitive endoderm that expressed a panel of endodermal genes. Moreover, the genomic modification did not impact the formation of NKX6.1+/SOX9+ pancreatic progenitor cells following directed differentiation. In conclusion, these findings demonstrate for the first time that CRISPR-Cas9 can be used to modify OCT4 and highlight the feasibility of creating cell-type specific reporter hESC lines utilizing genome-editing tools that facilitate homologous recombination.

  View details for DOI 10.1371/journal.pone.0114275

  View details for PubMedID 25474420

  View details for PubMedCentralID PMC4256397

• A regulatory network controls nephrocan expression and midgut patterning. Development (Cambridge, England) Hou, J., Wei, W., Saund, R. S., Xiang, P., Cunningham, T. J., Yi, Y., Alder, O., Lu, D. Y., Savory, J. G., Krentz, N. A., Montpetit, R., Cullum, R., Hofs, N., Lohnes, D., Humphries, R. K., Yamanaka, Y., Duester, G., Saijoh, Y., Hoodless, P. A. 2014; 141 (19): 3772?81

  Abstract

  Although many regulatory networks involved in defining definitive endoderm have been identified, the mechanisms through which these networks interact to pattern the endoderm are less well understood. To explore the mechanisms involved in midgut patterning, we dissected the transcriptional regulatory elements of nephrocan (Nepn), the earliest known midgut specific gene in mice. We observed that Nepn expression is dramatically reduced in Sox17(-/-) and Raldh2(-/-) embryos compared with wild-type embryos. We further show that Nepn is directly regulated by Sox17 and the retinoic acid (RA) receptor via two enhancer elements located upstream of the gene. Moreover, Nepn expression is modulated by Activin signaling, with high levels inhibiting and low levels enhancing RA-dependent expression. In Foxh1(-/-) embryos in which Nodal signaling is reduced, the Nepn expression domain is expanded into the anterior gut region, confirming that Nodal signaling can modulate its expression in vivo. Together, Sox17 is required for Nepn expression in the definitive endoderm, while RA signaling restricts expression to the midgut region. A balance of Nodal/Activin signaling regulates the anterior boundary of the midgut expression domain.

  View details for DOI 10.1242/dev.108274

  View details for PubMedID 25209250

  View details for PubMedCentralID PMC4197584

• Npas4 is a novel activity-regulated cytoprotective factor in pancreatic ?-cells. Diabetes Sabatini, P. V., Krentz, N. A., Zarrouki, B., Westwell-Roper, C. Y., Nian, C., Uy, R. A., Shapiro, A. M., Poitout, V., Lynn, F. C. 2013; 62 (8): 2808?20

  Abstract

  Cellular homeostasis requires intrinsic sensing mechanisms to temper function in the face of prolonged activity. In the pancreatic ?-cell, glucose is likely a physiological trigger that activates an adaptive response to stimulation, thereby maintaining cellular homeostasis. Immediate early genes (IEGs) are activated as a first line of defense in cellular homeostasis and are largely responsible for transmitting an environmental cue to a cellular response. Here we examine the regulation and function of the novel ?-cell IEG, neuronal PAS domain protein 4 (Npas4). Using MIN6 cells, mouse and human islets, as well as in vivo infusions, we demonstrate that Npas4 is expressed within pancreatic islets and is upregulated by ?-cell depolarizing agents. Npas4 tempers ?-cell function through a direct inhibitory interaction with the insulin promoter and by blocking the potentiating effects of GLP-1 without significantly reducing glucose-stimulated secretion. Finally, Npas4 expression is induced by classical endoplasmic reticulum (ER) stressors and can prevent thapsigargin- and palmitate-induced dysfunction and cell death. These results suggest that Npas4 is a key activity-dependent regulator that improves ?-cell efficiency in the face of stress. We posit that Npas4 could be a novel therapeutic target in type 2 diabetes that could both reduce ER stress and cell death and maintain basal cell function.

  View details for DOI 10.2337/db12-1527

  View details for PubMedID 23656887

  View details for PubMedCentralID PMC3717850