Biology subjects

Wende, A. R.

Publications and source records attributed to Wende, A. R..

3 recordsLinked to original sources

bioRxiv2026

ER Stress-Induced beta-Cell Apoptosis is Linked to Novel Select Lipid Signaling at the Transcriptional Level: Implications in T1D Development

Type 1 diabetes (T1D) is a consequence of {beta}-cell death. ER stress precedes T1D onset and prolonged ER stress in {beta}-cells can lead to {beta}-cell apoptosis. We reported that lipid signaling generated by the Ca2+-independent phospholipase A2{beta} (iPLA2{beta}), encoded by Pla2g6, participates in ER stress-mediated {beta}-cell apoptosis. {beta}-Cell membranes are enriched in arachidonic acid containing glycerophospholipids and the iPLA2{beta} catalyzes the hydrolysis of arachidonic acid in ER stressed {beta}-cells. Metabolism of arachidonic acid leads to the generation of various proinflammatory lipids, raising the possibility that they contribute to ER stress and {beta}-cell death leading to T1D. However, molecular mechanisms by which such {beta}-cell-iPLA2{beta}-derived lipid (iDL) signaling contributes to {beta}-cell apoptosis are not understood. It is well known that ER stress-mediated {beta}-cell apoptosis is associated with induction of transcription factors, NF{kappa}B and STAT1. We report here that both induce Pla2g6 and, unexpectedly, we find that iPLA2{beta}, which lacks DNA-binding motifs, associates with NFkB, Stat1, and Pla2g6 promoter regions. Consistently, p65-NF{kappa}B and pSTAT1 induction is reduced with select inhibition or knockdown of iPLA2{beta}. Surprisingly, iPLA2{beta} expression is also reduced by select inhibition of iPLA2{beta}, raising the possibility of feedback regulation by iDLs. In support, we find that select iDLs, recognized to be proinflammatory, enhance association of iPLA2{beta} with Pla2g6, Nfkb, and Stat1 promoter regions leading to induction of all three gene products and {beta}-cell apoptosis. Our findings reveal previously unrecognized transcriptional regulation by iDL signaling and, iPLA2{beta} itself, that leads to gene products that promote {beta}-cell apoptosis. Analogous findings in human islets validate this mechanism raising the possibility that targeting select lipid signaling can reduce ER stress in {beta}-cells and ameliorate T1D development.

cell biology↗

bioRxiv2025

A Transient Increase in Cardiomyocyte Protein O-GlcNAcylation Enhances Susceptibility to Pressure Overload-Induced Cardiac Remodeling

BACKGROUNDThe observation that diabetic patients always under tight-glycemic control consistently show better cardiovascular disease outcomes compared to patients who transition to tight-glycemic control after prior conventional glycemic control lead to the concept of metabolic memory. Mechanisms such as epigenetics possibly mediate the lasting metabolic memory effects, our understanding of the underlying mechanisms remains limited. Increased cardiac protein posttranslational O-linked {beta}-N-acetylglucosamine (O-GlcNAc) modification is implicated in cardiac remodeling observed in diabetes, and our previous work shows chronically elevated cardiomyocyte O-GlcNAc causes adverse cardiac changes. Therefore, the current study hypothesized that transiently increased cardiomyocyte O-GlcNAcylation leads to exacerbated adverse cardiac remodeling after subsequent pressure-overload. METHODS AND RESULTSUsing our previously described inducible cardiomyocyte specific, dominant-negative O-GlcNAcase (dnOGAh) mouse and single transgenic littermate controls (Con), we induced O-GlcNAc levels for 2wk (ON), followed by a 2wk washout (OFF); mice then underwent transverse-aortic constriction (TAC) or Sham surgery. We observed the expected cardiac remodeling in TAC groups, including decreased cardiac function, and increased hypertrophy and fibrosis. Moreover, these pathologic measures were exacerbated in the ON/OFF-TAC vs. Con-TAC mice; additionally, transcriptomic analysis of LV-tissue from each experimental group showed pathways which not only supported our fibrosis, hypertrophy and functional results of exacerbated cardiac remodeling, but also, revealed potential novel molecular pathways underlying this pathologic remodeling. CONCLUSIONSWe observed exacerbated cardiac pathology between ON/OFF-TAC vs. Con-TAC groups supporting the concept of "O-GlcNAc memory" as a component of metabolic memory. Moreover, transcriptomic analysis provides insight into potential molecular pathways underpinning this metabolic/O-GlcNAc memory such as Ccn2/CTGF-driven fibrosis, and/or Nox4-driven oxidative stress. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/657956v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@717ea9org.highwire.dtl.DTLVardef@132bdcaorg.highwire.dtl.DTLVardef@4a2bdaorg.highwire.dtl.DTLVardef@18508d9_HPS_FORMAT_FIGEXP M_FIG C_FIG Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIWe provide a novel paradigm to study phenotypic and molecular effects of specific, transiently increased cardiomyocyte O-GlcNAcylation on the heart. C_LIO_LIOur results show exacerbated adverse cardiac remodeling due to transiently increased cardiomyocyte O-GlcNAc with pressure-overload, supporting the concept of "O-GlcNAc memory" as a component of metabolic memory. C_LIO_LITranscriptomic insights show gene expression basis for not only observed exacerbated adverse cardiac remodeling (e.g., hypertrophy, fibrosis, cardiac dysfunction), but also potential molecular pathways that could drive cardiac pathology exacerbation of O-GlcNAc memory. C_LI What are the clinical implications?O_LIThis study supports a concept of "O-GlcNAc memory", where previously increased cardiomyocyte protein O-GlcNAcylation can impact the later development of differential cardiac pathology--like the pathology seen in metabolic memory research. C_LIO_LIThe potential role of O-GlcNAc in mediating metabolic memory will help focus future translational research on this modification and downstream cardiac effects in diabetes. C_LIO_LITranscriptomic profiling of cardiac remodeling in this model provides an investigational roadmap for future molecular and functional studies to identify novel therapeutics that ameliorate heart disease induced by differential metabolic memory. C_LI

molecular biology↗

bioRxiv2018

Prolactin Receptor Signaling Regulates a Pregnancy-Specific Transcriptional Program in Mouse Islets

Pancreatic {beta}-cells undergo profound hyperplasia during pregnancy to maintain maternal euglycemia. Failure to reprogram {beta}-cells into a more replicative state has been found to underlie susceptibility to gestational diabetes mellitus (GDM). We recently identified a requirement for prolactin receptor (PRLR) signaling in the metabolic adaptations to pregnancy, where mice lacking {beta}-cell PRLR ({beta}PRLRKO) exhibit a metabolic phenotype consistent with GDM. However, the underlying transcriptional program that is responsible for the PRLR-dependent metabolic adaptations during gestation remains incompletely understood. To identify PRLR signaling gene regulatory networks and target genes within {beta}-cells during pregnancy, we performed a transcriptomic analysis of pancreatic islets isolated from either {beta}PRLRKO mice or littermate controls in late gestation. Gene set enrichment analysis identified Forkhead box protein M1 (Foxm1) and polycomb repressor complex 2 (PRC2) subunits, Suz12 and Ezh2, as novel candidate regulators of PRLR-dependent {beta}-cell adaptation. GO-term pathway enrichment revealed both established and novel PRLR signaling target genes that together describe a state of increased cellular metabolism and/or proliferation. In contrast to the requirement for {beta}-cell PRLR signaling in maintaining euglycemia during pregnancy, PRLR target genes were not induced following high-fat-diet feeding. Altogether, the current study expands our understanding of which transcriptional regulators and networks mediate gene expression required for islet adaptation during pregnancy. The current work also supports the presence of pregnancy-specific adaptive mechanisms distinct from those activated by nutritional stress.

bioinformatics↗