Biology subjects

Pin, C. L.

Publications and source records attributed to Pin, C. L..

5 recordsLinked to original sources

bioRxiv2023

EZH2 deletion does not impact acinar cell regeneration but restricts progression to pancreatic cancer in mice

Enhancer of Zeste Homologue 2 (EZH2) is part of the Polycomb Repressor Complex 2, which induces trimethylation of lysine 27 on histone 3 (H3K27me3) and promotes genes repression. EZH2 is overexpressed in many cancers including pancreatic ductal adenocarcinoma (PDAC). Previous studies in mice attributed both pro-oncogenic and tumor suppressive functions to EZH2. Deletion of the EZH2 enhances de novo KRAS-driven neoplasia following pancreatic injury by preventing acinar cell regeneration, while increased EZH2 expression in PDAC is correlated to poor prognosis, suggesting a context-dependant effect for EZH2 in PDAC progression. In this study, we examined EZH2 function in pre-and early neoplastic stages of PDAC. Using an inducible model to generate deletion of EZH2 only in adult acinar cells (EZH2{Delta}SET), we showed loss of EZH2 activity did not prevent acinar cell regeneration in the absence of oncogenic KRAS (KRASG12D), nor lead to increased PanIN formation in the presence of KRASG12D in adult mice. However, loss of EZH2 did reduce recruitment of inflammatory cells and, when combined with a PDAC model, promoted widespread PDAC progression. Loss of EZH2 function also correlated to remodeling of the tumor microenvironment, which favors cancer cell progression. This study suggests expression of EZH2 in adult acinar cells restricts PDAC initiation and progression by affecting both the tumour microenvironment and acinar cell differentiation.

cancer biology↗

bioRxiv2023

Defining the SPCA2C interactome identifies unique links to store-operated calcium entry

Calcium (Ca2+) is critical for normal cell function and several protein networks are required for Ca2+ signaling. In the pancreas, regulated changes in cytosolic Ca2+ allow for the exocytosis of zymogen granules and altered Ca2+ signaling underlies pancreatic pathologies. Previously, our laboratory showed a pancreas-specific isoform of secretory pathway Ca2+-ATPase 2 (SPCA2C) affects multiple pathways involved in Ca2+ homeostasis. The goal of this study was to define the SPCA2C interactome that contributes to these processes. Using proximity-dependent biotin identification, BioID, we expressed SPCA2C-BirA*HA in HEK293 cells with constitutive Orai1 expression. In silico modeling of SPCA2C showed a highly dynamic cytosolic C-terminus, revealing a putative site for interactions and was selected for BirA* fusion. 150 candidate SPCA2C interactors were identified. Gene Ontology and KEGG Pathway analyses supported localization of SPCA2C to the endoplasmic reticulum as well as function in Ca2+ signaling and suggested roles in vesicular transport. SPCA2C interactions with stromal interaction molecule 1 (STIM1), extended synaptotagmin-1 (ESYT1), and aspartate beta-hydroxylase (ASPH) were validated. Coiled-coil domain containing protein 47 (CCDC47) ranked as a high confidence SPCA2C-interactor which was confirmed through immunoprecipitation and co-localization with SPCA2C. CCDC47 interactions with SPCA2C, STIM1 and Orai1 were maintained following deletion of the CCDC47 luminal and cytosolic domains while deletion of only the coiled-coil domain altered CCDC47 localization and decreased interactions with STIM1 and Orai1. Overall, this study defines several novel protein interactions for SPCA2C and suggests it may be involved in affecting CCDC47, STIM1 and Orai1 function.

cell biology↗

bioRxiv2023

KRASG12D-mediated PanIN progression in mice is affected by gene driving cre recombinase expression

The fundamental biology of pancreatic ductal adenocarcinoma has been greatly impacted by the characterization of genetically modified mouse models that allow temporal and spatial activation of oncogenic KRAS (KRASG12D). The most commonly used model involves targeted insertion of a cre recombinase into the Ptf1a gene. However, this approach disrupts the Ptf1a gene, resulting in haploinsufficiency that likely affects sensitivity to oncogenic KRAS (KRASG12D). The goal of this study was to determine if Ptf1a haploinsufficiency affected the acinar cell response to KRASG12D before and after induction of pancreatic injury. We performed morphological and molecular analysis of three mouse lines that express a tamoxifen-inducible cre recombinase to activate KRASG12D in acinar cells of the pancreas. The cre-recombinase was targeted to the acinar-specific transcription factor genes, Ptf1a and Mist1/Bhlha15, or expressed within a BAC-derived Elastase transgene. Up to two months after tamoxifen induction of KRASG12D, morphological changes were negligible. However, induction of pancreatic injury by cerulein resulted in stark differences in tissue morphology between lines within seven days, which were maintained for at least five weeks after injury. Ptf1acreERT pancreata showed widespread PanIN lesions and fibrosis, while the Mist1creERT and Ela-creERT models showed reduced amounts of pre-neoplastic lesions. RNA-seq analysis prior to inducing injury suggested Ptf1acreERT and Mist1creERT lines have unique profiles of gene expression that predict a differential response to injury. Multiplex analysis of pancreatic tissue confirmed different inflammatory responses between the lines. These findings suggest understanding the mechanisms underlying the differential response to KRASG12D will help in further defining the intrinsic KRAS-driven mechanisms of neoplasia initiation.

cancer biology↗

bioRxiv2020

NUPR1 protects liver from lipotoxic injury by improving the endoplasmic reticulum stress response

Background and AimsNon-alcoholic fatty liver disease and related hepatic syndromes affect up to one third of the adult population. The molecular mechanisms underlying NAFL etiology remain elusive. Nuclear Protein 1 (NUPR1) expression increases upon cell injury in all organs and recently we report its active participation in the activation of the Unfolded Protein Response (UPR). The UPR typically maintains protein homeostasis, but downstream mediators of the pathway regulate metabolic functions, including lipid metabolism. NUPR1 and UPR increase have been reported in obesity and liver pathologies and the goal of this study was to investigate the roles of NUPR1 in this context. MethodsWe used patient-derived liver biopsies and in vitro and in vivo NUPR1 loss of functions models. First, we analysed NUPR1 expression in a cohort of morbidly obese patients (MOPs), with either simple fatty liver (NAFL) or more severe steatohepatitis (NASH). Next, we explored the metabolic roles of NUPR1 in wild type (Nupr1+/+) or Nupr1 knockout mice (Nupr1-/-) fed ad libitum with a high fat diet (HFD) for up to 15 weeks. ResultsNUPR1 expression is inversely correlated to hepatic steatosis progression. We found that NUPR1 participates in the activation of PPAR- signalling via UPR. PPAR- signalling, is involved in the maintenance of fat metabolism and proper lipid homeostasis and energy balance. As PPAR- signalling is controlled by UPR, collectively, these findings suggest a novel function for NUPR1 in protecting liver from metabolic distress by controlling lipid homeostasis, possibly through the UPR. ObjectiveNon-alcoholic fatty liver (NAFL) disease and related hepatic syndromes affect up to one third of the adult population in industrialised and developing countries. However, the molecular mechanisms underlying NAFL etiology remain elusive. Nuclear Protein 1 (NUPR1) expression increases upon cell injury in all organs including the liver. Recently, we report NUPR1 actively participates in activation of the Unfolded Protein Response (UPR). The UPR typically maintains protein homeostasis, but downstream mediators of the pathway regulate metabolic functions, including lipid metabolism. NUPR1 and UPR increase have been reported in obesity and liver pathologies and the goal of this study was to investigate the roles of NUPR1 in this context. DesignWe used patient-derived liver biopsies and in vitro and in vivo NUPR1 loss of functions models. First, we analysed NUPR1 expression in a cohort of morbidly obese patients (MOPs), with either simple fatty liver (NAFL) or more severe steatohepatitis (NASH). Next, we explored the metabolic roles of NUPR1 in wild type (Nupr1+/+) or Nupr1 knockout mice (Nupr1-/-) fed ad libitum with a high fat diet (HFD) for up to 15 weeks. ResultsNUPR1 expression is inversely correlated to hepatic steatosis progression. Mechanistically, we found NUPR1 participates in the activation of PPAR- signalling via UPR. PPAR- signalling, is involved in the maintenance of fat metabolism and proper lipid homeostasis and energy balance. As PPAR- signalling is controlled by UPR, collectively, these findings suggest a novel function for NUPR1 in protecting liver from metabolic distress by controlling lipid homeostasis, possibly through the UPR. ConclusionsAs PPAR- signalling is controlled by UPR, collectively, these findings suggest a novel function for NUPR1 in protecting liver from metabolic distress by controlling lipid homeostasis, possibly through the UPR. Lay summaryNUPR1 is activated during high caloric intake in both mice and patients. Decrease in expression or inhibition of NUPR1 worsens lipid deposition and hepatic damage. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=192 SRC="FIGDIR/small/350652v1_ufig1.gif" ALT="Figure 1"> View larger version (46K): org.highwire.dtl.DTLVardef@1d370c0org.highwire.dtl.DTLVardef@8f8dc9org.highwire.dtl.DTLVardef@a5aa49org.highwire.dtl.DTLVardef@4eb585_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LINUPR1 protects liver from high caloric intake hepatic damage C_LIO_LIThe function of NUPR1 in this context is to control the lipid homeostasis through the UPR and more specifically through PPAR- signalling. C_LIO_LINUPR1 could be used as a predictive marker for the gravity of NAFL progression. Moreover, as clinical interest is being raised around NUPR1 inhibitors to treat liver and pancreatic cancer, care should be taken in monitoring lipotoxic parameters. C_LI

cell biology↗

bioRxiv2020

Loss of Activating Transcription Factor 3 prevents KRAS-mediated pancreatic cancer

The unfolded protein response (UPR) is activated in pancreatic pathologies and suggested as a target for therapeutic intervention. In this study, wxe examined Activating Transcription Factor 3 (ATF3), a mediator of the UPR which promotes acinar-to-ductal metaplasia (ADM) in response to pancreatic injury. Since ADM is an initial step in the progression to pancreatic ductal adenocarcinoma (PDAC), we hypothesized ATF3 is required for initiation and progression of PDAC. We generated mice carrying a germ line mutation of Atf3 (Atf3-/-) combined with acinar-specific induction of oncogenic KRAS (Ptf1acreERT/+KrasLSL-G12D). Atf3-/- mice with (termed APK) and without KRASG12D were exposed to cerulein-induced pancreatitis. In response to recurrent pancreatitis, Atf3-/- mice showed decreased ADM and enhanced regeneration based on morphological and biochemical analysis. Similarly, an absence of ATF3 reduced spontaneous pancreatic intraepithelial neoplasia formation and PDAC in Ptf1acreERT/+KrasLSL-G12D mice. In response to injury, KRASG12D bipassed the requirement for ATF3 with a dramatic loss in acinar tissue and PanIN formation observed regardless of ATF3 status. However, unlike Ptf1acreERT/+KrasLSL-G12D mice, APK mice exhibited a cachexia-like phenotype, did not progress through to PDAC, and showed altered pancreatic fibrosis and immune cell infiltration. These findings suggest a complex, multifaceted role for ATF3 in pancreatic cancer pathology.

cancer biology↗