JUL 29, 2020 11:00 AM EDT

STAT3 phosphorylation during phagocytosis is required to activate autophagy and prevent macrophage immuno-senescence

C.E. Credits: Florida CE P.A.C.E. CE
Speaker
  • Research Fellow, Post-doctoral research Associa, Centre for Regenerative Medicine, University of Edinburgh
    BIOGRAPHY

Abstract

Background: Acute liver injury (ALI) is characterised by hepatocyte death and liver inflammation. Macrophages play a pivotal role in ALI by phagocytosing dead cells and producing pro-regenerative signals. We have previously demonstrated that phagocytic cargo-dependent activation of phosphoSTAT3 is required to maintain phagocytosis efficiency in macrophages. In this study, we aim to understand the molecular mechanisms underlying the pro-phagocytic function of phosphoSTAT3.

Methods: Phagocytosing bone marrow derived macrophages (BMDMs) treated with and without a phosphoSTAT3 inhibitor, or from mice deficient for the cargo digestion step of phagocytosis (Gpnmb-), were analysed using flow cytometry, transmission electron microscopy (TEM), and qPCR. We used paracetamol overdose (POD) as mouse model for ALI. We FAC-Sorted and analysed infiltrating macrophages from livers at early stages of POD (10h post-overdose) with the nCounter® technology (Nanostring) and using proteomics.

Results: Gpnmb- mice are unable to regenerate their liver efficiently after POD: infiltrating phagocytosing macrophages FAC-Sorted from these mice showed increased expression of senescence-related genes, such as Tnfrsf1b and Cdkn1a, but not of apoptosis-related genes, such as Card9. This suggests that macrophages unable to process the internalised cargo enter immuno-senescence, a condition characterised by elevated production of inflammatory cytokines and reduced phagocytosis. TEM and qPCR analyses showed that both Gpnmb- and phosphoSTAT3 inhibitor-treated BMDMs develop a senescent phenotype during phagocytosis, suggesting that cargo digestion-dependent phosphorylation of STAT3 prevents immuno-senescence in phagocytosing macrophages. Autophagy is a mechanism widely used by cells to cope with stress: interestingly, TEM and qPCR analyses unveiled a lower activation of autophagy in Gpnmb- and phosphoSTAT3 inhibitor-treated BMDMs.

Conclusions: Phagocytosing macrophages require phosphoSTAT3 activation.

 

Learning Objectives:

1. Understand the use of flow cytometry-based medium throughput screening assays as an essential tool to investigate macrophage phagocytosis

2. Describe the role of pSTAT3 as a pro-phagocytic pathway in macrophages

3. Explain that other pathways are controlled downstream of pSTAT3, including autophagy and senescence


Show Resources
You May Also Like
SEP 14, 2021 7:00 AM PDT
C.E. CREDITS
SEP 14, 2021 7:00 AM PDT
Date: September 14, 2021 Time: 7am PDT, 10am EDT, 4pm CEST A conventional thermal cycler has long been a commodity product in the lab and end-point PCR techniques can be completed almost wit...
SEP 17, 2021 12:00 PM CST
C.E. CREDITS
SEP 17, 2021 12:00 PM CST
Date: September 16, 2021 Time: 9:00pm (PDT), 12:00am (EDT) 3D cellular models like organoids and spheroids offer an opportunity to better understand complex biology in a physiologically rele...
MAY 11, 2021 10:00 AM PDT
C.E. CREDITS
MAY 11, 2021 10:00 AM PDT
Date: May 11, 2021 Time: 10:00zm PDT Your samples are some of the most valuable assets in the laboratory. After spending countless hours on extraction and preparation, your conclusions could...
JUN 09, 2021 7:00 AM PDT
C.E. CREDITS
JUN 09, 2021 7:00 AM PDT
Date: June 9, 2021 Time: 09 June 2021, 7am PDT, 10am EDT, 4pm CEST cells with dramatic implications on the validity of past cell culture related research. The fact that at least 509 cell lin...
JUL 15, 2021 9:00 AM PDT
JUL 15, 2021 9:00 AM PDT
Date: July 15, 2021 Time: 9:00am (PDT), 12:00pm (EDT) The Pisces workflow robust, easy-to-use, end-to-end multi-omics solution for highly multiplexed targeted Spatial RNA analysis. VeranomeB...
OCT 20, 2021 10:00 AM PDT
C.E. CREDITS
OCT 20, 2021 10:00 AM PDT
Date: October 20, 2021 Time:10:00am (PDT), 1:00pm (EDT) As the prevalence of Diabetes continues to rise in many areas across the globe, healthcare providers continue to look for methods that...
Loading Comments...
Show Resources