TY  - JOUR
A1  - Meir, Michael
A1  - Kannapin, Felix
A1  - Diefenbacher, Markus
A1  - Ghoreishi, Yalda
A1  - Kollmann, Catherine
A1  - Flemming, Sven
A1  - Germer, Christoph-Thomas
A1  - Waschke, Jens
A1  - Leven, Patrick
A1  - Schneider, Reiner
A1  - Wehner, Sven
A1  - Burkard, Natalie
A1  - Schlegel, Nicolas
T1  - Intestinal epithelial barrier maturation by enteric glial cells is GDNF-dependent
JF  - International Journal of Molecular Sciences
N2  - Enteric glial cells (EGCs) of the enteric nervous system are critically involved in the maintenance of intestinal epithelial barrier function (IEB). The underlying mechanisms remain undefined. Glial cell line-derived neurotrophic factor (GDNF) contributes to IEB maturation and may therefore be the predominant mediator of this process by EGCs. Using GFAP\(^{cre}\) x Ai14\(^{floxed}\) mice to isolate EGCs by Fluorescence-activated cell sorting (FACS), we confirmed that they synthesize GDNF in vivo as well as in primary cultures demonstrating that EGCs are a rich source of GDNF in vivo and in vitro. Co-culture of EGCs with Caco2 cells resulted in IEB maturation which was abrogated when GDNF was either depleted from EGC supernatants, or knocked down in EGCs or when the GDNF receptor RET was blocked. Further, TNFα-induced loss of IEB function in Caco2 cells and in organoids was attenuated by EGC supernatants or by recombinant GDNF. These barrier-protective effects were blunted when using supernatants from GDNF-deficient EGCs or by RET receptor blockade. Together, our data show that EGCs produce GDNF to maintain IEB function in vitro through the RET receptor.
KW  - enteric glial cells
KW  - neurotrophic factors
KW  - intestinal epithelial barrier
KW  - GDNF5
KW  - RET6
KW  - inflammatory bowel disease
KW  - enteric nervous system
KW  - gut barrier
KW  - intercellular junctions
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258913
SN  - 1422-0067
VL  - 22
IS  - 4
ER  - 
TY  - JOUR
A1  - Burkard, Natalie
A1  - Meir, Michael
A1  - Kannapin, Felix
A1  - Otto, Christoph
A1  - Petzke, Maximilian
A1  - Germer, Christoph-Thomas
A1  - Waschke, Jens
A1  - Schlegel, Nicolas
T1  - Desmoglein2 Regulates Claudin2 Expression by Sequestering PI-3-Kinase in Intestinal Epithelial Cells
JF  - Frontiers in Immunology
N2  - Inflammation-induced reduction of intestinal desmosomal cadherin Desmoglein 2 (Dsg2) is linked to changes of tight junctions (TJ) leading to impaired intestinal epithelial barrier (IEB) function by undefined mechanisms. We characterized the interplay between loss of Dsg2 and upregulation of pore-forming TJ protein Claudin2. Intraperitoneal application of Dsg2-stablising Tandem peptide (TP) attenuated impaired IEB function, reduction of Dsg2 and increased Claudin2 in DSS-induced colitis in C57Bl/6 mice. TP blocked loss of Dsg2-mediated adhesion and upregulation of Claudin2 in Caco2 cells challenged with TNFα. In Dsg2-deficient Caco2 cells basal expression of Claudin2 was increased which was paralleled by reduced transepithelial electrical resistance and by augmented phosphorylation of AKT\(^{Ser473}\) under basal conditions. Inhibition of phosphoinositid-3-kinase proved that PI-3-kinase/AKT-signaling is critical to upregulate Claudin2. In immunostaining PI-3-kinase dissociated from Dsg2 under inflammatory conditions. Immunoprecipitations and proximity ligation assays confirmed a direct interaction of Dsg2 and PI-3-kinase which was abrogated following TNFα application. In summary, Dsg2 regulates Claudin2 expression by sequestering PI-3-kinase to the cell borders in intestinal epithelium.
KW  - Claudin2
KW  - Dsg2
KW  - inflammation
KW  - intestinal barrier
KW  - PI-3-kinase
KW  - inflammatory bowel disease
KW  - desmosome
KW  - tight junction
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-247059
SN  - 1664-3224
VL  - 12
ER  -