Papers you should know

Question 1

Yes-associated Protein (YAP) Promotes Cell Survival by Inhibiting Proapoptotic Dendrin Signaling

Kirk N. Campbell et al, 2013

Mount Sinai, Division of Nephrology

Answer 1

Significance: podocytes lacking YAP in vitro are more susceptible to injury(staurosporine)

Model: Mouse podocytes in vitro and in vivo

Background: Dendrin can relocate from the cytoplasm to the nucleus to promote podocyte apoptosis.

Methods: Co-IP to determine if YAP binds dendrin via WW domains; to directly test whether endogenous YAP could confer anti-
apoptotic properties in podocytes, used a gene silencing approach(shRNA) to reduce the expression of YAP in differentiated podocytes

Results: YAP is constitutively expressed in podocyte nuclei, binds to dendrin, and inhibits dendrin-mediated podocyte apoptosis

Question 2

Podocyte-Specific Deletion of Yes-Associated Protein
Causes FSGS and Progressive Renal Failure

Monica Schwartzman( Kirk Campbell group)

2015

Answer 2

Significance: Podocyte specific deletion of YAP leads to FSGS in mice

Model: Mouse model, with human FSGS biopsy samples to confirm staining

Methods: Yap was selectively silenced in podo-
cytes using Cre-mediated recombination controlled by the podocin promoter. Meaured proteinuria(Coomassie staining, renal function was determined by measuring serumc reatinine by liquid chromatography–tandem mass spectrometry. ) histology, morhpology of shed podocytes in urine

Results: YAP silencing resulted in increased apoptosis, podocyte depletion, and protenuria. This suggests a role for YAP as a physiologic antagonist of podocyte apoptosis, essential for maintaining glomerular barrier

Question 3

YAP-mediated mechanotransduction determines the podocyte’s response to damage

Markus M Rinschen
(2017)

Department of Internal Medicine, Cologne, Germny

Answer 3

Model: Semi-immortalized human podocytes, mouse podocytes, mouse model containing Tet-on for wt mouseYAP and constitutive mouse YAP

Background: Cytoskeletal/morphological changes of podocytes associated with proteinuric disease

Methods: Time resolved proteomics to identify upregulated proteins in rat model of PAN induced nephrosis; performed proteomics analysis on both undiff and diff human podocytes; qPCR for YAP target genes; tested effects of substrate rigidity using engineered matrices/ cytoD

Results: YAP/TAZ cytoplasmically located in rat glomeruli under control conditions; PAN causes reduction of YAP(slightly) and YAP target genes/ protein in vitro, BUT NOT IN VIVO; YAP overexpression associated wtih mild albinuria in vivo, but no other adverse effects/histology; in vitro YAP overexpression associated with ECM protein production, leading authors to speculate it may be pro-fibrotic

Question 4

Nuclear YAP localization as key regulator of podocyte function

Jakob Bonse( Beate Vollenbroker)
2018
Department of Nephrology, Internal Medicine University Hospital Muenster, Muenster, Germany

Answer 4

_Significance:_ Supports the notion that nuclear YAP localization in cultured podocytes indeed reects the in vivo situation and can be used as an appropriate model system. Further show 
 function of nuclear YAP as a pro-survival factor for podocytes.

Background: Induction of Hippo pathway in vitro via KIBRA overexpression increased podocyte apoptosis; in mice, deletion of YAP in podocytes led to FSGS; human FSGS patients have increased pYAP. Other studies suggest cytoplasmic YAP is normal in control conditions(mouse model)

Methods: Assessed affects of Hippo activation in 3 ways: plated cells on very soft matrices(<12kPA) to test YAP mechanosensitivity; treated cells with Datsinib ; overexpressed LATS kinase

Results: Cells plated on soft matrices not viable, caused cytoplasmic localization of YAP; cells treated with Datsinib reduced viabilty, increased cyto YAP; LATs overexpression increased apoptosis, increased cyto YAP

Conclusions