SV40 small T antigen and PP2A phosphatase in cell transformation

Alterations involving serine-threonine phosphatase PP2A subunits occur in a range of human cancers, and partial loss of PP2A function contributes to cell transformation. Displacement of regulatory B subunits by the SV40 Small T antigen (ST) or mutation/deletion of PP2A subunits alters the abundance and types of PP2A complexes in cells, leading to transformation. Here, we show that ST not only displaces common PP2A B subunits but also promotes A-C subunit interactions with alternative B subunits (B’’’, striatins) that are components of the Striatin-interacting phosphatase and kinase (STRIPAK) complex. We found that STRN4, a member of STRIPAK, is associated with ST and is required for ST-PP2A-induced cell transformation. ST recruitment of STRIPAK facilitates PP2A-mediated dephosphorylation of MAP4K4 and induces cell transformation through the activation of the Hippo pathway effector YAP1. These observations identify an unanticipated role of MAP4K4 in transformation and show that the STRIPAK complex regulates PP2A specificity and activity.

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Critical Role for SV40 Small-t Antigen in Human Cell Transformation

Virology ◽

10.1006/viro.2001.1204 ◽

2001 ◽

Vol 290 (2) ◽

pp. 192-198 ◽

Cited By ~ 87

Author(s):

Jing Yu ◽

Anita Boyapati ◽

Kathleen Rundell

Keyword(s):

Human Cell ◽

Cell Transformation ◽

Critical Role ◽

T Antigen ◽

Small T Antigen ◽

Sv40 Small T

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Cellular Targets of the SV40 Small-t Antigen in Human Cell Transformation

Cell Cycle ◽

10.4161/cc.3.5.836 ◽

2004 ◽

Vol 3 (5) ◽

pp. 604-608 ◽

Cited By ~ 22

Author(s):

Christine Skoczylas ◽

Kelly M. Fahrbach ◽

Kathleen Rundell

Keyword(s):

Human Cell ◽

Cell Transformation ◽

T Antigen ◽

Cellular Targets ◽

Small T Antigen ◽

Sv40 Small T

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STRIPAK directs PP2A activity toward MAP4K4 to promote oncogenic transformation

10.1101/823096 ◽

2019 ◽

Author(s):

Jong Wook Kim ◽

Christian Berrios ◽

Miju Kim ◽

Amy E. Schade ◽

Guillaume Adelmant ◽

...

Keyword(s):

Cell Transformation ◽

Hippo Pathway ◽

T Antigen ◽

Subunit Interactions ◽

C Subunit ◽

B Subunits ◽

Small T Antigen ◽

Sv40 Small T ◽

The Hippo Pathway

AbstractAlterations involving serine-threonine phosphatase PP2A subunits occur in a range of human cancers and partial loss of PP2A function contributes to cell transformation. Displacement of regulatory B subunits by the SV40 Small T antigen (ST) or mutation/deletion of PP2A subunits alters the abundance and types of PP2A complexes in cells, leading to transformation. Here we show that ST not only displaces common PP2A B subunits but also promotes A-C subunit interactions with alternative B subunits (B’’’, striatins) that are components of the Striatin-interacting phosphatase and kinase (STRIPAK) complex. We found that STRN4, a member of STRIPAK, is associated with ST and is required for ST-PP2A-induced cell transformation. ST recruitment of STRIPAK facilitates PP2A-mediated dephosphorylation of MAP4K4 and induces cell transformation through the activation of the Hippo pathway effector YAP1. These observations identify an unanticipated role of MAP4K4 in transformation and show that the STRIPAK complex regulates PP2A specificity and activity.

Download Full-text