MK2 promotes Tfcp2l1 degradation via β-TrCP ubiquitin ligase to regulate mouse embryonic stem cell self-renewal

Area of Science:

• Stem cell biology
• Molecular and cell biology
• Epigenetics and gene regulation

Background:

• Tfcp2l1 is crucial for maintaining mouse embryonic stem cell (mESC) self-renewal.
• The regulatory mechanisms governing Tfcp2l1 protein stability are not well understood.
• Understanding these mechanisms is key to controlling stem cell pluripotency.

Purpose of the Study:

• To elucidate the posttranslational modifications regulating Tfcp2l1 protein stability.
• To investigate the role of β-transducin repeat-containing protein (β-TrCP) and mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2) in Tfcp2l1 regulation.
• To determine how these regulatory events impact mESC self-renewal and differentiation.

Main Methods:

• Investigated Tfcp2l1 ubiquitination and degradation pathways.
• Utilized site-directed mutagenesis to alter phosphorylation sites within the β-TrCP binding motif of Tfcp2l1.
• Employed gene overexpression and inhibition techniques for MK2 and β-TrCP.

Main Results:

• β-TrCP targets Tfcp2l1 for ubiquitination and degradation in an MK2-dependent manner.
• MK2 phosphorylates serine residues in the Tfcp2l1 β-TrCP binding motif (DSGDNS), facilitating β-TrCP recognition.
• Mutating these serine residues or inhibiting MK2 enhances Tfcp2l1 stability, promoting mESC self-renewal and repressing differentiation.

Conclusions:

• A novel posttranslational modification pathway regulating Tfcp2l1 stability has been identified.
• This pathway involves MK2-mediated phosphorylation and subsequent β-TrCP-dependent degradation of Tfcp2l1.
• These findings expand the understanding of the regulatory network governing stem cell pluripotency and differentiation.