CSNK1a1 Regulates PRMT1 to Maintain the Progenitor State in Self-Renewing Somatic Tissue

Area of Science:

• Cell Biology
• Developmental Biology
• Dermatology

Background:

• Somatic progenitors are vital for tissue self-renewal, balancing proliferation with controlled differentiation.
• The role of protein arginine methyltransferases (PRMTs) in progenitor cell function remains largely undefined.
• PRMT1 is highly expressed in epidermal progenitors and significantly downregulated during differentiation.

Purpose of the Study:

• To investigate the function of PRMT1 in epidermal progenitor maintenance and self-renewal.
• To identify interacting partners of PRMT1 involved in progenitor cell regulation.
• To elucidate the molecular mechanisms by which PRMT1 and its partners control differentiation.

Main Methods:

• Targeted mouse knockouts to assess PRMT1 function in vivo.
• Analysis of long-term regenerated human mosaic epidermis.
• Mass spectrometry to identify PRMT1 protein interactome.
• In vitro kinase assays and phosphorylation site mapping.

Main Results:

• Loss of PRMT1 in epidermal progenitors abolished self-renewal and induced premature differentiation in both mouse models and human epidermis.
• CSNK1a1 kinase was identified as a key PRMT1 interactor essential for progenitor maintenance.
• CSNK1a1 directly binds and phosphorylates PRMT1, regulating its genomic targeting to control gene expression.
• Derepression of GRHL3 was identified as a critical event leading to premature differentiation upon PRMT1 or CSNK1a1 loss.

Conclusions:

• PRMT1 and CSNK1a1 cooperate to maintain epidermal progenitor function.
• This cooperation involves sustaining proliferation gene expression and suppressing differentiation.
• Loss of this partnership leads to premature differentiation, exemplified by GRHL3 derepression.