Trichothiodystrophy-associated MPLKIP maintains DBR1 levels for proper lariat debranching and ectodermal...

Area of Science:

• Genetics
• Molecular Biology
• Dermatology

Background:

• Trichothiodystrophy (TTD) is a genetic disorder with diverse symptoms, often linked to unstable gene expression factors.
• Mutations in MPLKIP/TTDN1 are associated with TTD, but the underlying molecular mechanism involving protein stability remained unclear.

Purpose of the Study:

• To investigate the molecular function of MPLKIP in TTD pathogenesis.
• To establish a link between MPLKIP mutations, protein stability, and gene expression defects.

Main Methods:

• Interaction proteomics using mass spectrometry to identify MPLKIP binding partners.
• Analysis of DBR1 protein levels in MPLKIP-deficient fibroblasts.
• Assessment of keratinocyte differentiation and splicing in Human Skin Equivalents (HSEs).

Main Results:

• MPLKIP was found to interact with core splicing factors and the lariat debranching protein DBR1.
• MPLKIP deficiency led to reduced steady-state levels of DBR1 protein.
• Impaired keratinocyte differentiation, compromised mRNA splicing, and proteome imbalance were observed in HSEs derived from MPLKIP-deficient individuals.

Conclusions:

• MPLKIP plays a crucial role in mRNA splicing through its function in stabilizing DBR1.
• Defects in MPLKIP-mediated splicing contribute to the pathophysiology of TTD, affecting skin development and potentially the immune system.