A role for the MHC class I-like Mill molecules in nutrient metabolism and wound healing

Area of Science:

• Immunology
• Molecular Biology
• Cell Biology

Background:

• MHC class I molecules have functions beyond antigen presentation.
• The Mill subfamily, including Mill1 and Mill2, is structurally related to NKG2D ligands but does not bind NKG2D.
• Hereditary haemochromatosis protein (HFE) shows high similarity to Mill proteins.

Purpose of the Study:

• To investigate the structure, expression, and function of the Mill subfamily.
• To explore the potential role of Mill proteins in cellular metabolism and nutrient uptake.
• To assess the therapeutic significance of Mill proteins, particularly in wound healing.

Main Methods:

• Protein sequence analysis and computer-based modeling to determine structural similarity.
• Immunohistochemistry to identify the expression patterns of Mill1 and Mill2 on various cell types.
• Use of soluble Mill proteins to detect serum ligands.
• In vivo studies using antibodies to assess the effect of Mill2 on wound healing in skin.

Main Results:

• Mill1 and Mill2 are expressed on cycling thymocytes, proliferating smooth muscle cells, and fibroblasts.
• A soluble ligand for Mill proteins was detected in serum.
• Skin was identified as one of the few organs expressing both Mill1 and Mill2 transcripts.
• Antibodies against Mill2 enhanced wound healing in skin.

Conclusions:

• The Mill family, including Mill1 and Mill2, likely plays a role in cellular metabolism and nutrient processing, similar to HFE.
• Mill proteins have potential therapeutic applications, particularly demonstrated by Mill2's role in accelerating skin wound healing.