Proteomic analysis of human nail plate

Area of Science:

• Biochemistry
• Proteomics
• Human Biology

Background:

• The human nail plate's complex protein composition is not fully understood.
• Previous research has primarily focused on keratin structures, with limited exploration of other protein constituents.

Purpose of the Study:

• To comprehensively identify proteins within the human nail plate using shotgun proteomic analysis.
• To compare protein profiles across different ethnic groups and between nail plate and hair shaft.
• To investigate potential protein alterations in response to arsenic exposure.

Main Methods:

• Shotgun proteomic analysis was performed on human nail plate samples from Caucasian and Inner Mongolian volunteers.
• Protein identification and quantification were conducted using mass spectrometry.
• Real-time polymerase chain reaction (PCR) was used to assess mRNA levels of novel identified proteins.

Main Results:

• A total of 144 proteins were identified in the human nail plate, with keratins and keratin-associated proteins dominating the proteome (90% of mass).
• Cytoplasmic, membrane, junctional proteins, and histones were also identified, suggesting extensive cross-linking by transglutaminases.
• Two novel membrane proteins, also found in hair shafts, were identified with low mRNA expression in other tissues.
• Nail plate protein profiles were consistent across Caucasian and Inner Mongolian populations and showed significant overlap with hair shaft proteomes.
• Arsenic exposure minimally altered protein levels, but suggested potential for sensitive individual detection.

Conclusions:

• The human nail plate proteome is diverse, extending beyond keratins to include structural and functional proteins.
• Nail plate protein composition is conserved across different ethnic groups and shares similarities with hair.
• The identified novel proteins and proteomic profiles may serve as potential biomarkers for specific conditions or exposures.