Identification of proteins involved in aggregation of human dermal papilla cells by proteomics

The dermal papilla is a major component of hair, which signals the follicular epithelial cells to prolong the hair growth process. To date, little is known about the significance of the specific protein(s) express in the dermal papilla cells (DPC) with regard to their aggregative behaviour.

To identify proteins involved in aggregative behaviour of DPC, we comparatively analyzed the proteome of cells with and without aggregative behaviour.

A series of methods were used, including two-dimensional gel electrophoresis (2-DE), PDQuest software analysis of 2-DE gels, peptide mass fingerprinting based on matrix-assisted laser desorption/ionisation-time of flight-mass spectrometry (MALDI-TOF-MS), and NCBInr database searching, to separate and identify differentially expressed proteins. Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) were used to validate the differentially expressed proteins.

Image analysis revealed that averages of 618+/-22 and 568+/-47 protein spots were detected in passages 3 and 10 DPC, respectively. Twenty-four differential protein spots were measured with MALDI-TOF-MS. A total of 17 spots yielded good spectra, and 15 spots matched with known proteins after database searching. Western blotting confirmed that heat shocking protein 70 was up-regulated in passage 3 DPC. Over-expression of mitochondrial ribosomal protein S7 was confirmed by RT-PCR, indicating that they are involved in aggregation of DPC through some signaling pathway.

The clues provided by the comparative proteome strategy utilized here will shed light on molecular mechanisms of DPC in aggregative behaviour.