Ultrasensitive Proteome
Profiling for 100 Living Cells
by Direct Cell Injection, Online Digestion and Nano-LC-MS/MS Analysis
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Abstract
Single-cell proteome analysis has
always been an exciting goal
because it provides crucial information about cellular heterogeneity
and dynamic change. Here we presented an integrated proteome analysis
device (iPAD) for 100 living cells (iPAD-100) that might be suitable
for single-cell analysis. Once cells were cultured, the iPAD-100 could
be applied to inject 100 living cells, to transform the living cells
into peptides, and to produce protein identification results with
total automation. Due to the major obstacle for detection limit of
mass spectrometry, we applied the iPAD-100 to analyze the proteome
of 100 cells. In total, 813 proteins were identified in a DLD-cell
proteome by three duplicate runs. Gene Ontology analysis revealed
that proteins from different cellular compartments were well-represented,
including membrane proteins. The iPAD-100 greatly simplified the sampling
process, reduced sample loss, and prevented contamination. As a result,
proteins whose copy numbers were lower than 1000 were identified from
100-cell samples with the iPAD-100, showing that a detection limit
of 200 zmol was achieved. With increased sensitivity of mass spectrometry,
the iPAD-100 may be able to reveal bountiful proteome information
from a single cell in the near future