Proteome Profiling of Developing Murine Lens Through Mass Spectrometry.

Purpose: We previously completed a comprehensive profile of the mouse lens transcriptome. Here, we investigate the proteome of the mouse lens through mass spectrometry-based protein sequencing at the same embryonic and postnatal time points.

Methods: We extracted mouse lenses at embryonic day 15 (E15) and 18 (E18) and postnatal day 0 (P0), 3 (P3), 6 (P6), and 9 (P9). The lenses from each time point were preserved in three distinct pools to serve as biological replicates for each developmental stage. The total cellular protein was extracted from the lens, digested with trypsin, and labeled with isobaric tandem mass tags (TMT) for three independent TMT experiments.

Results: A total of 5404 proteins were identified in the mouse ocular lens in at least one TMT set, 4244 in two, and 3155 were present in all three TMT sets. The majority of the proteins exhibited steady expression at all six developmental time points; nevertheless, we identified 39 proteins that exhibited an 8-fold differential (higher or lower) expression during the developmental time course compared to their respective levels at E15. The lens proteome is composed of diverse proteins that have distinct biological properties and functional characteristics, including proteins associated with cataractogenesis and autophagy.

Conclusions: We have established a comprehensive profile of the developing murine lens proteome. This repository will be helpful in identifying critical components of lens development and processes essential for the maintenance of its transparency.