Identification of Proteins Involved in Human Sperm Motility Using High-Throughput Differential Proteomics

Mammalian sperm motility is a prerequisite
for in vivo fertilization,
and alterations in this parameter are commonly observed in infertile
males. However, we still do not have a complete understanding of the
molecular mechanisms controlling it. The aim of this study was to
identify proteins involved in human sperm motility deficiency by using
TMT protein labeling and LC–MS/MS. Two complementary approaches
were used: comparison between sperm samples differing in motility
(asthenozoospermic versus normozoospermic) and comparison between
sperm subpopulations of fractionated normozoospermic samples differing
in motility (non-migrated versus migrated). LC–MS/MS resulted
in the identification of 1157 and 887 proteins in the first and second
approaches, respectively. Remarkably, similar proteomic alterations
were detected in the two experiments, with 80 proteins differentially
expressed in the two groups of samples and 93 differentially expressed
in the two groups of subpopulations. The differential proteins were
analyzed by GO, cellular pathways, and clustering analyses and resulted
in the identification of core deregulated proteins and pathways associated
with sperm motility dysfunction. These included proteins associated
with energetic metabolism, protein folding/degradation, vesicle trafficking,
and the cytoskeleton. Contrary to what is usually accepted, the outcomes
support the hypothesis that several metabolic pathways (notably, mitochondrial-related
ones) contribute toward regulating sperm motility.