Nematode sperm maturation triggered by protease involves sperm-secreted serine protease inhibitor (Serpin).
Spermiogenesis is a series of poorly understood morphological, physiological and biochemical processes that occur during the transition of immotile spermatids into motile, fertilization-competent spermatozoa. Here, we identified a Serpin (serine protease inhibitor) family protein (As_SRP-1) that is secreted from spermatids during nematode Ascaris suum spermiogenesis (also called sperm activation) and we showed that As_SRP-1 has two major functions. First, As_SRP-1 functions in cis to support major sperm protein (MSP)-based cytoskeletal assembly in the spermatid that releases it, thereby facilitating sperm motility acquisition. Second, As_SRP-1 released from an activated sperm inhibits, in trans, the activation of surrounding spermatids by inhibiting vas deferens-derived As_TRY-5, a trypsin-like serine protease necessary for sperm activation. Because vesicular exocytosis is necessary to create fertilization-competent sperm in many animal species, components released during this process might be more important modulators of the physiology and behavior of surrounding sperm than was previously appreciated.
Laboratory of Noncoding RNA, Institute of Biophysics,  Chinese Academy of Sciences, Beijing 100101,  China.
Yanmei
Y
Zhao
Wei
W
Sun
Pan
P
Zhang
Hao
H
Chi
Mei-Jun
MJ
Zhang
Chun-Qing
CQ
Song
Xuan
X
Ma
Yunlong
Y
Shang
Bin
B
Wang
Youqiao
Y
Hu
Zhiqi
Z
Hao
Andreas F
AF
Hühmer
Fanxia
F
Meng
Steven W
SW
L'hernault
Si-Min
SM
He
Meng-Qiu
MQ
Dong
Long
L
Miao
D000595:Amino Acid Sequence; D000818:Animals; D008297:Male; D008969:Molecular Sequence Data; D009348:Nematoda / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015843:Serpins / Q000737:chemistry / Q000502:physiology*; D013087:Spermatids / Q000502:physiology; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology*
D015843:Serpins; D010447:Peptide Hydrolases