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Characterization of the heat shock protein P70 in rat spermatogenic cells
Author(s) -
Raab Linda S.,
Polakoski Kenneth L.,
Hancock Larry W.,
Hamilton David W.
Publication year - 1995
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080400207
Subject(s) - biology , sperm , andrology , epididymis , spermatogenesis , germ cell , endocrinology , medicine , genetics , gene
A number of hsp70‐like proteins are associated with developing male germ cells. One of these molecules, P70, is not sensitive to heat stress and is germ cell‐specific, and its expression is developmentally regulated. We have characterized the association of the rat P70(rP70) with differentiating germ cells in the testis and with posttesticular sperm. An antibody originally raised against human sperm proacrosin (designated C3; Siegel et al., 1987: J Reprod Immunol 11:307–319) was found to immunostain rP70 by immunoblot analysis and was used in subsequent studies of the rP70 molecule. The C3 antibody reacted with P70 isoforms in rat, human, mouse, guinea pig, boar, and rooster testicular homogenates. In the developing rat testis, abundant rP70 protein levels were first detected on postnatal day 22, with upregulation to adult levels occurring after postnatal day 28. Purified populations of adult rat pachytene spermatocytes, round spermatids, and elongating spermatids, isolated by unit gravity velocity sedimentation, all expressed rP70. Posttesticular sperm exhibited a loss of the rP70 molecule; caput epididymal sperm were weakly immunoreactive for rP70, but no immunoreactivity was observed in either cauda epididymal sperm or epididymal fluid. In contrast to human ejaculated sperm, rat ejaculated sperm did not express rP70. The loss of P70 from rat posttesticular sperm may reflect species‐specific differences in P70 functions, which are thought to include a role in the structural modifications that occur during germ cell differentiation. © 1995 Wiley‐Liss, Inc.