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Title: TESTIS FASCIN (FSCN3): A NOVEL PARALOG OF THE ACTIN-BUNDLING PROTEIN FASCIN EXPRESSED SPECIFICALLY IN THE ELONGATE SPERMATID HEAD.

Author
item TUBB, BENJAMIN - BAYLOR COLLEGE MED
item MULHOLLAND, DAVID - UNIV BRITISH COLUMBIA
item VOGL, WAYNE - UNIV BRITISH COLUMBIA
item LAN, ZI-JIAN - BAYLOR COLLEGE MED
item NIEDERBERGER, CRAIG - UNIV ILLINOIS AT CHICAGO
item Cooney, Austin
item BRYAN, JOSEPH - BAYLOR COLLEGE MED

Submitted to: Experimental Cell Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2002
Publication Date: 4/15/2002
Citation: Tubb, B., Mulholland, D.J., Vogl, W., Lan, Z., Niederberger, C., Cooney, A., Bryan, J. 2002. Testis fascin (fscn3): a novel paralog of the actin-bundling protein fascin expressed specifically in the elongate spermatid head. Experimental Cell Research. 275(1):92-109.

Interpretive Summary: This is a peer reviewed article describing the finding of a new factor that is involved creating the form of the sperm head. It is a structural component of sperm that was characterized.

Technical Abstract: During spermiogenesis, significant morphological changes occur as round spermatids are remodeled into the fusiform shape of mature spermatozoa. These changes are correlated with a reorganization of microfilaments and microtubules in the head and tail regions of elongating spermatids. There is also altered expression of specialized actin- and tubulin-associated proteins. We report the characterization of a novel, spermatid-specific murine paralog of the actin-bundling protein fascin (FSCN1); this paralog is designated testis fascin or FSCN3. Testis fascin is distantly related to fascins but retains its primary sequence organization. cDNA clones of mouse testis fascin predict a 498 amino acid protein of molecular mass 56 kD that shares 29% identity with mouse fascin. Mapping of murine and human FSCN3 genes shows localization to the 7q31.3 chromosome. Northern analysis indicates that FSCN3 expression is highly specific to testis and that in situ hybridization further restricts expression to elongating spermatids. Antibodies raised against recombinant FSCN3 protein identify a band at 56 kD in testis, epididymis, and epididymal spermatozoa, suggesting that testis fascin persists in mature spermatozoa. In accord with the in situ hybridization results, immunofluorescent microscopy localizes testis fascin protein to areas of the anterior spermatid head that match known distributions of F-actin in the dorsal and ventral subacrosomal spaces. It is possible that testis fascin may function in the terminal elongation of the spermatid head and in microfilament rearrangements that accompany fertilization.