title: Cystatin-related epididymal spermatogenic aggregates in the epididymis.
abstract: Cystatin-related epididymal spermatogenic (CRES) is the defining member of  a reproductive subgroup within the family 2 cystatins of the cystatin  superfamily of cysteine protease inhibitors. CRES is synthesized and secreted  by the initial segment of the epididymis and is present in the sperm acrosome,  suggesting roles in sperm maturation and fertilization. We have previously  demonstrated that CRES is present within the epididymal lumen as monomeric (14  and N-glycosylated 19-kd forms) as well as sodium dodecyl  sulfate-sensitive and sodium dodecyl sulfate-resistant  high-molecular mass complexes. We have also shown that recombinant CRES  protein will self-aggregate and form amyloid structures in vitro, raising the  possibility that CRES might also form amyloid in vivo. Amyloid is a large  protein aggregate with a specific cross-β sheet structure, and its  presence is usually associated with disease. This review discusses protein  aggregation in the epididymis and provides a brief overview of amyloid  formation, including recent studies in other organ systems identifying  examples of amyloid that are nonpathologic and carry out biologic functions  (ie, functional amyloid). Studies that were carried out to determine if  amyloid is present in the epididymal lumen and if CRES is associated with  these structures are also described. The presence of CRES amyloid in the mouse  epididymal lumen and the absence of pathology suggest either the presence of  mechanisms to neutralize the cytotoxicity associated with pathologic amyloid  or that CRES is a new example of a functional amyloid with roles in epididymal  function.
authors.affiliation: Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430, USA. Gail.Cornwall@ttuhsc.edu
authors.forename: Gail A
authors.initials: GA
authors.lastname: Cornwall
authors.forename: H Henning
authors.initials: HH
authors.lastname: Von Horsten
authors.forename: Sandra
authors.initials: S
authors.lastname: Whelly
mesh_terms: D000682:Amyloid / Q000378:metabolism; D000818:Animals; D002449:Cell Aggregation; D015891:Cystatins / Q000378:metabolism*; D004822:Epididymis / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D008297:Male; D051379:Mice; D051381:Rats; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D000682:Amyloid; D015891:Cystatins