title: Cathepsin L plays an active role in involution of the mouse mammary gland.
abstract: Involution of the mammary gland after weaning occurs in two stages. The first stage is reversible, whereas the second stage is characterized by the irreversible collapse of the alveolar structure. A differential display analysis using cDNAs from tissues obtained at various times after forced weaning of pups identified cathepsin L as up-regulated during early involution. Levels of cathepsin L mRNA were dramatically increased within 24 hr after weaning. Cathepsin L protein detected by immunoblot was also increased during involution, reaching near maximal levels by 36 hr after weaning. In situ immunohistochemistry detected pronounced cathepsin L protein in the cytoplasm and cell periphery. Mice treated with a specific inhibitor of cathepsin L exhibited substantially reduced numbers of apoptotic cells at times up to 72 hr after weaning when compared with untreated animals. The cathepsin L inhibitor did not alter levels of cathepsin L detected in immunoblots or influence molecular weight of the cathepsin L species detected. These data suggest that cathepsin L plays a regulatory role early in the process of mammary gland involution.
authors.affiliation: Department of Biology, Villanova University, Villanova, Pennsylvania 19085, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Burke
authors.forename: Dorothy
authors.initials: D
authors.lastname: Hutter
authors.forename: Rita P
authors.initials: RP
authors.lastname: Reshamwala
authors.forename: Janice E
authors.initials: JE
authors.lastname: Knepper
mesh_terms: D000818:Animals; D017209:Apoptosis; D015152:Blotting, Northern; D056668:Cathepsin L; D002403:Cathepsins / Q000502:physiology*; D003546:Cysteine Endopeptidases; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D007150:Immunohistochemistry; D008321:Mammary Glands, Animal / Q000254:growth & development* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D015854:Up-Regulation; D014886:Weaning
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse