{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,16]],"date-time":"2026-09-16T00:29:24Z","timestamp":1789518564729,"version":"build-2803163510"},"reference-count":21,"publisher":"S. Karger AG","issue":"2-4","license":[{"start":{"date-parts":[[2011,1,1]],"date-time":"2011-01-01T00:00:00Z","timestamp":1293840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"},{"start":{"date-parts":[[2011,1,1]],"date-time":"2011-01-01T00:00:00Z","timestamp":1293840000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells Tissues Organs"],"published-print":{"date-parts":[[2011]]},"abstract":"<i>Background:<\/i> The enamel layerof kallikrein 4 (Klk4)-null mice has a normal thickness and a decussating pattern of enamel rods, but it contains residual enamel proteins, is less highly mineralized, and fractures in its deepest part just above the dentino-enamel junction (DEJ). The plane of fracture is puzzling because the deepest enamel is deposited earliest and, through the action of the secretory stage enamel protease (Mmp20), is the most mature part of the enamel layer at the time of the onset of <i>Klk4<\/i> expression. <i>Objectives:<\/i> To characterize the planes of fracture in <i>Mmp20-<\/i> and <i>Klk4<\/i>-null mice and to localize <i>Klk4<\/i> expression in developing teeth. <i>Methods:<\/i><i>Klk4<\/i>- and <i>Mmp20<\/i>-null mice were sacrificed at 7 weeks and their mandibular incisors were characterized by scanning electron microscopy. <i>Klk4<\/i><sup>+\/<\/sup><sup>lac<\/sup><sup>Z<\/sup> mice were mated with <i>Klk4<\/i><sup>+\/<\/sup><sup>lac<\/sup><sup>Z<\/sup> mice. Offspring were genotyped by polymerase chain reaction. <i>Klk4<\/i><sup>+\/<\/sup><sup>+<\/sup>, <i>Klk4<\/i><sup>+\/<\/sup><sup>lac<\/sup><sup>Z<\/sup>, and <i>Klk4<\/i><sup>lac<\/sup><sup>Z\/<\/sup><sup>lac<\/sup><sup>Z<\/sup> (null) littermates on postnatal days 5, 8, 11, and 14 were processed for \u03b2-galactosidase histochemistry. <i>Results:<\/i> The enamel layer fractures at the DEJ in <i>Mmp20<\/i>-null mice, and fractures occur in enamel above the DEJ in <i>Klk4<\/i>-null mice. Klk4 is not expressed by secretory-stage ameloblasts, murine odontoblasts beneath the secretory stage, or maturation-stage ameloblasts. Klk4 is specifically expressed by transition and maturation-stage ameloblasts. <i>Conclusions:<\/i> The breakage of enamel near the DEJ in <i>Klk4<\/i>-null mice is not due to a failure of odontoblasts to express Klk4, but it relates to a progressive hypomineralization of enamel with depth.<\/jats:p>","DOI":"10.1159\/000324260","type":"journal-article","created":{"date-parts":[[2011,5,6]],"date-time":"2011-05-06T07:11:41Z","timestamp":1304665901000},"page":"211-215","source":"Crossref","is-referenced-by-count":29,"title":["Why Does Enamel in <i>Klk4<\/i>-Null Mice Break above the Dentino-Enamel Junction?"],"prefix":"10.1159","volume":"194","author":[{"given":"James P.","family":"Simmer","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuanyuan","family":"Hu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amelia S.","family":"Richardson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John D.","family":"Bartlett","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan C.-C.","family":"Hu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"127","published-online":{"date-parts":[[2011,5,6]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1177%2F10454411990100040101"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1046%2Fj.0909-8836.1998.eos106510.x"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1111%2Fj.1600-0722.2006.00293.x"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.1074%2Fjbc.M209100200"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1177%2F0022034510366903"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.1016%2F0378-1119%2896%2900035-2"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.1177%2F154405910208101003"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1136%2Fjmg.2003.017657"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1074%2Fjbc.M710565200"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1177%2F00220345000790011301"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1034%2Fj.1600-0722.2002.21301.x"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1016%2FS0378-1119%2800%2900203-1"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1177%2F154405910708600209"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.1136%2Fjmg.2004.024505"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.1177%2F0022034509352844"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1177%2F0022034509342694"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.1177%2F154405910508401112"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.1177%2F154405910808700109"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1177%2F00220345990780030601"},{"key":"ref20","doi-asserted-by":"publisher","DOI":"10.1034%2Fj.1600-0722.2002.21349.x"},{"key":"ref21","doi-asserted-by":"publisher","DOI":"10.1074%2Fjbc.M109.013623"}],"container-title":["Cells Tissues Organs"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/324260","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/324260","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,4,23]],"date-time":"2025-04-23T19:29:15Z","timestamp":1745436555000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000324260"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011]]},"references-count":21,"journal-issue":{"issue":"2-4","published-online":{"date-parts":[[2011,8,1]]},"published-print":{"date-parts":[[2011,8,10]]}},"URL":"https:\/\/doi.org\/10.1159\/000324260","archive":["Portico"],"relation":{},"ISSN":["1422-6405","1422-6421"],"issn-type":[{"value":"1422-6405","type":"print"},{"value":"1422-6421","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011]]}}}