Matsui Hitoshi, Takano Naoharu, Takahashi Takayuki
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Nishi-8, Kita-ku, Sapporo, 060-0810, Japan.
Int J Biochem Cell Biol. 2005 Nov;37(11):2333-43. doi: 10.1016/j.biocel.2005.05.011.
Mouse kallikrein 24 is thought to encode a functional serine protease belonging to the mouse glandular kallikrein gene family. Preliminary results suggest that this kallikrein may play a role in testis function in adult mice. In order to obtain insights into its physiological functions, we undertook molecular and biochemical analyses of this enzyme. We cloned a cDNA for kallikrein 24 from the adult mouse testis cDNA library. Kallikrein 24 was expressed in the kidney, submandibular glands, ovary, epididymis, and testis of the mouse. In the testis, kallikrein 24 mRNA was detectable at 4 weeks of postnatal development, and became more prominent thereafter. The kallikrein 24 gene was expressed exclusively in the Leydig cells of adult mice. When Leydig cells isolated from a 2-week-old mouse testis were cultured in the presence of testosterone, kallikrein 24 expression was induced. Active recombinant enzyme showed trypsin-like specificity, favorably cleaving Arg-X bonds of synthetic peptide substrates. The enzymatic activity was strongly inhibited by typical serine protease inhibitors. Mouse kallikrein 24 degraded casein, gelatin, fibronectin and laminin. These results suggest that the enzyme may play a role in the degradation of extracellular matrix proteins in the interstitial area surrounding the Leydig cells of the adult mouse testis. The present findings should contribute to future physiological studies of this mouse testis protease.
小鼠激肽释放酶24被认为编码一种属于小鼠腺体激肽释放酶基因家族的功能性丝氨酸蛋白酶。初步结果表明，这种激肽释放酶可能在成年小鼠的睾丸功能中发挥作用。为了深入了解其生理功能，我们对这种酶进行了分子和生化分析。我们从小鼠成年睾丸cDNA文库中克隆了激肽释放酶24的cDNA。激肽释放酶24在小鼠的肾脏、颌下腺、卵巢、附睾和睾丸中表达。在睾丸中，出生后4周可检测到激肽释放酶24 mRNA，此后更加明显。激肽释放酶24基因仅在成年小鼠的睾丸间质细胞中表达。当从2周龄小鼠睾丸分离的睾丸间质细胞在睾酮存在下培养时，激肽释放酶24的表达被诱导。活性重组酶表现出胰蛋白酶样特异性，能有效切割合成肽底物的精氨酸-X键。酶活性受到典型丝氨酸蛋白酶抑制剂的强烈抑制。小鼠激肽释放酶24能降解酪蛋白、明胶、纤连蛋白和层粘连蛋白。这些结果表明，该酶可能在成年小鼠睾丸间质细胞周围间质区域的细胞外基质蛋白降解中发挥作用。目前的研究结果应为今后对这种小鼠睾丸蛋白酶的生理学研究做出贡献。
