TY - JOUR
T1 - Proteolytic processing of human growth hormone by multiple tissue kallikreins and regulation by the serine protease inhibitor Kazal-Type5 (SPINK5) protein
AU - Komatsu, Nahoko
AU - Saijoh, Kiyofumi
AU - Otsuki, Norio
AU - Kishi, Tadaaki
AU - Micheal, Iacovos P.
AU - Obiezu, Christina V.
AU - Borgono, Carla A.
AU - Takehara, Kazuhiko
AU - Jayakumar, Arumugam
AU - Wu, Hua Kang
AU - Clayman, Gary L.
AU - Diamandis, Eleftherios P.
N1 - Funding Information:
Work on kallikreins was supported by grants from the Natural Sciences and Engineering Council of Canada (NSERC) and IBEX Technologies Inc., Canada. This work was also supported in part by the University of Texas M.D. Anderson Cancer Center SPORE in Head and Neck Cancer NIH-NCI P50 CA097007 (G.L.C), NIH R01 DE013954 G.L.C), Cancer Center Support Grant NIH P30 CA016672 (G.L.C), Alando J. Ballantyne Distinguished Chair in Head and Neck Surgery award (G.L.C), Michael A. O'Bannon Endowment for Cancer Research (G.L.C), Betty Berry Cancer Research Fund (G.L.C), and NIH INRS Award T32 CA060374 (G.L.C), 2004 AAO-HNSF Percy Memorial Grant (G.L.C.).
PY - 2007/2/2
Y1 - 2007/2/2
N2 - Background: Human growth hormone (hGH) is naturally present in numerous isoforms, some of which arise from proteolytic processing in both the pituitary and periphery. The nature of the enzymes that proteolytically cleave hGH and the regulation of this process are not fully understood. Our objective is to examine if members of a newly discovered human tissue kallikrein family (KLKs) are expressed in the pituitary and if these enzymes can cleave hGH in-vitro. Methods: Expression of 12 of the KLKs (KLKs 4-15) and serine protease inhibitor Kazal-type 5 (SPINK5) genes and their proteins in the pituitary was examined by RT-PCR and immunohistochemistry. Recombinant hGH was digested by various recombinant KLKs and fragments were characterized by N-terminal sequencing. SPINK5 recombinant fragments were used for inhibition of KLK activities. Results: We here describe for the first time expression of numerous KLKs (KLKs 5-8, 10-14) and SPINK5 in the pituitary. KLK6 and SPINK5 appeared to be localized to hGH-producing cells. KLKs 4-6, 8, 13 and 14 were able to cleave hGH, yielding various isoforms, in vitro. Inhibitor SPINK5 fragments were able to suppress activity of KLKs 4, 5 and 14 in vitro. Based on these data, we propose a model for the proteolytic processing of hGH in the pituitary and the regulation of this system by SPINK5 inhibitory domains. We speculate that loss of SPINK5 inhibitory domains, as in the case of Netherton syndrome, may lead to proteolytic over-processing of hGH and to growth retardation. Conclusion: We conclude that many KLKs and SPINK5 are expressed in the pituitary. This serine protease-inhibitor system is likely to participate in the regulated proteolytic processing of hGH in the pituitary, leading to generation of hGH fragments. Our data suggest that KLKs 5, 6 and 14 might be involved in this process.
AB - Background: Human growth hormone (hGH) is naturally present in numerous isoforms, some of which arise from proteolytic processing in both the pituitary and periphery. The nature of the enzymes that proteolytically cleave hGH and the regulation of this process are not fully understood. Our objective is to examine if members of a newly discovered human tissue kallikrein family (KLKs) are expressed in the pituitary and if these enzymes can cleave hGH in-vitro. Methods: Expression of 12 of the KLKs (KLKs 4-15) and serine protease inhibitor Kazal-type 5 (SPINK5) genes and their proteins in the pituitary was examined by RT-PCR and immunohistochemistry. Recombinant hGH was digested by various recombinant KLKs and fragments were characterized by N-terminal sequencing. SPINK5 recombinant fragments were used for inhibition of KLK activities. Results: We here describe for the first time expression of numerous KLKs (KLKs 5-8, 10-14) and SPINK5 in the pituitary. KLK6 and SPINK5 appeared to be localized to hGH-producing cells. KLKs 4-6, 8, 13 and 14 were able to cleave hGH, yielding various isoforms, in vitro. Inhibitor SPINK5 fragments were able to suppress activity of KLKs 4, 5 and 14 in vitro. Based on these data, we propose a model for the proteolytic processing of hGH in the pituitary and the regulation of this system by SPINK5 inhibitory domains. We speculate that loss of SPINK5 inhibitory domains, as in the case of Netherton syndrome, may lead to proteolytic over-processing of hGH and to growth retardation. Conclusion: We conclude that many KLKs and SPINK5 are expressed in the pituitary. This serine protease-inhibitor system is likely to participate in the regulated proteolytic processing of hGH in the pituitary, leading to generation of hGH fragments. Our data suggest that KLKs 5, 6 and 14 might be involved in this process.
KW - Human growth hormone
KW - Protease inhibitors
KW - SPINK5
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U2 - 10.1016/j.cca.2006.10.009
DO - 10.1016/j.cca.2006.10.009
M3 - Article
C2 - 17140555
AN - SCOPUS:33845429546
SN - 0009-8981
VL - 377
SP - 228
EP - 236
JO - Clinica Chimica Acta
JF - Clinica Chimica Acta
IS - 1-2
ER -