SMU Medical Journal

Arumugam Jayakumar ¹, Hua-Kang Wu ¹, Katrina Briggs ¹, Thomas Shellenberger ¹, Ya'an Kang ¹, Kenji Mitsudo ¹, Mary Wang ¹, Mitchell J. Frederick ¹, Ying Henderson ¹, Paula R. Holton ¹, Venugopal Radjendirane ², Karthik Jayakumar ³, Dieter Brömme ⁴

Affiliations
1 Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, US
2 Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, US
3 The American University of Antigua, Mount Sinai School of Medicine, New York, New York 10029-6574, US
4 Department of Human Genetics Mount Sinai School of Medicine, New York, New York 10029-6574, US

Abstract

Cathepsin K is a protease with high collagenolytic and elastinolytic activity. A full-length cDNA clone of human cathepsin K was used to construct an expression system in insect cells. The recombinant protein had a C-terminal tag of six histidine residues, which allowed purification of this protein by a one-step Co²⁺-Sepharose affinity chromatography. Minimal amounts of pro-cathepsin K were secreted into the medium but most of the cathepsin K was present within infected cells. Very little processing of pro-enzyme to mature form occurred in High Five cells. Spontaneous in vitro activation of pro-cathepsin K to mature-cathepsin K occurred at pH 4.0. The ∼29 kDa mature-cathepsin K efficiently hydrolyzed the fluorogenic peptide substrate and r-headpin, a serine protease inhibitor down-regulated in head and neck cancer cell lines and tumor tissues, potently inhibited the r-catK activity in vitro. Taking cathepsin K as an example, we present a strategy, which should facilitate the expression of perhaps other cathepsins or proteases in general in insect cells.

Keywords

Cathepsink, Sf9, Metal Affinity Chromatography, HNSCC, Headpin.

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Arumugam Jayakumar ¹, Venugopal Radjendirane ¹

Affiliations
1 Department of Experimental Therapeutics, The University of Texas, M. D. Anderson Cancer Center, Houston, Texas 77054, US

Abstract

Serine Protease Inhibitor Kazal-type 5 (SPINK5) gene encodes 3 different Lympho-Epithelial Kazal-Type-Inhibitor (LEKTI) isoforms, which differ in their C-terminal sequence, are organized into longer than 15, 15, and 13 inhibitory domains. Pro-LEKTI is processed intracellular and the bioactive LEKTI fragments are secreted. LEKTI shows a restricted expression pattern in skin, thymus, oral mucosa, vaginal epithelium, Bartholin's glands, pituitary, tonsils, and parathyroid glands. Recombinant full-length LEKTI and rLEKTI fragments inhibit the activity of plasmin, subtilisin A, cathepsin G, neutrophil elastase, trypsin, caspase 14, and kallikreins (KLK) 5, 6, 7, 13, and 14 (involved in skin desquamation and growth hormone processing) to varied extents. Loss-of-function mutations, polymorphisms, and transcriptional inactivation of the cognate SPINK5 gene resulting in LEKTI loss or defective LEKTI processing is linked to Netherton syndrome (NS), head and neck squamous cell carcinomas (HNSCC), asthma, and chronic rhinosinusitis. Here, we give a brief review on the published work of LEKTI.

Keywords

SPINK5, LEKTI, NS, HNSCC, Proteinases, KLK, ECM, Invasion.

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