{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T10:28:41Z","timestamp":1790418521329,"version":"4.1.0"},"reference-count":18,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,1,26]],"date-time":"2018-01-26T00:00:00Z","timestamp":1516924800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Proinsulin-transferrin fusion protein (ProINS-Tf) has been designed and successfully expressed from the mammalian HEK293 cells (HEK-ProINS-Tf). It was found that HEK-ProINS-Tf could be converted into an activated form in the liver. Furthermore, HEK-ProINS-Tf was demonstrated as an extra-long acting insulin analogue with liver-specific insulin action in streptozotocin (STZ)-induced type 1 diabetic mice. However, due to the low production yield from transfected HEK293 cells, there are other interesting features, including the oral bioavailability, which have not been fully explored and characterized. To improve the protein production yield, an alternative protein expression system, ExpressTec using transgenic rice (Oryza sativa L.), was used. The intact and active rice-derived ProINS-Tf (ExpressTec-ProINS-Tf) was successfully expressed from the transgenic rice expression system. Our results suggested that, although the insulin-like bioactivity of ExpressTec-ProINS-Tf was slightly lower in vitro, its potency of in vivo blood glucose control was considerably stronger than that of HEK-ProINS-Tf. The oral delivery studies in type 1 diabetic mice demonstrated a prolonged control of blood glucose to near-normal levels after oral administration of ExpressTec-ProINS-Tf. Results in this report suggest that ExpressTec-ProINS-Tf is a promising insulin analog with advantages including low cost, prolonged and liver targeting effects, and most importantly, oral bioactivity.<\/jats:p>","DOI":"10.3390\/ijms19020378","type":"journal-article","created":{"date-parts":[[2018,1,29]],"date-time":"2018-01-29T07:46:20Z","timestamp":1517211980000},"page":"378","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Characterization and Oral Delivery of Proinsulin-Transferrin Fusion Protein Expressed Using ExpressTec"],"prefix":"10.3390","volume":"19","author":[{"given":"Yu-Sheng","family":"Chen","sequence":"first","affiliation":[{"name":"Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles, CA 90089, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2905-1349","authenticated-orcid":false,"given":"Jennica","family":"Zaro","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles, CA 90089, USA"},{"name":"Department of Pharmaceutical Sciences, West Coast University School of Pharmacy, Los Angeles, CA 90004, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Deshui","family":"Zhang","sequence":"additional","affiliation":[{"name":"Ventria Bioscience Inc., 2718 Industrial Drive, Junction City, KS 66441, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ning","family":"Huang","sequence":"additional","affiliation":[{"name":"Ventria Bioscience Inc., 2718 Industrial Drive, Junction City, KS 66441, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew","family":"Simon","sequence":"additional","affiliation":[{"name":"Ventria Bioscience Inc., 2718 Industrial Drive, Junction City, KS 66441, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei-Chiang","family":"Shen","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles, CA 90089, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1016\/j.jconrel.2011.06.029","article-title":"Receptor-mediated activation of a proinsulin-transferrin fusion protein in hepatoma cells","volume":"155","author":"Wang","year":"2011","journal-title":"J. Controll. Release"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1779","DOI":"10.2337\/db13-0973","article-title":"Proinsulin-transferrin fusion protein as a novel long-acting insulin analog for the inhibition of hepatic glucose production","volume":"63","author":"Wang","year":"2014","journal-title":"Diabetes"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2641","DOI":"10.1021\/acs.molpharmaceut.6b00168","article-title":"Proinsulin-transferrin fusion protein exhibits a prolonged and selective effect on the control of hepatic glucose production in an experimental model of type 1 diabetes","volume":"13","author":"Shao","year":"2016","journal-title":"Mol. Pharm."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"261","DOI":"10.2337\/diacare.3.2.261","article-title":"Role of the liver in glucose homeostasis","volume":"3","author":"Sherwin","year":"1980","journal-title":"Diabetes Care"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1445","DOI":"10.2337\/db14-0056","article-title":"The importance of the liver in insulin replacement therapy in insulin-deficient diabetes","volume":"63","author":"Geho","year":"2014","journal-title":"Diabetes"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e1156804","DOI":"10.1080\/21688370.2016.1156804","article-title":"Tissue barriers and novel approaches to achieve hepatoselectivity of subcutaneously-injected insulin therapeutics","volume":"4","author":"Shao","year":"2016","journal-title":"Tissue Barriers"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"5471","DOI":"10.2174\/1381612811319310002","article-title":"Commercial aspects of pharmaceutical protein production in plants","volume":"19","author":"Fischer","year":"2013","journal-title":"Curr. Pharm. Des."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"794","DOI":"10.1038\/nrg1177","article-title":"The production of recombinant pharmaceutical proteins in plants","volume":"4","author":"Ma","year":"2003","journal-title":"Nat. Rev. Genet."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"425","DOI":"10.1111\/pbi.12149","article-title":"A fusion protein derived from plants holds promising potential as a new oral therapy for type 2 diabetes","volume":"12","author":"Choi","year":"2014","journal-title":"Plant. Biotechnol. J."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.pep.2010.04.019","article-title":"Expression, purification, and characterization of recombinant human transferrin from rice (Oryza sativa L.)","volume":"74","author":"Zhang","year":"2010","journal-title":"Protein Expr. Purif."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Zhang, D., Lee, H.F., Pettit, S.C., Zaro, J.L., Huang, N., and Shen, W.C. (2012). Characterization of transferrin receptor-mediated endocytosis and cellular iron delivery of recombinant human serum transferrin from rice (Oryza sativa L.). BMC Biotechnol., 12.","DOI":"10.1186\/1472-6750-12-92"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.jconrel.2009.09.007","article-title":"Human growth hormone-transferrin fusion protein for oral delivery in hypophysectomized rats","volume":"141","author":"Amet","year":"2010","journal-title":"J. Controll. Release"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"7292","DOI":"10.1073\/pnas.0500062102","article-title":"Recombinant granulocyte colony-stimulating factor-transferrin fusion protein as an oral myelopoietic agent","volume":"102","author":"Bai","year":"2005","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1021\/mp1003064","article-title":"Effects of receptor binding on plasma half-life of bifunctional transferrin fusion proteins","volume":"8","author":"Chen","year":"2011","journal-title":"Mol. Pharm."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"561","DOI":"10.1124\/pr.54.4.561","article-title":"Targeted drug delivery via the transferrin receptor-mediated endocytosis pathway","volume":"54","author":"Qian","year":"2002","journal-title":"Pharmacol. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Fagerholm, S., Ortegren, U., Karlsson, M., Ruishalme, I., and Stralfors, P. (2009). Rapid insulin-dependent endocytosis of the insulin receptor by caveolae in primary adipocytes. PLoS ONE, 4.","DOI":"10.1371\/journal.pone.0005985"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1198","DOI":"10.2337\/diabetes.48.5.1198","article-title":"Banting Lecture 1997. Control of glucose uptake and release by the liver in vivo","volume":"48","author":"Cherrington","year":"1999","journal-title":"Diabetes"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1376","DOI":"10.1021\/bc050344k","article-title":"Synthesis and characterization of insulin-transferrin conjugates","volume":"17","author":"Kavimandan","year":"2006","journal-title":"Bioconjug. Chem."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/19\/2\/378\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:52:44Z","timestamp":1760194364000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/19\/2\/378"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,1,26]]},"references-count":18,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2018,2]]}},"alternative-id":["ijms19020378"],"URL":"https:\/\/doi.org\/10.3390\/ijms19020378","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,1,26]]}}}