Zinc finger protein 263
transcription cis-regulatory region binding
ZNF263 is a transcriptional regulator of heparin and heparan sulfate biosynthesis.
Heparin is the most widely prescribed biopharmaceutical in production globally. Its potent anticoagulant activity and safety makes it the drug of choice for preventing deep vein thrombosis and pulmonary embolism. In 2008, adulterated material was introduced into the heparin supply chain, resulting in several hundred deaths and demonstrating the need for alternate sources of heparin. Heparin is a fractionated form of heparan sulfate derived from animal sources, predominantly from connective tissue mast cells in pig mucosa. While the enzymes involved in heparin biosynthesis are identical to those for heparan sulfate, the factors regulating these enzymes are not understood. Examination of the promoter regions of all genes involved in heparin/heparan sulfate assembly uncovered a transcription factor-binding motif for <i>ZNF263</i>, a C2H2 zinc finger protein. CRISPR-mediated targeting and siRNA knockdown of <i>ZNF263</i> in mammalian cell lines and human primary cells led to dramatically increased expression levels of <i>HS3ST1</i>, a key enzyme involved in imparting anticoagulant activity to heparin, and <i>HS3ST3A1,</i> another glucosaminyl 3-<i>O</i>-sulfotransferase expressed in cells. Enhanced 3-<i>O</i>-sulfation increased binding to antithrombin, which enhanced Factor Xa inhibition, and binding of neuropilin-1. Analysis of transcriptomics data showed distinctively low expression of <i>ZNF263</i> in mast cells compared with other (non-heparin-producing) immune cells. These findings demonstrate a novel regulatory factor in heparan sulfate modification that could further advance the possibility of bioengineering anticoagulant heparin in cultured cells.