Hs3st3-Modified Heparan Sulfate Controls KIT+ Progenitor Expansion by Regulating 3-O-Sulfotransferases

Abstract

Summary The exquisite control of growth factor function by heparan sulfate (HS) is dictated by the tremendous structural heterogeneity of sulfated modifications. It is not known how specific HS structures control growth factor-dependent progenitor expansion during organogenesis. We isolated KIT+ progenitors from fetal salivary glands during a stage of rapid progenitor expansion and profiled HS biosynthetic enzyme expression. Enzymes generating a specific type of 3-O-sulfated-HS (3-O-HS) are enriched, and FGF10/FGFR2b signaling directly regulates their expression. Bioengineered 3-O-HS binds FGFR2b and stabilizes FGF10/FGFR2b complexes in a receptor- and growth factor-specific manner. Rapid autocrine feedback increases 3-O-HS, KIT and progenitor expansion. Knockdown of multiple Hs3st isoforms limits fetal progenitor expansion, but is rescued with bioengineered 3-O-HS, which also increases adult progenitor expansion. Rapidly altering a specific 3-O-sulfated epitope provides a cellular mechanism to modulate the response to FGFR2b signaling and control progenitor expansion. 3-O-HS may expand KIT+ progenitors in vitro for regenerative therapy.

Synthesis of 3-O-Sulfated Oligosaccharides to Understand the Relationship between Structures and Functions of Heparan Sulfate

“…HS exhibits important physiological and pathological functions, including regulating embryonic development, inflammatory responses, blood coagulation and viral/bacterial infections 1–3 . Most notably, heparin, a highly sulfated form of HS, is a widely used anticoagulant drug in clinics for the treatment of patients with thrombotic disorders 4 …”

“…The 3- O -sulfation is critically important for anticoagulant activity 19 , facilitates the entry of herpes simplex virus into host cells to establish infection 20 , regulates axon guidance and growth of neurons 18 and controls the progenitor cell expansion for salivary gland development 3 . Effects in model organisms were also reported, including neurogenesis in Drosophila 21 , neurite branching in C. elegans 22 and cardiac contraction in zebra fish 23 .…”

The contribution of specific cell subpopulations to submandibular salivary gland branching morphogenesis

“…miR-200 decreases Krt5 gene expression in a Fgfr-dependent manner [58], possibly contributing to timing of end bud differentiation. Embryonic kit+ cells can be stimulated to proliferate by heparin sulfate modification in a Fgf10/Fgfr2b-dependent manner [59] and Fgfr2b signaling positively regulates kit ligand (kitl) expression within the epithelium [53]. kitl is also produced by the mesenchyme.…”

Heparan sulfate provides a mechanism to respond to FGFR2b and control regenerative expansion

“…KIT Heparan sulfate proteoglycans has gained a lot of attention for the modulation of growth factor activities among other functions. Patel et al (2014), show in KIT+ progenitors cells from fetal salivary glands under expansive progenitor expansion, that 3-O sulfotransferases (3-O-HS) (enzymes responsible to modify heparan sulfate proteoglycans) are enriched and its expression is directly regulated by the FGF-10/FGFR2b. Autocrine feedback increases 3-O-HS, KIT, and progenitor expansion.…”