Molecular cues for development and regeneration of tooth roots: 

From the clinical point of view, roots are the most important part of tooth, which provide support for natural or artificial crown and are not replaceable with current technologies. The formation and homeostasis of tooth roots require sequential and reciprocal interaction between dental epithelia and mesenchyme mediated by protein messengers known as signaling molecules. Dr. Liu’s recent work revealed that Wnt (wingless/int), Bone Morphogenetic Protein (BMP) and Sonic hedgehog (SHH) signaling pathways play essential roles at early stages of tooth development, now his group is examining the roles of these pathways in tooth root formation and regeneration.

Molecular cues for regeneration of salivary glands:

Salivary gland destruction is a major consequence of various pathological conditions such as radiation therapy for head and neck cancer and Sojagren's syndrome. Currently available treatments for dry mouth cannot restore salivary gland functions. Stem cells based regenerative therapy is a promising direction to treat this condition. Dr. Liu’s recent work revealed that Wnt and SHH signaling signaling promote expansion of salivary gland stem cells. Further studies on modulation of signaling activities to promote salivary gland regeneration are planned.

Reprogramming of salivary gland stem cells to produce insulin-secreting beta-cells:

Pancreatic beta-cells are one of the most important targets in regenerative medicine, but sources of human pancreatic stem/progenitor cells are very limited. Salivary gland stem cells can be induced to differentiate into cells with endocrine pancreatic phenotype, but their continuous cell division ability is limited and pancreatic differentiation ceases at the immature stage. Recent studies found cellular signaling pathways direct the development of pancreas and proved the feasibility of cell reprogramming. The group will examine the potential of modulating signal activities to direct the pancreatic-differentiation of salivary gland stem cells.