Table 1. Mouse models for Hedgehog (Hh) signaling and taste organ maintenance.
Mouse models | Function | Expression pattern/Location/Phenotype | Ref. |
---|---|---|---|
Reporters | |||
ShhlacZ | identify Shh-producing cells | in basal cells of taste bud, of FGP and CVP | 35, 67 |
Gli1lacZ | identify HH-responding cells | in basal epithelial cells, perigemmal cells, and stromal cells, of FGP and CVP | 35, 38 |
Gli2lacZ | identify Gli2-expressing cells | in basal cells throughout the lingual epithelium; and in perigemmal cells and stromal cells, of FGP and of CVP (unpublished data) | 35 |
Ptch1lacZ | Identify HH-responding cells | in basal epithelial cells, perigemmal cells, of FGP and CVP; and in stromal cells, of FGP and of CVP (unpublished data) | 35, 67 |
Lineage trace | |||
Gli1-CreERT2;R26RlacZ | identify Gli1+ HH-responding cells and descendents | progeny in TB, epithelium and stroma of FGP and nearby FILIFP | 35 |
Shh-CreERT2;ROSAlacz | identify embryonic SHH+ cells and descendents | progeny in adult TB (Type I and II cells) of FGP, but SHH+ cells lost after 4 months; also in intragemmal basal and perigemmal cells, of FGP | 72 |
Shh-CreERT2;R26RlacZ/EGFP | identify SHH+ cells and descendents | progeny in all 3 TB cell types, of FGP, CVP and soft palate | 18 |
HH misexpression | |||
K14-CreERT2;SHH-YFP | constitutive expression of SHH in K14+ cells | ectopic K8+ clusters induced in FILIFP, molecular similarities to taste cells, not innervated | 81 |
HH constitutive activation | |||
K5-rtTA;TRE-GLI2* | GLI2, oncogeneic form, expressed in K5+ cells | loss of FGP and TB, and FILIFP spines; some FGP retain thin TB and innervation; suprabasal cell proliferation | 35 |
HH/GLI suppression | |||
K5-rtTA;tetO-Gli2ΔC4 | Gli2 dominant- negative repressor expressed in K5+ cells | TB reduced and/or lost, proliferation reduced, innervation and Gli1lacZ+ cells in stroma retained in FGP and CVP | 38 |
K5-Cre;R26- LSL-rtTA;tetOGli2ΔC4 | Gli2 dominant- negative repressor expressed in K5+ cells and progeny | FGP, CVP, and FILIFP structure disrupted; TB and cell proliferation reduced; innervation and Gli1lacZ+ cells in stroma retained in FGP and CVP | 38 |
K5-rtTA;tetO-Cre;Gli2fl/fl | Gli2 deleted in K5+ cells | TB reduced and Gli1lacZ+ cells eliminated except from stroma; cell proliferation reduced and innervation retained in FGP and CVP | 38 |
K5-rtTA;tetO-Cre; Gli2fl/fl;Gli1lacZ/lacZ | Gli2 in K5+ cells and Gli1 globally deleted | TB reduced, innervation retained; cell proliferation reduced; Gli1lacZ+ cells eliminated except from stroma in FGP and CVP | 38 |
HH/SMO inhibition | |||
K5rtTA;tetO-Cre;Smofl/fl | Smo deleted in K5+ cells | TB reduced; innervation and Gli1lacZ+ cells in stroma retained in FGP | 86 |
R26rtTA M2+/wt;tetO-Cre;Smofl/fl | Smo deleted globally | TB rapidly reduced; innervation and Gli1lacZ+ cells in stroma retained in FGP | 82 |
LDE225 oral gavage | Pharmacologic SMO blockade | in FGP, all TB cell types and cell proliferation reduced; taste nerve chemical responses reduced and/or lost; innervation and Gli1lacZ+ cells in stroma retained | 83, 85 |
Vismodegib oral gavage | Pharmacologic SMO blockade | in CVP, TB smaller; cell proliferation reduced | 84 |
HH/WNT interaction | |||
SHH-CreERT2;Ctnnb1(Ex3)/fl;R26RYFP | β-catenin activated in SHH+ cells | increased Type I TB type cells in non-cell autonomous manner, in FGP and CVP | 87 |
Abbreviations: CVP, circumvallate papilla; FGP, fungiform papilla; FILIFP, filiform papilla; Shh, Sonic Hedgehog; TB, taste bud.