Table 5.

Current mouse models to study the function of Ift anterograde motors in bone development

Gene	Mouse models	Mutation	Cilia	Phenotype	Pathways	Ref
Kif3a	Kif3a-Null	Removal exon 2 in ESCs	Cilia loss	Structural abnormalities, defects in left and right asymmetry and cilia loss in embryonic node.	Not reported	(94)
	Kif3aflox/flox; Wnt1-Cre	Deletion in neural crest lineage cells	Not reported	Die shortly after birth due to respiratory failure, severe craniofacial defects with clefting and widened frontonasal prominence.	Enhanced Hh signaling in facial mesenchyme. Impaired Hh signaling in Kif3a-deficient neural crest-derived mesenchyme.	(218, 219)
	Kif3aflox/flox; Dermo1-Cre	Deletion in trunk and limb skeletal progenitor cells	Not reported	Die at birth, split sternum, polydactyly and defects in ribs, knee joints and limbs.	Not reported	(218)
	Kif3aflox/flox; Prx1-Cre	Deletion in the lateral plate mesoderm	Cilia loss	Forelimb polydactyly and profound shortening of limb bones.	Disrupted Hh signaling in long bones.	(174, 218)
	Kif3aflox/flox; Col2α1-Cre	Deletion in cartilage	Cilia disrupted (93, 220)	Postnatal dwarfism. Abnormal cranial base development and altered synchondrosis growth plate organization and function at postnatal stages.	Hh signaling significantly reduced within growth plates but enhanced and widespread all along perichondrial tissues. Chondrocytes proliferation reduced but the hypertrophic differentiation is unregulated in growth plate, Hh signaling is unchanged.	(93, 220)
	Kif3aflox/flox; Oc-Cre	Deletion in mature osteoblast	Reduced cilia number and length	Osteopenia by 6 weeks of age and partially recovered at 16 weeks.	Impaired osteoblastic differentiation, impaired intracellular calcium response to fluid flow shear stress, and reduced Hh and Wnt response.	(221)
	Kif3a; Col3a; I 2.3-Cre	Deletion in osteoblast progenitor	Not reported	No obvious skeletal defects. Reduced bone formation in response to mechanical ulnar loading.	Not reported	(222)
Kif3b	Kif3b-Null	Null mutation with first exon replaced by neo cassette	Cilia loss	Die at mid-gestation and exhibited randomized left–right asymmetry, growth retardation, pericardial sac ballooning and neural tube disorganization.	Not reported	(225)
Kif17	Kif17−/−(231)	Frame shift with function loss	Not reported	No gross defects	Not reported	(231)
Kif7	Kif7flox/flox; NLS-Cre	Ubiquitous deletion with NLS-Cre	Not reported	Die at birth with severe malformations, including exencephaly, polydactyly and sternal defects.	Up-regulated full-length Gli2 while down-regulated truncated 83-kD repressor Gli3 in total embryo lysates.	(215)
	Kif7maki	ENU- mutagenesis, Loss of function	Normal cilia	Die at the end of gestation with abnormal motor neurons and preaxial polydactyly.	Reduced processed Gli3 proteins and the ratio of processed Gli3/full-length Gli3.	(206)
	Ift172wimKif7maki	Double mutants (206)	Disrupt cilia	Similar to Ift172wim.	Not reported	(206)
	Dync2h1mmiKif7maki	Double mutants (206)	Not reported	Similar to Kif7maki with greater loss of ventral neural cell types.	A stronger loss of Shh signaling than Dync2h1mmi.	(206)
	Kif7-KO	Knockout allele	Normal cilia	Spinal cord defects, preaxial polydactyly, exencephaly, and microphthalmia, which mimic the Gli3 mutants phenotypes.	Reduced proteolytic processing of Gli3. Reduce Gli2 and Gli3 accumulation at the tip of cilia in response to Hh.	(216)