Cell cycle progression is disrupted in murine MPS VII growth plate leading to reduced chondrocyte proliferation and transition to hypertrophy

Altered IHH signaling contributes to reduced chondrocyte proliferation in the growth plate of MPS VII mice

“…Founder animals for MPS VII ( Gus mps/mps strain), a naturally occurring model of MPS VII comprising a 1 bp deletion on exon 10 resulting in premature stop codon and no detectable residual enzyme activity [ 15 ], were obtained from Jackson Labs (stock number 006407). MPS and normal (homozygous) mice were bred from heterozygous parents and affected pups identified by PCR and restriction enzyme digest as previously described [ 13 , 16 , 17 ]. Mice were housed in a 14/10 light/dark cycle with food and water ad libitum .…”

“…RNA was isolated from micro-dissected proliferative zone of normal and MPS VII mice tibiae as previously described [ 13 ]. The concentration of RNA was determined using a Thermo Scientific NanoDrop 1000 and its operating software, version 3.8.1 (Thermo Scientific,VIC, Australia).…”

“…RNA was reverse transcribed into cDNA using the QuantiTect® Reverse Transcription Kit (Qiagen, Maryland, USA). Quantitative real-time PCR was performed as previously described [ 13 ]. Data were normalized to cyclophilinA ( CycA ) and the fold change to normal calculated using the ΔΔCt method [ 18 ].…”

“…Accumulation of undegraded GAG results in failure of multiple tissues and organs, including the skeletal system [ 12 ]. Using the MPS VII mouse model, our lab previously found a progressive bone shortening accompanied by an impaired growth plate characterized by reduced proliferation and hypertrophy [ 13 ]. MPS VII mice also have a reduced gene expression level of Ihh in the growth plate [ 13 , 14 ]; however; the expression pattern of the morphogen IHH in the growth plate and its effect on MPS chondrocyte proliferation in MPS remained unclear.…”

“…Using the MPS VII mouse model, our lab previously found a progressive bone shortening accompanied by an impaired growth plate characterized by reduced proliferation and hypertrophy [ 13 ]. MPS VII mice also have a reduced gene expression level of Ihh in the growth plate [ 13 , 14 ]; however; the expression pattern of the morphogen IHH in the growth plate and its effect on MPS chondrocyte proliferation in MPS remained unclear. Thus, to investigate how chondrocyte proliferation is regulated in the MPS growth plate, the ability of MPS VII chondrocytes to proliferate in response to exogenous IHH was assessed in vitro .…”