Description

Background: This receptor binds insulin-like growth factor with a high affinity. It has tyrosine kinase activity. The insulin-like growth factor I receptor plays a critical role in transformation events. Cleavage of the precursor generates alpha and beta subunits. It is highly overexpressed in most malignant tissues where it functions as an anti-apoptotic agent by enhancing cell survival. 

Targeting strategy: 

• A chimeric CDS that encodes mouse Igf1r signal peptide and human extracellular domain, human IGF1R transmembrane and mouse cytoplasmic domain, followed by mouse Igf1r 3’UTR region, are inserted right after mouse Igf1r exon 2 to replace the exon 2 of mouse Igf1r gene. The chimeric IGF1R protein expression will be driven by endogenous mouse Igf1r promoter, while mouse Igf1r gene transcription and translation will be disrupted. 

• Mouse IGF1R was only detectable in wild-type C57BL/6 mice. Human IGF1R was exclusively detectable in homozygous B-hIGF1R mice plus but not in wild-type mice. IGF1R was detectable in heart, liver, spleen, lung, kidney, brain and colon from both C57BL/6N and homozygous B-hIGF1R mice plus, as the antibody was cross-reactive between human and mouse. Function assay showed that human IGF1 can activate the phosphorylation of IGF1R and AKT, and this phosphorylation can be inhibited by the positive drug Figitumumab.

Application: For example, this product can be used for pharmacodynamics and safety evaluation of antibody drugs for cancers. Also, this product can be used to evaluate the pharmacodynamics and safety of treatments for tumors and neurodegenerative diseases, as well as to assess the potential of drugs to penetrate the blood-brain barrier.

Gene targeting strategy for B-hIGF1R mice plus. A chimeric CDS that encodes mouse Igf1r signal peptide and human extracellular domain, human IGF1R transmembrane and mouse cytoplasmic domain, followed by mouse Igf1r 3’UTR region, are inserted right after mouse Igf1r exon 2 to replace the exon 2 of mouse Igf1r gene. The chimeric IGF1R protein expression will be driven by endogenous mouse Igf1r promoter, while mouse Igf1r gene transcription and translation will be disrupted. 

Strain specific analysis of IGF1R mRNA expression in wild-type C57BL/6N mice and B-hIGF1R mice by RT-PCR. Kidney RNA were isolated from wild-type C57BL/6N mice (+/+) (n=1, 14-week-old, male) and homozygous B-hIGF1R mice (H/H) (n=1, 8-week-old, male) and homozygous B-hIGF1R mice plus (H/H) (n=1, 14-week-old, male), then cDNA libraries were synthesized by reverse transcription, followed by PCR with IGF1R primers. Mouse Igf1r was only detectable in wild-type C57BL/6N mice. Human IGF1R was exclusively detectable in homozygous B-hIGF1R mice and homozygous B-hIGF1R mice plus but not in wild-type mice. No-RT: no reverse-transcripted.

Western blot analysis of IGF1R protein expression in wild-type C57BL/6N mice and homozygous B-hIGF1R mice plus by WB. Various tissues were collected from wild-type C57BL/6N mice (+/+) and homozygous B-hIGF1R mice plus (H/H), and then analyzed by western blot with anti-IGF1R antibody (CST, 3027S). 40 μg total proteins were loaded for western blotting analysis. GAPDH were detected as internal control. IGF1R was detectable in heart, liver, spleen, lung, kidney, brain and colon from both C57BL/6N and homozygous B-hIGF1R mice plus, as the antibody was cross-reactive between human and mouse. M, marker.

Western blot analysis of phospho-IGF1R/AKT protein expression in wild-type C57BL/6N mice and homozygous B-hIGF1R mice plus. Kidney cells were collected from wild-type C57BL/6N mice (+/+), homozygous B-hIGF1R mice (H/H) and homozygous B-hIGF1R mice plus (H/H), and then cultured with Figitumumab (1 μg/mL) or/and recombinant human IGF1 protein (200 ng/mL). Finally, these cells were analyzed by western blot with anti-IGF1R antibody (CST, 3027S), anti-phospho-IGF1R antibody (CST, 3024S) and anti-phospho-AKT antibody (CST, 9271S). Human IGF1R was detected in homozygous B-hIGF1R mice, and human IGF1 can activate the phosphorylation of IGF1R and AKT, and this phosphorylation can be inhibited by the positive drug Figitumumab in homozygous B-hIGF1R mice plus. M, marker.