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Catalog Number: C001558
Strain Name: C57BL/6JCya-Agrpem2(IRES-Cre/ERT2-P2A-tdTomato)/Cya
Genetic Background: C57BL/6JCya
Reproduction: Heterozygote x WT or Heterozygote x Heterozygote
Strain 설명
The AGRP gene encodes Agouti-related protein (AgRP), a neuropeptide synthesized by AgRP/NPY neurons predominantly located in the arcuate nucleus of the hypothalamus, as well as in the kidneys and adrenal glands. The expression of AGRP is modulated by various factors, including nutritional status and hormonal signals. Notably, AGRP expression is markedly upregulated during periods of starvation and rapidly downregulated following refeeding. AgRP is exclusively synthesized in the ventromedial part of the arcuate nucleus within neuropeptide Y (NPY)-containing cells, where it is co-expressed with NPY. This neuropeptide plays a pivotal role in enhancing appetite, reducing metabolic rate, and decreasing energy expenditure, making it one of the most potent and enduring appetite stimulators. AgRP exerts its orexigenic effects by antagonizing melanocortin receptor 4 (MC4R), thereby promoting food intake and inhibiting energy expenditure, which is crucial for weight regulation. Mutations in the AGRP gene have been implicated in conditions such as late-onset obesity and anorexia nervosa, underscoring its significant role in energy homeostasis and body weight control.
The Agrp-IRES-CreERT2-P2A-tdTomato mouse model was generated by integrating the IRES-CreERT2-P2A-tdTomato gene expression cassette into the endogenous Agrp locus via gene editing technology. Under the control of the mouse endogenous Agrp gene regulatory elements, this mouse expresses tamoxifen-inducible CreERT2 recombinase. Additionally, the cassette includes a red fluorescent protein (tdTomato) for lineage tracing of Agrp-positive cells. In the absence of tamoxifen, CreERT2 recombinase remains cytoplasmic. Upon tamoxifen administration, CreERT2 translocates to the nucleus to mediate recombination. When Agrp-IRES-CreERT2-P2A-tdTomato mice are crossed with mice containing loxP sites, tamoxifen induction can trigger Cre recombinase-mediated sequence recombination between loxP sites in AgRP-positive neurons of the offspring.
Strain 유전자 편집 전략
The IRES-CreERT2-P2A-tdTomato cassette was inserted 3 bp downstream of the TAG stop codon of the mouse Agrp gene to mimic the expression pattern of the mouse endogenous gene.
검증 데이터
A. Method
Agrp-IRES-CreERT2-P2A-tdTomato mice were crossed with LSL_Zsgreen mice, which conditionally express the Zsgreen fluorescent protein. At 6 weeks of age, the offspring were administered tamoxifen at a dose of 100 mg/kg via intraperitoneal injection for 5 consecutive days. This tamoxifen induction facilitates Cre recombinase-mediated excision of the LSL element, resulting in Zsgreen expression in Cre-positive cells. Seven days post-induction, hypothalamic tissue was harvested and subjected to cryosectioning to detect Zsgreen fluorescence, thereby confirming Cre recombinase activity. Additionally, immunofluorescence staining (IF) for tdTomato protein was performed to identify the specific cell types labeled in this model.
B. Result
Figure 1. Expression of Cre recombinase in the hypothalamus. The results demonstrate that, following tamoxifen treatment, spontaneous green fluorescence signals were observed in the arcuate nucleus (ARC) region of the hypothalamus in Agrp-IRES-CreERT2-P2A-tdTomato; LSL_Zsgreen double-positive mice. This indicates Cre recombinase-mediated Zsgreen protein expression in this tissue. Conversely, no green fluorescence signals, and thus no Cre recombinase activity, were detected in the hypothalamus of Agrp-IRES-CreERT2-P2A-tdTomato; LSL_Zsgreen mice treated with corn oil or in LSL_Zsgreen mice.
2. Co-localization of tdTomato fluorescent protein and Zsgreen fluorescent protein expression in the hypothalamus
Figure 2. Co-localization of Cre recombinase-mediated Zsgreen expression with endogenous Agrp-regulated tdTomato expression in the hypothalamus. The results indicate that in tamoxifen-treated Agrp-IRES-CreERT2-P2A-tdTomato; LSL_Zsgreen double-positive mice, both tdTomato and Zsgreen signals are present in the hypothalamus. The Zsgreen signal, induced by Cre recombinase, co-localizes with the tdTomato signal regulated by endogenous Agrp. This co-localization suggests that the expression pattern of Cre recombinase aligns with that of endogenous Agrp in this model.
C. Summary
In the Agrp-IRES-CreERT2-P2A-tdTomato mouse model, Cre recombinase expression is predominantly localized to the arcuate nucleus (ARC) of the hypothalamus. This model serves as a valuable tool for investigating the physiological role of GABAergic neurotransmission in AgRP neurons within the hypothalamus.
공지 사항
The CreERT2 recombinase gene expression cassette is integrated into chromosome 8 in this strain. It is recommended that breeding with Flox mice targeted on the same chromosome is avoided.