The Transferrin receptor (TFRC) gene encodes Transferrin Receptor 1 (TFR1), a protein that is expressed at low levels in most normal cells but shows increased expression in highly proliferative cells, such as basal epidermal cells, intestinal epithelium, and certain activated immune cells. Brain capillary endothelial cells, which constitute the blood-brain barrier (BBB), also express this receptor at high levels ^[1]. TFR1 plays a critical role in maintaining iron metabolism and homeostasis by facilitating receptor-mediated endocytosis of iron-bound transferrin (Tf) via Tf cycling, thereby promoting iron uptake ^[2]. Cellular iron deficiency can lead to apoptosis, while cellular transformation requires substantial iron to sustain proliferation, with iron overload contributing to tumor progression. The high expression of TFR1 in many tumors makes it a potential tumor marker, offering a target for therapies to inhibit tumor growth and metastasis ^[1]. Moreover, TFR1 is implicated in anemia and iron metabolism disorders. Studies have shown that elevated TFR1 expression in cardiomyocytes is associated with exacerbated inflammation in myocarditis patients ^[3]. Various clinical drugs targeting TFR1 are currently under development, including antisense oligonucleotides (ASOs), antibody-drug conjugates (ADCs), and antibody-oligonucleotide conjugates, applicable to diseases such as cancer, anemia, and neurodegenerative disorders. Research indicates that enhancing antibody transport across the blood-brain barrier via TFR1, by forming specific bispecific antibodies with anti-β-amyloid antibodies, can improve therapeutic outcomes in Alzheimer's patients ^[4-5]. As research progresses, TFR1 is expected to become an effective clinical target for multiple diseases and a synergistic target for drug delivery across the blood-brain barrier (BBB).

Parkinson's disease (PD) is a neurodegenerative disease with a high prevalence mainly in the middle-aged and elderly population. It is the second most common neurodegenerative disease after Alzheimer's disease (AD). The main clinical symptoms include resting tremors, limb stiffness, bradykinesia, loss of voluntary movement, etc. The typical pathological process of PD is the formation of Lewy bodies (LB) in the central nervous system (CNS), which results in the gradual death and loss of dopaminergic neurons, leading to the disease ^[6-7]. The main components of Lewy bodies are insoluble aggregates of abnormal α-synuclein (α-syn), and the SNCA gene, which encodes α-synuclein, is one of the key causative genes in Parkinson's disease. Mutations in this gene cause overexpression of α-syn, leading to the formation of Lewy bodies, ultimately leading to PD ^[8]. In addition, SNCA mutations are also associated with diseases such as dementia with Lewy bodies (DLB) and multiple system atrophy (MSA).

B6-huTFRC/huSNCA(3'UTR) mice are a dual-gene humanized model generated by crossing B6-huTFRC mice (Catalog No.: C001860) with B6-hSNCA (3'UTR) mice (Catalog No.: C001698). This model can be used for research on neurodegenerative diseases such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), as well as iron metabolism disorders and tumorigenesis and development. It is also applicable for the development of TFRC/SNCA-targeted drugs.