ERBB2

What is ERBB2 Protein?

ERBB2 gene (erb-b2 receptor tyrosine kinase 2) is a protein coding gene which situated on the long arm of chromosome 17 at locus 17q12. This gene encodes a member of the epidermal growth factor (EGF) receptor family of receptor tyrosine kinases. This protein has no ligand binding domain of its own and therefore cannot bind growth factors. However, it does bind tightly to other ligand-bound EGF receptor family members to form a heterodimer, stabilizing ligand binding and enhancing kinase-mediated activation of downstream signalling pathways, such as those involving mitogen-activated protein kinase and phosphatidylinositol-3 kinase. The ERBB2 protein is consisted of 1255 amino acids and ERBB2 molecular weight is approximately 137.9 kDa.

What is the Function of ERBB2 Protein?

The ERBB2 protein, also known as HER2 or glioma retention factor 2 (neu), is a cell surface receptor tyrosine kinase that is a member of the ErbB receptor family. This family also includes ErbB1/EGFR/HER1, ErbB3/HER3, and ErbB4/HER4. ERBB2 protein plays an important role in the regulation of cell proliferation, migration, differentiation, apoptosis and cell movement. In addition to its function as a receptor on the cell surface, ERBB2 also plays a role inside the nucleus. For example, ERBB2 migrates into the nucleus via endocytic vesicles and regulates the transcriptional activity of several downstream genes, including COX-2.

Fig1. Participation of HER2 in the regulation of apoptosis. (A A Daks, 2020)

ERBB2 Related Signaling Pathway

ERBB receptors are activated by binding to corresponding ligands, such as EGFR binding to EGF. ERBB2 itself has no known direct ligand, but can form heterodimers with other ERBB family members and be activated. Once ERBB receptors are activated, they trigger a cascade of downstream signaling, including pathways such as PI3K/Akt, RAS/MAPK, and JAK/STAT. These signaling pathways play a central role in regulating cell growth, differentiation, and survival. Activation of the ERBB signaling pathway can promote cell proliferation and inhibit cell death, thus playing an important role in tissue repair and regeneration.

ERBB2 Related Diseases

ERBB2 (also known as HER2) is a gene associated with a variety of cancers, and its mutation or overexpression is strongly associated with tumor development and progression. Erbb2-related diseases mainly include breast cancer, stomach cancer, ovarian cancer, and non-small cell lung cancer. In these cancers, abnormal activation of ERBB2 can promote the proliferation and survival of cancer cells, making it an important therapeutic target. In addition to its role in tumors, studies in recent years have found that ERBB2 also has a protective effect in heart disease. ErbB2 may play an important role in myocardial infarction, myocardial ischemia-reperfusion injury, myocardial hypertrophy, heart failure, doxorubicin-induced cardiotoxic injury, diabetic cardiomyopathy and other heart diseases, and may become a clinical diagnostic marker and therapeutic target for heart diseases.

Bioapplications of ERBB2

In the field of cancer therapy, ERBB2 is an important therapeutic target for breast cancer, stomach cancer, ovarian cancer and other tumors. Targeted therapeutic drugs for ERBB2, such as Herceptin (Herceptin), Perjeta (Perjeta), Paklizumab (Kadcyla), Lapatinib (Lapatinib) and ositinib (Tukysa), have achieved good clinical therapeutic effects. The survival and quality of life of patients were significantly improved. However, ERBB2-targeted therapy may also be accompanied by some side effects and adverse reactions, such as cardiotoxicity, skin reactions, gastrointestinal problems, etc., which need to be monitored and managed during treatment.

Case Study 1: Mengmeng Zheng, 2021

Inhibition of human epidermal growth factor receptor 2 mediated cell signaling pathway is an important therapeutic strategy for HER2-positive cancers. Although monoclonal antibodies are currently used as marketed drugs, their large molecular weight, high cost of production and susceptibility to proteolysis could be a hurdle for long-term application. This study reported a strategy for the development of artificial antibody based on γ-AApeptides to target HER2 extracellular domain (ECD). To achieve this, researchers synthesized a one-bead-two-compound (OBTC) library containing 320,000 cyclic γ-AApeptides, from which we identified a γ-AApeptide, M-3-6, that tightly binds to HER2 selectively. Subsequently, they designed an antibody-like dimer of M-3-6, named M-3-6-D, which showed excellent binding affinity toward HER2 comparable to monoclonal antibodies. Intriguingly, M-3-6-D was completely resistant toward enzymatic degradation. In addition, it could effectively inhibit the phosphorylation of HER2, as well as the downstream signaling pathways of AKT and ERK.

Fig1. Scheme showing the overall strategy involved in library screening against HER2.

Fig2. Western blot analyses of SKBR3 cell lysates following M-3-6 incubation in vitro.

Case Study 2: Yasmina Noubia Abdiche, 2015

The neonatal Fc receptor (FcRn) is expressed by cells of epithelial, endothelial and myeloid lineages and performs multiple roles in adaptive immunity. Characterizing the FcRn/IgG interaction is fundamental to designing therapeutic antibodies because IgGs with moderately increased binding affinities for FcRn exhibit superior serum half-lives and efficacy. Using surface plasmon resonance biosensor assays that eliminated confounding experimental artifacts, researchers present data supporting an alternate hypothesis: 2 FcRn molecules saturate an IgG homodimer with identical affinities at independent sites. They find that human FcRn binds human IgG1 with an equilibrium dissociation constant (KD) of 760 ± 60 nM (N = 14) at 25°C and pH 5.8, and shows less than 25% variation across the other human subtypes. Human IgG1 binds cynomolgus monkey FcRn with a 2-fold higher affinity than human FcRn, and binds both mouse and rat FcRn with a 10-fold higher affinity than human FcRn. FcRn/IgG interactions from multiple species show less than a 2-fold weaker affinity at 37°C than at 25°C and appear independent of an IgG's variable region.

Fig3. Kinetic analysis at pH 5.8 of FcRn binding to trastuzumab hIgG1-N434Y captured by biotinylated mFcRn or hErbB2 on Biacore C1 chips with neutravidin.

Fig4. One-shot kinetic analysis at pH 5.8 of mFcRn binding as analyte to trastuzumab homodimers.

ERBB2 has several biochemical functions, for example, ATP binding,ErbB-3 class receptor binding,Hsp90 protein binding. Some of the functions are cooperated with other proteins, some of the functions could acted by ERBB2 itself. We selected most functions ERBB2 had, and list some proteins which have the same functions with ERBB2. You can find most of the proteins on our site.

ERBB2 has direct interactions with proteins and molecules. Those interactions were detected by several methods such as yeast two hybrid, co-IP, pull-down and so on. We selected proteins and molecules interacted with ERBB2 here. Most of them are supplied by our site. Hope this information will be useful for your research of ERBB2.

ERBB3