Analyzing cell interactions was always vital for biological studies, but a simple approach from microscopy fails to provide any information on receptors and ligands involved in these interactions. Scientists have developed a method of bacterial sortase labeling involving a fluorescent LPXTG peptide motif and Staphylococcus aureus transpeptidase Sortase A (SrtA) that can be readily detected using flow cytometry. The group coined this approach as Labeling Immune Partnerships by SorTagging Intercellular Contacts, or LIPSTIC for short. LIPSTIC is even more useful in the fact that the LPETG peptide and SrtA reaction allows analysis of cell-cell interactions both in vitro and in vivo.
LPETG peptide and SrtA reaction to label receptor and ligand interactions.
LifeTein supplied the group with the necessary Biotin-ahx-LPETG peptide, where in the LIPSTIC method a ligand or receptor of note that is fused with a tag consisting of five N-terminal glycine residues (G5) has the fluorescent peptide donated to it by the SrtA. The acceptor cell can then be monitored via the label after separation. The group is confident that LIPSTIC is an efficient method to label receptor-ligand interactions both in vitro and in vivo, even able to detect rare or low-intensity interactions.
Pasqual G, Chudnovskiy A, Tas JMJ, Agudelo M, Schweitzer LD, Cui A, Hacohen N, Victora GD. Monitoring T cell-dendritic cell interactions in vivo by intercellular enzymatic labelling. Nature. 2018 Jan 25;553(7689):496-500. doi: 10.1038/nature25442. Epub 2018 Jan 17. PMID: 29342141; PMCID: PMC5853129.
Glioblastoma (GBM) is the most commonly occurring terminal brain cancer. Due to complications in the brain like the blood brain barrier, methods of treating GBM are few and far between. Therefore, treatment in the region is generally left to specific chemotherapeutics like temozolomide (TMZ), which has the unique capability to bypass the brain blood barrier. However, matters become more complicated as many subpopulations of GBM, namely the glioma stem cell populations, are resistant to TMZ. Researchers are looking into ways to bypass this resilience, namely connexin 43 (Cx43) hemichannels that when inhibited by mimetic peptides allow the glioma stem cell populations to be treated significantly more effectively by TMZ
Cx43 mimetic peptides weaken cancer’s resistance to TMZ
Researchers used LifeTein’s peptide synthesis service to create two mimetic peptides of Cx43, αCT11 and αCT1, to inhibit Cx43 hemichannels and then sensitize the glioma cells and other GBM cell populations to TMZ in a 3D hyaluronic acid and collagen hydrogel-based tumor organoid system. After testing this model extensively, the group found that only the αCT1 peptide in combination with TMZ proved effective in treating the cell lines. It is believed that the αCT1 is more successful due to its cell penetrating sequence when compared to αCT11.
Overall, the group emphasizes that the model used does not accurately mimic the cellular heterogeneity of GBM, but the results are a fantastic start and can be used as a tool to further study treatment of this aggressive brain cancer. Further work can optimize this treatment and can hopefully provide a chance for those who have to go against this fatal ailment.
Jingru Che, Thomas J. DePalma, Hemamylammal Sivakumar, et al. αCT1 Peptide Sensitizes Glioma Cells to Temozolomide in a Glioblastoma Organoid Platform. Authorea. April 29, 2022.
LifeTein is unveiling an expedited peptide synthesis program, promising to place peptides in its customers’ hands within 3-5 business days. The RushPep™ peptide synthesis service was designed to circumvent the existing limitations of conventional solid-phase peptide synthesis (SPPS), which involves a long coupling time and low yield. RushPep™ shortens the time needed for individual coupling, deprotection and washing steps. The proprietary methodology renders processing ten times faster than in classical synthesis while simultaneously circumventing the limitations caused by the formation of by-products or intermediates to which traditional SPPS approaches are subject.
LifeTein’s Rush Custom Peptide Synthesis Service
“When designing the RushPep™ methodology, our focus was to not only to produce peptides of high quality and purity but also to offer a streamlined solution that would increase the efficiency of researchers’ protein discovery workflows,” stated Dr. Ya Chen, Head of LifeTein’s Rush Peptide Synthesis Group. “RushPep™ achieves these goals by synthesizing the peptides in 3–5 business days to accelerate research and discovery.”
Chen continued, “The reliability of RushPep™ rush peptide synthesis ensures that the peptides are finished in 3–5 business days with high-batch-to-batch reproducibility. ” Most of the crude peptides have a purity of over 80%. RushPep™ peptide service is valuable for the scientists and researchers because it allows them to finish their proteomics projects in a fast and cost-efficient manner.
Biotinylated wild-type and modified (pT27 and T27W) ID2 peptides (amino acids 14–34) were synthesized by LifeTein. ID2 binds to the VHL ubiquitin ligase complex.This ID2 peptide could be used to inhibit tumour growth for patients with glioblastoma.
The anti-apoptotic factor Bcl-2 is over-expressed in B-cell lymphoma cells as their main survival mechanism by binding to IP3R2 on endoplasmic reticulum (ER). In this study, a cell-penetrating version of BIRD-2 peptide (Bcl-2/IP3R Disrupter-2 peptide with a TAT sequence) made by LifeTein was used to break up the complex formed by Bcl-2 and IP3R2 in human diffuse large B-cell lymphoma (DLBCL) cells. Ca2+ signaling-related events are suggested to be the killing mechanism of BIRD-2 peptide on DLBCL cells.
A patent has been published that describes new methods of manipulating plant stomatal development through artificially controlling how CRSP is expressing in plant cells. The cleavage of epidermal patterning factor 2 (EPF2) by a serine protease CRSP is a key regulating mechanism in plant stomatal development. A 30-mer EPF2 peptide, dual-tagged with DABCYL and EDANS, was synthesized by LifeTein to evaluate the protease activity of synthetic CRSP in a FRET assay.
MAP is a pathogenic bacterium infecting livestock and found prevalent in dairy products. Because some of its proteins are sequentially homologous to human zinc transporter 8 (ZnT8) protein and proinsulin (PI), children could develop autoimmunity against ZnT8 and PI after being exposed to MAP in dairy foods, and generating antibodies against MAP, and might subsequently develop type I diabetes. The hypothesis was tested by using ZnT8, PI and MAP peptides synthesized by LifeTein to assess the cross-reactivity of antibodies in sera samples from at-risk children.
The therapeutic monoclonal antibody cetuximab is among the latest arsenal developed for war on cancer, designed to block tumor growth by specifically targeting the extracellular domain of EGFR on the surface of cancer cells. Alarmingly, resistance to cetuximab has been observed. Using peptides containing methylated arginine residues synthesized by LifeTein to generated specific antibodies in mice, the researchers were able to pinpoint Arg198 and Arg200 of EGFR were methylated by protein arginine methyltransferase 1 (PRMT1) in colorectal cancer cells, which could be critical for cetuximab resistance. Their results paved a way for developing better treatment for cancer patients.
Peptide library is increasingly used to define antibody epitopes and substrate specificities of protein kinases. For epitope mapping, overlapping peptides are made to span the antigenic protein sequence. The antigenic determinant recognized by a monoclonal antibody can then be screened and defined. The alanine scanning method can also be used to assess that residue’s contribution to antibody binding and to determine which substitutions affect antibody recognition (mutational analysis). Unrelated synthetic peptides can be used to evaluate the antibody cross-reactivity.
Peptide by LifeTein Cited in Cell
Overlapping peptides from LifeTein were used to map the region of Fragment 3 by epitope mapping of anti-Fzd2 antibody. This anti-Fzd2 antibody was found to reduce tumor growth. Wnt signaling plays a critical role in colorectal cancer. Researchers found that Wnt receptor Frizzled2 (Fzd2) and its ligands Wnt5a/b are elevated in metastatic liver, lung, colon, and breast cancer cell lines. Their high level expression correlates with markers of epithelial-mesenchymal transition (EMT). By epitope mapping using synthetic peptides from LifeTein, the researchers mapped the epitope to a specific region. The antibody to Fzd2 was found to reduce cell migration and invasion. Targeting this pathway may provide a cure for patients with tumors expressing high amount of Fzd2 and Wnt5a/b.
We have developed an antibody to Fzd2 that reduces cell migration and invasion and inhibits tumor growth and metastasis in xenografts. We propose that targeting this pathway could provide benefit for patients with tumors expressing high levels of Fzd2 and Wnt5a/b.