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T-Cell Synapse Formation Is Restrained by PTPN22–PSTPIP1 Signaling
T cells don’t simply switch on—they reshape themselves. When these immune sentinels recognize a target, they rapidly reorganize their internal scaffolding to build an immunological synapse, a nanoscale interface that determines how strongly they respond. But that architectural overhaul needs brakes. Without them, T cells risk becoming hypersensitive, reacting to weak cues, and drifting toward autoimmunity. Now, new work reveals that one of those brakes—PTPN22 (proline-serine-threonine phosphatase–interacting protein 1)—acts not only on signaling molecules but also on the cytoskeletal machinery that sculpts the synapse itself.
In a study published in Science Signaling, lead author Megan Joseph, PhD, of University College London and colleagues uncover how PTPN22 interacts with the cytoskeletal adaptor protein PSTPIP1 to restrain actin remodeling at the T‑cell synapse. Their paper, “PTPN22 regulates T-cell synapse formation through PSTPIP1-dependent actin remodeling,” shows that this phosphatase plays a previously unappreciated role at the plasma membrane, shaping how T cells respond to antigens of varying affinity. As the authors wrote, “These findings uncover a PTPN22–PSTPIP1 signaling axis that is critical for regulating cytoskeletal remodeling and receptor organization, providing insights into T-cell hyperactivation that may be relevant to autoimmune disease.”
PTPN22 is already well known as a negative regulator of early T‑cell activation. Variants in the gene, including the autoimmune‑associated R620W allele, have been linked to diseases ranging from lupus to rheumatoid arthritis. Using super‑resolution DNA‑PAINT imaging, Joseph et al. visualized how T cells reorganize their actin networks as they engage activating ligands. In wild‑type Jurkat cells, PTPN22 helped maintain orderly actin dynamics. In its absence, however, PSTPIP1 accumulated at T cell receptors (TCRs), disrupting Arp2/3‑dependent actin polymerization and generating dense central F‑actin foci, as well as enhanced Ca2+ signaling, especially under low-affinity stimulation of the TCR, according to the paper.
This hyper‑remodeling had functional consequences. PTPN22‑deficient cells became unusually sensitive to low‑affinity antigens, responding more vigorously than their wild‑type counterparts. “Autoimmunity is inherently linked to immune tolerance mechanisms normally associated with low-affinity TCR responses to self, which, when breeched lead to inappropriate immune reactions. To better understand how PTPN22 contributes to these processes, we used WT and PTPN22 KO TCR−/− Jurkat cells engineered to express a transgenic TCR with high affinity for the pTax peptide and low affinity for the pHuD peptide,” the authors wrote.
Joseph and colleagues suggest that understanding this axis could inform both autoimmune research and efforts to modulate T‑cell activation in cancer immunotherapy. By mapping how PTPN22 and PSTPIP1 coordinate actin remodeling, the study provides a mechanistic foothold for exploring how synapse architecture shapes immune outcomes.
The post T-Cell Synapse Formation Is Restrained by PTPN22–PSTPIP1 Signaling appeared first on GEN – Genetic Engineering and Biotechnology News.
Hosted by Drug Discovery World and supported by Sartorius and BioIVT, this webinar will explore the opportunities and challenges that exist within cancer research drug discovery and development.
You will hear from Dr Sudha Rao, Chief Scientific Officer of Kazia Therapeutics, Karol Budzik, PhD, Business Development Associate at Vyriad Therapeutics and Lars van der Veen, Chief Scientific Officer at iOnctura.
Presentations will cover how cancer treatments have shifted towards reprogramming the biology driving tumour growth, immune escape and treatment resistance, the trajectory that in vivo CAR-T treatments are taking, and how challenging tumours burdened by stroma and immune-mediated resistance can be tackled.
Q&A with the speakers follows the presentations.
The post New webinar: Tackling drug discovery challenges in cancer research appeared first on Drug Discovery World (DDW).
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New Spectrometry Technique Could Aid Formulation Development
New Spectrometry Technique Could Aid Formulation Development
A new technique combining two forms of spectrometry could help biopharmaceutical companies improve their choice of formulation buffer for antibody manufacturing by revealing how molecular forms and three-dimensional shapes of complex biologics respond to their environment. That’s the view of Christian Bleiholder, PhD, a professor at Florida State University who helped develop the technique.
According to Bleiholder, what happens structurally when a complex biological molecule, such as an antibody or viral spike protein, binds to its target is currently poorly understood.
“This is where [this approach] can help with the bioprocessing and formulation,” he says, as structural changes “can affect the lifespan [of the product] and lead to issues, such as aggregation.”
Because antibodies are complex, existing techniques tend to be powerful at different levels of complexity, he explains. Mass spectrometry is particularly powerful for distinguishing molecular composition, while structural approaches such as X-ray crystallography and cryo-electron microscopy can provide high-resolution structural information.
The challenge is understanding the link between these things within a heterogeneous sample, he says.
To overcome this, Bleiholder and his team worked with Bruker Daltonics to develop Tandem-Trapped Ion Mobility Spectrometry (Tandem-TIMS). This combines tandem ion mobility spectrometry with tandem mass spectrometry to disentangle three overlapping layers of molecular complexity: molecular form, three-dimensional shape, and binding or assembly state, he says.
He explains that, if the proteins have different structures, they can be characterized with tandem ion mobility spectrometry, and then mass spectrometry can be used to look at their molecular forms and binding states.
Going forward, Bleiholder hopes the technique can be used for formulation development but also earlier, during drug discovery of new products, such as multi-specific antibodies, to determine which molecular states are important and how those change when a biologic engages its target. He also plans to look at automating the technique.
Bleiholder spoke about using Tandem-TIMS at the Bioprocessing Summit in Boston earlier this year.
The post New Spectrometry Technique Could Aid Formulation Development appeared first on GEN – Genetic Engineering and Biotechnology News.
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