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6 recordsLinked to original sources
PubMed2025

CoDIAC: A comprehensive approach for interaction analysis reveals novel insights into SH2 domain function and regulation.

Protein domains are conserved structural and functional units that serve as building blocks of proteins. Through evolutionary expansion, domain families are represented by multiple members in diverse configurations with other domains, evolving new specificities for their interacting partners. Here, we develop a structure-based interface analysis to comprehensively map domain interfaces from experimental and predicted structures, including interfaces with macromolecules and intraprotein interfaces. We hypothesized that comprehensive contact mapping of domains could yield new insights into domain selectivity, conservation of domain-domain interfaces across proteins, and identify conserved post-translational modifications (PTMs), relative to interaction interfaces, allowing for the inference of specific effects due to PTMs or mutations. We applied this approach to the human SH2 domain family, a modular unit central to phosphotyrosine-mediated signaling, identifying a novel approach to understanding binding selectivity and evidence of coordinated regulation of SH2 domain binding interfaces by tyrosine and serine/threonine phosphorylation and acetylation. These findings suggest multiple signaling systems can regulate protein activity and SH2 domain interactions in a coordinated manner. We provide the extensive features of the human SH2 domain family and this modular approach as an open source Python package for COmprehensive Domain Interface Analysis of Contacts (CoDIAC).

SH2 domains↗
PubMed2025

Structure-informed theoretical modeling defines principles governing avidity in bivalent protein interactions.

In signaling cascades, where domain-motif interactions tend to interact with relatively low affinity (allowing for reversibility), signaling proteins often encode multiple domains or motifs, which present the possibility of avidity - drastically increasing the interaction strength and duration as a result of multivalent binding. However, given the large combinatorial space, predicting and validating multivalent interactions that interact with avidity is a challenge. Here, we integrate mechanistic modeling, structure-based analysis, and experimental approaches as a framework for defining the conditions under which avidity plays a role. We explore the tandem SH2 domain family of interactions with bisphosphorylated partners as a multivalent archetype, which encompasses key secondary messengers in tyrosine kinase signaling networks. While certain multivalent interactions have been shown to be necessary in immune receptor recruitment of partners, bivalent recruitment of tandem SH2 domains more broadly is poorly understood. Theoretical modeling suggests that maximum avidity occurs with closely spaced or flexibly linked phosphotyrosine sites, combined with moderate monovalent affinities - exactly around the innate range of SH2 domain affinity. Surprisingly, despite sequence diversity, structure-based analysis showed remarkably conserved three-dimensional spacing between SH2 domains across all tandem SH2 families, which we corroborate experimentally, suggesting evolutionary optimization for avidity interactions. The combination of structure-based analysis of domain spacing with available monovalent experimental data appears to be sufficiently accurate to predict and rank order high affinity interactions of tandem SH2 domain recruitment to the EGFR C-terminal tail. These approaches lay the groundwork for larger utility in multivalent prediction and testing to help better understand protein interactions that drive cell signaling.

BLI↗
PubMed2026

Structure-informed theoretical modeling defines principles governing avidity in bivalent protein interactions.

In signaling cascades, signaling proteins often encode multiple domains or motifs, which presents the possibility for avidity -- where multivalent binding drastically increases interaction strength and duration. However, predicting and validating multivalent interactions that interact with avidity is a challenge. Here, we integrate mechanistic modeling, structure-based analysis, and experimental approaches as a framework for defining the conditions under which avidity plays a role. We explore the tandem SH2 domain family of interactions with bisphosphorylated partners as a multivalent archetype, which encompasses key secondary messengers in tyrosine kinase signaling networks. Theoretical modeling suggests that maximum avidity occurs with closely spaced tyrosine phosphorylation sites combined with moderate monovalent affinities - exactly around the innate range of SH2 domain affinity - or with phosphorylation sites separated by sufficiently flexible linkers. Surprisingly, despite sequence diversity, structure-based analysis showed relatively conserved three-dimensional spacing between SH2 domains across all tandem SH2 families, which we corroborate experimentally, suggesting evolutionary optimization for avidity interactions. The combination of structure-based analysis of domain spacing with available monovalent experimental data appears, along with iterative experimental refinement of biophysical parameters, can identify high affinity interactions of tandem SH2 domain recruitment to the EGFR C-terminal tail. Using these principles, we extended bivalent predictions into the full phosphoproteome space and structural parameterization of other partners of SH2 domain binding, providing resources and methods for more rapid expansion of bivalent analysis. These approaches lay the groundwork for larger utility in multivalent prediction and testing to help better understand protein interactions that drive cell signaling.

BLI↗
PubMed2025

The super-enhancer regulatory gene SH2D1A promotes the progression of T cell acute lymphoblastic leukemia by activating CHI3L2.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive leukemia subtype and a prevalent malignancy in children, with poor prognosis, high relapse rates, and drug resistance. Recent research has shown that super-enhancer-regulated genes play crucial roles in T-ALL progression. In this study, we identified SH2 domain containing 1 A (SH2D1A) as a gene regulated by super-enhancers, and is overexpressed, which correlates with unfavorable clinical outcomes in T-ALL. To investigate its role, we silenced SH2D1A expression in T-ALL cell models using RNA interference. This led to a significant reduction in cell proliferation, colony formation, and promoted apoptosis, as demonstrated by CCK-8 assays, soft agar colony formation, and flow cytometry analysis. In vivo, knockdown of SH2D1A significantly inhibited tumor growth and prolonged survival in mice bearing T-ALL. Mechanistically, we found that SH2D1A contributes to T-ALL progression by upregulating CHI3L2, a downstream effector that promotes cell proliferation and inhibits apoptosis. Using ChIP-Seq and RNA-seq technologies, we confirmed that SH2D1A regulates CHI3L2 expression through super-enhancer-mediated regulation in T-ALL cells. Our findings suggest that SH2D1A and CHI3L2 act as oncogenes in T-ALL, and may represent novel therapeutic targets. This research offers new insights into the molecular mechanisms of T-ALL and highlights potential avenues for therapeutic intervention.

Precursor T-Cell Lymphoblastic Leukemia-Lymphoma↗
PubMed2025

SH2-mediated steric occlusion of the C2 domain regulates autoinhibition of SHIP1 inositol 5-phosphatase.

The Src homology 2 (SH2) domain containing inositol polyphosphate 5-phosphatase 1 (SHIP1) is an immune cell specific enzyme that regulates phosphatidylinositol-(3,4,5)-trisphosphate signaling at the plasma membrane following receptor activation. SHIP1 plays an important role in processes such as directed cell migration, endocytosis, and cortical membrane oscillations. Alterations in SHIP1 expression have been shown to perturb myeloid cell chemotaxis and differentiation. In the brain, SHIP1 regulate microglial cell behaviors, which has been linked to Alzheimer's disease. Understanding the structural and functional relationships of SHIP1 is critical for developing ways to modulate SHIP1 membrane localization and lipid phosphatase activity during immune cell signaling. Recently, we discovered that the N-terminal SH2 domain of SHIP1 suppresses lipid phosphatase activity. SHIP1 autoinhibition can be relieved through interactions with receptor-derived phosphotyrosine (pY) peptides presented on membranes or in solution. Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) we identified intramolecular contacts between the N-terminal SH2 domain and CBL1 motif of the C2 domain that limit SHIP1 membrane localization and activity. Single molecule measurements of purified SHIP1 on supported lipid bilayers and in neutrophil-like cells support a model in which the SH2 domain blocks membrane binding of the central catalytic module. Mutations that disrupt autoinhibition enhance the membrane binding frequency and increase the catalytic efficiency of SHIP1. Although dimerization of SHIP1 enhances membrane localization and the apparent phosphatase activity, it is not required for SHIP1 autoinhibition. Overall, our results provide new insight concerning SHIP1's structural organization, membrane binding dynamics, and the mechanism of autoinhibition.

Journal Article↗
PubMed2026

Dual functional genomics reveals a broad and convergent landscape of asciminib resistance in BCR::ABL1.

BACKGROUND: Drug resistance is a constantly evolving challenge. The allosteric inhibitor asciminib is a novel therapy for chronic myelogenous leukemia (CML) that targets the myristoyl pocket of the BCR::ABL1 kinase. While it can overcome resistance to active-site inhibitors like imatinib, new resistance mutations to asciminib are emerging. The complete landscape of these mutations, particularly those outside the kinase domain or those arising from epistatic interactions between mutations, are not well understood. METHODS: This study employed a dual functional genomics approach in CML cell line models. A high-throughput adenosine base editing (ABE) screen was used to identify broad hotspots of asciminib resistance across the entire BCR::ABL1 protein. Deep mutational scanning (DMS) was then used to create a high-resolution map of all possible amino acid changes within these hotspots. An "edit-on-edit" screen was performed to investigate epistasis by introducing a library of mutations into a cell line that was pre-edited to incorporate the common imatinib-resistance mutation, Y253H. Finally, a novel Förster resonance energy transfer (FRET) biosensor was developed to measure the conformational state of BCR::ABL1 in live cells and link it to drug sensitivity. RESULTS: The screens identified 279 asciminib resistance mutations and revealed resistance hotspots distributed across the SH3, SH2, and kinase domains, in contrast to imatinib resistance, which is largely confined to the kinase domain. The study uncovered a potent epistatic interaction between a mutation in the SH3 domain (V73A) and a mutation in the kinase domain P-loop (Y253H), which synergistically conferred high-level resistance. The FRET biosensor demonstrated that asciminib resistance mutations tend to destabilize the "closed" inactive conformation of the ABL1 kinase. CONCLUSIONS: The landscape of asciminib resistance is broader and more complex than previously appreciated, involving mutations across multiple domains that disrupt ABL1 autoinhibition. Epistasis between mutations acquired during sequential therapies can create unexpected and potent resistance. However, these diverse genetic resistance mechanisms converge on a single biophysical measurement of the openness of the active ABL1 conformation. This provides a unified framework for understanding asciminib resistance and underscores the need for routine clinical resistance monitoring to include the SH3 and SH2 domains in first line and later line therapy.

Fusion Proteins, bcr-abl↗