Phospho-DNM1 (S778) Antibody

What is Phospho-DNM1 (S778) Antibody and what molecular target does it recognize?

Phospho-DNM1 (S778) Antibody is a polyclonal antibody that specifically recognizes the dynamin-1 protein (DNM1) when phosphorylated at serine 778. This antibody is typically derived from rabbit hosts and is designed to detect endogenous levels of DNM1 protein exclusively in its S778-phosphorylated state . The antibody targets a synthetic peptide derived from human Dynamin-1 around the phosphorylation site of S778, typically within the amino acid range of 751-800 . DNM1 is a GTPase protein essential for vesicle fission during endocytosis, and its phosphorylation state at S778 plays a critical regulatory role in its function and localization at synapses. The antibody demonstrates reactivity with human, mouse, and rat species, making it versatile for comparative mammalian studies .

What are the validated applications for Phospho-DNM1 (S778) Antibody in laboratory research?

Phospho-DNM1 (S778) Antibody has been validated primarily for Western Blot (WB) and Enzyme-Linked Immunosorbent Assay (ELISA) applications, though the specific applications may vary between manufacturers . For Western Blot applications, the recommended dilution range is typically 1:500-1:2000, while ELISA applications may require higher dilutions, up to 1:20000 . The antibody has been successfully used to detect phosphorylated dynamin in brain tissue samples, particularly in neuronal cells where DNM1 is predominantly expressed . These applications allow researchers to quantify phosphorylation levels of dynamin at S778 under various experimental conditions, including neuronal activity states and pharmacological treatments that affect endocytosis.

What methodological considerations are important when working with Phospho-DNM1 (S778) Antibody?

When working with Phospho-DNM1 (S778) Antibody, several methodological considerations are critical for experimental success:

• Sample Preparation: Phosphorylation states can be labile; therefore, samples should be collected with phosphatase inhibitors to preserve the phosphorylation status of DNM1.

• Antibody Specificity Validation: Researchers should validate the specificity of the antibody using appropriate controls, including phosphatase-treated samples and samples from tissues known to express varying levels of phosphorylated DNM1.

• Storage Conditions: The antibody should be stored according to manufacturer recommendations, typically at -20°C for up to one year from the date of receipt, while avoiding repeated freeze-thaw cycles that can degrade antibody performance .

• Buffer Compatibility: The antibody is typically formulated in PBS containing 50% glycerol, 0.5% BSA, and 0.02% sodium azide . Researchers should ensure compatibility between this formulation and their experimental systems.

• Phosphorylation-State Specificity: Since the antibody detects only phosphorylated S778, results should be interpreted in the context of total DNM1 levels, which may require parallel experiments with antibodies that recognize DNM1 regardless of phosphorylation state.

How does phosphorylation at S778 regulate dynamin function and its interaction with binding partners?

Phosphorylation at S778 of DNM1 serves as a critical regulatory mechanism that modulates dynamin's interaction with its binding partners, particularly Syndapin 1. When S778 (and the nearby S774) are dephosphorylated, DNM1 exhibits strong binding to Syndapin 1, whereas phosphorylation at these sites significantly reduces this interaction by approximately 70% . This phosphorylation-dependent interaction is specific to Syndapin 1, as the binding of other partners like Endophilin A is less affected by the phosphorylation status of these sites (with the exception of Endophilin A1, which shows a ~60% reduction in binding to phosphomimetic S774/778E mutations) .

The phospho-regulated interaction domain containing S774 and S778 acts as a molecular switch that controls dynamin's participation in endocytosis. Dephosphorylation promotes dynamin's assembly at endocytic sites through enhanced Syndapin 1 binding, while phosphorylation leads to more diffuse cytosolic distribution of dynamin . This mechanism allows for rapid recruitment of dynamin to endocytic sites when needed, bypassing slower recruitment processes and thereby accelerating endocytosis, particularly the ultrafast endocytosis observed at synapses.

What experimental evidence demonstrates the impact of S778 phosphorylation on endocytic kinetics?

Experimental evidence has convincingly demonstrated that phosphorylation at S778 significantly impacts endocytic kinetics. Studies using phosphomimetic mutations (S774/778D or S774/778E) have revealed that these mutations cause delays in endocytosis compared to the dephosphorylated state . Specifically:

• Morphological Evidence: Electron microscopy studies have shown that endocytic pits in neurons expressing Dyn1xA S774/778D mutants exhibit a different morphological progression compared to those in dynamin knockout neurons. While knockout neurons display endocytic pits with wide openings that persist over time (pit width at 1s: median 61.67 nm; at 10s: median 58.33 nm), neurons expressing the phosphomimetic mutant show progressive constriction of the pit openings (pit width at 1s: median 58.33 nm; at 10s: reduced to median 33.33 nm, P<0.0001) . This indicates that endocytosis proceeds in the presence of phosphomimetic dynamin but at a significantly slower rate.

• Localization Studies: Fluorescence imaging has demonstrated that the majority of Dyn1xA S774/778D remains cytosolic and diffusely distributed throughout axons, in contrast to the more punctate distribution of dephosphorylated dynamin . This suggests that the delayed endocytosis observed with phosphomimetic mutants is largely due to the slower recruitment of dynamin to endocytic sites.

• Functional Assays: pHluorin-based endocytosis assays have confirmed these findings, showing that phosphorylation sites S774/778 control the kinetics of endocytosis, with dephosphorylation promoting faster vesicle recycling .

How can researchers use Phospho-DNM1 (S778) Antibody to investigate phase separation properties of dynamin?

Recent research has revealed that dynamin undergoes phase separation as part of its functional mechanism, and Phospho-DNM1 (S778) Antibody can be a valuable tool for investigating this phenomenon:

• Phosphorylation-Dependent Phase Separation: Studies using fluorescence recovery after photobleaching (FRAP) have shown that dynamin's phase separation properties are influenced by its phosphorylation status . Researchers can use Phospho-DNM1 (S778) Antibody in combination with total DNM1 antibodies to quantify the proportion of phosphorylated versus non-phosphorylated dynamin in different cellular compartments or phase-separated condensates.

• Experimental Approach:

  • Immunofluorescence studies comparing the distribution of phosphorylated (detected with Phospho-DNM1 (S778) Antibody) versus total dynamin can reveal differences in localization.

  • Western blot analysis of fractionated cellular components can quantify the relative abundance of phosphorylated dynamin in different subcellular compartments.

  • Co-immunoprecipitation experiments using Phospho-DNM1 (S778) Antibody can identify interaction partners that specifically associate with the phosphorylated form of dynamin.

• Pharmacological Manipulations: Researchers can use kinase inhibitors (like GSK3β inhibitor CHIR990201, which blocks phosphorylation at S774) or phosphatase inhibitors (like calcineurin inhibitor FK506) to manipulate dynamin's phosphorylation state and then assess changes in phase separation properties using Phospho-DNM1 (S778) Antibody . This approach can help determine how phosphorylation status affects dynamin's ability to form functional condensates at endocytic sites.

How is DNM1 phosphorylation at S778 implicated in neurological disorders?

While the search results do not directly address the role of S778 phosphorylation in pathological conditions, they provide context for understanding potential implications:

What methodological approaches can researchers use to study the role of DNM1 S778 phosphorylation in synaptic function?

Researchers interested in studying the role of DNM1 S778 phosphorylation in synaptic function can employ several methodological approaches:

• Temporal Analysis of Phosphorylation: Using Phospho-DNM1 (S778) Antibody in combination with synaptic activity markers, researchers can correlate changes in DNM1 phosphorylation with different phases of synaptic transmission and plasticity.

• Genetic Manipulations:

  • Expression of phosphomimetic (S778D/E) or phospho-deficient (S778A) mutants to assess the impact on synaptic vesicle recycling

  • CRISPR-Cas9 knock-in of mutations at endogenous loci to ensure physiological expression levels

  • Comparing the effects of disease-causing mutations (identified in DNM1 encephalopathy patients) with manipulations of S778 phosphorylation status

• High-Resolution Imaging: Using electron microscopy and advanced light microscopy techniques in combination with Phospho-DNM1 (S778) Antibody immunolabeling to visualize:

  • The distribution of phosphorylated versus non-phosphorylated dynamin at synapses

  • Changes in endocytic pit morphology correlating with dynamin phosphorylation status

  • Temporal dynamics of dynamin dephosphorylation during synaptic activity

• Functional Assays:

  • Using pHluorin-based assays to measure endocytosis rates in neurons expressing different DNM1 phospho-mutants

  • Electrophysiological recordings to correlate changes in synaptic transmission with dynamin phosphorylation status

  • Measuring synaptic vesicle pool sizes and mobilization in the context of altered DNM1 phosphorylation

What controls should be included when using Phospho-DNM1 (S778) Antibody in experimental designs?

When using Phospho-DNM1 (S778) Antibody, researchers should include the following controls to ensure experimental validity:

• Phosphatase Treatment Control: Treating a portion of the sample with lambda phosphatase to dephosphorylate all proteins, which should eliminate or significantly reduce the signal from Phospho-DNM1 (S778) Antibody.

• Kinase/Phosphatase Inhibitor Controls: Treating samples with inhibitors of relevant kinases (e.g., GSK3β inhibitor) or phosphatases (e.g., calcineurin inhibitor FK506) to manipulate phosphorylation levels as positive and negative controls.

• Peptide Competition: Pre-incubating the antibody with the phosphorylated peptide immunogen to confirm specificity.

• Knockout/Knockdown Controls: Using DNM1 knockout or knockdown samples to confirm the specificity of the detected band.

• Cross-Reactivity Assessment: Testing the antibody with purified phosphorylated and non-phosphorylated DNM1 protein to confirm its phospho-specificity.

• Species Validation: When working with samples from different species, validating the antibody's reactivity with the species of interest, even though the product information indicates reactivity with human, mouse, and rat DNM1 .

How can researchers optimize Western Blot protocols for Phospho-DNM1 (S778) Antibody?

Optimizing Western Blot protocols for Phospho-DNM1 (S778) Antibody requires attention to several key factors:

• Sample Preparation:

  • Include phosphatase inhibitors in lysis buffers to preserve phosphorylation status

  • Process samples quickly and keep them cold to minimize phosphatase activity

  • Consider comparing different extraction methods to optimize phospho-protein yield

• Antibody Dilution:

  • Test different dilutions within the recommended range (1:500-1:2000)

  • Optimize blocking conditions to reduce background while maintaining specific signal

• Detection System:

  • Compare different detection methods (chemiluminescence, fluorescence) for optimal signal-to-noise ratio

  • Consider longer exposure times if the phosphorylated form is present at low abundance

• Multiplexing:

  • When possible, use a dual-color detection system to simultaneously visualize phosphorylated DNM1 and total DNM1 on the same blot

  • This approach allows for direct calculation of the phosphorylation ratio within each sample

• Quantification:

  • Always normalize phospho-DNM1 signal to total DNM1 levels to account for variations in total protein expression

  • Include a loading control (β-actin, GAPDH) to ensure equal loading across lanes

How does the study of DNM1 S778 phosphorylation contribute to our understanding of ultrafast endocytosis?

The study of DNM1 S778 phosphorylation has significantly advanced our understanding of ultrafast endocytosis, particularly through these key findings:

• Priming Mechanism: Research has shown that dephosphorylation at S778 (and S774) promotes the association of DNM1 with Syndapin 1 , effectively priming dynamin for rapid recruitment to endocytic sites. This priming mechanism is critical for ultrafast endocytosis, which occurs on a millisecond timescale.

• Phase Separation: Dephosphorylated dynamin appears to undergo phase separation, forming concentrated pools that can be rapidly mobilized for endocytosis . This represents a novel mechanism for controlling the speed of endocytic processes.

• Kinetic Regulation: Experiments with phosphomimetic mutations (S774/778D) have demonstrated that phosphorylation status directly affects the rate of endocytosis, with dephosphorylation promoting faster endocytic kinetics . This provides a molecular explanation for the ultrafast nature of certain forms of endocytosis.

• Morphological Progression: Electron microscopy studies have revealed that the phosphorylation status of dynamin affects the morphological progression of endocytic pits, with phosphomimetic mutants showing delayed but progressive constriction of pit openings compared to the stalled wide openings observed in dynamin knockout neurons .

These findings collectively suggest that the phosphorylation cycle of DNM1 at S778 serves as a regulatory switch that controls the availability of dynamin for rapid endocytosis, with dephosphorylation promoting phase separation and rapid recruitment to endocytic sites, thereby facilitating ultrafast endocytosis.

What are the emerging research questions regarding DNM1 phosphorylation and neurological disorders?

Several emerging research questions link DNM1 phosphorylation to neurological disorders, offering promising directions for future investigation:

• Phosphorylation Status in DNM1 Encephalopathy: Do disease-causing mutations in DNM1 affect its phosphorylation status at S778, potentially contributing to the pathophysiology of DNM1 encephalopathy ?

• Therapeutic Targeting: Could modulation of DNM1 phosphorylation at S778 represent a potential therapeutic approach for disorders characterized by disrupted vesicle recycling?

• Synaptic Plasticity Mechanisms: How does the phosphorylation status of DNM1 at S778 contribute to activity-dependent synaptic plasticity, and is this mechanism altered in neurological disorders?

• Developmental Regulation: Given that DNM1 expression increases postnatally in parallel with synapse formation , how is S778 phosphorylation regulated during development, and could disruptions in this regulation contribute to neurodevelopmental disorders?

• Interaction with Other Disease Mechanisms: How does DNM1 phosphorylation interact with other pathological processes in neurological disorders, such as protein aggregation, inflammation, or mitochondrial dysfunction?

Addressing these questions will require integrative approaches combining biochemical studies using tools like Phospho-DNM1 (S778) Antibody with advanced imaging, electrophysiology, and animal models of neurological disorders.