LATS1/LATS2 Antibody

What are the structural and functional differences between LATS1 and LATS2 kinases?

LATS1 and LATS2 are paralogous serine/threonine kinases that show extensive sequence similarity but possess distinct functional properties. Both kinases function as core components of the Hippo signaling pathway, where they phosphorylate and regulate YAP and TAZ transcriptional co-activators to control cell proliferation and apoptosis. Despite their similarities, these paralogs exhibit important differences in their regulatory networks and cellular functions. LATS1 localizes to the centrosome and mitotic spindle, controlling G2/M transition through negative regulation of cdc2 kinase activity and participating in the G1 tetraploidy checkpoint via p53 regulation .

LATS2, while sharing the ability to phosphorylate YAP/TAZ, has been shown to have divergent functions in certain cellular contexts. The genomic duplication event that led to two related kinases in higher organisms has increased the complexity of this signaling network. Notably, while both kinases can converge on similar pathways and outcomes, they demonstrate differential mRNA expression patterns, protein-binding partners, and subcellular localizations that contribute to their unique functions . In hepatocellular carcinoma, LATS1 has been reported to have unexpectedly higher expression compared to normal tissue and correlates with poor prognosis, while LATS2 shows lower expression and better survival association, highlighting their divergent roles in certain cancer contexts .

How do LATS1/LATS2 antibodies help elucidate the Hippo signaling pathway components?

LATS1/LATS2 antibodies serve as critical tools for investigating the complex regulation and interactions within the Hippo signaling cascade. These antibodies enable researchers to detect both total and phosphorylated forms of LATS1/LATS2, which is essential for understanding their activation status and subsequent downstream effects. The Hippo pathway consists of a kinase cascade wherein STK3/MST2 and STK4/MST1, in complex with SAV1, phosphorylate and activate LATS1/LATS2, which then phosphorylate and inactivate YAP1 and WWTR1/TAZ .

Antibodies specific to phosphorylated residues, such as those targeting phospho-T1079 in LATS1 and phospho-T1041 in LATS2, allow precise monitoring of the activation state of these kinases . Similarly, antibodies recognizing phospho-Ser909/Ser872 provide insights into another critical regulatory phosphorylation event . These tools enable researchers to map signaling dynamics through techniques such as western blotting, immunoprecipitation, and immunohistochemistry, offering visual and quantitative evidence of kinase activation. Through such applications, researchers have established that LATS1/LATS2 function redundantly in certain contexts, such as liver development, where their deletion results in failure of proper hepatoblast differentiation and BEC development .

What experimental considerations are important when selecting between LATS1 and LATS2 antibodies?

When selecting antibodies for LATS1 or LATS2 research, researchers must consider several critical factors that will impact experimental outcomes. First, determine whether the research question requires detection of total protein or specific phosphorylated forms. For phospho-specific detection, antibodies targeting sites like T1079/T1041 or Ser909/Ser872 provide information about activation status . For total protein detection, antibodies like LATS1 (C66B5) Rabbit mAb offer high sensitivity for endogenous protein levels .

Species cross-reactivity is another crucial consideration. Many commercially available antibodies show reactivity with human, mouse, and monkey samples, but verification for your specific model system is essential. The LATS1 (C66B5) Rabbit mAb, for instance, demonstrates reactivity with human, mouse, and monkey samples . Additionally, consider the application requirements for your experimental design. Some antibodies perform optimally in specific applications like western blotting (typically at 1:1000 dilution) or immunoprecipitation (at 1:100 dilution) , while others may be validated for immunohistochemistry on paraffin-embedded tissues .

For studies examining redundant functions versus unique roles, researchers may need both LATS1 and LATS2 antibodies. This becomes particularly important when investigating contexts where these kinases show distinct behaviors, such as in hepatocellular carcinoma where LATS1 may promote resistance to sorafenib while LATS2 maintains tumor suppressive functions .

How can researchers effectively use LATS1/LATS2 antibodies to study kinase-dependent versus kinase-independent functions?

Distinguishing between kinase-dependent and kinase-independent functions of LATS1/LATS2 requires a methodical approach utilizing appropriate antibodies. To investigate this distinction, researchers should combine antibody-based detection methods with genetic and pharmacological manipulation of LATS kinase activity. For example, studies have revealed that LATS1's effect on cell viability appears independent of its canonical kinase activity, as both wild-type (WT) and kinase-dead (KD) versions of LATS1 reduced cell death in hepatocellular carcinoma cells .

For methodological implementation, researchers should: (1) Use phospho-specific antibodies targeting the activation sites (T1079/T1041) to confirm kinase activation status; (2) Compare results with total LATS1/LATS2 antibodies to determine protein expression levels independent of phosphorylation; (3) Employ genetic approaches with siRNA knockdown followed by rescue experiments with WT or KD mutants to differentiate functions; and (4) Analyze downstream targets like YAP/TAZ phosphorylation to confirm kinase activity effects .

This integrated approach has revealed important biological insights, such as in liver development where LATS1/LATS2 redundantly restrict YAP/TAZ activity during hepatocyte maturation and biliary epithelial cell differentiation. Knockout studies confirmed that this regulation requires kinase activity, as double knockout mice experienced perinatal lethality with defects in bile duct formation and hepatocyte function, all of which were dependent on YAP/TAZ hyperactivation .

What techniques can be employed to analyze differential expression and activation of LATS1/LATS2 in tumor versus normal tissues?

Analyzing differential expression and activation of LATS1/LATS2 in tumor versus normal tissues requires a multi-faceted approach combining antibody-based detection methods with transcriptomic analysis. For protein-level assessment, immunohistochemistry (IHC) using LATS1/LATS2 antibodies on paired tumor and normal tissue sections provides spatial information about expression patterns. Phospho-specific antibodies can simultaneously reveal activation status in these tissues . Western blotting of tissue lysates offers quantitative comparison of both total and phosphorylated LATS1/LATS2, with appropriate loading controls to ensure accurate normalization.

To validate these findings, researchers should perform functional studies in relevant cell lines, using siRNA-mediated knockdown or overexpression approaches with subsequent phenotypic assays. For example, knockdown of upregulated LATS1 in sorafenib-resistant HCC cells led to reduced cell viability and decreased colony formation, supporting its unexpected pro-tumorigenic role in this context .

How can LATS1/LATS2 phosphorylation be effectively monitored in response to upstream Hippo pathway activation?

Monitoring LATS1/LATS2 phosphorylation in response to upstream Hippo pathway activation requires a systematic approach utilizing phospho-specific antibodies. Researchers should implement a time-course analysis following stimulation of the Hippo pathway (e.g., by cell contact inhibition, serum starvation, or direct activation of MST1/2) and collect samples at multiple timepoints for western blotting. Phospho-specific antibodies targeting key regulatory sites like Ser909/Ser872 or Thr1079/Thr1041 will reveal the dynamics of LATS1/LATS2 activation .

For methodology implementation, prepare cellular lysates in phosphatase inhibitor-containing buffers to preserve phosphorylation status, and perform western blotting with a combination of phospho-specific and total LATS1/LATS2 antibodies. Calculate the ratio of phosphorylated to total protein to determine relative activation levels. This approach can be complemented by monitoring downstream targets, particularly YAP/TAZ phosphorylation, which serves as a functional readout of LATS kinase activity.

For advanced analysis, immunoprecipitation with LATS1/LATS2 antibodies followed by in vitro kinase assays using recombinant YAP as substrate can directly measure kinase activity. Additionally, proximity ligation assays can visualize interactions between LATS1/LATS2 and upstream regulators like MST1/2 or downstream targets, providing spatial information about signaling events within individual cells. When implemented in model systems like liver progenitor cells, these techniques have revealed that LATS1/LATS2 are redundantly required to restrict YAP/TAZ activity during hepatocyte maturation and biliary epithelial cell differentiation .

How can researchers differentiate between LATS1/LATS2 direct substrates versus secondary effects in experimental systems?

Differentiating between direct LATS1/LATS2 substrates and secondary effects requires a multi-faceted experimental approach. For rigorous substrate identification, researchers should first establish the consensus phosphorylation motif (H-X-R/H/K-X-X-S/T) recognized by LATS1/LATS2 kinases. Then, implement a systematic workflow combining in vitro and cellular validation: (1) Perform in vitro kinase assays with purified recombinant LATS1/LATS2 and candidate substrates, detecting phosphorylation with phospho-specific antibodies or mass spectrometry; (2) Validate cellular phosphorylation by immunoprecipitating the candidate substrate and probing with phospho-specific antibodies; (3) Generate phospho-deficient mutants (S/T to A) of the candidate substrate to confirm the specific site; and (4) Perform rescue experiments in LATS1/LATS2-depleted cells to differentiate direct versus indirect effects .

This approach has successfully identified both canonical substrates like YAP/TAZ and non-canonical targets. For example, LATS2 has been shown to directly phosphorylate SNAI1 in the nucleus, leading to its nuclear retention and stabilization, which enhances epithelial-mesenchymal transition and tumor cell invasion/migration activities—a tumor-promoting function independent of YAP/TAZ regulation . Similarly, LATS1 affects cytokinesis by regulating actin polymerization through negative modulation of LIMK1 and interacts with phosphorylated zyxin to influence actin filament assembly . These methodical approaches help distinguish primary kinase targets from secondary pathway effects.

What are the optimal experimental designs for investigating functional redundancy versus specificity between LATS1 and LATS2?

Investigating functional redundancy versus specificity between LATS1 and LATS2 requires carefully designed genetic approaches combined with comprehensive phenotypic and molecular analyses. The optimal experimental design should include: (1) Single knockdown/knockout experiments for LATS1 and LATS2 individually, allowing comparison of phenotypes to identify kinase-specific functions; (2) Double knockdown/knockout experiments to reveal redundant functions that might be masked in single knockdown studies; and (3) Rescue experiments with wild-type or mutant versions of each kinase to determine domain-specific contributions to observed phenotypes .

For cellular systems, researchers should employ siRNA-mediated knockdown, CRISPR/Cas9-mediated knockout, or inducible systems for temporal control. In mouse models, conditional knockout approaches using tissue-specific promoters (e.g., Albumin-cre for liver-specific deletion) enable study of redundancy in developmental contexts while avoiding embryonic lethality. This approach revealed that while single knockouts of either Lats1 or Lats2 in the liver were viable, double knockout resulted in perinatal lethality with defects in bile duct formation and hepatocyte function .

Analysis should include multiple readouts: (1) Phenotypic assessment (viability, proliferation, differentiation); (2) Molecular profiling (transcriptomics or proteomics); and (3) Biochemical analysis of downstream pathway activation. For example, gene expression profiling of Albumin-cre; Lats1/2 double knockout livers compared to wild-type revealed significant dysregulation of the Hippo pathway. Importantly, comparison with Albumin-cre; Yap, Taz double knockout livers confirmed that the primary function of LATS1/2 in the liver is indeed to inhibit YAP/TAZ activity .

How can researchers effectively account for tissue-specific differences in LATS1/LATS2 expression and function when designing experiments?

Designing experiments that account for tissue-specific differences in LATS1/LATS2 expression and function requires a systematic approach that integrates tissue-relevant models with appropriate detection methods. Researchers should first conduct preliminary expression analysis using tissue-specific databases (e.g., GTEx, Human Protein Atlas) to determine baseline expression levels of LATS1/LATS2 in the tissue of interest. This initial assessment should guide antibody selection based on sensitivity requirements—tissues with low expression may require more sensitive detection methods such as immunoprecipitation followed by western blotting .

For experimental design, researchers should prioritize physiologically relevant models. Primary cells derived from the tissue of interest provide the most authentic context, while established cell lines should be carefully selected to match the tissue of origin. For in vivo studies, tissue-specific conditional knockout models (using promoters like Albumin-cre for liver) allow precise targeting of LATS1/LATS2 in specific tissues while avoiding systemic effects . When analyzing tissues with complex cellular composition, single-cell approaches or cell type-specific isolation methods should be employed to avoid masking cell type-specific effects.

Experimental readouts should incorporate tissue-specific markers and functional assays. For example, in liver studies, biliary epithelial cell development can be assessed through histological examination of bile duct formation, while hepatocyte function can be evaluated through glycogen accumulation (PAS staining) and serum markers like ALT/AST . These tissue-specific approaches have revealed important context-dependent functions, such as the surprising finding that LATS1 expression is elevated in hepatocellular carcinoma and correlates with poor prognosis—contradicting its canonical tumor suppressor role in other tissues .

What optimization strategies can improve specificity and sensitivity when using LATS1/LATS2 antibodies in various applications?

Optimizing LATS1/LATS2 antibody usage requires application-specific strategies to enhance both specificity and sensitivity. For western blotting applications, researchers should first determine the optimal antibody dilution through titration experiments, starting with manufacturer-recommended dilutions (typically 1:1000 for LATS1 antibodies) . Blocking conditions should be optimized to reduce background, with 5% BSA often preferred over milk for phospho-specific antibodies. Extended transfer times may be necessary for high-molecular-weight proteins like LATS1 (140 kDa) . Validation of specificity should include positive controls (overexpression lysates) and negative controls (siRNA knockdown samples).

For immunoprecipitation, adjust antibody amounts based on protein abundance (typically 1:100 dilution) . Pre-clearing lysates with protein A/G beads reduces non-specific binding. For co-immunoprecipitation studies investigating LATS1/LATS2 interactions with binding partners, gentler lysis conditions preserving protein complexes should be employed. Validation through reciprocal co-IP strengthens interaction findings.

Regardless of application, all antibodies should undergo thorough validation, including verification of the expected molecular weight (140 kDa for LATS1) , demonstration of knockdown-dependent signal reduction, and ideally, testing in multiple species when cross-reactivity is claimed .

What are the recommended protocols for detecting phosphorylated forms of LATS1/LATS2 in experimental systems?

Detecting phosphorylated forms of LATS1/LATS2 requires specialized protocols to preserve phosphorylation status and ensure specific detection. Begin sample preparation by lysing cells in phosphatase inhibitor-containing buffers (including sodium fluoride, sodium orthovanadate, and β-glycerophosphate) to prevent dephosphorylation during processing. For tissue samples, rapid freezing in liquid nitrogen followed by homogenization in cold phosphatase inhibitor-containing buffer is recommended. All steps should be performed at 4°C to minimize phosphatase activity.

For western blotting, specific phospho-antibodies targeting key regulatory sites are essential. Several commercial antibodies target critical phosphorylation sites, including Ser909/Ser872 and Thr1079/Thr1041 . Use 5% BSA rather than milk for blocking and antibody dilution, as milk contains phosphatases that may reduce signal. Include appropriate positive controls, such as lysates from cells treated with stimuli known to activate the Hippo pathway. Membrane stripping and reprobing with total LATS1/LATS2 antibodies allows calculation of the phospho/total ratio for accurate activation assessment.

For immunohistochemistry of phosphorylated LATS1/LATS2 in tissues, immediate fixation is critical to preserve phosphorylation status. Heat-induced epitope retrieval in citrate buffer (pH 6.0) often yields optimal results for phospho-epitopes. Signal amplification systems may be necessary due to the typically low abundance of phosphorylated species. Always include technical controls by treating serial sections with lambda phosphatase to confirm phospho-specific staining.

For enhanced sensitivity in detecting low-abundance phosphorylated forms, consider immunoprecipitation with total LATS1/LATS2 antibodies followed by western blotting with phospho-specific antibodies .

How can researchers quantitatively compare LATS1 versus LATS2 expression and activation in the same experimental system?

Quantitatively comparing LATS1 versus LATS2 expression and activation in the same experimental system requires careful methodological considerations to ensure accurate and comparable measurements. For mRNA-level comparisons, researchers should design qPCR primers with similar amplification efficiencies for both genes, and validate them using standard curves to ensure linearity across a range of template concentrations. Reference genes should be carefully selected based on stability across experimental conditions.

For protein-level comparisons, western blotting with antibodies of comparable affinity is ideal, though this can be challenging to validate. To address this limitation, researchers can use recombinant LATS1 and LATS2 proteins as standards to create calibration curves for each antibody, allowing more accurate comparison of endogenous protein levels. Alternatively, epitope-tagged versions of both proteins can be expressed at known levels to create reference standards.

To compare activation states, phospho-specific antibodies targeting equivalent phosphorylation sites (e.g., Ser909 in LATS1 and Ser872 in LATS2) should be used, with results normalized to total protein levels determined in parallel samples. For absolute quantification, mass spectrometry-based approaches using isotope-labeled peptide standards can precisely measure both total and phosphorylated forms of each protein.

For spatial information in tissues or cells, multiplexed immunofluorescence with directly labeled primary antibodies allows simultaneous detection of both kinases in the same sample, enabling direct comparison of expression patterns and subcellular localization. When combined with phospho-specific detection, this approach can reveal cell-type or subcellular compartment-specific activation patterns of each kinase.

How can LATS1/LATS2 antibodies be utilized to investigate non-canonical functions beyond the Hippo pathway?

LATS1/LATS2 antibodies provide powerful tools for investigating non-canonical functions beyond the established Hippo pathway. To explore these alternative roles, researchers should implement a systematic approach combining co-immunoprecipitation with mass spectrometry to identify novel interaction partners. This approach begins with immunoprecipitation using well-validated LATS1 or LATS2 antibodies , followed by proteomics analysis to identify co-precipitating proteins. Candidates should be confirmed through reciprocal co-IP and proximity ligation assays to visualize interactions in situ.

For functional characterization, researchers should combine genetic manipulation (knockdown or knockout) with rescue experiments using wild-type versus kinase-dead LATS1/LATS2 variants. This strategy has revealed that LATS1 affects cytokinesis by regulating actin polymerization through negative modulation of LIMK1, and also binds phosphorylated zyxin to influence actin filament assembly and promote its localization to the mitotic spindle . Similarly, LATS2 has been shown to phosphorylate SNAI1 in the nucleus, leading to its nuclear retention and stabilization, which enhances epithelial-mesenchymal transition—a function independent of YAP/TAZ regulation .

What methodologies can researchers employ to investigate the paradoxical pro-tumorigenic role of LATS1 observed in certain cancer contexts?

For functional validation, researchers should implement loss-of-function and gain-of-function studies in relevant cancer models. LATS1 knockdown in sorafenib-resistant hepatocellular carcinoma cells reduced cell viability and decreased colony formation, supporting its pro-tumorigenic role in this context . These studies should be complemented by rescue experiments comparing wild-type and kinase-dead LATS1 variants to determine whether these functions depend on canonical kinase activity. Notably, both wild-type and kinase-dead versions of LATS1 reduced cell death in hepatocellular carcinoma cells, suggesting kinase-independent mechanisms .

To elucidate molecular mechanisms, researchers should employ immunoprecipitation with LATS1-specific antibodies followed by mass spectrometry to identify context-specific interaction partners. Phosphoproteomic analysis comparing LATS1-proficient and LATS1-deficient cells can reveal differential substrate phosphorylation. These approaches should be complemented by transcriptomic analysis to identify LATS1-dependent gene expression changes that might explain its context-specific functions.

For in vivo validation, researchers should develop conditional LATS1 knockout and overexpression models in relevant cancer types, assessing tumor initiation, progression, and therapy response. These approaches could help explain the seemingly contradictory roles of LATS1 across different cancer contexts and potentially identify new therapeutic vulnerabilities.

How can researchers design experiments to investigate the developmental redundancy versus adult tissue specificity of LATS1/LATS2 functions?

Designing experiments to investigate developmental redundancy versus adult tissue specificity of LATS1/LATS2 functions requires sophisticated genetic approaches with temporal and spatial control. Researchers should implement an integrated experimental design utilizing conditional and inducible genetic systems. First, establish tissue-specific conditional knockout models (e.g., using Cre-loxP system with tissue-specific promoters) for Lats1, Lats2, and combined Lats1/2 deletion. This approach revealed that while single knockouts of either Lats1 or Lats2 in the liver were viable, double knockout resulted in perinatal lethality with defects in bile duct formation and hepatocyte function .

For temporal control, employ tamoxifen-inducible Cre systems (CreERT2) to delete Lats1/2 at specific developmental stages or in adult tissues. This strategy allows direct comparison between developmental versus adult functions. Complementary approaches include AAV-Cre delivery to adult tissues or inducible shRNA systems for reversible knockdown with temporal control.

Analysis should include comprehensive phenotypic, histological, and molecular characterization across multiple timepoints. For liver studies, assessments should include bile duct formation, hepatocyte function (glycogen storage, metabolic enzyme activities), and serum markers of liver function (ALT/AST levels) . Molecular analysis should combine transcriptomic profiling, proteomics, and phosphoproteomics to identify stage-specific targets and pathways.

To distinguish kinase-dependent from kinase-independent functions, implement rescue experiments with wild-type versus kinase-dead versions of each protein. Finally, for mechanistic insight, perform parallel deletion of downstream effectors (e.g., YAP/TAZ) to determine which phenotypes depend on canonical Hippo signaling versus alternative pathways. This approach confirmed that in liver development, LATS1/2 primarily function by inhibiting YAP/TAZ activity .

How can researchers integrate LATS1/LATS2 findings across different model systems to develop a unified understanding of their functions?

Integrating LATS1/LATS2 findings across different model systems requires a systematic approach that accounts for context-specific variations while identifying conserved mechanisms. Researchers should implement meta-analysis strategies combining data from diverse experimental systems—cell lines, organoids, animal models, and human samples—with standardized analytical frameworks. This approach begins with establishing comparable experimental endpoints across systems, such as phosphorylation status of key residues (Ser909/Ser872, Thr1079/Thr1041) and effects on downstream targets like YAP/TAZ .

For molecular mechanism integration, researchers should develop comprehensive interaction maps incorporating all validated binding partners and substrates across systems. This approach has revealed both conserved functions, such as YAP/TAZ regulation, and context-specific roles, such as LATS1's unexpected pro-tumorigenic function in hepatocellular carcinoma . Network analysis tools can identify core pathway components versus tissue-specific modulators.

Computational modeling incorporating quantitative data on protein expression, activation kinetics, and downstream effects can predict context-dependent outcomes. These models should integrate genetic perturbation data from multiple systems, such as the finding that LATS1 and LATS2 function redundantly during liver development but may have opposing roles in certain cancer contexts .

For translational relevance, correlative analysis between model system findings and human patient data is essential. For example, the observation that LATS1 mRNA levels are elevated in hepatocellular carcinoma and correlate with poor prognosis provides important context for interpreting functional studies in cell lines . This integrative approach can resolve apparent contradictions between systems and develop a unified understanding of how these kinases function across developmental, homeostatic, and pathological contexts.

What future directions and technological advances might enhance LATS1/LATS2 antibody-based research?

Future directions in LATS1/LATS2 antibody-based research will likely be driven by technological advances in several key areas. Development of highly specific monoclonal antibodies distinguishing phosphorylation at individual sites will improve precision in mapping activation patterns. These could be complemented by conformation-specific antibodies that recognize active versus inactive kinase states, providing functional information beyond simple phosphorylation status.

Advances in multiplexed imaging technologies will allow simultaneous visualization of multiple LATS1/LATS2 phosphorylation sites and interaction partners within individual cells. Techniques like Multiplexed Ion Beam Imaging (MIBI) or Co-Detection by Indexing (CODEX) could enable visualization of entire Hippo pathway components in tissue sections, preserving spatial context. Similarly, proximity labeling approaches using LATS1/LATS2 antibodies conjugated to enzymes like BioID or APEX2 would enable mapping of the local protein environment in different subcellular compartments.

For dynamic studies, development of FRET-based biosensors incorporating LATS1/LATS2-specific antibody fragments could enable real-time monitoring of kinase activation in living cells. These could be combined with optogenetic approaches for precise spatiotemporal control of pathway activation. At the tissue level, advances in spatial transcriptomics and proteomics will allow correlation between LATS1/LATS2 protein expression/activation and downstream gene expression patterns with preserved spatial information.

In therapeutic contexts, development of LATS1/LATS2 antibody-drug conjugates could provide targeted approaches for contexts where these kinases promote pathological processes, such as LATS1's role in sorafenib resistance in hepatocellular carcinoma . Similarly, antibodies distinguishing between LATS1 and LATS2 could enable selective targeting in contexts where they have opposing functions.