phlda2 Antibody

What is the biological function of PHLDA2 in normal tissues?

PHLDA2 (Pleckstrin Homology-Like Domain Family A, Member 2) plays a critical role in regulating placenta growth and is expressed at high levels in placenta and adult prostate, with lower expression in liver, lung, and brain tissues. Research indicates that PHLDA2 functions as a negative growth regulator during normal human development . This protein is imprinted and expressed predominantly from the maternal allele in human and mouse placenta, with no evidence of expression in neuronal tissues . PHLDA2 contains a pleckstrin homology (PH) domain that competes with other PH domain-containing proteins, preventing their binding to membrane lipids . This competitive binding mechanism is central to PHLDA2's biological role.

How is PHLDA2 expression regulated in different tissues and developmental stages?

PHLDA2 expression exhibits specific temporal and spatial patterns. It is imprinted on placenta, liver, and fetal tissues during embryogenesis and this imprinting is typically removed once development is complete . The gene is located within a single imprinted domain called IC2 on mouse chromosome 7/human chromosome 11p15, and is exclusively imprinted in Eutherians . Research has demonstrated that the methylation levels of PHLDA2 are lower in hepatocellular carcinoma (HCC) tissues compared to normal liver tissues . Additionally, in experimental models, PHLDA2 expression can be induced by TGF-β in vitro, and treatments such as sorafenib or cisplatin have been shown to significantly up-regulate PHLDA2 mRNA levels .

What are the most suitable applications for PHLDA2 antibodies in basic research?

Based on validated applications from commercial sources and published research, PHLDA2 antibodies have been successfully employed in several key methodologies:

For most accurate results, titration of the antibody should be performed for each specific experimental system . Positive controls that have been validated include L02 cells, human placenta tissue, MCF-7 cells, and PC-3 cells for Western blotting .

How can PHLDA2 antibodies be utilized to study its role in AKT signaling pathway inhibition?

Research has established PHLDA2 as a negative regulator of AKT signaling. To investigate this interaction, researchers can:

• Perform co-immunoprecipitation studies using PHLDA2 antibodies to identify binding partners in the PI3K/AKT pathway

• Conduct protein-lipid overlay experiments to assess PHLDA2 binding to phosphoinositides. Published data shows that GST-PHLDA2 binds to most PIPs, including PtdIns(3,4)P2 and PtdIns(3,4,5)P3

• Use competitive binding assays to evaluate how PHLDA2 interferes with AKT binding to PIPs. In vitro experiments demonstrated that when PHLDA2 and AKT were mixed in a 1:1 molar ratio, AKT binding to PI(3,4,5)P3 and PI(3,4)P2 was significantly inhibited

• Employ immunofluorescence microscopy with PHLDA2 antibodies to visualize subcellular localization changes in response to pathway activation

These approaches allow researchers to probe the mechanism by which PHLDA2 represses AKT activity by competitively binding PI(3,4,5)P3 and PI(3,4)P2, thereby preventing AKT translocation to the plasma membrane and subsequent activation .

What is the significance of PHLDA2 expression correlation with p-AKT in tumor samples, and how can this be assessed?

Immunohistochemical studies have revealed a strong correlation between PHLDA2 and p-AKT expression in human lung cancer tissue microarrays (correlation coefficient = 0.336, p = 0.0002) . This correlation suggests that PHLDA2 may function as a biomarker for AKT pathway activation. To assess this relationship:

• Use dual immunohistochemistry with PHLDA2 and p-AKT antibodies on tissue microarrays

• Score expression levels (no staining, mild, moderate, strong) for both markers

• Perform statistical analysis to determine correlation coefficients

The table below shows the distribution pattern observed in one study:

How can PHLDA2 antibodies be employed to investigate tumor microenvironment remodeling in hepatocellular carcinoma?

PHLDA2 has been identified as playing an essential role in tumor microenvironment (TME) remodeling and treatment resistance in hepatocellular carcinoma (HCC) . To investigate this role:

• Perform multiplex immunohistochemistry using PHLDA2 antibodies alongside markers for different immune cell populations

• Use flow cytometry with PHLDA2 antibodies to analyze changes in immune cell infiltration

• Conduct co-culture experiments with HCC cell lines and immune cells, using PHLDA2 antibodies to track protein expression changes

• Implement PHLDA2 knockdown or overexpression studies followed by immunophenotyping

Research has shown noteworthy associations between PHLDA2 expression and immune infiltration in HCC, with PHLDA2 upregulation closely associated with stemness features and immunotherapy or chemotherapy resistance . These approaches enable researchers to elucidate the mechanisms through which PHLDA2 influences the tumor immune microenvironment.

What are the critical validation steps required before using PHLDA2 antibodies in translational research?

Before employing PHLDA2 antibodies in translational research, comprehensive validation is essential:

• Specificity validation:

  • Western blot analysis confirming band at expected molecular weight (17 kDa calculated; 20-25 kDa observed)

  • Positive and negative control tissues (high expression in placenta; low/absent in neuronal tissues)

  • Knockdown/knockout controls (siRNA, CRISPR) to confirm antibody specificity

• Application-specific validation:

  • For IHC: Optimize antigen retrieval methods (TE buffer pH 9.0 or citrate buffer pH 6.0)

  • For WB: Validate in multiple cell lines with known PHLDA2 expression (L02, MCF-7, PC-3 cells)

  • For ELISA: Determine detection range (e.g., 78.125-5000 pg/mL) and sensitivity

• Cross-reactivity assessment:

  • Test antibody against related PHLDA family members (PHLDA1, PHLDA3)

  • Verify species reactivity if using in comparative studies

• Reproducibility testing:

  • Different antibody lots

  • Independent laboratory validation

  • Multiple detection methods

What are the optimal protocols for detecting PHLDA2 in formalin-fixed, paraffin-embedded (FFPE) tissue samples?

For optimal PHLDA2 detection in FFPE samples:

• Tissue preparation and section cutting:

  • Cut 4-5 μm thick sections

  • Mount on positively charged slides

  • Allow sections to dry overnight at room temperature

• Deparaffinization and rehydration:

  • Standard xylene/ethanol series protocol

• Antigen retrieval (critical step):

  • Primary method: Heat-induced epitope retrieval using TE buffer pH 9.0

  • Alternative method: Citrate buffer pH 6.0

  • Perform at 95-98°C for 15-20 minutes

• Blocking and antibody incubation:

  • Block endogenous peroxidase (3% H₂O₂, 10 minutes)

  • Block non-specific binding (5% normal serum)

  • Primary antibody dilution: 1:50-1:500

  • Incubation: Overnight at 4°C in humid chamber

• Detection and visualization:

  • HRP-conjugated secondary antibody or labeled polymer detection system

  • DAB substrate for visualization

  • Hematoxylin counterstain

• Controls:

  • Positive control: Human placenta tissue or prostate cancer tissue

  • Negative control: Antibody diluent without primary antibody

This protocol has been validated for detecting PHLDA2 in human prostate cancer tissue and other human samples .

How can researchers accurately quantify PHLDA2 protein levels in biological samples?

Accurate quantification of PHLDA2 protein requires selection of appropriate methods based on sample type and research objectives:

• ELISA-based quantification:

  • Sandwich ELISA kits are available with detection ranges of 78.125-5000 pg/mL

  • Minimum detection limit: 46.875-78.125 pg/mL

  • Suitable for serum, plasma, and other biological fluids

  • Follow manufacturer's protocol for sample preparation, standard curve generation, and data analysis

• Western blot quantification:

  • Use recommended antibody dilution: 1:500-1:1000

  • Include recombinant PHLDA2 protein standards at known concentrations

  • Employ housekeeping proteins (β-actin, GAPDH) as loading controls

  • Use digital image analysis software for densitometry

  • Normalize band intensity to loading controls

• Mass spectrometry-based quantification:

  • For absolute quantification: Isotope-labeled PHLDA2 peptides as internal standards

  • For relative quantification: Label-free or isobaric labeling approaches

  • Target PHLDA2-specific peptides identified through in silico digestion

• Flow cytometry:

  • For cellular protein quantification

  • Requires cell permeabilization for this intracellular protein

  • Use appropriate fluorophore-conjugated antibodies

  • Include calibration beads for quantitative analysis

For comparative studies, maintain consistent protocols across all samples to ensure reliable results.

How does PHLDA2 contribute to drug resistance in cancer, and what experimental approaches can elucidate this mechanism?

PHLDA2 has been implicated in treatment resistance in multiple cancer types. Research has shown that PHLDA2 upregulation is closely associated with immunotherapy or chemotherapy resistance in HCC . To investigate this mechanism:

• Drug-induced expression changes:

  • In vitro experiments have demonstrated that sorafenib or cisplatin significantly up-regulate PHLDA2 mRNA levels

  • Treat cancer cell lines with therapeutic agents and monitor PHLDA2 expression changes using antibodies and qRT-PCR

• Manipulation of PHLDA2 expression:

  • PHLDA2 knockdown experiments have shown markedly decreased sensitivity of HCC cells to chemotherapy drugs

  • Use siRNA, shRNA, or CRISPR-Cas9 to alter PHLDA2 expression levels

  • Assess drug sensitivity using cell viability assays, apoptosis assays, and colony formation assays

• Pathway analysis:

  • GSEA and in vitro experiments indicate PHLDA2 may promote HCC progression via activating the AKT signaling pathway

  • Use phospho-specific antibodies to monitor changes in pathway activation

  • Employ pathway inhibitors to determine if they can reverse PHLDA2-mediated effects

• Clinical correlation:

  • Analysis of patient samples before and after treatment failure

  • Immunohistochemical staining for PHLDA2 in responders versus non-responders

  • Correlation with other resistance biomarkers

These approaches can help elucidate how PHLDA2 contributes to treatment resistance and identify potential strategies to overcome this resistance.

What is the relationship between PHLDA2 expression and prognosis in hepatocellular carcinoma?

Research has established PHLDA2 as an independent prognostic factor in hepatocellular carcinoma (HCC):

These findings suggest that PHLDA2 antibody-based detection could serve as a valuable prognostic biomarker in HCC and potentially other cancer types.

How can researchers investigate the role of PHLDA2 in maternal-fetal interactions and pregnancy complications?

PHLDA2 plays a critical role in placental development and fetal growth. To investigate its role in maternal-fetal interactions:

• Expression analysis in normal and complicated pregnancies:

  • Use PHLDA2 antibodies for immunohistochemical analysis of placental tissues

  • Compare expression patterns between normal placentas and those from pregnancies with complications

  • Abnormally elevated expression of PHLDA2 has been reported in the placenta of human babies with fetal growth restriction (FGR)

• Animal models for functional studies:

  • Mouse models with altered Phlda2 expression have demonstrated:

    • 2-fold increased expression resulted in placental endocrine insufficiency

    • Elevated Phlda2 drove fetal growth restriction of transgenic offspring

    • Impaired maternal care by wildtype mothers of transgenic offspring

  • Use PHLDA2 antibodies to track protein expression in these models

• Mechanistic investigations:

  • Examine the relationship between PHLDA2 and other key placental factors

  • Investigate how PHLDA2 influences placental hormone production

  • Study the impact of PHLDA2 on placental nutrient transport

• Long-term developmental consequences:

  • Mouse studies have shown that elevated Phlda2 is associated with increased anxiety-like behaviors, deficits in cognition, and atypical social behaviors in offspring, with greater impact on males

  • Analyze the transcriptome of adult offspring brain regions (hippocampus, hypothalamus, amygdala)

  • Use PHLDA2 antibodies in combination with neuronal markers to investigate developmental mechanisms

This research area highlights the importance of PHLDA2 beyond cancer biology, extending to developmental origins of health and disease.

What are common issues encountered when using PHLDA2 antibodies in Western blotting, and how can they be resolved?

When working with PHLDA2 antibodies in Western blotting, researchers may encounter several challenges:

• Discrepancy between predicted and observed molecular weight:

  • PHLDA2 has a calculated molecular weight of 17 kDa but is typically observed at 20-25 kDa

  • Solution: Include positive controls (e.g., human placenta tissue, MCF-7 cells) to confirm band identity

  • Consider post-translational modifications that may affect migration

• Weak or absent signal:

  • Ensure appropriate antibody dilution (1:500-1:1000 recommended)

  • Extend primary antibody incubation time (overnight at 4°C)

  • Optimize protein loading amount (start with 20-40 μg total protein)

  • Check transfer efficiency with Ponceau S staining

  • Use enhanced chemiluminescence detection systems for higher sensitivity

• High background or non-specific bands:

  • Increase blocking time and concentration (5% non-fat dry milk or BSA)

  • Add 0.1-0.3% Tween-20 to washing buffers

  • Optimize secondary antibody dilution

  • Pre-absorb antibody with blocking peptide to confirm specificity

• Inconsistent results between experiments:

  • Standardize sample preparation protocols

  • Use purified recombinant PHLDA2 as a positive control

  • Aliquot antibodies to avoid freeze-thaw cycles

  • Maintain consistent electrophoresis and transfer conditions

• Degradation products:

  • Add protease inhibitors to lysis buffers

  • Keep samples cold during preparation

  • Reduce sample processing time

Following published protocols, such as the WH0007262M1 protocol for PHLDA2 antibody Western blotting, can help ensure reliable results .

How can researchers optimize immunohistochemical detection of PHLDA2 in different tissue types?

Optimizing PHLDA2 immunohistochemistry across different tissue types requires careful consideration of several factors:

• Tissue-specific antigen retrieval optimization:

  • For epithelial tissues: TE buffer pH 9.0 is generally recommended

  • For stromal-rich tissues: Citrate buffer pH 6.0 may be preferable

  • Optimize heating time (15-20 minutes) and method (microwave, pressure cooker, water bath)

  • For difficult tissues, consider protease-induced epitope retrieval as an alternative

• Antibody concentration titration:

  • Perform a dilution series (e.g., 1:20, 1:50, 1:100, 1:200, 1:500)

  • Evaluate signal-to-noise ratio at each dilution

  • Select concentration that provides specific staining with minimal background

  • Different tissue types may require different optimal dilutions

• Signal amplification strategies:

  • For low-expressing tissues: Consider using polymer-based detection systems

  • For high background tissues: Biotin-free detection systems may reduce non-specific binding

  • Tyramide signal amplification for extremely low abundance targets

• Tissue-specific controls:

  • Positive control tissues should include known PHLDA2 expressors:

    • Human placenta (high expression)

    • Human prostate cancer tissue (validated control)

  • Negative controls should include tissues with minimal PHLDA2 expression

  • Include isotype controls to assess non-specific binding

• Counterstaining optimization:

  • Adjust hematoxylin counterstaining time based on tissue type

  • For tissues with high endogenous pigmentation, consider alternative counterstains

Following manufacturer's IHC protocols, such as those provided with commercial PHLDA2 antibodies, provides a solid starting point for optimization .

What strategies can be employed to overcome cross-reactivity issues with PHLDA2 antibodies in experimental applications?

Cross-reactivity can compromise the reliability of PHLDA2 antibody applications. Several strategies can address this issue:

• Antibody selection and validation:

  • Choose antibodies raised against unique epitopes of PHLDA2

  • Verify specificity using knockout/knockdown models

  • Test against related proteins (particularly PHLDA1 and PHLDA3, which share PH domains)

  • Consider monoclonal antibodies for higher specificity

• Blocking and pre-absorption:

  • Use blocking peptides specific to the antibody's epitope

  • Pre-absorb antibodies with recombinant related proteins

  • Optimize blocking conditions (concentration, time, blocking agent)

• Technical modifications:

  • Increase stringency of washing steps

  • Adjust salt concentration in buffers

  • Reduce primary antibody concentration

  • Shorter incubation times at higher temperatures

• Alternative detection methods:

  • If cross-reactivity persists in one application, try alternative techniques

  • For example, if IHC shows cross-reactivity, confirm findings with Western blot

  • Consider RNA-based methods (qRT-PCR, RNA-seq) as complementary approaches

• Computational analysis:

  • Perform in silico analysis of antibody epitopes against protein databases

  • Identify potential cross-reactive proteins based on sequence homology

  • Design experiments to explicitly test and control for anticipated cross-reactivity