PDLIM5 Antibody

What is PDLIM5 and what cellular functions does it serve?

PDLIM5, also known as Enigma homolog protein (ENH), is a cytoskeletal protein that plays critical roles in cell adhesion, migration, and signaling pathways . It possesses a PDZ domain at the N-terminus and one to three LIM domains at the C-terminus, allowing it to function as a scaffold protein that mediates protein-protein interactions . PDLIM5 has been localized to multiple cellular compartments including the actin cytoskeleton, cell projections, cytosol, postsynaptic density, presynapse, and Z-disc in muscle cells . This distribution reflects its diverse functions in cytoskeletal organization and signaling. The protein participates in muscle development processes, with studies showing that specific isoforms can either promote or inhibit myogenic differentiation depending on their structural characteristics .

What applications are PDLIM5 antibodies validated for?

PDLIM5 antibodies have been extensively validated for multiple research applications with specific protocols and considerations for each method:

The applications have been confirmed across human and mouse samples, with citations also indicating reactivity in rat tissues . For optimal results, researchers should titrate the antibody concentration for their specific experimental system.

How do I select the appropriate PDLIM5 antibody for my research?

When selecting a PDLIM5 antibody, consider several critical factors to ensure successful experimental outcomes. First, determine which epitope recognition is needed for your application - some antibodies target sequences within amino acids 300-400 of human PDLIM5 (NP_006448.5) , while others may target different regions. This is particularly important if you're studying specific splice variants or if your experimental conditions might mask certain epitopes.

Second, assess species reactivity requirements - validated reactivity includes human and mouse models, with some antibodies showing cross-reactivity with rat samples . Finally, consider the validated applications and sample types. For example, commercial antibodies like CAB22013 and 10530-1-AP have been validated in multiple applications including WB, IHC, IF, IP, and ELISA . If working with tissue samples, consider antibodies with successful antigen retrieval protocols established for immunohistochemistry, such as those using TE buffer (pH 9.0) or citrate buffer (pH 6.0) .

What expression patterns of PDLIM5 are observed in different tissue types?

PDLIM5 shows distinct tissue-specific expression patterns that researchers should consider when designing experiments. In muscle tissue, PDLIM5 expression changes during different developmental stages, with studies in pigs showing its role in myoblast proliferation and differentiation . Different isoforms predominate in different tissues - for example, PDLIM5-short is the main splice variant in pig muscle tissue .

In cancer research, PDLIM5 overexpression has been detected in several tumor types including papillary thyroid carcinoma, prostate cancer, and non-small cell carcinoma . Expression analysis using PDLIM5 antibodies has revealed that elevated levels correlate with increased tumor proliferation rates in some cancer types . In cardiovascular tissues, PDLIM5 expression has been linked to vascular remodeling processes and cardiac hypertrophy, with specific isoforms playing protective roles against stress-induced ventricular cardiomyocyte hypertrophy .

How does PDLIM5 influence myoblast proliferation and differentiation at the molecular level?

PDLIM5 regulates myogenesis through multiple mechanisms that can be investigated using specific antibody applications. Recent research has demonstrated that PDLIM5-short negatively regulates both myoblast proliferation and differentiation . At the molecular level, overexpression of PDLIM5-short significantly downregulates key proliferative genes including cyclin D1 (CCND1), Ki67, proliferating cell nuclear antigen (PCNA), and cyclin-dependent kinase 4 (CDK4) . This can be effectively demonstrated through western blot analysis using validated PDLIM5 antibodies to correlate PDLIM5 expression with these downstream markers.

During differentiation, PDLIM5-short overexpression reduces transcript levels of myogenic markers including myogenin (MyoG), myogenic differentiation (MyoD), and myosin heavy chain (MyHC) at different stages of differentiation . Interestingly, the function of PDLIM5 in myogenesis is isoform-specific - while PDLIM5 isoform 1 promotes expression of myogenic genes and myotube formation, PDLIM5 isoform 4 (short) abrogates myotube-like morphological changes without altering MyoD and myogenin expression . Researchers can utilize immunofluorescence techniques with PDLIM5 antibodies and myotube markers to visualize these effects, as demonstrated by studies showing fewer myotubes formed in myoblasts overexpressing PDLIM5-short .

What role does PDLIM5 play in cardiovascular diseases and cancer progression?

PDLIM5 functions as a multifunctional regulator in both cardiovascular pathologies and cancer development, with distinct mechanistic roles that can be investigated using antibody-based approaches. In cardiovascular research, PDLIM5 has been identified as a regulator of vascular remodeling and a potential pro-atherosclerotic factor . Studies using knockout models have shown that SMC-specific deletion of PDLIM5 enhances hypoxia-mediated vascular remodeling, while its overexpression inhibits the TGF-β/Smad signaling pathway and prevents hypoxia-induced pulmonary hypertension in vivo .

In cancer biology, PDLIM5 appears to function as an oncogene in several contexts. It is upregulated in papillary thyroid carcinoma tissues, where elevated expression promotes migration, invasion, and proliferation of cancer cells by activating the RAS-ERK pathway . PDLIM5 overexpression is also observed in prostate cancer tissue, with serum and urine PDLIM5 levels serving as potential diagnostic indicators and predictors of progression risk in advanced prostate cancer . Mechanistically, PDLIM5 regulates cancer cell proliferation and invasion by binding to AMPK and modulating its activation and degradation . These interactions can be studied using co-immunoprecipitation techniques with PDLIM5 antibodies to isolate and identify protein complexes in different cancer models.

How can I study PDLIM5 SNPs and their functional consequences using antibody-based approaches?

Studying PDLIM5 SNPs and their functional effects requires an integrated approach combining genetic analysis with protein expression studies. Research has identified significant SNPs in the PDLIM5 promoter region (-258 A > T and -191 T > G) that influence promoter activity and are associated with muscle growth rate in pigs . To investigate such variants, researchers can employ dual-luciferase reporter assays using constructs containing the PDLIM5 promoter with different SNP variants to measure their impact on transcriptional activity .

To connect genotype with protein expression, western blot analysis using validated PDLIM5 antibodies can quantify whether SNP-related transcriptional changes translate to altered protein levels. For functional consequences, researchers can correlate PDLIM5 expression levels in tissues carrying different SNP variants with phenotypic outcomes such as muscle development parameters or disease risk factors. Additionally, chromatin immunoprecipitation (ChIP) assays can identify transcription factors that differentially bind to PDLIM5 promoter regions containing SNP variants, providing mechanistic insights into how these genetic variations affect gene expression.

The study of PDLIM5 SNPs extends beyond muscle development, as 25 different SNPs in PDLIM5 have been reported to interact with steroids, potentially affecting cancer development and progression . This gene-environment interaction can be explored using cell culture models treated with steroids, followed by PDLIM5 antibody-based detection methods to assess expression changes in different SNP backgrounds.

What are the optimal sample preparation methods for PDLIM5 detection in different tissue types?

Successful PDLIM5 detection requires tissue-specific sample preparation protocols. For muscle tissue, where PDLIM5 plays key roles in development, optimal preservation of protein-protein interactions is essential. Fresh muscle tissue should be immediately snap-frozen in liquid nitrogen and stored at -80°C to prevent protein degradation. When extracting proteins, use buffers containing protease inhibitors and phosphatase inhibitors to preserve post-translational modifications that may affect antibody recognition .

For cultured cells, such as myoblasts used in differentiation studies, researchers should consider the cellular localization of PDLIM5. Since PDLIM5 localizes to multiple compartments including the actin cytoskeleton, cell projections, cytosol, and specific structures like Z-discs , different extraction methods may yield varying results. For total protein extraction, RIPA buffer with protease inhibitors is generally effective, while cytoskeletal-associated PDLIM5 may require more stringent extraction conditions using detergents like Triton X-100 or NP-40.

For immunohistochemistry applications using PDLIM5 antibodies on tissue sections, formalin fixation and paraffin embedding (FFPE) is appropriate, but researchers should optimize antigen retrieval conditions. Evidence suggests that TE buffer (pH 9.0) provides effective antigen retrieval for PDLIM5 detection, although citrate buffer (pH 6.0) can serve as an alternative . Processing tissue samples consistently is crucial for comparative studies of PDLIM5 expression across different experimental conditions or disease states.

What controls should be included when using PDLIM5 antibodies in Western blot experiments?

Rigorous controls are essential for reliable PDLIM5 detection in Western blot experiments. First, include positive control samples from validated cell lines such as HeLa, A549, HUVEC, or NIH/3T3 cells, which have been confirmed to express detectable levels of PDLIM5 . These controls help verify antibody performance and provide reference band patterns.

For negative controls, consider using PDLIM5 knockdown or knockout samples generated through siRNA or CRISPR-Cas9 approaches. Studies have used si-RNA targeting PDLIM5 in gastric cancer cells and other models , which can serve as specific negative controls. Loading controls such as β-actin, GAPDH, or β-tubulin are essential for normalization, particularly in comparative expression studies.

Given that PDLIM5 exists in multiple splice variants with different molecular weights, researchers should carefully interpret band patterns. The expected molecular weight of PDLIM5 is approximately 64 kDa, with observed weights ranging from 63-68 kDa . Isoform-specific controls may be necessary for studies focusing on particular variants like PDLIM5-short, which plays distinct roles in myoblast regulation . When investigating phosphorylation states or other post-translational modifications of PDLIM5, appropriate treatments (such as phosphatase treatment) should be included as additional controls.

How can I optimize PDLIM5 immunoprecipitation for studying protein interactions?

Optimizing immunoprecipitation (IP) protocols for PDLIM5 requires careful consideration of several factors to preserve protein-protein interactions while maximizing specificity. Begin by selecting an appropriate lysis buffer that preserves interactions of interest - for cytoskeletal interactions, use milder non-ionic detergents like 0.5% NP-40 or Triton X-100, while RIPA buffer may be more suitable for general applications with stronger solubilization properties.

PDLIM5 antibodies for IP should be validated specifically for this application, such as the polyclonal antibody 10530-1-AP, which has been successfully used for immunoprecipitation in A549 cells using 0.5-4.0 μg antibody per 1.0-3.0 mg of total protein lysate . Pre-clearing lysates with protein A/G beads before adding the PDLIM5 antibody reduces non-specific binding.

For co-immunoprecipitation (co-IP) studies investigating PDLIM5 interaction partners, crosslinking approaches may help stabilize transient interactions. This is particularly relevant for studying PDLIM5's role in protein complexes, such as its interaction with AMPK in cancer cells or components of the TGF-β/Smad signaling pathway in cardiovascular models . Always include appropriate negative controls using non-specific antibodies of the same isotype and validate results using reciprocal co-IP when possible.

Why might I observe multiple bands in Western blot when using PDLIM5 antibodies?

Multiple bands in PDLIM5 Western blots can result from several biological and technical factors that researchers should systematically evaluate. Primarily, PDLIM5 exists in multiple splice variants with different molecular weights. Research has identified several isoforms including PDLIM5 isoform 1 and PDLIM5-short (isoform 4), which have distinct functional properties in muscle development . These variants emerge from alternative splicing and will appear as bands of different molecular weights even with highly specific antibodies.

Post-translational modifications also contribute to band pattern complexity. PDLIM5 undergoes phosphorylation, particularly relevant at Ser177, which affects its downstream signaling interactions with the Rac1-Arp2/3 pathway . These modifications alter protein mobility during electrophoresis, resulting in higher molecular weight bands or band shifts. Additionally, proteolytic processing during sample preparation can generate PDLIM5 fragments that appear as lower molecular weight bands.

To distinguish between these possibilities, researchers should first compare observed bands with the expected molecular weight range of 63-68 kDa for full-length PDLIM5 . Treatment of samples with phosphatase can help identify phosphorylation-dependent bands, while using tissue-specific positive controls can help identify known isoforms predominant in particular tissues. For definitive identification, consider performing immunoprecipitation followed by mass spectrometry to characterize the protein variants detected by your antibody.

How do I interpret conflicting PDLIM5 expression data between different experimental approaches?

Different antibodies may recognize distinct epitopes that are differentially accessible in various experimental conditions. The PDLIM5 antibody CAB22013 targets a sequence within amino acids 300-400 , while other antibodies may target different regions that could be masked by protein folding, post-translational modifications, or protein-protein interactions in certain contexts. When comparing mRNA and protein expression data, remember that post-transcriptional regulation can cause discrepancies - PDLIM5 is a target of microRNAs like miR-21 and the miR-17~92 cluster , which may suppress protein expression without affecting transcript levels.

To resolve conflicting data, use complementary approaches targeting different aspects of PDLIM5 biology. For instance, combine Western blot quantification with subcellular fractionation to determine compartment-specific expression levels, or use multiple antibodies targeting different PDLIM5 epitopes to confirm expression patterns. When studying specific isoforms, employ PCR-based approaches with isoform-specific primers alongside protein detection methods.