LASP1 Human

What is the basic structure of human LASP1?

Human LASP1 is a 261 amino acid protein with a molecular mass of 29.7 kDa, though it typically migrates at 37-38 kDa in Western blot analysis. The protein contains multiple conserved domains: an N-terminal cysteine-rich LIM (Lin11-Isl1-Mec3) domain (region 5-57), two Nebulin-repeats (NEBU, regions 62-92 and 98-128), and a C-terminal SH3 (Src homology 3) domain (region 203-261). The gene encoding LASP1 is located on chromosome 17q11-21.3, in proximity to the proto-oncogene c-ERBB2 (HER2) and the breast cancer susceptibility gene BRCA1 . For experimental investigations of LASP1 structure, researchers should consider domain-specific antibodies or tagged constructs to analyze specific protein interactions mediated by different domains.

What are the primary cellular functions of LASP1?

LASP1 functions primarily as a cytoskeletal protein involved in cell signaling and transcriptional regulation. Research indicates that LASP1 participates in signal transduction, regulation of transcription from the RNA polymerase II promoter, apoptotic processes, and the negative regulation of apoptotic processes . It localizes to multiple cellular compartments including the cytoplasm, nucleus, cytosol, and membrane, suggesting diverse functional roles . Methodologically, subcellular fractionation combined with immunoblotting provides insights into compartment-specific functions, while co-immunoprecipitation experiments help identify context-specific binding partners.

How is LASP1 expressed in normal human tissues?

In physiological conditions, LASP1 is ubiquitously expressed at low levels in normal human tissues (except smooth muscle) and is highly expressed in the hematopoietic system. Studies show that LASP1 mRNA is expressed at distinct levels within non-neuronal normal tissues but at rather similar levels in various neuronal tissues . Notably, LASP1 mRNA is expressed at very high levels in fetal brain and liver, suggesting a prominent role in fetal development . For comprehensive expression analysis, researchers should employ both RNA-seq and protein-level detection methods, as post-transcriptional regulation may cause discrepancies between mRNA and protein levels.

How does LASP1 contribute to cancer progression?

LASP1 has been established as a driver of tumorigenesis and cancer progression rather than a mere passenger event. In multiple cancer models, LASP1 promotes aggressive phenotypes through several mechanisms:

• Enhancing cell migration and invasion

• Promoting cell proliferation

• Facilitating epithelial-mesenchymal transition (EMT)

• Activating multiple signaling pathways including MAPK, PI3K/Akt, and Smad

Functionally, LASP1 silencing reduces proliferation by inducing cell cycle arrest in the G2/M phase, as demonstrated in breast cancer (BT-20), ovarian cancer (SKOV-3), and oral squamous cell carcinoma cell lines . To study these mechanisms, researchers should implement cell-cycle synchronization protocols followed by flow cytometry analysis and protein expression profiling at different cell cycle stages.

Which signaling pathways involve LASP1 in cancer progression?

LASP1 influences multiple signaling cascades critical for cancer progression. Studies in colorectal cancer cells demonstrated that LASP1 induces phosphorylation of proteins in the MAPK, PI3K/Akt, and Smad signaling pathways . Additionally, LASP1 upregulates S100A4, a cytosolic and nuclear protein involved in cell cycle progression and differentiation, and is required for TGFβ-mediated EMT . For pathway analysis, researchers should implement phosphoproteomic approaches combined with inhibitor studies to delineate causative relationships between LASP1 and signaling activation.

What is the role of LASP1 in rheumatoid arthritis?

LASP1 plays a significant role in chronic inflammatory arthritis. Research shows that during chronic destructive arthritis, LASP1 is induced in rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) and constitutes a functional part of cadherin-11 adhesion structures . It functions as an important binding partner of the Cadherin-11/β-Catenin complex in zipper-like cell-to-cell contacts. In vitro studies demonstrate that loss or blocking of LASP1 alters pathological tissue formation, migratory behavior, and platelet-derived growth factor response of arthritic FLS. Furthermore, deletion of Lasp1 in arthritic human TNF transgenic mice reduces arthritic joint destruction . For investigating LASP1 in inflammatory conditions, researchers should consider dual immunofluorescence approaches to simultaneously visualize LASP1 with inflammatory markers or adhesion proteins.

What are effective methods for modulating LASP1 expression in experimental models?

Several approaches have proven effective for manipulating LASP1 expression in research settings:

• RNA interference: siRNA-mediated LASP1 knockdown has been successfully used in multiple cancer cell lines including BT-20 and MCF-7 (breast cancer), SKOV-3 (ovarian cancer), LNCaP (prostate cancer), and SW620 (colorectal cancer) . This approach typically results in decreased cell migration and proliferation.

• Overexpression models: Ectopic LASP1 overexpression in cell lines with minimal endogenous LASP1 (such as PTK-2 non-cancer cells or SW480 colorectal cancer cells) results in increased cell motility and, in xenograft models, promotes tumor growth and metastasis .

• Knockout models: Lasp1 knockout mice exhibit interesting and sometimes paradoxical phenotypes, including increased rates of wound healing and higher incidence of chemically induced skin tumors. This may be partially explained by compensatory overexpression of binding partners like LPP .

For optimal experimental design, researchers should include appropriate controls and validation of knockdown/overexpression efficiency through both mRNA and protein quantification.

How can LASP1 protein interactions be effectively studied?

To investigate LASP1 protein interactions, researchers can employ multiple complementary approaches:

• Co-immunoprecipitation (Co-IP): Effective for identifying direct binding partners of LASP1 in cell lysates.

• Proximity ligation assays: Provides spatial information about protein interactions within cells.

• Bioinformatics analysis: Tools like STRING can be used to predict and analyze LASP1 interactors based on existing data. Studies have shown that LASP1 interactors participate in signal transduction, regulation of transcription, and apoptotic processes .

• Domain-specific interaction studies: Using truncated constructs containing specific domains (LIM, NEBU, or SH3) to identify domain-specific interactions.

For comprehensive interaction analysis, researchers should combine multiple approaches and validate key interactions using different methodologies.

What are the challenges in studying LASP1 nuclear functions?

Investigating LASP1's nuclear functions presents several methodological challenges:

• Nuclear-cytoplasmic shuttling: LASP1 localizes to both cytoplasmic and nuclear compartments, with nuclear localization peaking during the G2/M phase of cell cycle . Researchers must synchronize cells and perform time-course analyses to capture dynamic localization patterns.

• Transcriptional regulation: While evidence suggests LASP1 influences transcriptional processes, delineating direct versus indirect effects requires chromatin immunoprecipitation (ChIP) assays and reporter gene studies.

• Protein interactions in the nucleus: Nuclear protein complexes containing LASP1 may differ from cytoplasmic complexes. Nuclear extraction protocols must be optimized to maintain complex integrity.

• Post-translational modifications: Phosphorylation and other modifications may regulate LASP1 nuclear import/export and function, necessitating modification-specific antibodies or mass spectrometry approaches.

Researchers should implement cell fractionation protocols with careful validation of compartment purity and consider live-cell imaging with fluorescently tagged LASP1 to track dynamics in real-time.

What role does LASP1 play in embryonic development?

LASP1 has been implicated in embryonic development, though its precise functions are still being elucidated. Studies using zebrafish as a vertebrate model have begun to shed light on this area. Research has identified and determined the expression of Lasp1 protein at various developmental stages, including 48 and 72 hours post-fertilization, 6 days post-fertilization, and in different organs of zebrafish adults .

The zebrafish Lasp1 consists of 234 amino acids and shares 68% sequence identity with human LASP1, with highly conserved functional domains: the LIM domain (80% identity), NEBU domains (86% and 97% identity), and SH3 domain (84% identity) . Experimental approaches for studying developmental roles include morpholino-mediated knockdown in zebrafish embryos, followed by detailed phenotypic analysis and assessment of apoptosis.

How does LASP1 influence cell adhesion and migration in normal tissues?

LASP1 plays crucial roles in cell adhesion and migration processes in normal physiological contexts. It has been identified as a functional component of cadherin-11 adhesion structures, particularly in fibroblast-like synoviocytes . Mechanistically, LASP1 interacts with the Cadherin-11/β-Catenin complex in zipper-like cell-to-cell contacts, influencing cellular junction formation and tissue remodeling .

Interestingly, fibroblasts from Lasp1 knockout mice show faster migration rates, increased focal adhesion numbers, and higher attachment rates compared to wild-type controls, suggesting complex and potentially tissue-specific roles in regulating cell adhesion and migration . To study these functions, researchers should employ adhesion assays, migration assays (wound healing, Boyden chamber), and live cell imaging of focal adhesion dynamics in LASP1-manipulated cells.

How do post-translational modifications regulate LASP1 function?

Post-translational modifications (PTMs) are critical regulators of LASP1 function, affecting its localization, interactions, and activity in different cellular contexts. While the search results don't provide extensive details on specific LASP1 PTMs, evidence suggests that phosphorylation plays an important role, particularly in regulating nuclear localization during cell cycle progression .

For comprehensive PTM analysis, researchers should employ:

• Phospho-specific antibodies for candidate phosphorylation sites

• Mass spectrometry-based proteomics to identify novel modification sites

• Pharmacological inhibitors or activators of relevant kinases/phosphatases

• Site-directed mutagenesis to create phosphomimetic or phospho-null LASP1 variants

These approaches will help elucidate how dynamic modifications regulate LASP1's diverse functions across different cellular compartments and conditions.

What is the significance of LASP1 as a biomarker in cancer prognosis?

LASP1 has emerged as a potential prognostic biomarker in multiple cancer types, though its clinical utility varies by cancer type and requires further validation in larger cohorts. Research findings include:

• LASP1 expression increases from normal mucosa to colorectal cancer (CRC) and metastatic CRC, making it a potential marker for disease progression .

• LASP1 was identified as component of a six-gene signature that strongly predicts disease progression and relapse in chronic myeloid leukemia (CML) patients .

• In bladder cancer, LASP1 shows potential as a biomarker in urinary cell pellets, with sensitivity of 83.1% and specificity of 85.3%, though urinary tract infections and hematuria can yield false positives .

For biomarker validation studies, researchers should employ multicenter cohorts with standardized sample collection and analysis protocols, and evaluate LASP1 in combination with other markers to improve prognostic accuracy.

How do LASP1 interactions with the epithelial-mesenchymal transition pathway influence cancer metastasis?

LASP1 plays a significant role in promoting epithelial-mesenchymal transition (EMT), a critical process in cancer metastasis. Studies in colorectal cancer have shown that LASP1 overexpression correlates inversely with epithelial markers E-cadherin and β-catenin, while enhancing the mesenchymal marker vimentin . Furthermore, LASP1 is upregulated upon TGFβ signaling and is required for TGFβ-mediated EMT .

The molecular mechanisms include:

• Induction of phosphorylation in MAPK, PI3K/Akt, and Smad signaling pathways

• Upregulation of S100A4, which regulates cell cycle progression and differentiation

• Modulation of cell adhesion molecules and cytoskeletal reorganization

To investigate these interactions, researchers should implement:

• Epithelial and mesenchymal marker profiling after LASP1 modulation

• TGFβ stimulation assays with/without LASP1 inhibition

• In vivo metastasis models with LASP1-manipulated cells

• RNA-seq analysis to identify global transcriptional changes affecting EMT

What are the key differences between LASP1 and its related protein LASP2?

While the search results don't provide comprehensive comparative data between LASP1 and LASP2, they mention that there are both similarities and differences between these related proteins . Based on the limited information provided, it appears that LASP2 shares structural similarities with LASP1 but may have distinct expression patterns and functions.

For comparative studies, researchers should consider:

• Sequence alignment and phylogenetic analysis of LASP1 and LASP2 across species

• Expression profiling of both proteins in the same tissues and developmental stages

• Functional assays comparing the effects of LASP1 versus LASP2 manipulation

• Co-immunoprecipitation studies to identify shared versus specific binding partners

This comparative approach would help delineate the unique and overlapping functions of these related proteins.

How conserved is LASP1 across species and what does this suggest about its fundamental functions?

The zebrafish Lasp1 consists of 234 amino acids and shares 68% sequence identity with human LASP1 . More importantly, the functional domains of LASP1 are highly conserved across species: the LIM domain shows 80% identity, the NEBU domains 86% and 97%, and the SH3 domain 84% identity between zebrafish and humans . This high degree of conservation, particularly in functional domains, suggests that LASP1 plays fundamental biological roles that have been maintained throughout vertebrate evolution.

The conservation of LASP1 across species makes comparative model systems highly valuable. Researchers can leverage this conservation by:

• Using model organisms (zebrafish, mice) to study basic LASP1 functions

• Performing cross-species rescue experiments to test functional conservation

• Analyzing evolutionary patterns of variation to identify critical versus flexible regions

• Investigating species-specific differences in regulation and expression