WWC1 Human

What is WWC1 and what are its alternative designations in scientific literature?

WWC1 (WW and C2 domain containing 1) is also known as KIBRA (KIdney and BRAin expressed protein), HBEBP3, MEMRYQTL, and PPP1R168 . The protein contains WW domains and a C2 domain, which facilitate protein-protein interactions that are crucial for its function. As its alternative name suggests, WWC1 is predominantly expressed in kidney and brain tissues. In humans, the WWC1 gene is located on chromosome 5, and it plays significant roles in memory formation, hippocampal function, and the Hippo signaling pathway .

What are the key structural domains of WWC1 protein and their functional significance?

WWC1 protein contains multiple conserved domains that support protein-protein interactions and cellular functions:

• WW domains: These interact with core components of the Hippo pathway, such as LATS1/2 and PTPN14, facilitating Hippo pathway activation

• C2 domain: Involved in calcium-dependent phospholipid binding

• WWC/KIBRA Hippo Pathway Regulators domain: Essential for its role in the Hippo signaling cascade

• Internal binding motifs: Mediate interactions with other proteins

These structural features enable WWC1 to scaffold multiple binding partners including AMPAR regulators such as PICK1, Dendrin, PKMζ, and various structural proteins of the cytoskeleton . These interactions are crucial for WWC1's functions in synaptic plasticity and memory formation.

How does WWC1 contribute to normal neuronal function?

WWC1 plays several critical roles in neuronal function:

• Regulates episodic learning and memory through its effects on synaptic plasticity

• Participates as a key component of AMPA-type glutamate receptor (AMPAR) complexes at postsynaptic sites

• Influences the formation and maintenance of dendritic spines, which are crucial for synaptic connections

• Functions as a scaffold protein that interacts with at least 10 partners involved in modifying synaptic plasticity, including synaptopodin, PKCζ, and Dendrin

• Participates in the Hippo signaling pathway, affecting neuronal development and function

Research demonstrates that WWC1 regulates AMPAR trafficking and function, processes that are crucial for long-term potentiation and memory formation in the hippocampus . Genetic studies have shown that common polymorphisms in WWC1 are associated with memory performance and cognitive ability in humans .

How does WWC1 interact with the Hippo signaling pathway in neurons?

WWC1 functions as a key regulator in the Hippo signaling cascade, particularly through its interactions with core kinases MST1/2 (mammalian sterile 20-like protein kinases 1 and 2) and LATS1/2 (large tumor suppressor kinases 1 and 2). In neurons, this interaction has significant implications for memory and learning:

• Phosphorylation of LATS1/2 by MST1/2 enhances the interaction between WWC1 and LATS1/2, effectively sequestering WWC1

• This sequestration reduces WWC1's availability for participating in AMPAR complexes, which are crucial for synaptic function and memory formation

• When MST1/2 activity is inhibited pharmacologically:

  • Phosphorylation of LATS1/2 decreases

  • WWC1 binding to LATS1/2 is reduced

  • More WWC1 becomes available for AMPAR complexes

  • This leads to increased postsynaptic AMPARs and improved synaptic function

These findings establish a direct link between the Hippo pathway (traditionally known for controlling organ growth) and the mechanisms of memory and learning through the regulation of WWC1 availability for synaptic processes .

What is the relationship between WWC1 and AMPAR trafficking in synaptic plasticity?

WWC1 plays a crucial role in AMPAR trafficking and synaptic plasticity through several mechanisms:

• Scaffold formation: WWC1 serves as a key component of AMPAR complexes that are enriched at postsynaptic sites in brain regions relevant to learning and memory

• Protein interaction network: WWC1 scaffolds multiple binding partners including potent AMPAR regulators such as:

  • Protein Interacting with C-kinase 1 (PICK1)

  • Dendrin

  • Protein kinase C, zeta (PKMζ)

  • Various structural proteins of the cytoskeleton

• Availability regulation: The interaction between WWC1 and LATS1/2 governs the synaptic availability of WWC1. When WWC1 is sequestered by LATS1/2, fewer WWC1 molecules are available to participate in AMPAR complexes, potentially reducing synaptic function

Experimental evidence shows that pharmacological disruption of the WWC1-LATS1/2 interaction leads to increased excitation of monosynaptic transmission and greater output from the polysynaptic hippocampal network. This is accompanied by an increase in GLUA1 and GLUA2 protein abundance in hippocampal membrane precipitates, indicating more postsynaptic AMPARs . These findings explain the observed increase in miniature excitatory postsynaptic current (mEPSC) frequency following such interventions.

How do WWC proteins regulate spinogenesis and cognitive function?

Recent research has revealed a novel mechanism by which WWC proteins (WWC1/2) regulate spinogenesis and cognitive function:

• WWC proteins bind directly to angiomotin (AMOT) family proteins (Motins) and recruit USP9X to deubiquitinate and stabilize Motins

• Deletion of WWC genes in different cell types leads to reduced protein levels of Motins

• In mice, neuron-specific deletion of both Wwc1 and Wwc2 results in:

  • Reduced expression of Motins

  • Lower density of dendritic spines in the cortex and hippocampus

  • Impaired cognitive functions including memory and learning

• Interestingly, ectopic expression of AMOT partially rescues the neuronal phenotypes associated with Wwc1/2 deletion

This research indicates that WWC proteins modulate spinogenesis and cognition, at least in part, by regulating the protein stability of Motins through deubiquitination processes . This adds another layer to our understanding of how WWC1 contributes to cognitive function beyond its interactions with the Hippo pathway and AMPAR trafficking.

What experimental approaches are most effective for studying WWC1's role in dendritic spine formation?

To investigate WWC1's role in dendritic spine formation, researchers should employ multiple complementary approaches:

• Genetic manipulation:

  • Conditional knockout of Wwc1 in specific neuronal populations

  • CRISPR/Cas9-mediated mutation of specific domains

  • Overexpression studies using viral vectors

• Imaging techniques:

  • Golgi staining for spine morphology analysis

  • Live-cell imaging with fluorescently tagged WWC1

  • Super-resolution microscopy to examine spine dynamics

• Molecular and biochemical assays:

  • Co-immunoprecipitation to identify interaction partners

  • Proximity ligation assays to study protein-protein interactions in situ

  • Western blotting to analyze protein levels after manipulation

• Functional assays:

  • Electrophysiological recordings to assess synaptic transmission

  • Calcium imaging to monitor neuronal activity

  • Behavioral testing to correlate spine changes with cognitive function

Recent research employed neuron-specific deletion of Wwc1 and Wwc2 in mice, demonstrating reduced density of dendritic spines in the cortex and hippocampus, associated with impaired cognitive functions . These phenotypes were partially rescued by ectopic expression of AMOT, suggesting that WWC proteins modulate spinogenesis at least partly by regulating the protein stability of Motins .

How can researchers effectively study the interaction between WWC1 and the ubiquitination pathway?

Studying the interaction between WWC1 and the ubiquitination pathway requires a multifaceted approach:

• Protein stability assays:

  • Cycloheximide chase experiments to determine protein half-life

  • Proteasome inhibitors (MG132) to assess ubiquitin-dependent degradation

  • Western blotting to monitor protein levels over time

• Ubiquitination detection:

  • Immunoprecipitation followed by ubiquitin Western blotting

  • Tandem ubiquitin binding entity (TUBE) pull-downs

  • Mass spectrometry to identify ubiquitination sites

• Deubiquitinase (DUB) interactions:

  • Co-immunoprecipitation with potential DUBs (e.g., USP9X)

  • DUB activity assays with fluorogenic substrates

  • CRISPR/Cas9 knockout of candidate DUBs

• Functional consequences:

  • Measure changes in target protein levels (e.g., Motins)

  • Assess downstream signaling pathway activation

  • Evaluate phenotypic outcomes in neurons (spine density, electrophysiology)

Recent research has revealed that WWC proteins bind directly to angiomotin (AMOT) family proteins (Motins) and recruit USP9X to deubiquitinate and stabilize Motins . Deletion of WWC genes leads to reduced protein levels of Motins, and this mechanism appears to be important for WWC's role in spinogenesis and cognition .

What animal models are most appropriate for studying WWC1 function in learning and memory?

Several animal models are appropriate for studying WWC1 function in learning and memory, each with specific advantages:

• Mouse models:

  • Conventional Wwc1 knockout mice

  • Conditional knockout using Cre-loxP system (neuron-specific, region-specific)

  • Knockin models of human WWC1 variants

  • Transgenic overexpression models

  Studies have shown that deletion of Wwc1 and Wwc2 in mice results in reduced density of dendritic spines in the cortex and hippocampus and impaired cognitive functions .

• Rat models:

  • CRISPR/Cas9-generated Wwc1 mutants

  • Viral vector-mediated gene manipulation

  • Pharmacological modulation of WWC1-related pathways

• Zebrafish models:

  • Morpholino knockdown of wwc1

  • CRISPR/Cas9 mutants

  • Transgenic fluorescent reporter lines

  In zebrafish, wwc1 is predicted to enable kinase binding activity and molecular adaptor activity, acting upstream of otic vesicle development and otolith formation .

• Human brain organoids:

  • 3D culture systems derived from human stem cells

  • Allow testing of WWC1 function in human neural tissue context

  • Enable pharmacological studies in a human cellular environment

  Research has utilized human brain organoids to demonstrate that MST1/2 inhibition promotes WWC1-AMPAR interactions in these 3D human neural tissue models .

Selection criteria for animal models should include alignment with specific research questions, technical feasibility, translational potential, ethical considerations, and available infrastructure and expertise.

How should researchers interpret contradictory findings regarding WWC1's association with memory?

When interpreting contradictory findings regarding WWC1's association with memory, researchers should consider several factors:

• Population heterogeneity:

  • Genetic background differences between study populations

  • Age-dependent effects (findings may differ between young adults and elderly populations)

  • Ethnic and geographical variations in allele frequencies

• Methodological differences:

  • Memory assessment techniques (different tests measure different aspects of memory)

  • Sample size and statistical power

  • Study design (cross-sectional vs. longitudinal)

• Molecular complexity:

  • Interaction with other genes and proteins

  • Environmental factors affecting gene expression

  • Compensation by paralogs (e.g., WWC2)

• Specific memory processes:

  • Evidence suggests WWC1 may specifically affect certain memory processes

  • Different studies may focus on different memory domains

For example, while the initial 2006 study associating WWC1 SNP rs17070145 with memory was not supported by a 2008 study with 584 subjects, it was replicated in a smaller sample of an elderly population . Subsequent studies in 2009 indicated that WWC1 is specifically associated with forgetting of non-semantic material and cognitive flexibility , suggesting that the gene may have more nuanced effects on specific aspects of memory rather than global memory function.

A systematic approach to reconciling contradictory findings includes meta-analysis of existing studies, replication studies with larger sample sizes, more precise phenotyping of memory functions, and investigation of interaction effects with other genes and environmental factors.

How can researchers differentiate between the functional roles of WWC1, WWC2, and WWC3 in neuronal systems?

To differentiate the functional roles of WWC1, WWC2, and WWC3 in neuronal systems, researchers should employ a systematic strategy:

• Expression analysis:

  • Quantitative PCR to measure mRNA levels in different brain regions

  • Single-cell RNA sequencing to determine cell-type-specific expression

  • Immunohistochemistry to visualize protein localization

  • Western blotting to quantify protein levels

• Genetic manipulation:

  • Single gene knockouts to determine individual functions

  • Double and triple knockouts to assess redundancy and compensation

  • Conditional knockouts to control timing and cell-type specificity

  • Domain swapping experiments to identify functional differences

• Protein interaction mapping:

  • Immunoprecipitation followed by mass spectrometry

  • Yeast two-hybrid screening for protein partners

  • Proximity labeling techniques (BioID, APEX)

  • Comparative interactome analysis between WWC family members

• Functional assays:

  • Electrophysiology to measure effects on synaptic transmission

  • High-content imaging of neuronal morphology

  • Behavioral testing in genetic models

  • Molecular pathway activation analysis

Emerging evidence suggests both functional redundancy and specificity among WWC family members. For example, neuron-specific deletion of both Wwc1 and Wwc2 causes more severe phenotypes than single gene deletions, including reduced density of dendritic spines and impaired cognitive functions . In Wwc1 knockout mice, MST inhibitor treatment still shows effects, possibly due to compensation by the highly homologous WWC2 . Experiments show that MST inhibition reduces the interaction between WWC2 and LATS1/2 while enhancing the binding of WWC2 to AMPAR regulators PKMζ and PICK1, suggesting overlapping functions between WWC1 and WWC2 in neuronal systems .

What is the evidence linking WWC1 variants to Alzheimer's disease risk and progression?

The evidence linking WWC1 variants to Alzheimer's disease (AD) risk and progression comes from several lines of research:

The current understanding suggests that WWC1 dysfunction in AD may occur through various mechanisms:

These findings suggest potential therapeutic strategies targeting the WWC1-LATS1/2 interaction to improve cognitive function in AD.

What is the relationship between WWC1 polymorphisms and stress-related disorders such as PTSD?

The relationship between WWC1 polymorphisms and stress-related disorders such as posttraumatic stress disorder (PTSD) involves several key findings:

• Genetic association evidence:

  • Studies have identified an association between WWC1 SNPs (particularly rs10038727 and rs4576167) and lifetime PTSD

  • These variants appear to influence the risk for developing PTSD after trauma exposure

  • The association has been replicated in independent samples from different populations, specifically in African conflict regions (Rwanda and Northern Uganda)

• Gene-environment interaction:

  • WWC1 polymorphisms modify the dose-response relationship between traumatic load and PTSD

  • Although each traumatic event adds to the probability of lifetime PTSD in a dose-dependent manner, carriers of specific minor alleles display a diminished risk

  • This suggests WWC1 variants may confer resilience to trauma

• Neurobiological mechanisms:

  • PTSD results from the formation of strong memory for sensory-perceptual and affective representations of traumatic experiences, which is detached from the corresponding autobiographical context information

  • WWC1's role in memory formation makes it biologically plausible as a PTSD risk modifier

  • The gene may influence the strengthening of fear memories following traumatic stress

Research demonstrated that carriers of the minor allele of SNPs rs10038727 and rs4576167 displayed a diminished risk of developing PTSD (odds ratio = .29, 95% confidence interval = .15–.54) . This effect was confirmed in an independent sample, suggesting a robust association between these WWC1 variants and resilience to trauma-induced psychopathology .

This research has significant implications for understanding individual differences in vulnerability to stress-related disorders and may inform personalized approaches to prevention and treatment based on genetic profiles.

How can WWC1 be targeted therapeutically to enhance cognitive function in neurodegenerative conditions?

WWC1 represents a promising therapeutic target for enhancing cognitive function in neurodegenerative conditions through several potential approaches:

• Hippo pathway modulation:

  • MST1/2 inhibitors: Pharmacological inhibition of MST1/2 reduces LATS1/2 phosphorylation, decreasing WWC1-LATS1/2 binding

  • LATS1/2 inhibitors: Direct targeting of these kinases may release WWC1 from sequestration

• WWC1-protein interaction modulation:

  • Small molecules or peptides that disrupt WWC1-LATS1/2 interaction

  • Compounds that enhance WWC1 binding to AMPAR-related proteins

• Downstream target enhancement:

  • AMPAR trafficking promoters to bypass WWC1 deficiency

  • Synaptic plasticity enhancers that work through alternative pathways

Evidence for therapeutic potential:
Research has demonstrated that MST1/2 inhibition promotes the dissociation of WWC1 from LATS1/2, leading to increased abundance of WWC1 in AMPAR complexes . This pharmacological approach enhanced AMPAR trafficking and enabled the formation of hippocampus-dependent long-term memories in both aged wild-type and ArcAβ mice (an AD model) . The treatment increased neuronal activity in the hippocampus of 23-month-old wild-type mice and improved spatial and object recognition memory .

This therapeutic strategy has shown efficacy in multiple models of cognitive decline:

• Aged wild-type mice (23 months old)

• ArcAβ mice (Alzheimer's disease model)

• Human brain organoids

The mechanism appears to work by releasing WWC1 from LATS1/2, making more WWC1 available to participate in AMPAR complexes at synapses, thereby enhancing synaptic function and memory formation . These findings suggest that targeting the WWC1-LATS1/2 interaction, particularly through Hippo pathway kinase inhibition, represents a promising therapeutic strategy for cognitive enhancement in neurodegenerative conditions.