GO:0097140 BIM-BCL-xl complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0097140 defines the BIM-BCL-xl complex, a heterodimeric protein complex of the pro-apoptotic BH3-only protein BIM and the anti-apoptotic BCL-xl.
• The BIM-BCL-xl complex is a cellular component that sequesters BIM, preventing it from activating Bax/Bak and blocking apoptosis.
• Disruption of the BIM-BCL-xl interaction by BH3 mimetics or genetic alterations promotes apoptosis in cancer cells.
• BCL-xl overexpression is common in B-cell malignancies and contributes to resistance to apoptosis.
• BIM and BCL-xl are key regulators of the intrinsic apoptotic pathway and are implicated in cancer, autoimmunity, and neurodegeneration.
• Studying the BIM-BCL-xl complex requires methods such as co-immunoprecipitation, FRET, and CRISPR-based knockout or knock-in models.
Description
The BIM-BCL-xl complex (GO:0097140) is a heterodimeric protein complex consisting of BIM (BCL2L11) and BCL-xl (BCL2L1), members of the Bcl-2 family of anti- and proapoptotic regulators. This complex is a key node in the intrinsic apoptotic pathway, where the balance between pro- and anti-apoptotic Bcl-2 proteins determines cell fate. Understanding the BIM-BCL-xl complex is essential for researchers studying apoptosis, cancer biology, and therapeutic resistance. The complex is a cellular component that can be targeted by BH3 mimetics, making it a focus of drug discovery. This article provides a comprehensive overview of the BIM-BCL-xl complex, its components, assembly, regulation, and methods for study, with a focus on CRISPR-based models.
BIM-BCL-xl complex At A Glance
| GO ID | GO:0097140 |
|---|---|
| GO term | BIM-BCL-xl complex |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Sequestration of pro-apoptotic BIM by anti-apoptotic BCL-xl, inhibiting apoptosis |
| Complex type | Heterodimer |
| Components | BIM (BCL2L11) and BCL-xl (BCL2L1) |
| Associated process | Intrinsic apoptotic pathway |
| Disease relevance | Cancer, autoimmunity, neurodegeneration |
What Is GO:0097140?
The BIM-BCL-xl complex is a heterodimeric protein complex formed by the binding of the pro-apoptotic BH3-only protein BIM to the anti-apoptotic protein BCL-xl. This interaction is mediated by the BH3 domain of BIM inserting into the hydrophobic groove of BCL-xl. The complex functions to sequester BIM, preventing it from activating the effector proteins Bax and Bak, thereby inhibiting apoptosis. The QuickGO definition (GO:0097140) describes it as a heterodimeric protein complex consisting of BIM and BCL-xl, members of the Bcl-2 family of anti- and proapoptotic regulators.
Why Is BIM-BCL-xl complex Important in Cell Biology?
The BIM-BCL-xl complex is a critical regulator of apoptosis, and its dysregulation contributes to cancer development and resistance to therapy. BCL-xl overexpression is observed in various B-cell tumors and is associated with poor prognosis. Targeting the BIM-BCL-xl interaction with BH3 mimetics, such as TW-37, has shown activity across a spectrum of B-cell tumors irrespective of their proliferative and differentiation status. Therefore, understanding the BIM-BCL-xl complex is vital for developing novel therapeutic strategies.
• Regulates intrinsic apoptosis by sequestering BIM.
• BCL-xl overexpression promotes tumor cell survival.
• BH3 mimetics targeting BCL-xl induce apoptosis in cancer cells.
• BIM-BCL-xl complex is a biomarker for apoptosis sensitivity.
• Dysregulation is linked to B-cell malignancies.
• Involved in resistance to chemotherapy.
• Potential target for autoimmune diseases.
• Key node in neurodegeneration.
• Studied using CRISPR knockout models.
• Relevant for drug discovery.
What Happens During BIM-BCL-xl complex?
Formation of the BIM-BCL-xl complex
In simple terms: BIM and BCL-xl bind together to form a complex.
The BIM-BCL-xl complex forms when the BH3 domain of BIM binds to the hydrophobic groove of BCL-xl. This interaction is a key event in the sequestration of BIM, preventing it from activating Bax/Bak.
Inhibition of apoptosis
In simple terms: The complex stops cells from dying.
By sequestering BIM, BCL-xl prevents BIM from activating the pro-apoptotic effectors Bax and Bak, thereby inhibiting apoptosis. This allows cells to survive under stress conditions.
Disruption by BH3 mimetics
In simple terms: Drugs can break the complex to trigger cell death.
BH3 mimetics such as TW-37 disrupt the BIM-BCL-xl interaction, releasing BIM to activate apoptosis. This approach has shown efficacy in B-cell tumors.
Regulation by Bik
In simple terms: Other BH3-only proteins can influence the complex.
The BH3-only protein Bik is involved in apoptosis induction and sensitivity to oxidative stress in multiple myeloma, potentially competing with BIM for BCL-xl binding.
Key Genes Involved in GO:0097140 BIM-BCL-xl complex
The BIM-BCL-xl complex involves several key genes and proteins that regulate apoptosis.
| Gene | Major Role | Research Relevance |
|---|---|---|
| BCL2L11 (BIM) | Pro-apoptotic BH3-only protein | Sequestration by BCL-xl inhibits apoptosis |
| BCL2L1 (BCL-xl) | Anti-apoptotic Bcl-2 family member | Overexpression promotes survival in cancer |
| BAX | Pro-apoptotic effector | Activated by BIM when released |
| BAK | Pro-apoptotic effector | Activated by BIM when released |
| BIK | BH3-only protein | Involved in apoptosis and oxidative stress |
| BCL2 | Anti-apoptotic | Related family member |
| MCL1 | Anti-apoptotic | Related family member |
| BID | BH3-only protein | Related family member |
| PUMA | BH3-only protein | Related family member |
| NOXA | BH3-only protein | Related family member |
| HRK | BH3-only protein | Related family member |
| BAD | BH3-only protein | Related family member |
| BMF | BH3-only protein | Related family member |
| BCL2L2 (BCL-w) | Anti-apoptotic | Related family member |
| CASP3 | Executioner caspase | Downstream of apoptosis |
| CASP9 | Initiator caspase | Downstream of apoptosis |
| APAF1 | Apoptosome component | Downstream of apoptosis |
| CYCS | Cytochrome c | Released during apoptosis |
How Is BIM-BCL-xl complex Regulated?
The BIM-BCL-xl complex is regulated by the balance of BH3-only proteins and anti-apoptotic Bcl-2 family members. Phosphorylation of BIM by JNK or ERK can modulate its binding to BCL-xl. Additionally, BH3-only proteins such as Bik can compete for BCL-xl binding, influencing apoptosis sensitivity.
BIM-BCL-xl complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| BCL2L1 | B-cell malignancies | Knockout or overexpression in lymphoma cell lines |
| BCL2L11 | Autoimmunity | Knockout mice or CRISPR KO in T cells |
| BIK | Multiple myeloma | Overexpression or KO in myeloma cell lines |
| BAX | Cancer | KO in cancer cell lines |
| BAK | Cancer | KO in cancer cell lines |
B-cell malignancies
BCL-xl overexpression is common in B-cell tumors and contributes to resistance to apoptosis. The BIM-BCL-xl complex is a target for BH3 mimetics like TW-37, which is active across a spectrum of B-cell tumors irrespective of their proliferative and differentiation status.
Multiple myeloma
In multiple myeloma, the BH3-only protein Bik is involved in apoptosis induction and sensitivity to oxidative stress, suggesting a role for the BIM-BCL-xl complex in disease progression.
Autoimmunity
Dysregulated apoptosis due to altered BIM-BCL-xl interactions can lead to autoimmune diseases, although specific evidence is limited.
Neurodegeneration
Apoptosis regulated by Bcl-2 family proteins, including the BIM-BCL-xl complex, is implicated in neurodegenerative disorders.
From BIM-BCL-xl complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does BCL-xl overexpression confer resistance to apoptosis? | Overexpression of BCL2L1 in cancer cell lines |
| What is the effect of BIM knockout on apoptosis? | CRISPR knockout of BCL2L11 |
| Can point mutations in BCL2L1 disrupt BIM binding? | Point mutation knock-in of BCL2L1 |
| How does BIM-BCL-xl complex assembly affect drug response? | Tagged knock-in of BCL2L11 and BCL2L1 |
| What is the role of Bik in myeloma? | Knockout or overexpression of BIK |
| Does BCL-xl inhibition synergize with chemotherapy? | Combination treatment in KO models |
How to Study the BIM-BCL-xl complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Co-IP | Protein-protein interaction | Detect BIM-BCL-xl complex |
| FRET | Interaction in live cells | Monitor complex dynamics |
| Annexin V | Apoptosis | Assess cell death |
| Caspase activity | Apoptosis | Measure caspase activation |
| CRISPR screen | Gene function | Identify modifiers of drug response |
| Western blot | Protein levels | Quantify BIM and BCL-xl |
| qPCR | mRNA levels | Measure gene expression |
Co-immunoprecipitation
Co-immunoprecipitation can detect the BIM-BCL-xl complex in cell lysates using antibodies against BIM or BCL-xl.
FRET and BRET
FRET or BRET assays can monitor the interaction between BIM and BCL-xl in live cells.
Apoptosis assays
Annexin V staining and caspase activity assays measure apoptosis induced by disruption of the BIM-BCL-xl complex.
CRISPR screening
Genome-wide CRISPR screens can identify genes that modulate sensitivity to BH3 mimetics targeting the BIM-BCL-xl complex.
How CRISPR Can Be Used to Study GO:0097140 BIM-BCL-xl complex
Knockout
CRISPR knockout of BCL2L11 (BIM) or BCL2L1 (BCL-xl) can abolish the BIM-BCL-xl complex, leading to altered apoptosis sensitivity.
Point Mutation
Point mutations in the BH3 domain of BIM or the hydrophobic groove of BCL-xl can disrupt complex formation, allowing structure-function studies.
Knock-in
Knock-in of tagged BIM or BCL-xl enables visualization and purification of the complex.
Overexpression
Overexpression of BCL-xl or BIM can shift the balance of the complex, affecting cell survival.
How EDITGENE Supports BIM-BCL-xl complex Research
Researchers studying BIM-BCL-xl complex-related genes often need to determine whether a candidate gene is causally involved in apoptosis regulation or disease. EDITGENE provides comprehensive CRISPR services to create precise cell models for such studies.
Contact EDITGENE today to design your custom CRISPR model for BIM-BCL-xl complex research.
Frequently Asked Questions About BIM-BCL-xl complex
What is the BIM-BCL-xl complex?
The BIM-BCL-xl complex is a heterodimeric protein complex consisting of the pro-apoptotic protein BIM and the anti-apoptotic protein BCL-xl, which inhibits apoptosis.
What genes are involved in the BIM-BCL-xl complex?
The main genes are BCL2L11 (BIM) and BCL2L1 (BCL-xl), along with other Bcl-2 family members like BAX, BAK, and BIK.
What is the function of the BIM-BCL-xl complex?
It sequesters BIM, preventing it from activating Bax/Bak and thus inhibiting apoptosis.
How is the BIM-BCL-xl complex regulated?
It is regulated by the balance of BH3-only proteins, phosphorylation of BIM, and competition from other BH3-only proteins like Bik.
What diseases are associated with the BIM-BCL-xl complex?
It is implicated in B-cell malignancies, multiple myeloma, autoimmunity, and neurodegeneration.
How can I study the BIM-BCL-xl complex?
Methods include co-immunoprecipitation, FRET, apoptosis assays, and CRISPR-based knockout or knock-in models.
What are BH3 mimetics?
BH3 mimetics are drugs that mimic BH3-only proteins and disrupt interactions like BIM-BCL-xl, inducing apoptosis.
Is the BIM-BCL-xl complex a drug target?
Yes, BH3 mimetics targeting BCL-xl, such as TW-37, are active in B-cell tumors.
What is the role of Bik in the BIM-BCL-xl complex?
Bik is a BH3-only protein that can compete with BIM for BCL-xl binding, influencing apoptosis and oxidative stress sensitivity.
How does CRISPR help study the BIM-BCL-xl complex?
CRISPR allows knockout, point mutation, knock-in, and overexpression of BIM and BCL-xl to dissect their functions.
Conclusion
The BIM-BCL-xl complex (GO:0097140) is a critical regulator of apoptosis, with significant implications for cancer and other diseases. Understanding its structure, assembly, and regulation provides insights into therapeutic strategies. CRISPR-based models are powerful tools for dissecting the BIM-BCL-xl interaction and identifying new drug targets.
References
- 1. Al-Katib AM et al.. 2009. SMI of Bcl-2 TW-37 is active across a spectrum of B-cell tumors irrespective of their proliferative and differentiation status.. J Hematol Oncol 2:8 PMID: 19220884
- 2. Bodet L et al.. 2010. BH3-only protein Bik is involved in both apoptosis induction and sensitivity to oxidative stress in multiple myeloma.. Br J Cancer 103(12):1808-14 PMID: 21063407
