Cellular Processes in Homeostasis

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Questions and Answers

Which of the following cellular processes is NOT mentioned as being involved in maintaining cellular homeostasis?

  • Oxidative phosphorylation
  • DNA replication (correct)
  • Protein ubiquitination
  • Sumoylation

Apoptosis is a process that involves uncontrolled cell death.

False (B)

What is the primary function of autophagy?

Autophagy is a catabolic process that breaks down and removes damaged proteins and organelles within the cell.

The enzymes responsible for breaking down cells during apoptosis are called ______.

<p>caspases</p> Signup and view all the answers

Match the following cell death mechanisms with their primary characteristics:

<p>Apoptosis = Controlled cell shrinkage, nuclear fragmentation, anti-inflammatory cytokine release Necrosis = Cell swelling, lysis, pro-inflammatory cytokine release Autophagy = Breakdown of damaged proteins and organelles within the cell</p> Signup and view all the answers

The influx of Ca2+ through specialized CRAC channels is necessary for the maintenance of NFAT proteins in the nucleus.

<p>True (A)</p> Signup and view all the answers

What is the primary characteristic that distinguishes CRAC channels from other SOCs?

<p>High Ca2+ selectivity (D)</p> Signup and view all the answers

NFAT interacts with ______ and enhances its transcriptional activity.

<p>MEF2D</p> Signup and view all the answers

What is the role of the COOH-terminal region of Cabin1 in the regulation of MEF2D activity?

<p>The COOH-terminal region of Cabin1 interacts with MEF2D and calmodulin in a mutually exclusive manner. This interaction is important for regulating MEF2D activity.</p> Signup and view all the answers

Match the following proteins with their respective functions:

<p>MEF2D = Transcription factor involved in the activation of Nur77 NFAT = Co-activator that enhances MEF2D transcriptional activity Cabin1 = Suppressor of MEF2D transcriptional activity p300 = Co-activator that facilitates MEF2D-mediated gene transcription Calcineurin = Phosphatase that activates NFAT Capn2 = Protease that cleaves Cabin1 to activate calcineurin</p> Signup and view all the answers

What is the main mechanism by which a Ca2+ signal promotes the activation of MEF2D?

<p>Calmodulin-mediated displacement of Cabin1 from MEF2D (A)</p> Signup and view all the answers

The cleavage of Cabin1 by Capn2 leads to the inactivation of calcineurin.

<p>False (B)</p> Signup and view all the answers

How does Cabin1 contribute to the regulation of MEF2D activity?

<p>Cabin1 directly binds to MEF2D, suppressing its transcriptional activity. However, upon Ca2+ signaling, calmodulin displaces Cabin1, allowing MEF2D to become active.</p> Signup and view all the answers

Which of the following is NOT a critical step in the activation of calcineurin?

<p>Binding of Cabin1 to calcineurin (A)</p> Signup and view all the answers

The interaction between Cabin1 and calcineurin is dependent on both ______ and ______ activation.

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What is the primary function of FAS-associated death domain (FADD) in the FAS signaling pathway?

<p>Acts as an adaptor protein, linking FAS receptor to caspase-8 (B)</p> Signup and view all the answers

The activation of NF-kappa B (NFκB) by TNFR1 signaling always leads to cell survival.

<p>False (B)</p> Signup and view all the answers

What are the two main types of immune cells that utilize the granule exocytosis pathway to eliminate infected or cancerous cells?

<p>Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells</p> Signup and view all the answers

The ______ pathway is triggered by the activation of ASK1, which is activated by the adaptor protein DAXX in the FAS signaling pathway.

<p>JNK</p> Signup and view all the answers

Match the following molecules with their respective roles in apoptosis:

<p>FAS = Death receptor involved in apoptosis FADD = Adaptor protein linking FAS receptor to caspase-8 tBID = Truncated form of BID, promotes release of cytochrome c APAF-1 = Apoptotic peptidase activating factor 1, forms the apoptosome SMAC/DIABLO = Inhibitor of apoptosis protein inhibitor</p> Signup and view all the answers

Which of the following molecules is responsible for directly activating caspase-9 in the apoptosome?

<p>Cytochrome c (D)</p> Signup and view all the answers

The granule exocytosis pathway employed by CTL and NK cells releases only granzymes into the immunological synapse.

<p>False (B)</p> Signup and view all the answers

What is the role of FLIP in TNFR1-mediated signaling?

<p>FLIP is a caspase-8 inhibitor that prevents apoptosis in TNFR1 signaling when NFκB is activated.</p> Signup and view all the answers

The release of ______ from mitochondria, triggered by the activation of tBID, is a pivotal step in the FAS-mediated apoptosis pathway.

<p>cytochrome c</p> Signup and view all the answers

Which of the following pathways is NOT directly involved in the FAS-mediated apoptosis pathway?

<p>NFκB pathway (B)</p> Signup and view all the answers

What is the role of Granzyme-B during apoptosis?

<p>It cleaves BID to produce tBID. (C)</p> Signup and view all the answers

Apoptosis results in the release of cellular contents into the extracellular space.

<p>False (B)</p> Signup and view all the answers

What are the two sources of intracellular free Ca2+ in T-Cells?

<p>Endoplasmic reticulum and extracellular space</p> Signup and view all the answers

Calcium (Ca2+) is a key signal for T-Cell ______.

<p>activation</p> Signup and view all the answers

Match the components involved in T-Cell activation with their roles:

<p>Antigen-MHC Class-II complex = Triggers T-Cell receptor activation PLC-γ1 = Cleaves PIP2 to generate DAG and IP3 DAG = Activates Protein Kinase C (PKC) IP3 = Increases intracellular calcium levels</p> Signup and view all the answers

Which of the following is NOT a consequence of apoptosis?

<p>Spreading viruses to neighboring cells (A)</p> Signup and view all the answers

Activated cytotoxic T lymphocytes (CTLs) are destroyed during the apoptosis process.

<p>False (B)</p> Signup and view all the answers

What enzyme is responsible for cleaving PIP2 in the plasma membrane?

<p>PLC-γ1</p> Signup and view all the answers

The binding of the antigen-MHC Class-II complex triggers the recruitment of ______ to the TCR/CD3/CD4 complex.

<p>tyrosine kinases</p> Signup and view all the answers

What is the effect of IP3 during T-Cell activation?

<p>Promotes accumulation of calcium in the cytosol (C)</p> Signup and view all the answers

What is the role of caspase 8 in apoptosis?

<p>It cleaves BID into tBID. (D)</p> Signup and view all the answers

FLIP is an activator of apoptosis.

<p>False (B)</p> Signup and view all the answers

Name the three types of autophagy.

<p>macroautophagy, microautophagy, chaperone-mediated autophagy</p> Signup and view all the answers

The kinase _______ is a critical regulator of autophagy induction.

<p>mTOR</p> Signup and view all the answers

Which molecule is indirectly associated with FADD through DAP3?

<p>TRAILR (B)</p> Signup and view all the answers

Match the following proteins to their function:

<p>Caspase 9 = Activates caspase 3 BID = Translocates to mitochondria mTOR = Regulates autophagy FLIP = Regulates apoptosis</p> Signup and view all the answers

Autophagy is generally activated by conditions of nutrient abundance.

<p>False (B)</p> Signup and view all the answers

Flashcards

Sumoylation

A process that modifies proteins to regulate cellular functions, including tumor growth.

Apoptosis

Programmed cell death regulated by signaling pathways for controlled cell shrinkage.

Caspases

Proteolytic enzymes that execute apoptosis by cleaving key proteins.

Necrosis

Uncontrolled cell death resulting in cell swelling and inflammation.

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Autophagy

The process of degrading damaged proteins and organelles within a cell.

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Tumor growth suppression

Therapeutic strategy aiming to inhibit the increase of tumor size.

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Metastasis

Spread of cancer cells from one part of the body to another.

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Homeostasis

The balance of cellular processes to maintain optimal function.

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TRAIL

A protein that binds to TRAIL receptors to initiate apoptosis.

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FADD

A molecular bridge recruited by TRAIL that activates caspase 8.

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Cytochrome c (CytoC)

A protein that, when released, activates caspase 9 to continue apoptosis.

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mTOR

A key regulator that suppresses or promotes autophagy based on nutrient levels.

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ULK1 Complex

A group of proteins activated to regulate autophagosome formation.

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Granzyme-B

An enzyme that activates apoptosis by cleaving substrates like BID.

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BID

BH3-Interacting Domain death agonist that gets cleaved by Granzyme-B.

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tBID

Truncated BID, a pro-apoptotic molecule produced from BID cleavage.

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Phagocytes

Cells that engulf and remove apoptotic cell fragments.

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Calcium (Ca2+)

A key signal molecule for T-Cell activation and death.

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T-Cell Activation

Process initiated by antigen-MHC complexes stimulating TCR.

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PLC-γ1

Enzyme that cleaves PIP2 to generate DAG and IP3 for Ca2+ signaling.

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DAG and IP3

Second messengers generated by PLC-γ1 leading to increased Ca2+.

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IP3R

Inositol trisphosphate receptor, which releases Ca2+ from the endoplasmic reticulum.

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FAS pathway

A signaling pathway that initiates apoptosis via FAS receptor engagement.

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DISC

Death-Inducing Signaling Complex; involved in FAS-mediated apoptosis.

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Cytochrome c

A protein released from mitochondria that activates APAF-1 and procaspase-9.

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apoptosome

A complex formed by cytochrome c, APAF-1, and procaspase-9 that activates caspase-9.

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TNF-R1 pathway

A signaling pathway that can lead to apoptosis or cell survival, involving NF-kappa B.

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Granule exocytosis

The process by which CTL and NK cells release perforin and granzymes to destroy infected or tumor cells.

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CRAC Channel

Calcium release-activated calcium channel in T-cells, highly selective for Ca2+.

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Ca2+ Signals

Intracellular calcium signals that stabilize T-cell interactions and cytoskeletal changes.

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NFAT

Nuclear factor of activated T-cells; maintains persistent Ca2+ signals.

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MEF2D

A protein that interacts with NFAT to enhance transcriptional activity.

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p300 Co-activator

Protein that assists in the transcription of NFAT and MEF2D target genes.

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Cabin1

A protein that suppresses MEF2D activity but is released with Ca2+ signals.

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Calmodulin

Protein that binds to Cabin1 in response to Ca2+ and activates MEF2D.

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Calcineurin

A phosphatase that activates downstream signaling processes in response to Ca2+.

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Capn2

A protein that cleaves Cabin1 to activate calcineurin and induce cell death.

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