PARP7

Key takeaways

PARP7 belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect PARP7 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of PARP7 from memory before moving on to harder problems.

Reference excerpt

Poly [ADP-ribose] polymerase 7 (PARP7), also known as TCDD-inducible poly-ADP-ribose polymerase (TIPARP), is an enzyme of the PARP family that catalyzes the transfer of ADP-ribose from NAD+ to specific amino acids of itself and other substrate proteins. It is encoded by the TIPARP gene on chromosome 3. The 17 members of the PARP family are divided into polyPARPs, monoPARPs, and PARPs without catalytic activity according to different catalytic functions. PARP7 is a monoPARP that catalyzes the transfer of single units of ADP-ribose onto substrates to change their function. PARP7 is involved in tumor generation and immune function recovery.

Structure of PARP7 PARP7 is characterized by a sequence consisting of 657 amino acids. The protein contains a CCCH-type zinc finger domain for DNA/RNA binding, a protein−protein interaction domain mediating iso-ADP-ribose interaction, a conserved ADP-ribosyltransferase catalytic domain with ADP-ribosyl transferase activity, and an N-terminal nuclear localization signal (NLS).

Functions of PARP7 PARP7 acts by adding a single unit of ADP-ribose to TANK-binding kinase 1 (TBK1), which prevents its activation and represses the type I Interferon (IFN-I) response. PARP7 is amplified in many cancers and acts as a "brake" in the type I IFN response to cytosolic nucleic acid. PARP7 is involved in various biological processes, including intrinsic immunity, cell division, response to viral infections, transcription regulation, receptor degradation, and nervous system development.

Role in viral infection PARP7 plays a dual role in viral replication, with its specific function depending on the type of virus. Following infection with coronavirus, upregulation of PARP7 expression influences the host's antiviral response. Modulating the expression and activity of PARP7 to strengthen the host's immune response represents a promising novel antiviral strategy. PARP7 modulates the antiviral activity of PARP13, an inactive member of the PARP family and plays a role in inhibiting the replication of a wide range of RNA viruses, through mono-ADP-ribosylation (MARylation) modification. Conversely, high expression levels of PARP7 inhibits the replication of specific viruses such as Venezuelan equine encephalitis virus, Getah virus, Sindbis virus, and other RNA viruses.

Role in tumor Activation of the signaling pathway for IFN-I release is an effective way for the human body to clear tumor cells. In the IFN-I signaling pathway, the activation of TBK1 is essential for signal transduction. PARP7 inhibits TBK1 activation via mono-ADP-ribosylation, resulting in the disruption of the IFN-I pathway, ultimately contributing to immune escape in tumor cells. Inhibition of PARP7 activity restores TBK1 phosphorylation function and activates the IFN-I signaling pathway. This cascade activates the Janus kinase (JAK) signal transducer and activator of transcription pathway, promoting the upregulation of CXCL10 expression and recruiting cytotoxic T cells to eliminate tumor cells. PARP7 inhibits the IFN-I signaling pathway by blocking the degradation of FRA1. Reducing the expression level of PARP7 promotes the degradation of FRA1 and restores the IFN-1 signaling. PARP7 inhibitors have clinical potential in treating FRA1-driven cancers, offering a new application strategy of PARP7 inhibitors for cancer therapy. The upregulation of PD-1/PD-L1 immune checkpoints obstructs the IFN-I signaling pathway, thereby impeding the recruitment of cytotoxic T lymphocytes. PARP7 inhibitors in combination with PD1/PD-L1 immune checkpoint inhibitor (ICIs) improve tumor prognosis and provide synergistic anti-tumor effects.

Application in cancer treatment The expression of PARP7 varies across different tumor types, and its role differs accordingly. Down-regulating the expression level of PARP7 has excellent therapeutic effects on a variety of cancers, so that the use of PARP7 inhibitors is widely used as a novel approach to immune-mediated anti-tumor therapy. In ovarian cancer, reducing the expression of PARP7 increases microtubule stability and slows the growth of ovarian cancer cells. Knockdown of the PARP7 gene leads to a decrease in cell growth and an increase in microtubule content. In prostate cancer, the activation of the Androgen Receptor (AR) signaling is important for tumor cell survival and growth. PARP7 modifies multiple cysteine residues of AR through ADP-ribosylation, thereby promoting the growth and survival of prostate cancer cells. The inhibition of PARP7 prevents AR from forming complexes with DTX3L and PARP9, limiting the growth and survival of prostate cancer cells. Ribon Therapeutics reported the first PARP7 inhibitor, RBN-2397. This compound has progressed to clinical phase II trials for the treatment of advanced and metastatic solid tumors. RBN-2397 exhibits extremely high inhibitory potency against PARP7 with an IC50 value of 5.0 M and significant growth inhibition of CT-26 tumor cells in a mouse xenograft model.

Role in other physiological functions Overactivation of astrocytes exacerbates brain damage and impairs the recovery of brain function following a stroke. The expression of PARP7 activates autophagy and stimulates astrocyte activation. By inhibiting PARP7 expression, the activation of astrocytes can be reduced, thereby positively influencing stroke treatment. PARP7 expression impacts hepatic energy metabolism and inflammatory response by decreasing NAD+ levels, consequently affecting glucose regulation and promoting the development of nonalcoholic fatty liver disease. PARP7 is also associated with blood pressure, oral cancer, uveal melanoma, meningioma, bone, and obesity diseases.

References

Worked examples

Example 1 — a first encounter with PARP7

Start with the simplest possible case. Write down what PARP7 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to PARP7 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about PARP7 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of PARP7

In research: PARP7 appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses PARP7 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: PARP7 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Enzymes, Genes on human chromosome 3, so understanding it makes those chapters shorter.
In everyday life: Look for PARP7 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study PARP7 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PARP7 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain PARP7 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PARP7 in simple terms?

Poly [ADP-ribose] polymerase 7 (PARP7), also known as TCDD-inducible poly-ADP-ribose polymerase (TIPARP), is an enzyme of the PARP family that catalyzes the transfer of ADP-ribose from NAD+ to specific amino acids of itself and other substrate proteins. It is encoded by the TIPARP gene on chromosom…

Why does PARP7 matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study PARP7?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on PARP7.