A phosphodiesterase (PDE) is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

that breaks a

phosphodiester bond In chemistry, a phosphodiester bond occurs when exactly two of the hydroxyl groups () in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. The "bond" involves this linkage . Discussion of phosphodiesters is d ...

. Usually, ''phosphodiesterase'' refers to

cyclic nucleotide A cyclic nucleotide (cNMP) is a single-phosphate nucleotide with a cyclic bond arrangement between the sugar and phosphate groups. Like other nucleotides, cyclic nucleotides are composed of three functional groups: a sugar, a nitrogenous base, a ...

phosphodiesterases, which have great clinical significance and are described below. However, there are many other families of phosphodiesterases, including

phospholipase A phospholipase is an enzyme that hydrolyzes phospholipids into fatty acids and other lipophilic substances. Acids trigger the release of bound calcium from cellular stores and the consequent increase in free cytosolic Ca2+, an essential step in ...

s C and D,

autotaxin Autotaxin, also known as ectonucleotide pyrophosphatase/phosphodiesterase family member 2 (E-NPP 2), is an enzyme that in humans is encoded by the ''ENPP2'' gene. Function Autotaxin (ectonucleotide pyrophosphatase/phosphodiesterase 2 (NPP2 or EN ...

sphingomyelin phosphodiesterase Sphingomyelin phosphodiesterase (EC 3.1.4.12, also known as neutral sphingomyelinase, sphingomyelinase, or SMase; systematic name sphingomyelin cholinephosphohydrolase) is a hydrolase enzyme that is involved in sphingolipid metabolism reactions. ...

DNase Deoxyribonuclease (DNase, for short) refers to a group of glycoprotein endonucleases which are enzymes that catalyze the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. The role of the DNase enzyme in cells ...

RNase Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within t ...

s, and

restriction endonuclease A restriction enzyme, restriction endonuclease, REase, ENase or'' restrictase '' is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class o ...

s (which all break the phosphodiester backbone of DNA or

RNA Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...

), as well as numerous less-well-characterized small-molecule phosphodiesterases. The

cyclic nucleotide phosphodiesterase 3′,5′-cyclic-nucleotide phosphodiesterases (EC 3.1.4.17) are a family of phosphodiesterases. Generally, these enzymes hydrolyze a nucleoside 3′,5′-cyclic phosphate to a nucleoside 5′-phosphate: :nucleoside 3′,5′-cyclic phosphate + ...

s comprise a group of

enzymes Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

that degrade the

in the

second messenger Second messengers are intracellular signaling molecules released by the cell in response to exposure to extracellular signaling molecules—the first messengers. (Intercellular signals, a non-local form or cell signaling, encompassing both first me ...

molecules

cAMP Camp may refer to: Outdoor accommodation and recreation * Campsite or campground, a recreational outdoor sleeping and eating site * a temporary settlement for nomads * Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...

and cGMP. They regulate the localization, duration, and amplitude of cyclic nucleotide signaling within subcellular domains. PDEs are therefore important regulators of

signal transduction Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellula ...

mediated by these second messenger molecules.

History

These multiple forms (isoforms or subtypes) of phosphodiesterase were isolated from rat brain using polyacrylamide gel electrophoresis in the early 1970s by Weiss and coworkers, and were soon afterward shown to be selectively inhibited by a variety of drugs in brain and other tissues, also by Weiss and coworkers. The potential for selective

phosphodiesterase inhibitor A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), thereby preventing the inactivation of the intracellular second messengers, cyclic adenosine monophosphate (cAMP) and cyc ...

s to be used as therapeutic agents was predicted in the 1970s by Weiss and coworkers. This prediction has now come to pass in a variety of fields (e.g.

sildenafil Sildenafil, sold under the brand name Viagra, among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. It is unclear if it is effective for treating sexual dysfunction in women. It is taken by ...

as a

PDE5 inhibitor A phosphodiesterase type 5 inhibitor (PDE5 inhibitor) is a vasodilating drug that works by blocking the degradative action of cGMP-specific phosphodiesterase type 5 (PDE5) on cyclic GMP in the smooth muscle cells lining the blood vessels supplyi ...

and

Rolipram Rolipram is a selective phosphodiesterase-4 inhibitor discovered and developed by Schering AG as a potential antidepressant drug in the early 1990s. It served as a prototype molecule for several companies' drug discovery and development efforts ...

as a

PDE4 inhibitor A phosphodiesterase-4 inhibitor, commonly referred to as a PDE4 inhibitor, is a drug used to block the degradative action of phosphodiesterase 4 (PDE4) on cyclic adenosine monophosphate (cAMP). It is a member of the larger family of PDE inhibitor ...

Nomenclature and classification

The PDE nomenclature signifies the ''PDE family'' with an Arabic numeral, then a capital letter denotes the ''gene in that family'', and a second and final Arabic numeral then indicates the ''

splice variant Alternative splicing, or alternative RNA splicing, or differential splicing, is an alternative splicing process during gene expression that allows a single gene to code for multiple proteins. In this process, particular exons of a gene may be in ...

'' derived from a single gene (e.g., PDE1C3: family 1, gene C, splicing variant 3). The superfamily of PDE enzymes is classified into 11 families, namely

PDE1 Phosphodiesterase 1, PDE1, EC 3.1.4.1, systematic name oligonucleotide 5′-nucleotidohydrolase) is a phosphodiesterase enzyme also known as calcium- and calmodulin-dependent phosphodiesterase. It is one of the 11 families of phosphodiesterase (PD ...

-PDE11, in

mammals Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

. The classification is based on: pde families

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

sequences * substrate specificities * regulatory properties * pharmacological properties * tissue distribution Different PDEs of the same family are functionally related despite the fact that their amino acid sequences can show considerable divergence. PDEs have different substrate specificities. Some are cAMP-selective hydrolases (PDE4, 7 and 8); others are cGMP-selective (PDE5, 6, and 9). Others can hydrolyse both cAMP and cGMP (PDE1, 2, 3, 10, and 11).

PDE3 PDE3 is a phosphodiesterase. The PDEs belong to at least eleven related gene families, which are different in their primary structure, substrate affinity, responses to effectors, and regulation mechanism. Most of the PDE families are composed of ...

is sometimes referred to as cGMP-inhibited phosphodiesterase. Although PDE2 can hydrolyze both cyclic nucleotides, binding of cGMP to the regulatory GAF-B domain will increase cAMP affinity and hydrolysis to the detriment of cGMP. This mechanism, as well as others, allows for cross-regulation of the cAMP and cGMP pathways. PDE12 cleaves 2',5'-phosphodiester bond linking adenosines of the 5'-triphosphorylated oligoadenylates. PDE12 is not a member of the cyclic nucleotide phosphodiesterase superfamily that contains PDE1 through PDE11.

Clinical significance

Phosphodiesterase enzymes have been shown to be different in different types of cells, including normal and leukemic lymphocytes and are often targets for pharmacological inhibition due to their unique tissue distribution, structural properties, and functional properties. Inhibitors of PDE can prolong or enhance the effects of physiological processes mediated by

or cGMP by inhibition of their degradation by PDE.

Sildenafil Sildenafil, sold under the brand name Viagra, among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. It is unclear if it is effective for treating sexual dysfunction in women. It is taken by ...

(Viagra) is an inhibitor of

cGMP-specific phosphodiesterase type 5 Cyclic guanosine monophosphate-specific phosphodiesterase type 5 is an enzyme () from the phosphodiesterase class. It is found in various tissues, most prominently the corpus cavernosum and the retina. It has also been recently discovered to p ...

, which enhances the vasodilatory effects of cGMP in the corpus cavernosum and is used to treat erectile dysfunction. Sildenafil is also currently being investigated for its myo- and cardioprotective effects, with particular interest being given to the compound's therapeutic value in the treatment of

Duchenne muscular dystrophy Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis fol ...

and

benign prostatic hyperplasia Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...

Paraxanthine Paraxanthine, or 1,7-dimethylxanthine, is a dimethyl derivative of xanthine, structurally related to caffeine. Production and metabolism Paraxanthine is not known to be produced by plants but is observed in nature as a metabolite of caffeine in a ...

, the main metabolite of

caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...

, is another cGMP-specific phosphodiesterase inhibitor which inhibits PDE9, a cGMP preferring phosphodiesterase. PDE9 is expressed as high as PDE5 in the corpus cavernosum.

Pharmacological effect of PDE inhibitors

PDE inhibitors have been identified as new potential therapeutics in areas such as pulmonary arterial

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

coronary heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...

dementia Dementia is a disorder which manifests as a set of related symptoms, which usually surfaces when the brain is damaged by injury or disease. The symptoms involve progressive impairments in memory, thinking, and behavior, which negatively affe ...

, depression,

asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, cou ...

COPD Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce mu ...

, protozoal infections (including

malaria Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...

) and

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...

. PDE also are important in seizure incidence. For example, PDE compromised the antiepileptic activity of adenosine. In addition, using of a PDE inhibitor (pentoxifylline) in pentylenetetrazole-induced seizure indicated the antiepileptic effect by increasing the time latency to seizure incidence and decreasing the seizure duration in vivo.

Cilostazol Cilostazol, sold under the brand name Pletal among others, is a medication used to help the symptoms of intermittent claudication in peripheral vascular disease. If no improvement is seen after 3 months, stopping the medication is reasonable. It ...

(Pletal) inhibits

. This inhibition allows

red blood cells Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek language, Greek ''erythros'' for "red" and ''k ...

to be more able to bend. This is useful in conditions such as

intermittent claudication Intermittent claudication, also known as vascular claudication, is a symptom that describes muscle pain on mild exertion (ache, cramp, numbness or sense of fatigue), classically in the calf muscle, which occurs during exercise, such as walking, and ...

, as the cells can maneuver through constricted veins and arteries more easily.

Dipyridamole Dipyridamole (trademarked as Persantine and others) is a nucleoside transport inhibitor and a PDE3 inhibitor medication that inhibits blood clot formation when given chronically and causes blood vessel dilation when given at high doses over a ...

inhibits PDE-3 and PDE-5. This leads to intraplatelet accumulation of cAMP and/or cGMP, inhibiting platelet aggregation.

Zaprinast Zaprinast was an unsuccessful clinical drug candidate that was a precursor to the chemically related PDE5 inhibitors, such as sildenafil (Viagra), which successfully reached the market. It is a phosphodiesterase inhibitor, selective for the subtyp ...

inhibits the growth of asexual blood-stage

parasites ( ''P. falciparum'') ''in vitro'' with an ED₅₀ value of 35 μM, and inhibits PfPDE1, a '' P. falciparum'' cGMP-specific phosphodiesterase, with an IC₅₀ value of 3.8 μM.

Xanthine Xanthine ( or ; archaically xanthic acid; systematic name 3,7-dihydropurine-2,6-dione) is a purine base found in most human body tissues and fluids, as well as in other organisms. Several stimulants are derived from xanthine, including caffeine ...

s such as

and

theobromine Theobromine, also known as xantheose, is the principal alkaloid of '' Theobroma cacao'' (cacao plant). Theobromine is slightly water-soluble (330 mg/L) with a bitter taste. In industry, theobromine is used as an additive and precursor to ...

are

-phosphodiesterase inhibitors. However, the inhibitory effect of xanthines on phosphodiesterases are only seen at dosages higher than what people normally consume. Sildenafil,

Tadalafil Tadalafil, sold under the brand name Cialis among others, is a medication used to treat erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension. It is taken by mouth. Onset is typically within half ...

and

Vardenafil Vardenafil is a PDE5 inhibitor used for treating erectile dysfunction that is sold under the brand name Levitra among others. Medical use Vardenafil's indications and contraindications are the same as with other PDE5 inhibitors; it is closel ...

are PDE-5 inhibitors and are widely used in the treatment of erectile dysfunction.

References

External links

* {{Portal bar, Biology, border=no EC 3.1.4 Molecular biology