Podocin

Last updated
nephrosis 2, idiopathic, steroid-resistant (podocin)
Identifiers
SymbolNPHS2
NCBI gene 7827
HGNC 13394
OMIM 604766
RefSeq NM_014625
UniProt Q9NP85
Other data
Locus Chr. 1 q25-q31
Search for
Structures Swiss-model
Domains InterPro

Podocin is a protein component of the filtration slits of podocytes. Glomerular capillary endothelial cells, the glomerular basement membrane and the filtration slits function as the filtration barrier of the kidney glomerulus. [1] Mutations in the podocin gene NPHS2 can cause nephrotic syndrome, such as focal segmental glomerulosclerosis (FSGS) or minimal change disease (MCD). [2] Symptoms may develop in the first few months of life (congenital nephrotic syndrome) or later in childhood. [3]

Contents

Structure

Podocin is a membrane protein of the band-7-stomatin family, consisting of 383 amino acids. It has a transmembrane domain forming a hairpin structure, with two cytoplasmic ends at the N- and C-terminus, the latter of which interacts with the cytosolic tail of nephrin, with CD2AP serving as an adaptor. [4]

Function

Podocin is localized on the membranes of podocyte pedicels (foot-like long processes), where it oligomerizes in lipid rafts together with nephrin to form the filtration slits. [4]

Related Research Articles

<span class="mw-page-title-main">Nephrotic syndrome</span> Collection of symptoms due to kidney damage

Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy urine. Complications may include blood clots, infections, and high blood pressure.

<span class="mw-page-title-main">Bowman's capsule</span> Kidney structure which performs the first step in blood filtration

Bowman's capsule is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine. A glomerulus is enclosed in the sac. Fluids from blood in the glomerulus are collected in the Bowman's capsule.

<span class="mw-page-title-main">Glomerulus (kidney)</span> Functional unit of nephron

The glomerulus is a network of small blood vessels (capillaries) known as a tuft, located at the beginning of a nephron in the kidney. Each of the two kidneys contains about one million nephrons. The tuft is structurally supported by the mesangium, composed of intraglomerular mesangial cells. The blood is filtered across the capillary walls of this tuft through the glomerular filtration barrier, which yields its filtrate of water and soluble substances to a cup-like sac known as Bowman's capsule. The filtrate then enters the renal tubule of the nephron.

Mesangial cells are specialised cells in the kidney that make up the mesangium of the glomerulus. Together with the mesangial matrix, they form the vascular pole of the renal corpuscle. The mesangial cell population accounts for approximately 30-40% of the total cells in the glomerulus. Mesangial cells can be categorized as either extraglomerular mesangial cells or intraglomerular mesangial cells, based on their relative location to the glomerulus. The extraglomerular mesangial cells are found between the afferent and efferent arterioles towards the vascular pole of the glomerulus. The extraglomerular mesangial cells are adjacent to the intraglomerular mesangial cells that are located inside the glomerulus and in between the capillaries. The primary function of mesangial cells is to remove trapped residues and aggregated protein from the basement membrane thus keeping the filter free of debris. The contractile properties of mesangial cells have been shown to be insignificant in changing the filtration pressure of the glomerulus.

<span class="mw-page-title-main">Podocyte</span> Type of kidney cell

Podocytes are cells in Bowman's capsule in the kidneys that wrap around capillaries of the glomerulus. Podocytes make up the epithelial lining of Bowman's capsule, the third layer through which filtration of blood takes place. Bowman's capsule filters the blood, retaining large molecules such as proteins while smaller molecules such as water, salts, and sugars are filtered as the first step in the formation of urine. Although various viscera have epithelial layers, the name visceral epithelial cells usually refers specifically to podocytes, which are specialized epithelial cells that reside in the visceral layer of the capsule. One type of specialized epithelial cell is podocalyxin.

<span class="mw-page-title-main">Glomerulonephritis</span> Term for several kidney diseases

Glomerulonephritis (GN) is a term used to refer to several kidney diseases. Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory component.

<span class="mw-page-title-main">Membranous glomerulonephritis</span> Medical condition

Membranous glomerulonephritis (MGN) is a slowly progressive disease of the kidney affecting mostly people between ages of 30 and 50 years, usually white people.

<span class="mw-page-title-main">Minimal change disease</span> Medical condition

Minimal change disease is a disease affecting the kidneys which causes nephrotic syndrome. Nephrotic syndrome leads to the loss of significant amounts of protein in the urine, which causes the widespread edema and impaired kidney function commonly experienced by those affected by the disease. It is most common in children and has a peak incidence at 2 to 6 years of age. MCD is responsible for 10–25% of nephrotic syndrome cases in adults. It is also the most common cause of nephrotic syndrome of unclear cause (idiopathic) in children.

<span class="mw-page-title-main">Focal segmental glomerulosclerosis</span> Kidney disease

Focal segmental glomerulosclerosis (FSGS) is a histopathologic finding of scarring (sclerosis) of glomeruli and damage to renal podocytes. This process damages the filtration function of the kidney, resulting in protein presence in the urine due to protein loss. FSGS is a leading cause of excess protein loss—nephrotic syndrome—in children and adults. Signs and symptoms include proteinuria and edema. Kidney failure is a common long-term complication of the disease. FSGS can be classified as primary, secondary, or genetic, depending on whether a particular toxic or pathologic stressor or genetic predisposition can be identified as the cause. Diagnosis is established by renal biopsy, and treatment consists of glucocorticoids and other immune-modulatory drugs. Response to therapy is variable, with a significant portion of patients progressing to end-stage kidney failure. An American epidemiological study 20 years ago demonstrated that FSGS is estimated to occur in 7 persons per million, with males and African-Americans at higher risk.

HIV-associated nephropathy (HIVAN) refers to kidney disease developing in association with infection by human immunodeficiency virus, the virus that causes AIDS. The most common, or "classical", type of HIV-associated nephropathy is a collapsing focal segmental glomerulosclerosis (FSGS), though other forms of kidney disease may also occur. Regardless of the underlying histology, kidney disease in HIV-positive patients is associated with an increased risk of death.

Congenital nephrotic syndrome is a rare kidney disease which manifests in infants during the first 3 months of life, and is characterized by high levels of protein in the urine (proteinuria), low levels of protein in the blood, and swelling. This disease is primarily caused by genetic mutations which result in damage to components of the glomerular filtration barrier and allow for leakage of plasma proteins into the urinary space.

<span class="mw-page-title-main">Nephrin</span> Mammalian protein found in Homo sapiens

Nephrin is a protein necessary for the proper functioning of the renal filtration barrier. The renal filtration barrier consists of fenestrated endothelial cells, the glomerular basement membrane, and the podocytes of epithelial cells. Nephrin is a transmembrane protein that is a structural component of the slit diaphragm. They are present on the tips of the podocytes as an intricate mesh and convey strong negative charges which repel protein from crossing into the Bowman's space.

<span class="mw-page-title-main">Glomerular basement membrane</span>

The glomerular basement membrane of the kidney is the basal lamina layer of the glomerulus. The glomerular endothelial cells, the glomerular basement membrane, and the filtration slits between the podocytes perform the filtration function of the glomerulus, separating the blood in the capillaries from the filtrate that forms in Bowman's capsule. The glomerular basement membrane is a fusion of the endothelial cell and podocyte basal laminas, and is the main site of restriction of water flow. Glomerular basement membrane is secreted and maintained by podocyte cells.

<span class="mw-page-title-main">NPHS2</span> Protein-coding gene in the species Homo sapiens

Podocin is a protein that in humans is encoded by the NPHS2 gene.

<span class="mw-page-title-main">CD2AP</span> Protein

CD2-associated protein is a protein that in humans is encoded by the CD2AP gene.

<span class="mw-page-title-main">MPV17</span> Protein-coding gene in the species Homo sapiens

Protein MPV17 is a protein that in humans is encoded by the MPV17 gene. It is a mitochondrial inner membrane protein, which has a so far largely unknown role in mtDNA maintenance. Protein MPV17 is expressed in human pancreas, kidney, muscle, liver, lung, placenta, brain and heart. Human MPV17 is the orthologue of the mouse kidney disease gene, Mpv17. Loss of function has been shown to cause hepatocerebral mtDNA depletion syndromes (MDS) with oxidative phosphorylation failure and mtDNA depletion both in affected individuals and in Mpv17−/− mice.

<span class="mw-page-title-main">KIRREL</span> Protein-coding gene in the species Homo sapiens

Kin of IRRE-like protein 1, also known as NEPH1, is a protein that in humans is encoded by the KIRREL gene.

Glomerulonephrosis is a non-inflammatory disease of the kidney (nephrosis) presenting primarily in the glomerulus as nephrotic syndrome. The nephron is the functional unit of the kidney and it contains the glomerulus, which acts as a filter for blood to retain proteins and blood lipids. Damage to these filtration units results in important blood contents being released as waste in urine. This disease can be characterized by symptoms such as fatigue, swelling, and foamy urine, and can lead to chronic kidney disease and ultimately end-stage renal disease, as well as cardiovascular diseases. Glomerulonephrosis can present as either primary glomerulonephrosis or secondary glomerulonephrosis.

Dendrin is a neural and renal protein whose exact function is still relatively unclear; however, its location in the brain and kidneys is well known as are some of the neural processes it affects. Within the brain, dendrin can be found in neurons and is most notably associated with sleep deprivation. Sleep deprivation causes some areas of the brain dendrin levels to increase, but this increase is insignificant and in total sleep deprivation causes a decrease of the mRNA and protein form of dendrin. Along with two other proteins, MAGI/S-SCAM and α-actinin, dendrin is linked to synaptic plasticity and memory formation in the brain. Nicotine levels have also been shown to have an effect on dendrin expression in the brain. Although unlike sleep deprivation, nicotine increases overall dendrin level. Originally thought to be a brain specific protein, there is now evidence to suggest that dendrin is also found in the kidneys. Dendrin is used to detect glomerulopathy or renal disease, based on its location in the kidneys. Within the kidneys it also works to prevent urinary protein loss. Most studies and information on dendrin pertain specifically to rat or mice brains.

Karl Tryggvason is an Icelandic medical researcher.

References

  1. Jarad G, Miner JH (May 2009). "Update on the glomerular filtration barrier". Current Opinion in Nephrology and Hypertension. 18 (3): 226–32. doi:10.1097/mnh.0b013e3283296044. PMC   2895306 . PMID   19374010.
  2. Mollet G, Ratelade J, Boyer O, Muda AO, Morisset L, Lavin TA, Kitzis D, Dallman MJ, Bugeon L, Hubner N, Gubler MC, Antignac C, Esquivel EL (October 2009). "Podocin inactivation in mature kidneys causes focal segmental glomerulosclerosis and nephrotic syndrome". Journal of the American Society of Nephrology. 20 (10): 2181–9. doi:10.1681/ASN.2009040379. PMC   2754108 . PMID   19713307.
  3. Avner ED, Harmon WE, Niaudet P, Yoshikawa N, Emma F, Goldstein SL (2016). Pediatric Nephrology. Springer. ISBN   9783662435960. OCLC   1050008865.
  4. 1 2 Tabassum A, Rajeshwari T, Soni N, Raju DS, Yadav M, Nayarisseri A, Jahan P (March 2014). "Structural characterization and mutational assessment of podocin - a novel drug target to nephrotic syndrome - an in silico approach". Interdisciplinary Sciences, Computational Life Sciences. 6 (1): 32–9. doi:10.1007/s12539-014-0190-4. PMID   24464702. S2CID   17163784.