Perforin-1

{{Short description|Mammalian protein found in Homo sapiens}} {{distinguish|Porphyrin}} {{cs1 config|name-list-style=vanc|display-authors=6}} {{Infobox_gene}} '''Perforin-1''' (PRF) is a pore-forming protein encoded in humans by the ''PRF1'' gene. It is stored in the secretory granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, collectively known as cytotoxic lymphocytes (CLs). Upon activation, these cells release perforin to form pores in the membranes of target cells, enabling the entry of granzymes that trigger apoptosis. Perforin is therefore a central effector molecule of the immune system, essential for the elimination of virus-infected and transformed cells.<ref name="Voskoboinik_2013">{{cite journal | vauthors = Voskoboinik I, Trapani JA | title = Perforinopathy: a spectrum of human immune disease caused by defective perforin delivery or function | journal = Frontiers in Immunology | volume = 4 | page = 441 | date = December 2013 | pmid = 24376445 | pmc = 3860100 | doi = 10.3389/fimmu.2013.00441 | doi-access = free }}</ref> Mutations in ''PRF1'' that impair perforin expression or function are associated with familial hemophagocytic lymphohistiocytosis (FHL) and related immune dysregulation syndromes, a spectrum of conditions sometimes collectively referred to as '''perforinopathies'''.<ref name="Voskoboinik_2013" />

== Discovery == Perforin was initially discovered in 1983 and subsequently cloned from an expression library in 1988 using anti-complement C9 antibody cross-reactivity. A sequence comparison showed a notable resemblance between the two proteins in a specific central region, termed the 'membrane attack complex/perforin' (MACPF) domain.<ref>{{cite journal | vauthors = Brennan AJ, Chia J, Trapani JA, Voskoboinik I | title = Perforin deficiency and susceptibility to cancer | journal = Cell Death and Differentiation | volume = 17 | issue = 4 | pages = 607–615 | date = April 2010 | pmid = 20075937 | doi = 10.1038/cdd.2009.212 }}</ref>

== Structure == Perforin is a pore-forming cytolytic protein composed of approximately 555 amino acids and has a molecular weight of 60–70 kDa. The protein contains several domains: the conserved N-terminal membrane attack complex/perforin (MACPF) domain which is central to its pore-forming function, a C-terminal membrane-docking C2 domain responsible for calcium-dependent interaction with target membranes, and an epidermal growth factor (EGF)-like domain that provides flexibility and links the MACPF and C2 domains. The structure of perforin is further stabilized by nine disulfide bonds, and its N-terminal domain binds calcium ions, a key feature required for activation and subsequent insertion into lipid membranes. Oligomerization of approximately 20 perforin monomers forms large, cylindrical pores in target cell membranes; these pores are hydrophobic and disrupt ionic homeostasis, leading to cell death.<ref name="Osińska_2014">{{cite journal | vauthors = Osińska I, Popko K, Demkow U | title = Perforin: an important player in immune response | journal = Central-European Journal of Immunology | volume = 39 | issue = 1 | pages = 109–15 | date = 2014 | pmid = 26155110 | pmc = 4439970 | doi = 10.5114/ceji.2014.42135 }}</ref><ref name="Ivanova_2022">{{cite journal | vauthors = Ivanova ME, Lukoyanova N, Malhotra S, Topf M, Trapani JA, Voskoboinik I, Saibil HR | title = The pore conformation of lymphocyte perforin | journal = Science Advances | volume = 8 | issue = 6 | article-number = eabk3147 | date = February 2022 | pmid = 35148176 | pmc = 8836823 | doi = 10.1126/sciadv.abk3147 }}</ref>

The lytic membrane-inserting region of perforin is the MACPF domain, which mediates pore formation.<ref>{{cite journal | vauthors = Tschopp J, Masson D, Stanley KK | title = Structural/functional similarity between proteins involved in complement- and cytotoxic T-lymphocyte-mediated cytolysis | journal = Nature | volume = 322 | issue = 6082 | pages = 831–834 | year = 1986 | pmid = 2427956 | doi = 10.1038/322831a0 | s2cid = 4330219 | author-link = Jürg Tschopp | bibcode = 1986Natur.322..831T }}</ref> This domain shares homology with cholesterol-dependent cytolysins of Gram-positive bacteria.<ref name="Rosado_2007">{{cite journal | vauthors = Rosado CJ, Buckle AM, Law RH, Butcher RE, Kan WT, Bird CH, Ung K, Browne KA, Baran K, Bashtannyk-Puhalovich TA, Faux NG, Wong W, Porter CJ, Pike RN, Ellisdon AM, Pearce MC, Bottomley SP, Emsley J, Smith AI, Rossjohn J, Hartland EL, Voskoboinik I, Trapani JA, Bird PI, Dunstone MA, Whisstock JC | title = A common fold mediates vertebrate defense and bacterial attack | journal = Science | volume = 317 | issue = 5844 | pages = 1548–1551 | date = September 2007 | pmid = 17717151 | doi = 10.1126/science.1144706 | s2cid = 20372720 | doi-access = free | bibcode = 2007Sci...317.1548R }}</ref> Perforin also shows structural similarity to complement component 9 (C9), another pore-forming protein that creates transmembrane tubules.<ref name="entrez">{{cite web | title = Entrez Gene: PRF1 perforin 1 (pore forming protein) | url = https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=ShowDetailView&TermToSearch=5551 }}</ref>

Purifying perforin has historically been difficult due to its loss of activity and stability in solution; only recently has a recombinant form been successfully produced.<ref name="Pipkin_2007">{{cite journal | vauthors = Pipkin ME, Lieberman J | title = Delivering the kiss of death: progress on understanding how perforin works | journal = Current Opinion in Immunology | volume = 19 | issue = 3 | pages = 301–308 | date = June 2007 | pmid = 17433871 | pmc = 11484871 | doi = 10.1016/j.coi.2007.04.011 | series = Lymphocyte activation/Lymphocyte effector functions }}</ref>

==Function== Perforin is a pore-forming cytolytic protein stored in the granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Upon degranulation, perforin is escorted to the target cell membrane by calreticulin, a chaperone protein that prevents its premature degradation. Perforin binds to the target cell's plasma membrane through interactions with membrane phospholipids, while calcium ions enhance this binding by stabilizing interactions with phosphatidylcholine<ref name="Osińska_2014" /> In a Ca2+-dependent process, perforin oligomerises to form pores that permit the entry of granzymes, a family of pro-apoptotic proteases.<ref name="Trapani_1995">{{cite journal | vauthors = Trapani JA | title = Target cell apoptosis induced by cytotoxic T cells and natural killer cells involves synergy between the pore-forming protein, perforin, and the serine protease, granzyme B | journal = Australian and New Zealand Journal of Medicine | volume = 25 | issue = 6 | pages = 793–799 | date = December 1995 | pmid = 8770355 | doi = 10.1111/j.1445-5994.1995.tb02883.x }}</ref>

Initially, perforin was thought to act only at the plasma membrane. However, subsequent findings revealed that granzyme B can be endocytosed independently of perforin. Washed cells that had internalized granzyme B underwent apoptosis when perforin was later added, even though perforin had not been present during endocytosis. These results led to the proposal that perforin's main function occurs at the endosomal rather than the plasma membrane, by disrupting endosomal integrity to release granzymes into the cytosol.<ref>{{cite journal | vauthors = Froelich CJ, Orth K, Turbov J, Seth P, Gottlieb R, Babior B, Shah GM, Bleackley RC, Dixit VM, Hanna W | title = New paradigm for lymphocyte granule-mediated cytotoxicity. Target cells bind and internalize granzyme B, but an endosomolytic agent is necessary for cytosolic delivery and subsequent apoptosis | journal = The Journal of Biological Chemistry | volume = 271 | issue = 46 | pages = 29073–29079 | date = November 1996 | pmid = 8910561 | doi = 10.1074/jbc.271.46.29073 | doi-access = free }}</ref><ref name="Pipkin_2007" /> Later studies confirmed that perforin pores in the endosomal membrane enable granzyme B to escape into the cytosol, thereby triggering apoptosis.<ref name="Thiery_2011">{{cite journal | vauthors = Thiery J, Keefe D, Boulant S, Boucrot E, Walch M, Martinvalet D, Goping IS, Bleackley RC, Kirchhausen T, Lieberman J | title = Perforin pores in the endosomal membrane trigger the release of endocytosed granzyme B into the cytosol of target cells | journal = Nature Immunology | volume = 12 | issue = 8 | pages = 770–777 | date = June 2011 | pmid = 21685908 | pmc = 3140544 | doi = 10.1038/ni.2050 }}</ref>

Through these mechanisms, perforin acts as a central effector molecule in CTL- and NK cell-mediated cytotoxicity.

== Clinical significance ==

=== Familial hemophagocytic lymphohistiocytosis === Mutations in ''PRF1'' that reduce or abolish perforin expression or pore-forming activity cause the autosomal-recessive disorder familial hemophagocytic lymphohistiocytosis (FHL) type 2 (FHL2). The loss of cytotoxic T lymphocyte (CTL) and natural killer (NK) cell function prevents effective granule-mediated cytotoxicity, leading to uncontrolled antigen presentation, T-cell hyperactivation, interferon-γ–driven macrophage activation, and severe hyperinflammation. ''PRF1'' mutations account for roughly 20–50% of familial cases, with disease severity depending on mutation type: hypomorphic alleles with residual activity may present later in childhood or adulthood, whereas null mutations typically manifest in infancy.<ref name="Sieni_2014">{{cite journal | vauthors = Sieni E, Cetica V, Hackmann Y, Coniglio ML, Da Ros M, Ciambotti B, Pende D, Griffiths GM, Aricò M | title = Familial hemophagocytic lymphohistiocytosis: when rare diseases shed light on immune system functioning | journal = Frontiers in Immunology | volume = 5 | page = 167 | date = April 2014 | pmid = 24795715 | pmc = 3997030 | doi = 10.3389/fimmu.2014.00167 | doi-access = free }}</ref><ref name="Voskoboinik_2013">{{cite journal | vauthors = Voskoboinik I, Trapani JA | title = Perforinopathy: a spectrum of human immune disease caused by defective perforin delivery or function | journal = Frontiers in Immunology | volume = 4 | page = 441 | date = December 2013 | pmid = 24376445 | pmc = 3860100 | doi = 10.3389/fimmu.2013.00441 | doi-access = free }}</ref><ref name="Gholam_2011">{{cite journal | vauthors = Gholam C, Grigoriadou S, Gilmour KC, Gaspar HB | title = Familial haemophagocytic lymphohistiocytosis: advances in the genetic basis, diagnosis and management | journal = Clinical and Experimental Immunology | volume = 163 | issue = 3 | pages = 271–283 | date = March 2011 | pmid = 21303357 | pmc = 3048610 | doi = 10.1111/j.1365-2249.2010.04302.x }}</ref><ref name="Risma_2012">{{cite journal | vauthors = Risma K, Jordan MB | title = Hemophagocytic lymphohistiocytosis: updates and evolving concepts | journal = Current Opinion in Pediatrics | volume = 24 | issue = 1 | pages = 9–15 | date = February 2012 | pmid = 22189397 | doi = 10.1097/MOP.0b013e32834ec9c1 }}</ref>

=== Perforinopathy === The concept of "perforinopathy" encompasses a spectrum of disease presentations linked to impaired perforin function.<ref name="Voskoboinik_2013" />

==== Acute ==== Complete loss of perforin activity causes a severe, often fatal, autosomal recessive immunoregulatory disorder in infants, typically presenting before 12 months of age as FHL. Effective treatment requires allogeneic bone marrow transplantation.<ref name="Voskoboinik_2013" /> Pathogenesis results from the inability of CTLs and NK cells to kill target cells, leading to the clinical syndrome defined in HLH-2004. Diagnosis is confirmed by impaired NK cell cytotoxicity and by mutations in ''PRF1'' or other FHL-associated genes such as ''UNC13D'', ''STX11'', and ''STXBP2''.<ref name="Voskoboinik_2013" />

==== Sub-acute ==== Sub-acute perforinopathies result from partial loss of CTL and NK cell function, usually due to bi-allelic hypomorphic mutations. Clinical manifestations are more variable and often milder than in acute disease, with intermittent courses, later onset, and responsiveness to immunosuppressive or immune-ablative therapy. These features make diagnosis more challenging.<ref name="Voskoboinik_2013" />

==== Chronic ==== Chronic perforinopathies arise from monoallelic mutations in genes linked to FHL. Instead of classic FHL, these patients may present with later-onset immune dysregulation, including macrophage activation syndrome in juvenile rheumatoid arthritis or an increased incidence of blood cancers. Symptoms usually appear after age 5. Associations between ''PRF1'' variants and outcomes following bone marrow transplantation have been reported, but remain controversial.<ref name="Voskoboinik_2013" />

=== Cancer === Perforin is a central effector in immune surveillance against cancer, enabling CTLs and NK cells to lyse transformed cells (a normal cell altered to grow uncontrollably with cancer-like traits). By forming membrane pores, perforin permits entry of granzymes that induce apoptosis. In both humans and mice, perforin deficiency or dysfunction markedly increases susceptibility to cancers, particularly lymphomas and other hematological malignancies. Some tumors evade perforin-mediated cytotoxicity by altering cell surface molecules, thereby resisting immune clearance and promoting cancer progression.<ref name="Guan_2024">{{cite journal | vauthors = Guan X, Guo H, Guo Y, Han Q, Li Z, Zhang C | title = Perforin 1 in Cancer: Mechanisms, Therapy, and Outlook | journal = Biomolecules | volume = 14 | issue = 8 | date = July 2024 | page = 910 | pmid = 39199299 | pmc = 11352983 | doi = 10.3390/biom14080910 | doi-access = free }}</ref><ref name="Tuomela_2022">{{cite journal | vauthors = Tuomela K, Ambrose AR, Davis DM | title = Escaping Death: How Cancer Cells and Infected Cells Resist Cell-Mediated Cytotoxicity | journal = Frontiers in Immunology | volume = 13 | issue = | article-number = 867098 | date = 2022 | pmid = 35401556 | pmc = 8984481 | doi = 10.3389/fimmu.2022.867098 | doi-access = free }}</ref><ref name="Osińska_2014">{{cite journal | vauthors = Osińska I, Popko K, Demkow U | title = Perforin: an important player in immune response | journal = Central-European Journal of Immunology | volume = 39 | issue = 1 | pages = 109–15 | date = 2014 | pmid = 26155110 | pmc = 4439970 | doi = 10.5114/ceji.2014.42135 }}</ref><ref name="Cullen_2010">{{cite journal | vauthors = Cullen SP, Brunet M, Martin SJ | title = Granzymes in cancer and immunity | journal = Cell Death and Differentiation | volume = 17 | issue = 4 | pages = 616–23 | date = April 2010 | pmid = 20075940 | doi = 10.1038/cdd.2009.206 }}</ref>

== Interactions ==

Perforin has been shown to interact with calreticulin.<ref name="Andrin_1998">{{cite journal | vauthors = Andrin C, Pinkoski MJ, Burns K, Atkinson EA, Krahenbuhl O, Hudig D, Fraser SA, Winkler U, Tschopp J, Opas M, Bleackley RC, Michalak M | title = Interaction between a Ca2+-binding protein calreticulin and perforin, a component of the cytotoxic T-cell granules | journal = Biochemistry | volume = 37 | issue = 29 | pages = 10386–10394 | date = July 1998 | pmid = 9671507 | doi = 10.1021/bi980595z }}</ref>

== See also == * Granzymes * Defensin * Complement membrane attack complex

== References == {{Reflist}}

== Further reading == {{refbegin |2}} * {{cite journal | vauthors = Trapani JA | title = Target cell apoptosis induced by cytotoxic T cells and natural killer cells involves synergy between the pore-forming protein, perforin, and the serine protease, granzyme B | journal = Australian and New Zealand Journal of Medicine | volume = 25 | issue = 6 | pages = 793–799 | date = December 1995 | pmid = 8770355 | doi = 10.1111/j.1445-5994.1995.tb02883.x }} * {{cite journal | vauthors = Peitsch MC, Amiguet P, Guy R, Brunner J, Maizel JV, Tschopp J | title = Localization and molecular modelling of the membrane-inserted domain of the ninth component of human complement and perforin | journal = Molecular Immunology | volume = 27 | issue = 7 | pages = 589–602 | date = July 1990 | pmid = 2395434 | doi = 10.1016/0161-5890(90)90001-G }} * {{cite journal | vauthors = Young JD, Hengartner H, Podack ER, Cohn ZA | title = Purification and characterization of a cytolytic pore-forming protein from granules of cloned lymphocytes with natural killer activity | journal = Cell | volume = 44 | issue = 6 | pages = 849–859 | date = March 1986 | pmid = 2420467 | doi = 10.1016/0092-8674(86)90007-3 | s2cid = 30182487 }} * {{cite journal | vauthors = Young JD, Cohn ZA, Podack ER | title = The ninth component of complement and the pore-forming protein (perforin 1) from cytotoxic T cells: structural, immunological, and functional similarities | journal = Science | volume = 233 | issue = 4760 | pages = 184–190 | date = July 1986 | pmid = 2425429 | doi = 10.1126/science.2425429 }} * {{cite journal | vauthors = Lichtenheld MG, Podack ER | title = Structure of the human perforin gene. A simple gene organization with interesting potential regulatory sequences | journal = Journal of Immunology | volume = 143 | issue = 12 | pages = 4267–4274 | date = December 1989 | pmid = 2480391 | doi = 10.4049/jimmunol.143.12.4267 | s2cid = 8326644 | doi-access = free }} * {{cite journal | vauthors = Shinkai Y, Takio K, Okumura K | title = Homology of perforin to the ninth component of complement (C9) | journal = Nature | volume = 334 | issue = 6182 | pages = 525–527 | date = August 1988 | pmid = 3261391 | doi = 10.1038/334525a0 | s2cid = 4348928 | bibcode = 1988Natur.334..525S }} * {{cite journal | vauthors = Lichtenheld MG, Olsen KJ, Lu P, Lowrey DM, Hameed A, Hengartner H, Podack ER | title = Structure and function of human perforin | journal = Nature | volume = 335 | issue = 6189 | pages = 448–451 | date = September 1988 | pmid = 3419519 | doi = 10.1038/335448a0 | s2cid = 4359028 | bibcode = 1988Natur.335..448L }} * {{cite journal | vauthors = Goebel WS, Schloemer RH, Brahmi Z | title = Target cell-induced perforin mRNA turnover in NK3.3 cells is mediated by multiple elements within the mRNA coding region | journal = Molecular Immunology | volume = 33 | issue = 4–5 | pages = 341–349 | year = 1996 | pmid = 8676885 | doi = 10.1016/0161-5890(95)00155-7 }} * {{cite journal | vauthors = Nöske K, Bilzer T, Planz O, Stitz L | title = Virus-specific CD4+ T cells eliminate borna disease virus from the brain via induction of cytotoxic CD8+ T cells | journal = Journal of Virology | volume = 72 | issue = 5 | pages = 4387–4395 | date = May 1998 | pmid = 9557729 | pmc = 109669 | doi = 10.1128/JVI.72.5.4387-4395.1998 }} * {{cite journal | vauthors = Andrin C, Pinkoski MJ, Burns K, Atkinson EA, Krahenbuhl O, Hudig D, Fraser SA, Winkler U, Tschopp J, Opas M, Bleackley RC, Michalak M | title = Interaction between a Ca2+-binding protein calreticulin and perforin, a component of the cytotoxic T-cell granules | journal = Biochemistry | volume = 37 | issue = 29 | pages = 10386–10394 | date = July 1998 | pmid = 9671507 | doi = 10.1021/bi980595z }} * {{cite journal | vauthors = Yu CR, Ortaldo JR, Curiel RE, Young HA, Anderson SK, Gosselin P | title = Role of a STAT binding site in the regulation of the human perforin promoter | journal = Journal of Immunology | volume = 162 | issue = 5 | pages = 2785–2790 | date = March 1999 | pmid = 10072525 | doi = 10.4049/jimmunol.162.5.2785 | s2cid = 26096007 | doi-access = free }} * {{cite journal | vauthors = Stepp SE, Dufourcq-Lagelouse R, Le Deist F, Bhawan S, Certain S, Mathew PA, Henter JI, Bennett M, Fischer A, de Saint Basile G, Kumar V | title = Perforin gene defects in familial hemophagocytic lymphohistiocytosis | journal = Science | volume = 286 | issue = 5446 | pages = 1957–1959 | date = December 1999 | pmid = 10583959 | doi = 10.1126/science.286.5446.1957 }} * {{cite journal | vauthors = Takahashi T, Nieda M, Koezuka Y, Nicol A, Porcelli SA, Ishikawa Y, Tadokoro K, Hirai H, Juji T | title = Analysis of human V alpha 24+ CD4+ NKT cells activated by alpha-glycosylceramide-pulsed monocyte-derived dendritic cells | journal = Journal of Immunology | volume = 164 | issue = 9 | pages = 4458–4464 | date = May 2000 | pmid = 10779745 | doi = 10.4049/jimmunol.164.9.4458 | doi-access = free }} * {{cite journal | vauthors = Badovinac VP, Tvinnereim AR, Harty JT | title = Regulation of antigen-specific CD8+ T cell homeostasis by perforin and interferon-gamma | journal = Science | volume = 290 | issue = 5495 | pages = 1354–1358 | date = November 2000 | pmid = 11082062 | doi = 10.1126/science.290.5495.1354 | bibcode = 2000Sci...290.1354B }} * {{cite journal | vauthors = Göransdotter Ericson K, Fadeel B, Nilsson-Ardnor S, Söderhäll C, Samuelsson A, Janka G, Schneider M, Gürgey A, Yalman N, Révész T, Egeler R, Jahnukainen K, Storm-Mathiesen I, Haraldsson A, Poole J, de Saint Basile G, Nordenskjöld M, Henter J | title = Spectrum of perforin gene mutations in familial hemophagocytic lymphohistiocytosis | journal = American Journal of Human Genetics | volume = 68 | issue = 3 | pages = 590–597 | date = March 2001 | pmid = 11179007 | pmc = 1274472 | doi = 10.1086/318796 }} * {{cite journal | vauthors = Clementi R, zur Stadt U, Savoldi G, Varoitto S, Conter V, De Fusco C, Notarangelo LD, Schneider M, Klersy C, Janka G, Danesino C, Aricò M | title = Six novel mutations in the PRF1 gene in children with haemophagocytic lymphohistiocytosis | journal = Journal of Medical Genetics | volume = 38 | issue = 9 | pages = 643–646 | date = September 2001 | pmid = 11565555 | pmc = 1734943 | doi = 10.1136/jmg.38.9.643 }} * {{cite journal | vauthors = Ambach A, Bonnekoh B, Gollnick H | title = Perforin granule release from cytotoxic lymphocytes ex vivo is inhibited by ciclosporin but not by methotrexate | journal = Skin Pharmacology and Applied Skin Physiology | volume = 14 | issue = 5 | pages = 249–260 | year = 2001 | pmid = 11586066 | doi = 10.1159/000056355 | s2cid = 30142804 }} {{refend}}

== External links == * {{MeshName|perforin}}

{{Pore-forming toxins}}

{{NLM}}

Category:Programmed cell death Category:Proteins