miR-203

miR-203
miR-203 microRNA secondary structure and sequence conservation
Identifiers
Symbol	mir-203
Rfam	RF00696
miRBase family	MIPF0000108
Entrez	406986
HUGO	31581
OMIM	611899
Other data
RNA type	microRNA
Domain(s)	Eukaryota; Euteleostomi

In molecular biology miR-203 is a short non-coding RNA molecule. MicroRNAs function to regulate the expression levels of other genes by several mechanisms, such as translational repression and Argonaute-catalyzed messenger RNA cleavage.^[1][2] miR-203 has been identified as a skin-specific microRNA, and it forms an expression gradient that defines the boundary between proliferative epidermal basal progenitors and terminally differentiating suprabasal cells.^[3] It has also been found upregulated in psoriasis^[4] and differentially expressed in some types of cancer.^[5][6]

Introduction

MicroRNAs are short (20-22nt), non-coding RNA molecules involved in the regulation of messenger RNAs (mRNAs) by pairing with their 3’ UTR and affecting their stability^[4] or directing their silencing or degradation.^[1] MicroRNAs are likely to play roles in most cellular processes, including proliferation, development, differentiation and apoptosis.^[5] They are located in intergenic and intragenic regions, and are transcribed as pri-miRNA by RNA polymerase II or RNA polymerase III.^[4] They then undergo extensive post-transcriptional modifications, starting with the processing of the pri-miRNA in the nucleus to generate a 70-100 nt long pre-miRNA by ribonucleases Drosha and DGCR8. This pre-miRNA is then transported out of the nucleus by Exportin-5, and is then further processed by Dicer into a mature 18-25 nt long double stranded microRNA.^[7] The guide strand of the miRNA is then loaded into RNA-induced silencing complex (RISC)^[7] and is then able to pair with its target. The passenger strand, denoted by a star, is commonly degraded, though this is not always the case.^[8]

MiR-203 is a microRNA that is specifically expressed in keratinocytes (the most abundant cell type in the epidermis) and in normal conditions promotes epidermal differentiation by restricting proliferative potential and inducing cell-cycle exit.^[3] It does so by repressing p63, an essential regulator of stem cell maintenance in epithelial stratified tissues.^[3] Other proposed targets are suppresor of cytokine signaling 3 (SOCS3) and ABL1.

As is the case with many other microRNAs, miR-203 expression has been found dysregulated in several malignancies, including psoriasis, rheumatoid arthritis and carcinogenesis.^{[5][9][10][11][12]}

Localization

In mice, miR-203 is located in chromosome 12, within a fragile 7-Mb region that is lost is some hematopoietic malignancies. This region encodes 52 mature miRNAs, ~12% of the mammalian miRNA genome. In humans, this region is conserved and located intergenically in 14q32.^[11]

Evidence

This microRNA was predicted using computational tools by comparison to mouse and tiger blowfish sequences.^[13] It has been validated in zebrafish and its expression confirmed in humans by cloning and sequencing, where it was found in the outer layer of epidermis.^[14]

Targets

miR-203 has one validated target, p63, conserved across vertebrate lineages. p63 is an essential regulator of stem cell maintenance in stratified epithelial tissues. Yi et al.^[3] confirmed p63 as a target of miR-203. They showed that miR-203 expression is conspicuous in terminally differentiating epithelial cells, but is not present on their proliferative progenitor compartments, and shows a mutually exclusive pattern of expression with p63. They also report downregulation of proteins downstream of p63, suggesting a mechanistic method for inhibition of proliferative potential of epidermal stem cells.

There is some controversy as to whether suppressor of cytokine signaling 3 (SOCS3) is also targeted by miR-203. In their study, Lena et al. (2008)^[12] showed that, despite bioinformatic alignment of miR-203 with SOCS3 3'UTR, the levels of SOCS3 transcripts increased in keratinocytes stimulated to differentiate in vitro, in parallel with miR-203. Then they exogenously expressed miR-203 in mouse keratinocytes and showed that SOCS3 is not repressed by miR-203.

In contrast, Wei et al. (2010)^[15] validated SOCS3 as a target for miR-203. In their study, they introduced the SOCS3 3'UTR fragment encompassing the putative target site in a luciferase reporter vector, and they observed a significant decrease in luciferase activity when miR-203 was introduced compared to controls. They also generated a mutation in the binding site and reported restoration of luciferase activity, as well as mutually exclusive localization with miR-203. They concluded that SOCS3 is targeted by miR-203, and hypothesize that miR-203 regulation of SOCS3 and thus of STAT3 could have implications in keratinocyte functions.

Another putative target is ABL1, which is found activated in hematopoietic malignancies where miR-203 is epigenetically silenced by hypermethylation.^[11]

Foetal skin development

Yi et al. showed that in mice, the expression of miR-203 is significantly upregulated between E13.5 and E15.5, suggesting that it may be absent from multipotent progenitors of single-layered epidermis, but is induced upon stratification and differentiation.^[3] It also was expressed at high levels in differentiating cells such as hair follicles, epidermis and sebaceous glands.

Wei et al.^[15] demonstrated that in humans, miR-203 expression is first detectable at 17 weeks gestation in the suprabasal layers of epidermis, and this localization was conserved in the adult skin. When miR-203 is expressed prematurely, basal cells diminish their proliferative potential; and when it is absent, proliferation is no longer restricted to the basal layer of epidermis.^[16]

Role in carcinogenesis

miR-203 has been found overexpressed in pancreatic adenocarcinoma and shows correlation with poor prognosis in patients that had undergone pancreatectomy, and has been suggested as a new prognostic marker for this disease.^[5][9] Also, miR-203 has been identified as target of human papillomavirus (HPV) protein E7,^[6] which causes its downregulation and thus de-repression of p63 and its downstream targets, ensuring proliferative potential on the host cell, required for the virus to replicate. High levels of miR-203 are inhibitory of HPV amplification.^[6]

miR-203 has also been proposed as a tumour-suppresive microRNA in hepatocellular carcinoma (HCC) and hematopoietic malignancies. In their study, Furuta et al.^[10] found miR-203, along with miR-124, epigenetically silenced in primary HCC tumours compared with non-tumorous liver tissues. Also, expression of miR-203 in HCC cells lacking their expression inhibited cell growth and downregulated a set of other possible targets. Bueno et al.^[11] also found silencing of miR-203 in some leukemias, as well as an inverse correlation between miR-203 and ABL1 levels (sometimes expressed as the BCR-ABL1 fusion protein). Supporting its role as a tumour suppressor, it has also been found upregulated upon UVC irradiation in the squamous cell carcinoma lines, suggesting a connection between miR-203 and the activation of the apoptotic program.^[12]

Role in psoriasis and rheumatoid arthritis

Sonkoly et al.^[17] identified miR-203, along with miR-146a, miR-21, and miR-125b; as a psoriasis-specific microRNA when compared with healthy human skin or atopic eczema. They also observed downregulation of SOCS3 concurrently with upregulation of miR-203 in psoriatic plaques, potentially having an effect in inflammatory responses.

Stanczyk et al.^[18] found overexpression of miR-203 in rheumatoid arthritis synovial fibroblasts (RASFs) compared to healthy or osteoarthritis samples; and inforced expression of miR-203 led to higher levels of MMP-1 and IL-6 and thus contributed to the activated phenotype of RASFs. MiR-203 regulation was found to be methylation-dependent.

See also

• MicroRNA

References

1. ^ ^{a b} Bartel DP (2009). "MicroRNAs: target recognition and regulatory functions.". Cell 136 (2): 215–33. doi:10.1016/j.cell.2009.01.002. PMID 19167326. 
2. ^ Bartel DP (2004). "MicroRNAs: genomics, biogenesis, mechanism, and function.". Cell 116 (2): 281–97. doi:10.1016/S0092-8674(04)00045-5. PMID 14744438. 
3. ^ ^{a b c d e} Yi R, Poy MN, Stoffel M, Fuchs E (2008). "A skin microRNA promotes differentiation by repressing ‘stemness’.". Nature 452 (7184): 225–9. doi:10.1038/nature06642. PMID 18311128. 
4. ^ ^{a b c} Bostjancic E, Glavac D (2008). "Importance of microRNAs in skin morphogenesis and diseases.". Acta Dermatovenerol Alp Panonica Adriat 17 (3): 95–102. PMID 18853072. 
5. ^ ^{a b c d} Ikenaga N, Ohuchida K, Mizumoto K, Yu J, Kayashima T, Sakai H, Fujita H, Nakata K, Tanaka M (2010). "MicroRNA-203 Expression as a New Prognostic Marker of Pancreatic Adenocarcinoma.". Ann Surg Oncol 17 (12): 3120–8. doi:10.1245/s10434-010-1188-8. PMID 20652642. 
6. ^ ^{a b c} Melar-New M, Laimins LA (2010). "Human papillomaviruses modulate expression of microRNA 203 upon epithelial differentiation to control levels of p63 proteins.". J Virol 84 (10): 5212–21. doi:10.1128/JVI.00078-10. PMC 2863797. PMID 20219920. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2863797. 
7. ^ ^{a b} Garzon R, Marcucci G, Croce CM (2010). "Targeting microRNAs in cancer: rationale, strategies and challenges.". Nat Rev Drug Discov. 9 (10): 775–89. doi:10.1038/nrd3179. PMID 20885409. 
8. ^ Guo L, Lu Z (2010). "The fate of miRNA* strand through evolutionary analysis: implication for degradation as merely carrier strand or potential regulatory molecule?". PLoS One 5 (6): e11387. doi:10.1371/journal.pone.0011387. PMC 2894941. PMID 20613982. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2894941. 
9. ^ ^{a b} Greither T, Grochola LF, Udelnow A, Lautenschläger C, Würl P, Taubert H (2010). "Elevated expression of microRNAs 155, 203, 210 and 222 in pancreatic tumors is associated with poorer survival.". Int J Cancer 126 (1): 73–80. doi:10.1002/ijc.24687. PMID 19551852. 
10. ^ ^{a b} Furuta M, Kozaki KI, Tanaka S, Arii S, Imoto I, Inazawa J (2010). "miR-124 and miR-203 are epigenetically silenced tumor-suppressive microRNAs in hepatocellular carcinoma.". Carcinogenesis 31 (5): 766–76. doi:10.1093/carcin/bgp250. PMID 19843643. 
11. ^ ^{a b c d} Bueno MJ, Pérez de Castro I, Gómez de Cedrón M, Santos J, Calin GA, Cigudosa JC, Croce CM, Fernández-Piqueras J, Malumbres M (2008). "Genetic and epigenetic silencing of microRNA-203 enhances ABL1 and BCR-ABL1 oncogene expression.". Cancer Cell 13 (6): 496–506. doi:10.1016/j.ccr.2008.04.018. PMID 18538733. 
12. ^ ^{a b c} Lena AM, Shalom-Feuerstein R, Rivetti di Val Cervo P, Aberdam D, Knight RA, Melino G, Candi E (2008). "miR-203 represses 'stemness' by repressing DeltaNp63.". Cell Death Differ 15 (7): 1187–95. doi:10.1038/cdd.2008.69. PMID 18483491. 
13. ^ Lim LP, Glasner ME, Yekta S, Burge CB, Bartel DP (2003). "Vertebrate microRNA genes.". Science 299 (1540): 1540. doi:10.1126/science.1080372. PMID 12624257. 
14. ^ Landgraf P, Rusu M, Sheridan R, Sewer A, Iovino N, Aravin A, Pfeffer S, Rice A, Kamphorst AO, Landthaler M, Lin C, Socci ND, Hermida L, Fulci V, Chiaretti S, Foa R, Schliwka J, Fuchs U, Novosel A, Muller RU, Schermer B, Bissels U, Inman J, Phan Q, Chien M (2007). "A mammalian microRNA expression atlas based on small RNA library sequencing.". Cell 129 (7): 1401–14. doi:10.1016/j.cell.2007.04.040. PMC 2681231. PMID 17604727. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2681231. 
15. ^ ^{a b} Wei T, Orfanidis K, Xu N, Janson P, StÃ¥hle M, Pivarcsi A, Sonkoly E (2010). "The expression of microRNA-203 during human skin morphogenesis.". Exp Dermatol 19 (9): 854–6. doi:10.1111/j.1600-0625.2010.01118.x. PMID 20698882. 
16. ^ Blanpain C, Fuchs E (2009). "Epidermal homeostasis: a balancing act of stem cells in the skin.". Nat Rev Mol Cell Biol. 10 (3): 207–17. doi:10.1038/nrm2636. PMC 2760218. PMID 19209183. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2760218. 
17. ^ Sonkoly E, Wei T, Janson PC, Sääf A, Lundeberg L, Tengvall-Linder M, Norstedt G, Alenius H, Homey B, Scheynius A, Ståhle M, Pivarcsi A (2007). "MicroRNAs: novel regulators involved in the pathogenesis of psoriasis?". PLoS One 2 (7): e610. doi:10.1371/journal.pone.0000610. PMC 1905940. PMID 17622355. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1905940. 
18. ^ Stanczyk J, Ospelt C, Karouzakis E, Filer A, Raza K, Kolling C, Gay R, Buckley CD, Tak PP, Gay S, Kyburz D (2010). "Altered expression of miR-203 in rheumatoid arthritis synovial fibroblasts and its role in fibroblast activation.". Arthritis Rheum. 63: [Epub ahead of print]. doi:10.1002/art.30115. PMID 20981815. 

Further reading

^[1][2][3]

1. ^ Stanczyk J, Ospelt C, Karouzakis E, Filer A, Raza K, Kolling C, Gay R, Buckley CD, Tak PP, Gay S, Kyburz D (2010). "Altered expression of miR-203 in rheumatoid arthritis synovial fibroblasts and its role in fibroblast activation.". Arthritis Rheum 63 (2): 373. doi:10.1002/art.30115. PMID 20981815. 
2. ^ McKenna DJ, McDade SS, Patel D, McCance DJ (2010). "MicroRNA 203 expression in keratinocytes is dependent on regulation of p53 levels by E6.". J Virol 84 (20): 10644–52. doi:10.1128/JVI.00703-10. PMC 2950558. PMID 20702634. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2950558. 
3. ^ Sonkoly E, Wei T, Pavez Loriè E, Suzuki H, Kato M, Törmä H, StÃ¥hle M, Pivarcsi A (2010). "Protein kinase C-dependent upregulation of miR-203 induces the differentiation of human keratinocytes.". J Invest Dermatol 130 (1): 124–34. doi:10.1038/jid.2009.294. PMID 19759552. 

External links

• Rfam page for mir-203 microRNA precursor family