SON (gene)

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SON DNA binding protein
Identifiers
Symbols SON ; BASS1; C21orf50; DBP-5; NREBP; SON3
External IDs OMIM182465 MGI98353 HomoloGene10551 GeneCards: SON Gene
RNA expression pattern
PBB GE SON 214988 s at tn.png
PBB GE SON 201085 s at tn.png
PBB GE SON 201086 x at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 6651 20658
Ensembl ENSG00000159140 ENSMUSG00000022961
UniProt P18583 Q9QX47
RefSeq (mRNA) NM_003103 NM_019973
RefSeq (protein) NP_115571 NP_064357
Location (UCSC) Chr 21:
34.91 – 34.95 Mb
Chr 16:
91.65 – 91.68 Mb
PubMed search [1] [2]

SON protein is a protein that in humans is encoded by the SON gene.[1][2]

SON is the name that has been given to a large Ser/Arg (SR)-related protein, which is a splicing co-factor that contributes to an efficient splicing within cell cycle progression.[3] It is also known as BASS1 (Bax antagonist selected in saccharomyces 1) or NRE-binding protein (Negative regulatory element-binding protein). The most common gene name of this splicing protein- which is only found in Humans (Homo sapiens)- is SON, but C21orf50, DBP5, KIAA1019 and NREBP can also be used as synonyms.[4]

The protein encoded by SON gene binds to a specific DNA sequence upstream of the upstream regulatory sequence of the core promoter and second enhancer of human hepatitis B virus (HBV). Through this binding, it represses HBV core promoter activity, transcription of HBV genes, and production of HBV virions. The protein shows sequence similarities with other DNA-binding structural proteins such as gallin, oncoproteins of the MYC family, and the oncoprotein MOS. It may also be involved in protecting cells from apoptosis and in pre-mRNA splicing.[2]

Structure[edit]

The sequence length of the SON protein consists in 2426 aminoacids and its sequence status is totally completed. Its molecular weight is 263,830 Daltons (Da) and its domain contains 8 types of repeats which are distributed in 3 regions. This protein is found in the 21st chromosome and is mostly located in Nucleus speckle. Its higher expression is seen in leukocyte and heart.[4][5]

Splicing process[edit]

Location of the gene that encodes the SON protein.

SON protein is essential for maintaining the subnuclear organization of the factors that are processed in the nucleus highlighting its direct role in pre-mRNA splicing.[6][page needed]

Splicing is known as the process within the maturation of the pre-RNAm takes place. The pre-RNAm which has just been transcript has sequences called introns and exons. Introns are non-active nucleotide sequences that have to be removed in order the exons (active sequences) to get joined. This process must be very controlled. The splicing takes place in the spliceosome, a complex that brings together a pre-RNAm and a variety of the binding proteins. These proteins together with the splicing factors (which are not found in the spliceosome) are in charge of recognizing the intron’s branch point sequence. The SON protein is known to be one of these binding proteins.[6][page needed]

Although there is a lack of knowledge about its exact splicing control in the progression of the cell cycle and it has remained largely unexplored, it’s certain that this splicing-associated protein is necessary for the maintenance of the embryonic stem cells because it influences the splicing of pluripotency regulators.[3][7]

SON plays an important role in the mRNA processing. Nevertheless, this process is still a little uncertain and this is why in a future it will be interesting to understand how exactly this protein interacts with the spliceosomal complex, its exact molecular function in the context of splicing. Not only the SON protein interferes in the splicing but also makes complex mechanisms such as the RNA post-transcriptional to cooperate with the splicing-mRNA processing.[8]

Human embryonic stem cells are able to undergo the process of differentiation into specific and relevant cells. To maintain the pluripotency of the embryonic stem cells, transcription factors and epigenetic modifiers play an important role despite the fact that little is known about the regulation of pluripotency throughout the process of splicing. The factor SON is identified as essential for the maintenance of this pluripotency. It is confirmed that SON regulates the splicing process of transcripts (RNAm) that will encode the gens that are going to regulate the pluripotency of the embryonic human cells.[9]

Function[edit]

SON protein's intervention in the splicing process.

On the one hand, SON protein is required to maintain the genome stability in order to ensure an efficient RNA processing of affected genes. It also facilitates the interaction of SR proteins with RNA polymerase II and is required for processing of weak constitutive splice sites, having also strong implications in cancer and other human diseases.[3][5]

On the other side, a deficiency or knockdown of SON protein causes various and severe defects in mitotic division arrangement, chromosome alignment and microtubule dynamics when spindle pole separation takes place.[3]

But as we could read in the article called “SON protein regulates GATA-2 through transcriptional control of the microRNA 23a-27-24-a clúster”, SON protein has even more functions in the organism. It has been found that these proteins may regulate the hematopoietic cells differentiation. They have a specific job in hematopoietic process, which is based on activating other proteins called GATA. As these ones are finally activated, the cell differentiation starts normally.[10]

Clinical significance[edit]

A recent study suggested that SON may be a novel therapeutic molecular target for pancreatic cancer as the results of a recent study show that this protein is very important as far as proliferation, survival and tumorigenicity of cancer cells are concerned. Specifically, these results revealed that the serine-arginine-rich protein involved in the RNA splicing process, could suppress pancreatic cell tumorigenicity.[8]

References[edit]

  1. ^ Cheng S, Lutfalla G, Uze G, Chumakov IM, Gardiner K (Aug 1993). "GART, SON, IFNAR, and CRF2-4 genes cluster on human chromosome 21 and mouse chromosome 16". Mamm Genome 4 (6): 338–42. doi:10.1007/BF00357094. PMID 8318737. 
  2. ^ a b "Entrez Gene: SON SON DNA binding protein". 
  3. ^ a b c d Ahn EY, DeKelver RC, Lo MC, Nguyen TA, Matsuura S, Boyapati A, Pandit S, Fu XD, Zhang DE (April 2011). "SON controls cell-cycle progression by coordinated regulation of RNA splicing". Mol. Cell 42 (2): 185–98. doi:10.1016/j.molcel.2011.03.014. PMC 3137374. PMID 21504830. 
  4. ^ a b "Protein SON". UniProt Consortium. 
  5. ^ a b "Son peptide". MyBioSource.com. 
  6. ^ a b Voet D, Voet JG (2011). Biochemistry. Hoboken, NJ: John Wiley Sons. ISBN 978-0-470-57095-1. 
  7. ^ Livyatan I, Meshorer E (October 2013). "SON sheds light on RNA splicing and pluripotency". Nat. Cell Biol. 15 (10): 1139–40. doi:10.1038/ncb2851. PMID 24084863. 
  8. ^ a b Furukawa T, Tanji E, Kuboki Y, Hatori T, Yamamoto M, Shimizu K, Shibata N, Shiratori K (2012). "Targeting of MAPK-associated molecules identifies SON as a prime target to attenuate the proliferation and tumorigenicity of pancreatic cancer cells". Mol. Cancer 11: 88. doi:10.1186/1476-4598-11-88. PMC 3576306. PMID 23227827. 
  9. ^ Lu X, Göke J, Sachs F, Jacques PÉ, Liang H, Feng B, Bourque G, Bubulya PA, Ng HH (October 2013). "SON connects the splicing-regulatory network with pluripotency in human embryonic stem cells". Nat. Cell Biol. 15 (10): 1141–52. doi:10.1038/ncb2839. PMID 24013217. 
  10. ^ Ahn EE, Higashi T, Yan M, Matsuura S, Hickey CJ, Lo MC, Shia WJ, DeKelver RC, Zhang DE (February 2013). "SON protein regulates GATA-2 through transcriptional control of the microRNA 23a~27a~24-2 cluster". J. Biol. Chem. 288 (8): 5381–8. doi:10.1074/jbc.M112.447227. PMID 23322776. 

Further reading[edit]