Biological Roles of Induction of Fetal Hemoglobin Production by Genetic Switching in Medical Practice: a Mini Review

Habib Nourani et al. Medical Research Archives vol 8 issue 4. Medical Research Archives

REVIEW ARTICLE

Biological Roles of Induction of Fetal hemoglobin Production by Genetic Switching In Medical Practice: A Mini Review

Authors Habib Nourani Khojasteh1, Amin Nooranikhojasteh2

Affiliations 1Hematologist-Oncologist, Dept of Internal Medicine, Shiraz University of Medical Sciences, Shiraz- Iran 2Undergradualte Bioinformatic Student, University Health Network, Toronto Canada

Correspondence Habib Nourani Email: [email protected]

Abstract

Fetal hemoglobin switching is a good model for application of reversing silenced genes in the treatment of hemoglobin diseases.By understanding of the mechanisms and targeting the silenced genes to reactivate the fetal hemoglobin by transcription factors ,in future it will be possible to control many hemoglobinopathies in human .From this aspect it is interesting to know about major molecular axis about negative regulators and positive regulators of fetal hemoglobin genes and also this field especially by using of CHRISPR, siRNA and shRNA can be used for the treatment of considerable spectrum of diseases.

KeyWords: Fetal Hemoglobin, Gene Silencing, Hemoglobinopathies

Habib Nourani et al. Medical Research Archives vol 8 issue 4. April 2020 Page 2 of 7

Introduction hemoglobin concentration,we can reduce Hemoglobin synthesis results from an fatal diseases theoretically by reactivation of orderly evolution of a series of the silenced gamma gene, increased embroynic,fetal,and adult hemoglobin .Fetal hemoglobin F decreases the sickle cells and hemoglobin is made from alfa and gamma inhibits polymerization of sickle hemoglobin globin, The gamma globin gene is expressed ,to reach at least twenty percent of HbF during fetal development.The alfa2 gamma2 concentration, ,and at that level the globin is the main oxygen transport protein symptoms of severe hemoglobinopathies can in the human fetus during last seven be ameliorated. 1,2,3 months.The gamma subunit is encoded on chromosome11 as is the beta globin,two Gamma Globin Synthesis similar copies of the gamma subunit globin Globin synthesis is highly regulated at genes exists,gamma G (glycine)position136 transcription level by complex interaction of and gamma A(alanine).At birth HbF DNA sequence to cis-promoters and constitutes 60% to 90% of total hemoglobin, enhancers and silencers soluble transcription It declines from 90% at 30thweeks to 7% factors. Globin synthesis is also regulated after 12 weeks post birth. The gene that during translation when the mRNA coding codes for alfa subunit is located on for the globin chain associates with chromosome 16 and present in duplicate. ribosomes to produce the polypeptides. Mutations in the Beta-globin locus give rise Many protein factors are required to control to the hemoglobiniopathies such as beta initiation, elongation, and termination steps thalassemia and sickle cell disease. Beta of translation. Fetal to adult hemoglobin thalassemia has 200 different mutations but switching is due to two stem cell lineage sickle cell disease has one point with different globin gene expression mutation.Starting from birth ,the molecular program .HbF is an interesting molecule and defects in beta thalassemia result in absent binds oxygen more strongly than adult or reduced Beta Globin synthesis, hemoglobin enabling for the transfer of hemoglobin A,then anemia and excess oxygen from the mother to feus. 4,5,6 imbalanced alfa globin deposition and Sequences involved in gamma gene ineffective erythropoiesis,iron loading with activation are located both in LCR and increased iron absorption with repeated gamma promotor region. Elevating blood transfusions, in contrast,in the sickle expression of the developmentally silenced cell disease ,the problem is abnormal beta gamma globin gene can supplant mutant or globin,substitution of valine for the glutamic inadequate levels by beta globin in human acid and subsequent sickle phenomenon disease state thereby suppressing the with high morbidity and mortality due to associated symptoms .Change from fetal hemolytic anemia and vascular catastrophe hemoglobin to adult hemoglobin from the in many organs,from these views with aspect of genetic system is interesting in the making to increase the gamma globin field of biology and the gene silencing in synthesis and subsequent rise in fetal postnatal state is a major genetic event. Fetal

Copyright 2020 KEI Journals. All Rights Reserved http://journals.ke-i.org/index.php/mra Habib Nourani et al. Medical Research Archives vol 8 issue 4. April 2020 Page 3 of 7 hemoglobin silencing genes is a model for Myb the gene manipulation and reactivation This gene encodes a transcription factor that genes in adults. 7,8,9 is critical for hematopoietic stem cells and progenitors, also is involved in fetal globin History of HbF Induction synthesis 11. The only HbF inducing agents that is currently approved by the United States BCL11A Food and Drug Aministration (FDA), is Is a potent silencer of gamma hydroxyurea, for the treatment of sickle globin.BCLA11A can be a target of for cell anemia, but only half of the cases therapeutic intervention of respond with elevation of HbF .5- hemoglobinopathies using genome editing Azacytidine can induce HbF induction in approaches.It is required for the function of human and primates, it can reverse several cell types and the ablation of methylation of gamma globin gene with this BCLA11 function can cause abnormal side mechanism; but the carcinogenecity of this effects such as leukemia or lymphomaes product is a problem. Like 5-azacytidine, besides, it is better to restrict target to only short chain fatty acids,erythropoietin erythroid lineage.12 stimulating agents and thalidomide derivatives have been evaluated in LCR thalassemia major to increase fetal Locus control region(LCR), has emerged as hemoglobin,because of their ability to an extremely important constituent in the switch on the gamma globin genes,to regulation of hemoglobin switching,it is a produce more gamma chains,the gamma good target for therapeutic modulation. chains then combine with excess alfa chains During the fetal stage of development there to form hemoglobin F,thus correcting alfa- is preferential interaction between the beta imbalance.Hydroxyurea can be helpful gamma genes and LCR and the beta globin for few thalassemic patients but not for genes are turned off competitively.On the majority of them.Another compound,Beta other hand,LCR postnatally interacts with hydroxybutirate is increased in the infants beta globin genes resulting silencing the with high HbF from the diabetic mothers gamma globin genes;also,discovery of the and can be a therapeutic model in LCR had a major impact on the hemoglobinopathies because of interfering investigation of mechanisms of switching in swiching off the fetal hemoglobin to and KLF1 and BCL11A axis. 13,14 adult globin;their mechanism of action is inhibiting histone deacetylase.Erythropoietin KLF1 MUTATION and HbF is another agent which can increase HbF 10 . Krupple like factor1 plays a key role in Erythropoietin and hydroxyurea can elevate gamma globin switch from gamma to beta. hemoglobin F synergistically. It preferentially binds and activate the beta globin chain.KLF1 also regulates the expression of repressors of globin gene

Copyright 2020 KEI Journals. All Rights Reserved http://journals.ke-i.org/index.php/mra Habib Nourani et al. Medical Research Archives vol 8 issue 4. April 2020 Page 4 of 7 transcription factors such BCL11A and that increased Hb F abolishes the anemic MYB. effect of beta thalassemia major.The GATA1 regulates hemoglobin synthesis, It opening of the field of recovering gene directly induce KLF1 expression,it is silencing in Hb F system is interesting involved in alfa and beta globin loci. Gata 1 regarding future planning of hemoglobin is a critical determinant of Hb synthesis,it diseases such as thalassemia,and sickle cell directly regulates expression of genes disease,the two entities with higher mortality encoding Hb subunits and heme and morbidity.The major players of the Hb F biosynthetic enzymes.Gata 1 regulates gene silencing in future are targeting hundreds of genes .15 BCL11A,GATA1, CMYB.Studies of HPFH is a condition characterized by hemoglobin switching have provided major elevated levels of hemoglobin F in adult insights on the control of gene loci by individuals.This disease is related to remote regulatory elements.During the fetal deletions or mutations of negative DNA stage development,there is interaction regulatory elements that repress gamma between the gamma genes and LCR the globin genes. BCL11A is a major regulatory LCR interacts preferentially with the beta repressor of gamma globin and mutation in gene during adult stage of development, BCLA11A regulatory DNA elements were resulting the gamma globin silencing,this associated with HPFH .Heterogenous competition by epsilon and gamma genes mutations in KLF1 cause HPHF.Deletional silences the beta gene in embryonic HPFH is associated with deletion of large erythropoiesis.Gene competition and regions of DNA between gamma and beta autonomos silencing are two mechanisms of globin locus 16. Point mutations in the turning off the gamma genes during proximal fetal gamma globin gene development.The targeting of the promoters are the cause of the transcription factors such as BCLA11A nonedeletional HPFH.this disease is good ,KLF1,MYB , by siRNA shRNA delivery model for gene silencing phenomenon. via genetic approach control hemoglobin disease and theoretically can be a treatment Discussion model in future. Thalidomide and related Sickle cell disease and Beta-thalassemia are drugs also can induces gamma globin gene unique among genetic disorders with high expression and the CHRISPR will be the mortality and morbidity with no curative modern therapeutic plan in thalassemia and treatment except allogenic hematopoietic other hemoglobin diseases. Chrispr/cas9 can stem cell transplantation but due to the break BCL11A and clinicians collect absence of appropriate donor and hematopoietic stem cells ,then with the transplantation related mortality,it is not an method which can induce a mutation in the ideal final treatment option .So the nature molecule.18,19,20 With CRISPR –CAS9 learned that with fetal hemoglobin editing and destructing the remaining bone induction, human can control these disorders marrow of the patient with chemotherapy .For the last fifty years ago,it was known ,then the CRISPR editing cells are injected

Copyright 2020 KEI Journals. All Rights Reserved http://journals.ke-i.org/index.php/mra Habib Nourani et al. Medical Research Archives vol 8 issue 4. April 2020 Page 5 of 7 into the patient to create HbF cells BCL11A=B cell providing higher oxygen in the body to lymphoma,leukemia11A,regulator of globin compensate the effect of hypoxia due to gene expression underlying hemoglobinopathy. KLF1=Krueppel-like factor1, encoded by the KLF1 gene,is a transcription factor that Conclusion is necessary for the proper maturation of The Future is bright for thalassemic and erythroid cells. sickle cell diseases regarding the GATA1= Erythroid Transcription Factor, it intervention in fetal hemoglobin gene is absent in other cell lineages types switching by uncovering the genetic HPFH=hereditary persistant fetal regulation of fetal hemoglobin.So,targeting hemoglobin BCL11A,MYB,KLF1 will be the therapeutic DNA=deoxribonucleic acid plan in the coming years. SOX6= A Transcription factor, is a protein coded by SOX6 gene Abbreviations SHRNA=Short Hairpin RNA Hb=hemoglobin SIRNA=small interfering RNA Hb F=fetal hemoglobin RNA=ribonucleic acid LCR=locus control region CRISPR=Clustered Regularly Interspaced MYB= myeloblastosis- a type of Short Palindromic Repeat,CRISPR- transcription factor associated9,Cas9 FDA=federal drug administration

References 1. Vijay G.Sankaran,Stuart H.Orkin The Therapies ,Daniel Scherman,Imperial switch from fetal to adult College Press,2014 hemoglobin,Cold Spring Harb Perspect 9. Row Wiber, Regulation of Fetal Med 2013,3 hemoglobin to Adult Hemoglobin 2. Amit Kessal,Nir Ben Tal ,introduction to Switching, New Therapeutic proteins,structure,function,motion,CRC Opportunities, Blood Journal press,Taylor and Francis Group,A 10. Giesele Cristine De Souse Carrocinina, Chapman and Hall Book Larissa Paola Rodrigues Venancio and 3. Rodaks Hematology Clinical Principles Caudia Regina Bonini Domingos and Applications, Elaine M Keohane, Screening a transcription factors Kary J Smith, Jeanine M Walenga, invovlved in fetal hemoglobin regulation Elsevier,2016 using phylogenetic footprinting 4. Koichi R.Katsumura, Andrew W Evolutionary bioinformatics 2015,11 Devilbiss, Nathaniel J.pope,kirbey D 11. Nancy F.Olivieri, D.J.Weatheral, Johnsons, Emery H.Bresnick, therapeutic reactivation of fetal Transcriptional Mechanisms Underlying hemoglobin,1998, human molecular Hemoglobin Synthesis,Cold spring Harb genetics, vol7, issue10, Pages1655-1658 Perspect Med 2013,3,3 12. Antonio Cao, Renzo Galanello, Beta 5. George Stamatoyannopoulos Control of Thalassemia, Genetics in In Medicine Globin Gene Expression During ,vol12,Number2,2010 Development and Erythroid 13. Antonio Cao,Paolo Moi, Regulation Of differentiation, Experimental Hemato- the Globin Genes,Pediatric Research logy , 33.3,259 Vol51,No4,2002 6. Rachael Davis, Aishawarya 14. Betty S Pace, Sima Zein, Uegies F Gurumurthy, Mir A Hossuain, Eliot M Understanding Mechanisms of Gamma Gunn, and George Bungert Engineering Globin Regulation to Develop Strategies Globin Gene Expression, Methods and for Pharmacologic Fetal Hemoglobin Clinical Development,Vol 12,2019 Induction, Developmental Dynamics, 7. Mikiku Suzuki, Masayoki Yamamato, 235:1727-1737 James Douglas Engel Fetal globin gene 15. Daniel E Bauer, Stuart H Orkin, Update repressor as drug targets for Molecualar On Fetal Hemoglobin Gene Regulation Therapis To Treat Hemogbinopathies, in Hemoglobinopathay, Current Opinion Molecular and Cellular pediatric,23,1,2011 Biology,Vol34,No19 16. Peter Ronner,Netters Essential of 8. Advanced Textbook On Gene Transfer, Biochemistry,Elsevier,pages 179- Gene therapy, genetic pharmacology, 189,2018 Principles, Delivery, and 17. Beeke Wienert, Gabriela E.Martyn, Pharmacological and Biomedical Alister P.W. Funnell, Kate G.R. Applications of Nucleotide Based Quinlan, Merlin Crossley E,Wake-up for

Sleepy Gene, Reactivating Fetal globin 19. Reciprocal regulation of gamma globin for Beta Hemoglobinopathy, Trends in expression by exomirnas,relevance to Genetics, 2018 gamma globin silencing in beta 18. Biaoru Li, Xingguo Zhu, Christine M thalassemia major. ward, Athena Starlard Davenport, 20. Ravirajsinh N.Jadeja, Pamela M Martin, mayuko Takezaki, Amber Berry, Data on The Role of miRNA144 in Alexander War, Caroline Wlder, Cindy regulating fetal hemoglobin production Neunert, Abdullah kutlar, Betty S Pace, in retinal pigmented epithelial cells, Data MIR-144-mediated NRF2 gene silencing In Brief,28,2020 inhibits fetal Hemoglobin Expression in Sickle Cell Disease, Experimental Hematology, 2019,70:85-96