KLF1 Dependent Pathways In Developmental Globin Gene Switching

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 5162-5162
Author(s):  
Alexander E. Felice
Keyword(s):  
Conflicts Of Interest ◽  
Expression Profiles ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Erythroid Progenitors ◽  
Gamma Globin ◽  
Genome Wide ◽  
Hereditary Persistence ◽  
Informative Family ◽  
Gene Switching

Abstract Abstract 5162 We provide additional data on members of the family from Malta with Hereditary Persistence of Fetal Hemoglobin (HPFH) due to KLF1 haplo-insufficiency. The data indicated a possible role of additional loci in the pathway of globin gene control. We showed that KLF1 functions as a master regulator of erythropoiesis and developmental globin gene switching (Borg et al., Nature Genetics doi: 10. 1038/ng.630, 2010), at least partly through BCL11A. Given the phenoytpes of the HPFH heterozygotes, the truncating KLF1 p.K288X was best described as a dominant mutation with variable penetrance; most likely due to interplay with other regulatory factors that we have been seeking. Genome-wide association analysis, in the context of genome-wide expression profiles from cultured Human Erythroid Progenitors (HEPs) of critically informative family members, revealed additional loci of potential interest. The effect of the Hb F inducer Hydroxyurea on the gamma globin profiles of the KLF1- (p.K288X) HPFH HEPs was enhanced compared to the wild type, and 74 loci were differentially expressed. It is anticipated that extensive re-sequencing of these new targets may reveal the extent of the molecular pathways under control of KLF1 in erythropoiesis and globin gene switching, and in particular those that may be targeted for therapeutics in patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Does Quantitative Heterogeneity of Human Fetal Hemoglobin (Hb F) Reveal Friends or Foes of KLF1 in Globin Gene Switching ?

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1092-1092
Author(s):  
Alexander E. Felice ◽  
Ruth Galdies ◽  
Joseph Borg ◽  
Godfrey Grech ◽  
Wilma Cassar ◽  
...  
Keyword(s):  
High Performance ◽  
Conflicts Of Interest ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Globin Genes ◽  
Erythroid Progenitors ◽  
Tight Linkage Disequilibrium ◽  
Small Set ◽  
Gene Switching

Abstract Abstract 1092 The chemical heterogeneity of fetal hemoglobin (Hb F) due to variable ratios of the Gγ and Aγ globin subunits reflects genetic complexity because of common dimorphisms such as Hb F Sardegna (or Aγ75(E19) Ile>Thr; also known as AγT) in Caucasians, and common variants such the Gγ globin variant, Hb F Malta I (or Gγ117(G19) His>Arg) that is in tight linkage disequilibrium with the β globin variant Hb Valletta (or β87(F3) Thr>Pro) and is found in 1.8% of neonates from Malta. Comprehensive and integrated maternal and neonatal testing has led to the finding of triple compound heterozygotes with Hb F Malta I in association with Hb F Sardegna and Hb Valletta in whom all globin genes that are functional in the transition from fetal to adult Hemoglobin profiles are genetically tagged, and quantifiable with High Performance Liquid Chromatography in the neonate or mRNA in the adult in the context of diverse XMNI −158 C>T Gγ globin and (AT)XTY −540 β globin haplotypes. The interaction between XMNI and (AT)XTY revealed “conditional” cis-trans interplay that appeared to be under developmental control. A family with members carrying Hb F Malta I in association with a rare form of the Hereditary Persistence of Fetal Hemoglobin has also been found. The genetic cause has been traced to haplo-insufficiency of the putative erythroid master regulator KLF1, and, as confirmed by functional assays in vitro. However, levels of Hb F expression varied considerably (3.3% – 19.5%) while a second family from Malta with the same KLF1 mutation (p.K288X) had normal Hb F indicating interplay of KLF1 with modifying genes. These data, together with comparative expression profiling of human erythroid progenitors, indicated a small set of additional gene products that may interact positively (friends) or negatively (foes) at the level of commitment or expression in globin gene switching with significant effects on the Mean Corpuscular - Hb F. Whole genome sequencing on critically informative family members currently in progress may further uncover the complex genetic interactions in developmental globin gene control. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Chinese A gamma fetal hemoglobin: C to T substitution at position-196 of the A gamma gene promoter

Blood ◽  
1986 ◽  
Vol 67 (6) ◽  
pp. 1777-1779 ◽  
Author(s):  
R Gelinas ◽  
M Bender ◽  
C Lotshaw ◽  
P Waber ◽  
H Jr Kazazian ◽  
...  
Keyword(s):  
Globin Gene ◽  
Gene Promoter ◽  
Fetal Hemoglobin ◽  
Nucleotide Sequence Analysis ◽  
Globin Genes ◽  
Gamma Globin ◽  
Hemoglobin C ◽  
Hereditary Persistence ◽  
Gene Switching ◽  
Chinese Individual

Abstract The molecular basis for the hereditary persistence of fetal hemoglobin (HPFH) phenotype was studied in a Chinese individual who was heterozygous for a nondeletion form of A gamma-HPFH. Both allelic A gamma-globin genes were isolated by molecular cloning and subjected to nucleotide sequence analysis. One A gamma gene promoter showed a cytosine to thymine transition at position -196, whereas the other promoter was normal. This mutation at position -196 has now ben found in unrelated individuals with the A gamma-HPFH phenotype from Italy, Sardinia, and China, suggesting that it may have arisen independently. The implications of this mutation for models of fetal globin gene switching are discussed.

scholarly journals Chinese A gamma fetal hemoglobin: C to T substitution at position-196 of the A gamma gene promoter

Blood ◽  
1986 ◽  
Vol 67 (6) ◽  
pp. 1777-1779
Author(s):  
R Gelinas ◽  
M Bender ◽  
C Lotshaw ◽  
P Waber ◽  
H Jr Kazazian ◽  
...  
Keyword(s):  
Globin Gene ◽  
Gene Promoter ◽  
Fetal Hemoglobin ◽  
Nucleotide Sequence Analysis ◽  
Globin Genes ◽  
Gamma Globin ◽  
Hemoglobin C ◽  
Hereditary Persistence ◽  
Gene Switching ◽  
Chinese Individual

The molecular basis for the hereditary persistence of fetal hemoglobin (HPFH) phenotype was studied in a Chinese individual who was heterozygous for a nondeletion form of A gamma-HPFH. Both allelic A gamma-globin genes were isolated by molecular cloning and subjected to nucleotide sequence analysis. One A gamma gene promoter showed a cytosine to thymine transition at position -196, whereas the other promoter was normal. This mutation at position -196 has now ben found in unrelated individuals with the A gamma-HPFH phenotype from Italy, Sardinia, and China, suggesting that it may have arisen independently. The implications of this mutation for models of fetal globin gene switching are discussed.

scholarly journals Hereditary persistence of fetal hemoglobin or (delta beta)o- thalassemia: three types observed in South-Chinese families

Blood ◽  
1985 ◽  
Vol 66 (6) ◽  
pp. 1430-1435
Author(s):  
YT Zeng ◽  
SZ Huang ◽  
B Chen ◽  
YC Liang ◽  
ZM Chang ◽  
...  
Keyword(s):  
Gene Mapping ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Restriction Enzymes ◽  
Large Deletion ◽  
Gamma Delta ◽  
Chinese Families ◽  
Gamma Globin ◽  
Hereditary Persistence ◽  
Fetal Hemoglobin Level

Hematological and hemoglobin composition data, and results from extensive gene mapping, using a battery of restriction enzymes and probes, have been used to distinguish different types of hereditary persistence of fetal hemoglobin (HPFH) (or delta beta-thal) among three Chinese families from the southern part of China. The first (Family Z) is an A gamma-(delta beta)+-HPFH without a detectable deletion and may be the same as, or similar to, that described by Farquhar et al (Am J Hum Genet 35:611, 1983). The second (Family C) resembles a G gamma(A gamma delta beta)o-thalassemia and is characterized by a large deletion of DNA originating 3′ to the G gamma globin gene and extending beyond sequences recognized by the pRK28 probe. Data from various digests indicate possible differences in the 3c′ end of the deletion when compared with data for some other types of G gamma(A gamma delta beta)o- thalassemia, described by Trent et al (Br J Haematol 57:279, 1984). The third (Family Zh) concerns a G gamma A gamma(delta beta)+-HPFH, which is characterized in heterozygotes by a fetal hemoglobin level of 20% to 25% with a G gamma value averaging 60% and by the absence of any DNA deletion detectable by extensive gene mapping analyses. The C----G mutation at position 202 5c′ to the G gamma globin gene [characteristic for the high G gamma-(delta beta)+-HPFH (Proc Natl Acad Sci USA 81:4894, 1984; Blood 64:1292, 1984)] was absent, but the Xmn I site at position 158 5c′ to the G gamma globin gene [characteristic for a modest increase in G gamma values and thus and increased G gamma to A gamma ratio (Blood)] was present. No indication has yet been obtained explaining the elevation in both G gamma and A gamma chains; haplotyping showed that the chromosome carrying this G gamma A gamma(delta beta)+ determinant is unusual among the Chinese population.

scholarly journals A fetal globin gene mutation in A gamma nondeletion hereditary persistence of fetal hemoglobin increases promoter strength in a nonerythroid cell.

1988 ◽  
Vol 8 (2) ◽  
pp. 713-721 ◽  
Author(s):  
M W Rixon ◽  
R E Gelinas
Keyword(s):  
Transient Expression ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Type A ◽  
Base Substitution ◽  
Globin Genes ◽  
Wild Type ◽  
Gamma Globin ◽  
Base Substitutions ◽  
Hereditary Persistence

Single base substitutions have been identified in the promoter regions of A gamma-globin genes from individuals with certain types of nondeletion A gamma hereditary persistence of fetal hemoglobin (HPFH). The presence of these mutations is closely associated with the A gamma HPFH phenotype, but proof that they are the nondeletion HPFH determinants is lacking. To test directly whether these base substitutions can result in an increase in A gamma-globin gene transcription, we studied cosmid clones containing the G gamma- through beta-globin gene regions from individuals with Greek-type (G-to-A base substitution at -117) and Chinese-type (C-to-T base substitution at -196) A gamma HPFH in a transient expression assay. When tested as part of a cosmid clone, the Greek HPFH A gamma-globin gene consistently produced about 1.4 times as much RNA as the wild-type A gamma-globin gene when standardized against RNA transcribed from the G gamma genes in cis. The relative strengths of the normal and HPFH A gamma-globin gene promoters were also compared in transient expression assays with plasmids containing the A gamma-globin genes. Pseudo-wild-type A gamma-globin genes containing a short, transcriptionally neutral deletion were used so that two A gamma-globin genes that differed in their promoter sequences could be compared in the same transfection. The plasmid transient expression results indicated a 1.3- to 1.4-fold increase in steady-state RNA levels from the Greek-type A gamma HPFH promoter compared with the wild-type A gamma promoter, while no difference was documented between the Chinese-type A gamma HPFH promoter and the wild-type A gamma promoter.

scholarly journals Expression of the affected A gamma globin gene associated with Greek nondeletion hereditary persistence of fetal hemoglobin.

1987 ◽  
Vol 7 (8) ◽  
pp. 2999-3003 ◽  
Author(s):  
C J Stoeckert ◽  
J E Metherall ◽  
M Yamakawa ◽  
J M Eisenstadt ◽  
S M Weissman ◽  
...  
Keyword(s):  
Transcription Initiation ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Mutant Gene ◽  
Retroviral Vector ◽  
Base Substitution ◽  
Gamma Globin ◽  
Erythroleukemia Cell ◽  
Hereditary Persistence ◽  
Globin Gene Expression

The overexpressed A gamma globin gene in the Greek type of nondeletion hereditary persistence of fetal hemoglobin has a unique single-base substitution located at position -117 relative to the site of transcription initiation. This gene and its normal counterpart were transferred into cultured cell lines by using a retroviral vector. The only difference in expression between the transferred normal and mutant gamma genes was observed in the human erythroleukemia cell line KMOE after exposure of the cells to cytosine arabinoside, a condition that resulted in an adult pattern of endogenous globin gene expression by the cells and was associated with increased expression of the mutant gene.

scholarly journals Sardinian G gamma-HPFH: a T----C substitution in a conserved "octamer" sequence in the G gamma-globin promoter

Blood ◽  
1988 ◽  
Vol 71 (3) ◽  
pp. 815-817 ◽  
Author(s):  
S Ottolenghi ◽  
S Nicolis ◽  
R Taramelli ◽  
N Malgaretti ◽  
R Mantovani ◽  
...  
Keyword(s):  
Globin Gene ◽  
Single Point ◽  
Point Mutations ◽  
Fetal Hemoglobin ◽  
Regulatory Elements ◽  
Globin Genes ◽  
Gamma Globin ◽  
New Type ◽  
Hereditary Persistence ◽  
Globin Promoter

Abstract A survey of hemoglobinopathies in Northern Sardinia allowed the identification of two subjects heterozygous for a new type of G gamma hereditary persistence of fetal hemoglobin (HPFH). The G gamma-globin gene from the HPFH chromosome shows the presence of a T----C substitution 175 nucleotides upstream of the CAP site, adding a new example of single-point mutations occurring in the promoter region of the gamma-globin genes and linked to HPFH phenotypes. In this case the mutation affects the 3′ end nucleotide of a conserved octamer sequence known to be present in other regulatory elements of several genes.

scholarly journals Hereditary persistence of fetal hemoglobin or (delta beta)o- thalassemia: three types observed in South-Chinese families

Blood ◽  
1985 ◽  
Vol 66 (6) ◽  
pp. 1430-1435 ◽  
Author(s):  
YT Zeng ◽  
SZ Huang ◽  
B Chen ◽  
YC Liang ◽  
ZM Chang ◽  
...  
Keyword(s):  
Gene Mapping ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Restriction Enzymes ◽  
Large Deletion ◽  
Gamma Delta ◽  
Chinese Families ◽  
Gamma Globin ◽  
Hereditary Persistence ◽  
Fetal Hemoglobin Level

Abstract Hematological and hemoglobin composition data, and results from extensive gene mapping, using a battery of restriction enzymes and probes, have been used to distinguish different types of hereditary persistence of fetal hemoglobin (HPFH) (or delta beta-thal) among three Chinese families from the southern part of China. The first (Family Z) is an A gamma-(delta beta)+-HPFH without a detectable deletion and may be the same as, or similar to, that described by Farquhar et al (Am J Hum Genet 35:611, 1983). The second (Family C) resembles a G gamma(A gamma delta beta)o-thalassemia and is characterized by a large deletion of DNA originating 3′ to the G gamma globin gene and extending beyond sequences recognized by the pRK28 probe. Data from various digests indicate possible differences in the 3c′ end of the deletion when compared with data for some other types of G gamma(A gamma delta beta)o- thalassemia, described by Trent et al (Br J Haematol 57:279, 1984). The third (Family Zh) concerns a G gamma A gamma(delta beta)+-HPFH, which is characterized in heterozygotes by a fetal hemoglobin level of 20% to 25% with a G gamma value averaging 60% and by the absence of any DNA deletion detectable by extensive gene mapping analyses. The C----G mutation at position 202 5c′ to the G gamma globin gene [characteristic for the high G gamma-(delta beta)+-HPFH (Proc Natl Acad Sci USA 81:4894, 1984; Blood 64:1292, 1984)] was absent, but the Xmn I site at position 158 5c′ to the G gamma globin gene [characteristic for a modest increase in G gamma values and thus and increased G gamma to A gamma ratio (Blood)] was present. No indication has yet been obtained explaining the elevation in both G gamma and A gamma chains; haplotyping showed that the chromosome carrying this G gamma A gamma(delta beta)+ determinant is unusual among the Chinese population.

scholarly journals Sequence analysis of the gamma-globin gene locus from a patient with the deletion form of hereditary persistence of fetal hemoglobin

Blood ◽  
1990 ◽  
Vol 75 (2) ◽  
pp. 499-504 ◽  
Author(s):  
CA Stolle ◽  
LA Penny ◽  
S Ivory ◽  
BG Forget ◽  
EJ Jr Benz
Keyword(s):  
Allelic Variation ◽  
Polymerase Chain Reaction Amplification ◽  
Globin Gene ◽  
Fetal Hemoglobin ◽  
Globin Genes ◽  
Chromosomal Dna ◽  
Gamma Globin ◽  
Allele Specific ◽  
Reaction Amplification ◽  
Hereditary Persistence

Abstract The gamma-globin genes from a patient homozygous for a deletion form of hereditary persistence of fetal hemoglobin (HPFH-1) have been cloned and sequenced. The DNA sequence of the patient's gamma-globin genes corresponds to a previously identified sequence framework (chromosome A) with the exception of 10 base changes. Seven of these base changes can be attributed to normal allelic variation generated by small gene conversion events. The remaining three base changes are present in a 0.76 kb HindIII fragment containing a putative enhancer located 3′ to the A gamma-globin gene. The same three base changes have also been described in the Seattle variant of nondeletion HPFH. We have analyzed 16 alleles from non-HPFH individuals and five alleles from individuals with nondeletion or deletion HPFH for the presence of these base changes by polymerase chain reaction amplification of cloned or chromosomal DNA and hybridization to allele-specific oligonucleotide probes. Although these base changes were found in an individual with HPFH-2, they were not found in the DNA from two patients with nondeletion HPFH. More importantly, all three base changes were detected in DNA from five non-HPFH individuals and appear to be common in blacks. We conclude that these base changes do not correlate with an HPFH phenotype and that the significant mutation in HPFH-1 is the deletion of over 100 kb of genomic DNA.

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