ELABELA (abbreviated ELA) is a secreted hormonal peptide

acting during embryogenesis and circulating in blood in the adult. 



Genomic


The ELABELA gene is located on chromosome 4q32.3 in humans.

It consists of 3 exons with the following genomic coordinates

(hg19)chr4:165,798,156-165,818,675 .


Exon 1 codes for all the 5’ UTR, the entire signal peptide 

and 3 residues of the mature peptide.

Exon 2 encodes the mature ELA peptide and its Stop codon.

Exon 3, which is the largest of all, is entirely consisting of 

3’ UTR. In primates but not in rodents, the exon 3 is larger and 

bears 2 Alu repeats of 300 bp each.

 

1 MRFQQFLFAFFIFIMSLLLISGQRPVNLTMRRKLRKHNCLQRRCMPLHSRVPFP 54
1         Exon 1           V           Exon 2            54

The GTT codon for Valine is overlapping splice sites between 

exon 1 and exon 2.

 

The open reading frame (ORF) encoded by the human ELA 

cDNA is 165 bp in length: 


>human ELABELA ORF

ATGAGATTTCAGCAATTCCTTTTTGCATTTTTTATTTTTATTAT

GAGTCTTCTCCTTATCAGCGGACAGAGACCAGTTAATTTGACC

ATGAGAAGAAAACTGCGCAAACACAATTGCCTTCAGAGGAGA

TGTATGCCTCTCCATTCACGAGTACCCTTTCCCTGA

 


Discovery


ELABELA is a novel peptide hormone that was identified, 

characterized and de-orphaned in 2013 by the team of

Dr. Bruno REVERSADE at the Institute of Medical Biology

in Singapore.

It's name stands for Epiboly LAte Because of Endoderm LAte

(or vice versa) which is the first observable phenotype when

knocked out in zebrafish.

 

Biosynthesis


The human ELABELA gene encodes a protein of 54 amino-acids, 

with a signal peptide in its N-terminal region. 

It is referenced in Uniprot under PODMC3.  
 

After cleavage of the signal peptide which consists of the

first 22 residues, the mature ELA hormone is 32 amino-acid 

long with an isoelectric point exceeding 12. 


ELA needs to be secreted to become active since deletion 

of 7 residues in its signal peptide causes a complete

loss-of-function in zebrafish.


Mature ELA bears 2 conserved di-arginine motifs 

(R31/R32 and R42/R43) suggesting that it may be further processed 

by Furin-like endopeptidaseIt is beleived that the N-terminal residue 

of the mature peptide can be substituted by a pyroglutamic acid (Pyr)

residue as is the case in APLN-13.


ELABELA

Primary Sequence

 Molecular Weight (Da)

 Isoelectric 
Point

full-length peptide    

MRFQQFLFAFFIFIMSLLLISGQRPVNLTMRRKLRKHNCLQRRCMPLHSRVPFP

6622

12.2

signal peptide 

MRFQQFLFAFFIFIMSLLLISG

2670

9.50 

mature peptide


QRPVNLTMRRKLRKHNCLQRRCMPLHSRVPFP
                                                                  

3970

12.1 

 

Antibodies

The full-length and mature endogenou ELA peptide can be

recognized by a mouse monoclonal or rabbit polyclonal antibody 

raised against this C-terminal 11-mer epitope CMPLHSRVPFP.

These antibodies referred to as "anti-C" can recognize ELA from

any species and have strong neutralizing activity towards 

ELA' s activity in hESCs.


The mature endogenous human ELA peptide can be

recognized by a mouse monoclonal or rabbit polyclonal antibody 

raised against the N-terminal 17-mer epitope 

QRPVNLTMRRKLRKHNCThese antibodies referred to as "anti-N" 

have strong neutralizing activity towards ELA' s activity in hESCs.


Phylogeny



The ELABELA protein is phylogenetically conserved across 

all vertebrate species with an invariable length of 54 amino acids. 

 

species

primary amino-acid sequence
signal peptide is underlined, mature ELA is in bold




Homo
Peromyscus
Rattus
Mus
Bos
Sus
Dasypus
Trichosurus
Gallus
Gekko
Anolis
Xenopus
Ambystoma

1          10         23     30        40         50 54
|          |          |      |         |          |  |
MRFQQFLFAFFIFIMSLLLISGQRPVNLTMRRKLRKHNCLQRRCMPLHSRVPFP
MRFQHYFLVFFIFAMSLLFITEQRPVNFPKKRKVYRHNCFRRRCVPLHSRVPFP
MRFQPLFWVFFIFAMSLLFITEEKSVNFPRRRKLYRHNCFRRRCISLHSRVPFP
MRFQPLFWVFFIFAMSLLFISEQKPVNFPRRRKLYRHNCFRRRCIPLHSRVPFP
MRFHQFFLLFVIFMLSLLLIHGQRQANLAMRRKLHRHNCLQRRCMPLHSRVPFP
MRFRQFFLVFFIFMMNLLLICGQRPANLAVRRKLHRHNCLQRRCMPLHSRVPFP
MKFQQFFYVFFVFIMSLLLINGQRPANLAMRRKLHRHNCFQRRCMPLHSRVPFP
MRFQLLFFLFLFFTMGILLIDGQRPGNLALRRKPHRHICPQRRCMPLHSRVPFP
MRLRRLLCVVFLLLVSLLPAAAQRPANLALRRKLHRHNCSHRRCMPLHSRVPFP
MRLQLLLLTCFLILTGVLLGNGQRPANLSLRRKLHRQHCSHRRCMPLHSRVPFP
MRLQQLLLTWFLLLAGALLINGQRPANLASRRKLHRHHCSHRRCMPLHSRVPFP
MDFQKLLYALFFILMSLLLINGQKPANLAQRRRIHRHNCFLKRCIPLHSRVPFP
MKWQKLLAILFWILMGALLVNGQRPVNAAHRRRLHRHNCSLRRCMPLHSRVPFP


However, in zebrafish (Danio rerio), Ela has an additional 

4 amino-acids. This insertion of 4 residues (DKHG) is predicted

to be part of the mature peptide:


1-MRFFHPLYLLLLLLTVLVLISA(DKHG)TKHDFLNLRRKYRRHNCPKKRCLPLHSRVPFP-58


Its carboxy terminal end is invariant across species and 

comprises the signature:  -HSRVPFPstop


ELA also contains a pair of conserved cysteines residues at 

position 39 and 44 that form an intermolecular disulphide bridge.


A mutant form of ELA with two carboxy missense mutations 

(p.F53A; p.P54A) is believed to act as an antagonist to APLNR.


A mutant form of ELA with two N-terminal missense mutations 

(p.R31G; p.R32G) can no longer bind to the cell surface of

 hESCs which express ELA' s alternate receptor. 


Two Receptors



ELA is the earliest known endogenous ligand

for the cell surface G protein-coupled receptor APLNR  

(also known as APJ and AGTRL1). 

The other known ligand for APLNR is the hormonal peptide

APELIN. Both ligands have similar binding kinetics to APLNR 

and can compete for one another suggesting similar binding

sites to this GPCR.


ELA possesses a second cell surface receptor in hESCs

which signals via  the PI3K/AKT signalling pathway to mediate

hESCs self-renewal. The identity of this second receptor is 

yet unknown.


Cardiac



ELABELA is expressed in naive cells of the ectoderm or epiblast 

and signals to the future endodermal cells expressing APLNR. 


In zebrafish embryos, ELABELA is needed for proper gata5 and

sox17 expression during gastrulation.


ELABELA regulates the migration of cell progenitors fated to

differentiate in cardiac tissue. 


ELABELA has been proposed to act as a motogen to promote 

cell motility during epiboly and as a classical chemo-attractant 

for the migration of angioblasts to the embryonic midline.


elabela knockout zebrafish have rudimentary heart or not heart

at all. In addition Ela mutant larvae show excess red blood cells

in the intermediate cell mass, no blood circulation, 

and variable posterior truncations as do double zebrafish

aplnra;aplnrb mutants.


Heart morphogenesis in aplnra;aplnrb double knockout fish can be 

partially rescued by elevating Nodal/TGFbeta signalling. 


Vascular



In zebrafish, the double ligand knockout of elabela;apelin , which

are expressed at the embryonic midline,impedes migration 

of angioblasts to form the primary vessels namely the aorta and

the cardinal vein. This process known as vasculogenesis is 

mediated by Aplnra and Aplnrb which are expressed at the cell

surface of angioblasts. 


In mouse, Elabela is needed for proper yolk sac vasculature and 

placental angiogenesis. Its mutation phenocopies that of Aplnr.

Pregnant mice lacking Ela, but not Apelin, develop symptoms of pre-

-eclampsia with gestational hypertension, proteinuria and IUGR. 

This symptoms can be rescued by infusing ELA indicating that the 

ELABELA-nergic may be of therapeutic value in hypertensive syndromes.  


hESCs



ELABELA is abundantly secreted by hESCs which do not

express APLNR. It reaches nM concentration in the extracellular

space and signals in an autocrine / paracrine manner.



By genetic deletion using CRISPR/Cas9, shRNA-mediated 

inhibition or extracellular blockage

using neutralizing antibodies, endogenous ELA is shown to be

required for self-renewal of hESCs.


ELA binds to an unknown alternate receptor present at the cell 

surface of hESCs and elicits immediate activation of the

PI3K/AKT pathway to promote hESCs survival. 


Unlike Insulin, a growth factor added to hESCs culture medium,

ELA can poise hESCs towards the mesendoderm lineage.



Adult Physiology



ELABELA is expressed in adult kidney in mouse, rat and humans. 

The ELA hormone circulates in blood where its half-life does not exceed 

a few minutes. Injection of synthetic ELA in the bloodstream of rats

is sufficient to lower blood pressure and increase heart contractility.

ELA has hypotensive properties during pregnancy where it can lower 
blood pressure, correct proteinuria and increase birth weight of mice 
and pups lacking ELA.


Non-coding function



The spliced mRNA of Elabela in mouse ES cells can bind  

the hnRNPL protein. This does not need the ORF encoding for 

the Ela peptide but instead its 3' UTR which functions a 

regulatory RNA. 

This non-coding function of murine Ela may not be conserved 

in human ELA which has a very distinct 3' UTR length and 

structure  with the insertion of two Alu repeats.


Miscellaneous


Unique Identifiers:


PODMC3
AK092578
LOC100506013
Hs. 105196
OTTHUMT00000364313
OMIM:615594
ENSG00000248329
NM_001297550

cDNA FLJ35259 fis
clone PROST2004251


 >human ELABELA cDNA (underlined is its ORF)

GCTTTTGGAGTACACTTCCACTAAAGTTATAGCATGCTTGAATGGTTTAT
TTCACCAATATTTGCTTATGGAAATAAAGGGGAGTGGCCGAGGAGAAAGG
AGAAGAGGAGTGGAGGAGGGGTTTGAGGCTGAGGGAGGCTCTGACCACAG
CACAGAGCACCGGCAACTTTGTCTAATGTGATCATTAACCTTCCTGCAAA
ACACAGCTGGCAGTTCTCTGAGGTTTGTCACTAGAATGTGAAGACAGCCA
CACAGATATTGCACAGACTATTTACAGATCGTTTGGTTTACATTGAGAGT
CATTGCTCTACTTTTGTGCGGTAGGAAAATGAGATTTCAGCAATTCCTTT
TTGCATTTTTTATTTTTATTATGAGTCTTCTCCTTATCAGCGGACAGAGA
CCAGTTAATTTGACCATGAGAAGAAAACTGCGCAAACACAATTGCCTTCA
GAGGAGATGTATGCCTCTCCATTCACGAGTACCCTTTCCCTGAGATCTCT
CTAGCTAACTTTACTGGATCTATCAGAAGAAGAAGAGGAGTGAAGGAAAG
ACACCCAGCCACACAAAAGAACTTCATGATGCCAACAGCGTGATTGCTTA
GAAGTTCCTACACAAAAAAAGGATCATTTGAAAGCACCTGGAATGGTTTA
TTAGCTTCACAGGATTTTATTCTTCTTGGCTTCTATTTGGAGGGAAAATA
ACATAAATTCAAAAGGATTCCAATCTGAAGCCCAAATCGTTTGCCTACAT
AACAAAAATATCTCATCTTTTCCTGCACATTATTATTCTTTTATGGGTTA
AAAAGAAAAATACCTTTTAGTGTTTTAGAACTCTCTCATGGTAAAAAGTG
CAAGAATTTAAAATGTTGCTTTCATATTCCTATAATTCTCCAAAAGTATT
AAATTCGTATATGTTTGAGTGATTTTCTAAAAACTGCTCAACCTGAAATC
AATTGCATTGACCATTTGGCTTCGCACAATAGGGAGAAAATAATTGGTTC
ATTGATTATATAGAGAGAAAGACTAAGAAAAGCTATTAATTGCTACCAAT
TTTATGATAAGCTTTAAGGTTTATGAAAGTATGTTTTTTTATTTAATGAG
TAATGTCCATTTGAAGTTGAAAGAAAACATGAAATCCTAATTGTAGTTCA
TTTTATGTTCAAATGAAACCATTGTTTTTGTTTTTGTTTTGAAACAGAGT
CTCACTCTGTTGCCCAAGGTGGAGAGAAGTGGCACGCTTTTGTCTCACTG
CAACCTCCACCTCCCGAGTTCAAGTGATTCTCGTGCCTCAACCTCCCAAT
TATAGGCTGGGATTACAGGTGTGCACCACTACACCCAGCTAATTCTTGTA
TTTTTTGTAGAGATGAGGTTTTACCCTGTTGCCCAGGCTGGTCTTGAACT
CAGGCTGGAACCATTCATTTTTTAACCTTTCTCATCATGTAATTATAGGA
ACCCAACGTTTGATTTCCTTTGAAGTTTTGTTATGTCCTTTATTATTTTG
TATGGATAATTTCTTTAAAAGTCTTACTTAAAGTTGACATCTAAAATACA
GTTATGCCAATGAAGTCCCACTCAGGGTGATATCTGTATCTAAAAGATGA
GTGCTCATCATCCTATTAGGCTTTGTCTTGGTGGTGTTCATCCTGAGATG
CTGAGACATGGAAATAAAAAATCAGAAGGAATTTAGGGATATGATTACTC
AAAAAAGAAACTATCCTGTCTAAATTTGAATTGTGTTGATAACTAGGTGT
TCCCCAGATGCTAAGATGTTCTTAATTTGTATTTATTGAAGGATTGTTAG
CTTAGTGCCACAAAATTTTTCTTACTTTATGTTAATTCCAGATAAGAAAT
TTACAAGTTTATATCTTTTTTTTTCTTTTTTTTAAGATGAGATCTGGCTC
TATCACCCAGGCTAAAGTGCAGTGGCATGATCTAGGCTAACTCCCTGGCT
CAAGCGATCCTTCCACCTCAGCCTCCCAAGTACCTGGGACTACAGGCACT
CACGGCCACACCTGACTAATTTTTGTATTTTTTTGTAGAGATGGAGTATC
GCCATGTTGCCCAGGTTGGTCTCAAACTCAGGCTGGTGAGCTCAAGTGAT
CCGCCTCCTTGGCCTCCCAAAATACTGGGATTACAGGCATGTGCCACCAT
GCTGGGCCACAAGTTCATATCTGGAGTAGAAGTTTTACTTTGTAAATATT
ATAAAGTAGAAGAAACCATAAACCATTTTGCTAAAATGAAAGGTTGGGGT
TAATATAAATGTAATTTTAAATAGAAAATCTGACAACACTGTCGAGTTTG
TCTTCCTGTCAAAGCTTATTAAAAGTGTCTTTGCGGATGAATGGTACTTT
CCACAAGTGCATTTGAGTAGAAGCATAACCTATTCTCAGTTATATTTATG
TTTAAAACATGTACTGGTTTGTATATTTTGTACTGAAAAAGAAAACACTT
TATAGTCAAGATACATCTCATTCAATACAAGTCTAAACTCTTTCAAATAC
AAATTCGCATATTCACAGAAAAAGTTACAAATCAGTTTTACTATTGTAAA
GTAATGAAATGGTTATACATTTCTTAATTGTTCAATAAAACACTCAATGA
TT

 

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