The analysis of heterotaxy patients reveals new loss-of-function variants of GRK5.
G protein-coupled receptor kinase 5 (GRK5) is a regulator of cardiac performance and a potential therapeutic target in heart failure in the adult. Additionally, we have previously classified GRK5 as a determinant of left-right asymmetry and proper heart development using zebrafish. We thus aimed to identify GRK5 variants of functional significance by analysing 187 individuals with laterality defects (heterotaxy) that were associated with a congenital heart defect (CHD). Using Sanger sequencing we identified two moderately frequent variants in GRK5 with minor allele frequencies <10%, and seven very rare polymorphisms with minor allele frequencies <1%, two of which are novel variants. Given their evolutionarily conserved position in zebrafish, in-depth functional characterisation of four variants (p.Q41L, p.G298S, p.R304C and p.T425M) was performed. We tested the effects of these variants on normal subcellular localisation and the ability to desensitise receptor signalling as well as their ability to correct the left-right asymmetry defect upon Grk5l knockdown in zebrafish. While p.Q41L, p.R304C and p.T425M responded normally in the first two aspects, neither p.Q41L nor p.R304C were capable of rescuing the lateralisation phenotype. The fourth variant, p.G298S was identified as a complete loss-of-function variant in all assays and provides insight into the functions of GRK5.
Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Davor
D
Lessel
Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Tariq
T
Muhammad
Institute for Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany.
Teresa
T
Casar Tena
Institute of Pharmacology and Toxicology, Ulm University Medical Center, 89081 Ulm, Germany.
Barbara
B
Moepps
Institute for Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany.
Martin D
MD
Burkhalter
Department of Congenital Heart Disease and Pediatric Cardiology, University Hospital Schleswig-Holstein, 24105 Kiel, Germany.
Marc-Phillip
MP
Hitz
Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Department of Pediatric Cardiology, 91054 Erlangen, Germany.
Okan
O
Toka
Department of Pediatric Cardiology, Saarland University Medical Center, 66421 Homburg, Germany.
Axel
A
Rentzsch
German Heart Institute Berlin, Department of Congenital Heart Disease and Pediatric Cardiology, 13353 Berlin, Germany.
Stephan
S
Schubert
Competence Network for Congenital Heart Defects/National Register for Congenital Heart Defects, 13353 Berlin, Germany.
Adelheid
A
Schalinski
Competence Network for Congenital Heart Defects/National Register for Congenital Heart Defects, 13353 Berlin, Germany.
Ulrike M M
UM
Bauer
Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany.
Christian
C
Kubisch
Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Stephanie M
SM
Ware
Institute for Biochemistry and Molecular Biology, Ulm University, 89081 Ulm, Germany.
Melanie
M
Philipp
D000595:Amino Acid Sequence; D000818:Animals; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D005260:Female; D054774:G-Protein-Coupled Receptor Kinase 5 / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D057809:HEK293 Cells; D059446:Heterotaxy Syndrome / Q000235:genetics* / Q000503:physiopathology; D006801:Humans; D017403:In Situ Hybridization; D000073658:Loss of Function Mutation; D008297:Male; D020641:Polymorphism, Single Nucleotide; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins / Q000235:genetics
D029961:Zebrafish Proteins; D054774:G-Protein-Coupled Receptor Kinase 5; C517898:GRK5 protein, human