Genetics of Cardiovascular Disease: Fishing for Causality

Abstract

Cardiovascular disease (CVD) is still the leading cause of death in all western world countries and genetic predisposition in combination with traditional risk factors frequently mediates their manifestation. Genome-wide association (GWA) studies revealed numerous potentially disease modifying genetic loci often including several SNPs and associated genes. However, pure genetic association does not prove direct or indirect relevance of the modifier region on pathogenesis, nor does it define within the associated region the exact genetic driver of the disease. Therefore, the relevance of the identified genetic disease associations needs to be confirmed either in monogenic traits or in experimental in vivo model system by functional genomic studies. In this review, we focus on the use of functional genomic approaches such as gene knock-down or CRISPR/Cas9-mediated genome editing in the zebrafish model to validate disease-associated genomic loci and to identify novel cardiovascular disease genes. We summarize the benefits of the zebrafish for cardiovascular research and highlight examples demonstrating the successful combination of GWA studies and functional genomics in zebrafish to broaden our knowledge on the genetic and molecular underpinnings of cardiovascular diseases.

Streamlining drug discovery assays for cardiovascular disease using zebrafish

“…Zebrafish are small (2-4 cm) and show a high fecundity allowing the weekly production of up to 300 eggs per breeding pair. The externally fertilized eggs develop rapidly, the developing embryos are optically translucent and their development is not completely dependent on the regular function of the cardiovascular system since adequate oxygen supply of all tissues and organs is guaranteed by passive diffusion from the surrounding medium for up to 120 hours postfertilization (hpf) [19,20]. This fact allows the assessment of the role of the loss of known and novel cardiovascular disease genes in vivo that usually results in early embryonic lethality in other animal model systems such as mice.…”

“…Since several years, the zebrafish is used as an attractive model organism to dissect the genetic and molecular underpinnings of cardiovascular development and (patho-)physiology [20,38,39].…”

“…Since early development of zebrafish embryos does not require proper blood circulation, this model organism is amenable to a broad range of functional genomic approaches including forward genetics by e.g. ENU-mutagenesis [57] and reverse genetics using innovative genome editing tools such as clustered regularly interspaced short palindromic repeats CRISPR/ Cas9 and transcription activator-like effector nuclease (TALEN) or Morpholino-oligonucleotide-mediated gene knockdown [18,20,[66][67][68][69]. Based on zebrafish transparency during embryogenesis functional impact on zebrafish cardiovascular system after genome/gene editing can be easily evaluated via simple light microscopy.…”

“…heart rate/rhythm, systolic/diastolic volume, ejection fraction, stroke volumes, and fractional shortening) to estimate drug performance. Over the past 25 years, the zebrafish evolved as an excellent non-mammalian vertebrate animal model to define the genetic and molecular etiology of cardiovascular diseases [20,38,39]. Furthermore, the unique arsenal of forward and reverse genetic approaches that includes state-of-the-art genome editing tools such as the CRISPR/Cas9 technology in combination with the substantial homology of physiology and pathophysiology to the human cardiovascular system turns the zebrafish into a valuable and reliable model organism to simulate human cardiovascular diseases, even in an individualized or personalized manner.…”

Metabolic Profiling of Glucocorticoid Deficiency: A “Fishing” Expedition

“…In the last two decades the zebrafish has been established as an excellent tool to decipher the genetic as well as molecular underpinnings of various human diseases, including metabolic or cardiovascular disorders [ [4] , [5] , [6] ]. Interestingly, several studies comparing development and function of the endocrine systems demonstrated a high degree of similarity between humans and zebrafish.…”