Overview

Genetics of Vascular Malformations.  A large part of our research program is the investigation of the genetics and pathobiology of vascular malformations.  Below I provide more detail on my major contributions to our understanding of each of the vascular malformations that we study.   

Cerebral Cavernous Malformations.  My lab (and independently, the Tournier-Lasserve lab) identified two of the three known causative genes (CCM1, Sahoo et al., 1999; CCM2, Liquori et al., 2003).  We, and others, hypothesized that CCM lesions followed a two-hit (germline plus somatic) mutation mechanism, and using a robust and highly sensitive molecular genetics approach developed in our lab, we showed that this was true for all three inherited forms of the disease. We genetically-sensitized the animals and found that in a p53 null background the Ccm1 heterozygotes displayed vascular lesions that resembled human CCM lesions in histopathology.   Our sensitized mice became the first authentic animal model of CCM disease.  Using floxed alleles and Cre recombinase, we generated a next-generation mouse model that enable us to model to study the clonal expansion of somatically mutated cells during lesion growth (Detter et al. 2018). We then created an even more robust and adult-onset mouse model of CCM3 disease which was used to investigate new therapies based on RhoA kinase (ROCK) inhibition by multiple different drugs. We recently also showed that highly aggressive CCM lesions acquire an activating, somatic PIK3CA mutation (Ren et al., 2021). We then showed that a benign vascular malformation, the developmental venous anomaly, is the genetic and anatomic precursor to the sporadic CCM (Snellings et al., 2022).  Most recently using single-cell DNA sequencing, we have identified another source of somatic loss of function mutation in some CCMs, caused by large, genomic events leading to somatic Loss of Heterozygosity in the lesion (Ressler et al., 2023).

a.     Detter MR, Snellings DA, and Marchuk DA.  Cerebral Cavernous Malformations Develop Through Clonal Expansion of Mutant Endothelial Cells.   Circ Res, 123:1143-51, 2018. PMCID: 6205520.

b.     Ren AA, Snellings DA, Su YS, Hong CC, Castro M, Tang AT, Detter MR, Hobson N, Girard R, Romanos S, Lightle R, Moore T, Shenkar R, Benavides C, Beaman MM, Mueller-Fielitz H, Chen M, Mericko P, Yang J, Sung DC, Lawton MT, Ruppert M, Schwaninger M, Körbelin J, Potente M, Awad IA, Marchuk DA, Kahn ML.  PIK3CA and CCM mutations fuel cavernomas through a cancer-like mechanism.  Nature, 594:271-6, 2021.  PMCID 8626098. 

c.     Snellings DA, Girard R, Lightle R, Srinath A, Romanos S, Li Y, Chen C, Ren AA, Kahn ML, Awad IA, Marchuk DA.  Developmental venous anomalies are a genetic primer for cerebral cavernous malformations.  Nature Cardiovasc Res 1:246-252., 2022. PMCID: 8958845.

d.     Ressler AK, Snellings DA, Girard R, Gallione CJ, Lightle R, Allen AS, Awad IA, Marchuk DA.  Single-nucleus DNA-sequencing reveals hidden somatic loss-of-heterozygosity in Cerebral Cavernous Malformations.   Nature Communications, Nov 2;14(1):70092023. PMCID 10622526.  

 Hereditary Hemorrhagic Telangiectasia.    Hereditary Hemorrhagic Telangiectasia (HHT or Osler-Weber-Rendu disease) is an autosomal dominant disorder characterized by hemorrhagic stroke, gastrointestinal bleeding, and other vascular pathology.  The clinical features result from the development of focal vascular malformations characterized by direct arteriovenous shunts with a loss of the capillary beds.  We have shown that HHT is a group of related disorders with overlapping but distinct phenotypes and genetic etiologies. We established genetic linkage at two distinct loci for HHT, and we subsequently identified the gene for HHT1 as endoglin (McAllister et al., 1994), a transforming growth factor beta binding protein of endothelial cells, and the HHT 2 locus as the activin-like kinase receptor, ALK-1, which has sequence homology to TGF-beta receptors (Johnson et al., 1996).   Some years later, we described a new combined phenotype syndrome of Juvenile Polyposis and Hereditary Hemorrhagic Telangiectasia caused by mutations in MADH4 gene encoding SMAD4, the common downstream effector of TGF beta family signaling (Gallione et al., 2004).    The applicant, Evon DeBose-Scarlette, recently identified somatic mutations in skin telangiectasias in HHT patients (Snellings et al., 2019).

 a.     McAllister KA, Grogg KM, Johnson DW, Gallione CJ, Baldwin MA, Jackson CE, Helmbold EA, Markel DS, McKinnon WC, Murrell J, McCormick MK, Pericak-Vance MA, Heutink P, Oostra B, Haitjema T, Westerman CJJ, Porteous ME, Guttmacher AE, Letarte M, Marchuk DA.   Endoglin, a TGF-beta binding protein of endothelial cells, is the gene for hereditary haemorrhagic telangiectasia type 1.   Nature Genetics 8:345-351, 1994.  PMID 7894484.

b.     Johnson DW, Berg JN, Baldwin MA, Gallione CJ, Marondel I, Yoon S-J, Stenzel TT, Speer M, Pericak-Vance MA, Diamond A, Guttmacher AE, Jackson CE, Attisano L, Kucherlapati R, Porteous MEM, Marchuk DA.  Mutations in the activin receptor-like kinase 1 gene in hereditary hemorrhagic telangiectasia type 2.  Nature Genetics 13:189-195, 1996.  PMID 8640225.

c.     Gallione CJ, Repetto GM, Legius E, Rustgi AK, Schelley SL, Tejpar S, Mitchell G, Drouin E, Westermann CJJ, Marchuk DA.   A combined syndrome of juvenile polyposis and hereditary haemorrhagic telangiectasia associated with mutations in MADH4 (SMAD4).  Lancet 363:852-859, 2004.  PMID 15031030.

d.     DeBose-Scarlett E, Ressler AK, Gallione CJ, Sapisochin Cantis, G, Friday C, Weinsheimer S, Schimmel K, Spiekerkoetter E, Kim H, Gossage JR, Faughnan ME, Marchuk DA.  Somatic Mutations in Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia Support a Biallelic Two-Hit Mutation Mechanism of Pathogenesis.   American Journal of Human Genetics,  111:2283-2298, 2024. PMID 39299239.

Sturge Weber Syndrome. We study different inherited vascular anomalies but in this case, we study a vascular syndrome that is not inherited. Sturge Weber syndrome (SWS) is a sporadic, congenital, neuro-cutaneous disorder characterized by a port-wine stain (PWS, a capillary vascular malformation) affecting the skin in the distribution of the ophthalmic branch of the trigeminal nerve, and abnormal capillary venous vessels in the leptomeninges of the brain and choroid, leading to glaucoma, seizures, stroke, and intellectual disability. In our collaborative work with Anne Comi and Jonathan Pevsner, Johns Hopkins Univ on this disease, we used whole genome sequencing of matched affected and unaffected tissues from SWS patients and identified a non-synonymous single-nucleotide variant (c.548G→A, p.R183Q) in GNAQ (encoding G alpha q) in most samples of affected tissue from both Sturge Weber syndrome and from non-syndromic PWS (Shirley et al., 2013). We further showed that this somatic mutation activates downstream ERK signaling, leading to the first scientifically based approaches for SWS therapy (Shirley et al., 2013). We recently investigated the molecular consequences of a novel somatic GNAQ mutation that we discovered in my lab. We have determined the consequences of various mutations in GNAQ, including this new mutation, in endothelial cells grown in culture. Additionally, using RNA sequencing analyses, we have provided new insight into the downstream consequences of this mutation in the disease-relevant cellular context (Galeffi et al., 2022).  We have recently developed a mouse model of Sturge Weber Syndrome based on a novel, engineered mutation switch cassette, that enables us to express the mutant allele at any time during embryonic and fetal development.  Using this novel mouse strain and various Cre drivers, we have validated Rudolf Happle’s decades old paradominant inheritance hypothesis; namely, that SWS and similar mosaic phenotypes are never inherited because they are lethal if passed through the germline (Wetzel-Strong et al., 2023). 

a.     Shirley MD, Tang H, Gallione CJ, Baugher JD, Frelin LP, Cohen B, North PE, Marchuk DA, Comi AM, Pevsner J.  Sturge Weber Syndrome and Port Wine stains caused by Somatic Mutation in GNAQ.  New England Journal of Medicine 368:1971-9, 2013. PMCID: 3749068.

b.     Galeffi F, Snellings DA, Wetzel-Strong S, Kastelic N, Bullock J, Gallione CJ, North PE, Marchuk DA. A novel somatic mutation in GNAQ in a capillary malformation provides insight into molecular pathogenesis. Angiogenesis, 25:493-502, 2022.   PMCID 9529792.

c.     Wetzel-Strong, SE, Galeffi F, Benavides C, Patrucco M, Bullock JL, Gallione CJ, Lee HK, and Marchuk DA.   Developmental Expression of the Sturge Weber Syndrome-associated Genetic Mutation in Gnaq:  A Formal Test of Happle’s Paradominant Inheritance Hypothesis.  Genetics. 224(4):iyad077, 2023.  PMID 37098137.

Genes Modulating Infarct Volume after Cerebral Ischemia.   Inbred mouse strains vary in the extent of neuronal cell death (infarct volume) after surgically induced cerebral ischemia.  The infarct size can vary over 50-fold across strains, illustrating the tremendous influence of natural genetic variation in the response of the brain tissue to ischemia.  We have exploited these profound differences to genetically map and identify genes modulating cerebral infarction.   During this work we have performed survival surgeries on over 4000 mice to induce cerebral ischemia and infarction and study genetic modulation of these phenotypes.

a.     Lee, HK, Keum S, Sheng H, Warner DS, Lo DC and Marchuk DA.  Natural allelic variation of the IL-21 receptor modulates ischemic stroke infarct volume. J Clinical Investigation 126:2827-38, 2016. PMCID 4966306. 

b.     Lee HK, Widmayer SJ, Huang MN, Aylor DL, Marchuk DA. Novel Neuroprotective Loci Modulating Ischemic Stroke Volume in Wild-Derived Inbred Mouse Strains. Genetics 213:1079-92, 2019. PMCID 6827375.

c.     Lee HK, Wetzel-Strong SE, Aylor DL, Marchuk DA. A Neuroprotective Locus Modulates Ischemic Stroke Infarction Independent of Collateral Vessel Anatomy. Front Neuroscience 15:705160, 2021.  PMCID: 8366065.

Lee, HK, Kwon DH, Aylor DL, Marchuk DA.  A cross-species approach using an in vivo evaluation platform in mice demonstrates that sequence variation in human RABEP2 modulates ischemic stroke outcomes. Am J Human Genetics. 109:1814-1827, 2022. PMCID:9606478

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