Currently LMI funded projects:
Investigator: Natasha Harvey, PhD
Institution: University of South Australia (Adelaide, Australia)
Title of Project: Defining the Mechanisms by which MDFIC Mutations Cause Central Conducting Lymphatic Anomaly (CCLA)
Project Overview: Central conducting lymphatic anomaly (CCLA), characterized by the dysfunction of core collecting lymphatic vessels including the thoracic duct and cisterna chyli and presenting with chylothorax, pleural effusions, chylous ascites and lymphoedema, is a severe disorder often resulting in fetal or perinatal demise. While mutations in genes including ARAF, EPHB4 and JAG1 have been documented in patients with CCLA, the genetic etiology of CCLA remains in large part, uncharacterized. We have identified homozygous, and compound heterozygous, mutations in MDFIC, encoding the MyoD family inhibitor domain containing protein, in fetuses presenting with non-immune hydrops fetalis and children with a history of hydrops fetalis, pleural and pericardial effusions and lymphoedema, consistent with CCLA. Generation of a mouse model of the human MDFIC truncating mutation (Met131fs*) found in patients revealed that homozygous Mdfic mutant mice die perinatally exhibiting chylothorax, the accumulation of lipid rich chyle in the thoracic cavity catalyzed by lymphatic vessel dysfunction. Characterization of the lymphatic vasculature of homozygous Mdfic mutant mice revealed profoundly mis-patterned lymphatic vessels and major defects in lymphatic vessel valve development. We hypothesize that MDFIC plays crucial roles during embryonic development of the lymphatic vasculature and that the mutations identified in patients with CCLA profoundly impact protein function. The goal of this proposal is to define the mechanisms by which MDFIC governs development and function of the lymphatic vasculature. Ultimately, understanding the genetic and mechanistic basis of CCLA will facilitate the development and implementation of new therapeutic approaches able to effectively treat this complex, devastating disease.
Investigator: Dong Li, PhD
Institution: Children’s Hospital of Philadelphia (Philadelphia, PA)
Title of Project: Identification and Characterization of Variants Underlying Complex Lymphatic Anomalies
Project Overview: Complex lymphatic anomalies, which include a variety of diagnoses, are chronically debilitating, devastating, and often life-threatening diseases with limited treatment options. Magnetic resonance (MR) lymphangiogram has allowed for visualization of lymphatics and intervention. Our preliminary studies have revealed multiple genes converging on PI3K and MAPK pathways and modeling mutations in cellular and zebrafish systems have recapitulated the essential morphological features seen in the patients. We have found a handful of MEK/ERK inhibitors and PI3K inhibitor showed the biochemistry and morphological reversal of the effects of mutations in these genes. Taken together, we have successfully implemented precision- medicine approaches for two patients with CCLA and KLA. The absence of data on the molecular etiology, and lack of understanding of the underlying molecular mechanisms have greatly hampered further research and precision medicine focused clinical trials. Our long-term goal is to identify efficacious therapies for complex lymphatic anomalies. The objective of this application is to uncover novel/recurrent disease-causing mutations in GLA/GSD/KLA/CCLA and use in vitro and in vivo models established in our previous studies to determine optimal treatment strategies, including PI3K, mTOR, MEK, and VEGFR3 inhibitors. This proposal will test the hypothesis that sequencing of highly informative patients referred by an integrated multidisciplinary lymphatic anomalies clinic will unveil novel/recurrent variants, and these can be rapidly interrogated through our established cellular and zebrafish models to further investigate the mutation phenotype spectrum effect. The results from these experiments will provide validated pre-clinical data for molecularly implemented precision-based therapies for clinical trials.