Talk abstracts
Talk on Friday 03:45-04:00pm submitted by Andrew Gupta
Development and characterization of an inducible, hepatocyte-specific mouse model of myotonic dystrophy type 1
Andrew Gupta (Department of Biochemistry, University of Illinois at Urbana-Champaign, IL), Zac Dewald (Department of Biochemistry, University of Illinois at Urbana-Champaign, IL), Ullas Chembazhi (Department of Biochemistry, University of Illinois at Urbana-Champaign, IL), Auinash Kalsotra (Department of Biochemistry, Carl R. Woese Institute for Genomic Biology, and Cancer Center at Illinois, University of Illinois at Urbana-Champaign, IL)
Abstract:
Myotonic Dystrophy Type 1 (DM1) is a multi-systemic human genetic disorder characterized by muscle wasting, myotonia, cardiac and gastrointestinal abnormalities, and cognitive impairment, among other symptoms. The disease originates from abnormal expansions of CTG repeats in the 3’ UTR of the DMPK gene which, upon transcription, generates DMPK RNA with extended CUG repeats. The repeat-containing RNA bind to and sequester muscleblind-like (MBNL) proteins, a family of alternative splicing regulators, into nuclear foci. Such sequestration induces missplicing of a wide variety of genes, leading to the disease phenotype. Although the disease phenotype has been well-characterized in muscle and heart, the effects of the disease in the liver remain poorly understood. To study the effects in the liver, we have developed a transgenic mouse model for DM1 that recapitulates the disease phenotype in an inducible, liver-specific manner. Namely, a DMPK gene containing 960 CTG repeats has been inserted into the mouse genome and placed under the control of a hepatocyte-specific Tetracycline-on system. We have characterized this mouse model by examining its molecular and physiological phenotypes. qPCR confirms that toxic mRNA is expressed at significant levels following induction with doxycycline. RNA-FISH and immunofluorescence performed on the mouse model shows the formation of toxic RNA foci and the sequestration of MBNL therein, consistent with known disease pathology. Furthermore, we have demonstrated that significant shifts in splicing patterns occur in the transgenic mice compared to wild-type mice. The physiological effects of the disease were then observed using histological stains, which revealed changes in liver morphology, inflammation, and lipid accumulation. Along with characterizing the mouse model, we have successfully used the model to investigate the therapeutic potential of a small-molecule compound.
References:
Chau, A. & Kalsotra, A. Developmental insights into the pathology of and therapeutic strategies for DM1: back to the basics. Developmental Dynamics, 244, 377-390 (2015).
Brook, J.D. et al. Molecular basis of myotonic dystrophy: expansion of a trinucleotide (CTG) repeat at the 3′ end of a transcript encoding a protein kinase family member. Cell, 68, 799-808 (1992).
Keywords: Myotonic Dystrophy Type 1, alternative splicing, mouse model