Position TitleAssociate Professor
Major Research Interests: To understand the role of oxidative stress and sterile inflammation in disease development and progression of diabetic retinopathy (DR), particularly the role played by thioredoxin-interacting protein in dysregulation of mitochondrial quality control and mitophagy leading to NLRP3 inflammasome activation; Targeted genomics, epigenomics and proteomics-based identification of early biomarkers of diabetes and its neuronal and vascular complications of the eyes via O-GlcNAc and S-nitrosylated proteins; RNAi technology and gene therapy approaches to prevent/slow down the progression of DR.
Research Educator, Full time, PhD, Histology and Cell Biology
- Ph.D., Biochemistry, Indian Institute of Science, Bangalore, India
- Associate Professor, Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI
Areas of Research
Diabetic Retinopathy – TXNIP, Mitophagy, UPRmt, Inflammasome activation, Neurovascular Protection, RNAi and Gene therapeutics
Previous research funded by: American Diabetes Association, National Kidney Foundation, JDRF Juvenile Diabetes Research Foundation, Mid-West Eye Banks
Our research is currently supported by NIH/NEI R01 grant EY023992.
Mitochondrial dysregulation and resultant energy imbalance is associated with various chronic diseases including neuro-degeneration, ischemia/reperfusion, and diabetic complications including diabetic retinopathy. Recently, we published that pro-oxidant thioredoxin interacting protein (TXNIP) is significantly up-regulated in diabetic retinas and under hyperglycemia in retinal cells in culture such as endothelial cells, pericytes and Muller cells (MC) and mediates cellular oxidative stress, inflammation and apoptosis. TXNIP has recently been implicated by several studies as a critical protein in the pathogenesis of diabetes and its complications. TXNIP binds to thioredoxin (Trx), a redox anit-oxidant protein, inhibiting its reactive oxygen species (ROS) scavenging and thiol reducing capacity; therefore, results in cellular oxidative/nitrosative (ROS/RNS) stress and aberrant protein s-nitrosylation. Furthermore, MC are important for retinal neuronal health and activated MC (gliosis) induces aberrant gene expression for cytokines and growth factors to maintain retinal homeostasis. However, prolonged MC activation is injurious in DR. Therefore, our overall hypothesis is that TXNIP is critical for MT dysfunction, mitophagy dysregulation, neurovascular injury, and MC activation in the development of DR. We are investigating the role of TXNIP in (i) MT dysfunction and retrograde stress responses (MT-UPR); and (ii) MT fission/fusion and mitophagy as a part of mitochondrial quality control in diabetic retinopathy. Is there a relationship between mitophagy deregulation and NLRP3 inflammasome activation and innate immune responses in diabetic retinopathy and, if any, to what extent TXNIP plays a role in this process are some of the questions being asked? To address these objectives, we will use streptozotocin (STZ)-induced type-1 diabetic models of rat and mouse in conjunction with manipulation of TXNIP expression levels (siRNA, CRISPR/Cas9-gRNA and knock-out mice) in the retina. In vitro studies using retinal MC, endothelial cells and neuronal cell cultures will be performed to dissect the molecular mechanisms as to how TXNIP induces MT dysfunction and mitophagy, which specifically removes damaged MT. Our studies may allow us to identify potential new targets for developing gene/drug therapies to prevent or slow down the progression of DR. We are also interested in identifying long noncoding RNAs and gene promoter methylome in retinal neurons in diabetes and after TXNIP knockdown (siRNAs) or knockout (CRISPR/Cas9-gRNAs). Currently; our research is supported by NIH/NEI grant, NIH/NEI Core grant to the Department of Anatomy and Cell Biology and Research to Prevent Blindness to the Department of Ophthalmology.
Links of Interest
- Devi TS#, Somayajulu M#,, Kowluru RA, Singh L.P. (2017) Txnip reglates mitophagy in retinal Muller cells under diabetic conditions: Implications for diabetic retinopathy. Cell Death Dis 8(5):e2777. doi: 10.1038/cddis.2017.190. #, Both considered as first authors.
PMID: 28492550 (#, Equal contributions)
- Pradhan P, Upadhyay N, Tiwari A, Singh L.P. (2016) Genetic and epigenetic modifications aimed at the pathogenesis of diabetic retinopathy: a molecular link to regulate gene expression. New Frontiers in Ophthalmology, 2(5): 192-204. PMID: 28691104
- Perrone L, Matrone C, Singh L.P. (2014) Epigenetic modifications and potential new treatment targets in diabetic retinopathy. J Ophthalmol. 2014:789120. PMID: 25165577
- Singh L.P. (2014) The NLRP3 Inflammasome and Diabetic Cardiomyopathy: Editorial to: "Rosuvastatin alleviates diabetic cardiomyopathy by inhibiting NLRP3 inflammasome and MAPK pathways in a type 2 diabetes rat model" by Beibei Luo et al. Cardiovasc Drugs Ther. 28(1):5-6. PMID: 24220800
- Singh L.P. (2013) Thioredoxin Interacting Protein (TXNIP) and Progression of Diabetic Retinopathy. J Clin Exp Ophthalmol, 4: 287.
- Devi TS, Hosoya KI, Terasaki T, Singh L.P. (2013) Critical role of TXNIP in oxidative stress, DNA damage, and apoptosis of pericytes in high glucose: Implications for diabetic retinopathy. Exp. Cell Res. 319:1001-1012. PMID: 23353834
- Singh, L.P., Devi, TS, Nantwi, KD. (2012) Theophylline Regulates Inflammatory and Neurotrophic factor Signals in Functional Recovery after C2-Hemisection in Adult Rats. Exp. Neurol., 238:79-88. PMID: 22981449
- Devi TS, Lee I, Huttemann M, Kumar A, Nantwi KC, Singh L.P. (2012) Txnip links innate host defense mechanisms to oxidative stress and inflammation in retinal Muller glia under chronic hyperglycemia: Implications for diabetic retinopathy. Exp. Diab Res., 2012;2012:438238. PMID: 22474421
- Devi TS, Hosoya K, Terasaki T, and Singh LP. (2011) GSK-3-CREB axis mediates IGF-1-induced ECM/adhesion molecule expression, cell cycle progression and monolayer permeability in retinal capillary endothelial cells: Implication for Diabetic Retinopathy. Biochim Biophys Acta-Molecular basis of disease 1812(9):1080-1088. PMID: 21549192
- Sbai O, Devi TS, Melone MA, Feron F, Khrestchatisky M, Singh L.P., and Perrone L. (2010). RAGE-TXNIP axis is required for S100B-promoted Schwann cell migration, fibronectin expression and cytokine secretion. J Cell Science 123(Pt 24):4332-4332
- Perrone L, Devi TS, Hosoya K, Terasaki T, and Singh LP. (2010). Inhibition of TXNIP Expression In Vivo Blocks Early Pathologies of Diabetic Retinopathy. Cell Death and Disease 1, e65; doi:10.1038/cddis.2010.42. PMID: 21364670
- Perrone L, Devi TS, Hosoya K, Terasaki T, and Singh LP. (2009). Thioredoxin-Interacting Protein (TXNIP) induces inflammation through chromatin modification in retinal capillary endothelial cells under diabetic conditions. J Cell Physiol. 221(1):262-272.