Education & Training
- M.D., Dayanand Medical College & Hospital, Ludhiana, India-1993
- Postdoctoral Fellowship, Georgetown University-1997
- Postdoctoral Fellowship, Temple University-1999
Research Interest Summary
Current research projects are aimed at elucidating the cellular and molecular mechanisms of liver pathophysiology. We are interested in understanding the process of liver regeneration. Using genetic knockout (inducible, conditional) we are in the process of determining the cell-molecule circuitry of the Wnt signaling during liver regeneration process. Similarly, we are interested in the regulation of the process of metabolic zonation where hepatocytes in different zones of the hepatic lobule are bestowed with different functional capacities owing to the differential gene expression. The pericentral gene expression is under the control of Wnt signaling, and the periportal gene signature has been suggested to be under the control of Yap signaling. This process of dynamic interactions between the two signaling pathways is also under investigation. Since hepatic repair after various injuries is dictated by the kind of injury and type of cell affected, several studies have shown the potential of hepatocytes and biliary epithelial cells to transdifferentiate into one another. We are examining the models and the molecular mechanisms that underlie these processes so as to exploit them for regulating repair process. A major sequela of multiple chronic liver diseases is in fact development of hepatic fibrosis. This involves in large part activation of hepatic stellate cells to form activated myofibroblasts, which are the source of collagen and scarring in the liver with the eventual development of cirrhosis. We are examining molecular signals that are relevant in stellate cell activation and biology, which can be targeted for development of anti-fibrotic therapies. Similarly, we are interested in role of macrophages in hepatic injury and repair process and their crosstalk with stellate cells. A common form of hepatic injury is cholestatic, where there is an impairment of bile flow in the liver causing retention of bile acids and injury to hepatic parenchyma as well as breach of blood bile barrier that results in bilirubin and bile acid leaking into systemic circulation. Using animal models, we are looking at novel ways to modulate bile acid metabolism to counteract cholestatic liver injury and repair. Similarly, we are investigating novel mechanisms that underlie the pathogenesis of various cholestatic liver diseases. We have identified the important role of adherens junctions, tight junctions, and desmosomes in maintenance of blood bile barrier through unique mechanisms and crosstalk. We have generated animal models to address such mechanisms and using innovative imaging methodologies like intravital microscopy, we have identified peculiar underpinnings of disorders such as PFIC. We hope to devise novel therapeutic interventions based on new findings. Lastly, we are interested in another relevant sequela of many chronic liver diseases. Liver tumors—especially hepatocellular cancer—develops mostly in the backdrop of chronic liver injury. We are interested in identifying patient-relevant molecular aberrations, and using a reductionist approach, we generate animal models to address biology and therapies. We use sleeping beauty transposon/transposase and hydrodynamic tail vein injections to deliver the plasmids into 1-5% of hepatocytes in a mouse to examine tumorigenesis. Using high throughput analysis of tumors (gene array), we are addressing gene expression changes, which are then correlated with existing human HCC databases, such as TCGA, to address the similarity of the animal model to the human disease. Such validation allows us to more confidently use this model as a representative of a subset of human HCC. Such approaches have also yielded novel information about other liver tumors like hepatoblastomas.
Russell JM, Lu W-Y, Okabe H, Abrams M, Oertel M, Poddar M, Singh S, Forbes S, Michael, Monga SP, Hepatocyte-specific-β-catenin deletion during severe liver injury provokes cholangiocytes to differentiate into regenerative hepatocytes. Hepatology (In Press).
Preziosi M, Okabe H, Poddar M, Singh S, Monga SP. Endothelial Wnts regulate β-catenin signaling in murine liver zonation and regeneration: A sequel to the Wnt-Wnt situation. Hepatol Commun. 2018 Jun 21;2(7):845-860. doi: 10.1002/hep4.1196. eCollection 2018 Jul. PubMed PMID: 30027142; PubMed Central PMCID: PMC6049069.
Molina L, Bell D, Tao J, Preziosi M, Pradhan-Sundd T, Singh S, Poddar M, Luo J, Ranganathan S, Chikina M, Monga SP. Hepatocyte-Derived Lipocalin 2 Is a Potential Serum Biomarker Reflecting Tumor Burden in Hepatoblastoma. Am J Pathol.2018 Jun 18. pii: S0002-9440(17)31236-1. doi: 10.1016/j.ajpath.2018.05.006. [Epub ahead of print] PubMed PMID: 29920228.
Russell JO, Ko S, Saggi HS, Singh S, Poddar M, Shin D, Monga SP. Bromodomain and Extraterminal (BET) Proteins Regulate Hepatocyte Proliferation in Hepatocyte-Driven Liver Regeneration. Am J Pathol. 2018 Mar 12. pii: S0002-9440(17)30773-3. doi: 10.1016/j.ajpath.2018.02.006. [Epub ahead of print] PubMed PMID: 29545201.
Preziosi M, Poddar M, Singh S, Monga SP. Hepatocyte Wnts are dispensable during diethylnitrosamine and carbon tetrachloride-induced injury and hepatocellular cancer. Gene Expr. 2018 Mar 8. doi: 10.3727/105221618X15205148413587. [Epub ahead of print] PubMed PMID: 29519268.
Zhan N, Adebayo Michael A, Wu K, Zeng G, Bell A, Tao J, Monga SP. The effect of selective c-met inhibitor on HCC in the Met-active, β-catenin mutated mouse model. Gene Expr. 2018 Feb 6. doi: 10.3727/105221618X15174108894682. [Epub ahead of print] PubMed PMID: 29409568.
Pradhan-Sundd T, Zhou L, Vats R, Jiang A, Molina L, Singh S, Poddar M, Russell JM, Stolz DB, Oertel M, Apte U, Watkins S, Ranganathan S, Nejak-Bowen KN, Sundd P, Monga SP. Dual catenin loss in murine liver causes tight junctional deregulation and progressive intrahepatic cholestasis. Hepatology. 2017 Oct 10. doi: 10.1002/hep.29585. PubMed PMID: 29023813. (Accompanying Editorial).
Puliga E, Min Q, Tao J, Zhang R, Pradhan-Sundd T, Poddar M, Singh S, Columbano A, Yu J, Monga SP. Thyroid Hormone Receptor-β Agonist GC-1 Inhibits Met-β-Catenin-Driven Hepatocellular Cancer. Am J Pathol. 2017 Nov;187(11):2473-2485. doi: 10.1016/j.ajpath.2017.07.005. Epub 2017 Aug 12. PubMed PMID: 28807594.
Kikuchi A, Pradhan-Sundd T, Singh S, Nagarajan S, Loizos N, Monga SP. Platelet-Derived Growth Factor Receptor α Contributes to Human Hepatic Stellate Cell Proliferation and Migration. Am J Pathol. 2017 Oct;187(10):2273-2287. doi: 10.1016/j.ajpath.2017.06.009. Epub 2017 Jul 20. PubMed PMID: 28734947. (Recommended by F1000)
Nejak-Bowen K, Moghe A, Cornuet P, Preziosi M, Nagarajan S, Monga SP. Role and regulation of p65/β-catenin association during liver injury and regeneration: a 'complex' relationship. Gene Expr. 2017 Apr 28.