Research
Ji, James, M.D., M.S.
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Contact: james.ji@uthct.edu
Research Interest:
Regulation of epithelial fluid transport
Current projects:
- Posttranslational regulation of lung epithelial sodium channels by reactive species and cGMP.
- Contribution of mesothelial ion transport to tuberculous pleural effusion.
- Salt and fluid transport at the cellular and molecular levels in bacteria and virus-induced pulmonary edema and acute lung injuries.
- Regulation of mucus clearance in inflammatic airway associated with asthma, chronic obstructive pulmonary disease (COPD), allergy, cigarette smoke, and occupational lung diseases.
Research Overview:
Epithelial sodium channel (ENaC) plays a critical role in airway mucus clearance and alveolar fluid clearance. Dysfunctional mucus/fluid clearance has been implicated in the pathogenesis of various pulmonary diseases/syndromes, for instance, Cystic fibrosis, Pseudohypoaldosteronism type 1 (PHA-1), viral and bacterial pneumonia, influenza, occupational/environmental bronchitis, chronic obstructive pulmonary disease (COPD), and allergic respiratory disorders. ENaC as a major pathway for fluid re-absorption contributes up to 70% of lavage/fluid clearance. ENaC activity is regulated by reactive oxygen/nitrogen species, protein kinases, proteinases, hormones, and toxins. Our studies on the regulation of ENaC function in lung epithelium will provide novel information to our understanding of the pathogenesis of edematous and hypersecretive pulmonary diseases.
Selected Papers:
- Su XF, Li Q, Shrestha K, Cormet-Boyaka E, Chen L, Smith PR, Sorscher EJ, Benos DJ, Matalon S, Ji HL. Interregulation of proton-gated Na(+) channel 3 and cystic fibrosis transmembrane conductance regulator. Journal of Biological Chemistry Dec 1, 281(48):36960-36968.
- Ji HL, Su XF, Shrestha K, Li J, Barbry P, Smith PR, Matalon S, Benos DJ. (2006) Delta-subunit confers novel biophysical features to alpha beta gamma-human epithelial sodium channel (ENaC) via a physical interaction. Journal of Biological Chemistry, Mar 24; 281(12):8233-8241.
- Ji HL. and Benos DJ. (2004) Degenerin sites mediate proton activation of deltabetagamma-epithelial sodium channel. Journal of Biological Chemistry June 25, 279(26):26939-26947.
- Ji HL, Bishop LR, Anderson SJ, Fuller CM, Benos DJ. (2004) The role of pre-H2 domains of alpha-and delta-ENaC in ion permeation, conductance, and amiloride sensitivity. Journal of Biological Chemistry Feb 27; 279(9):8428-8440.
- Bubien JK, Ji HL, Gillespie GY, Fuller CM, Markert JM, Mapstone TB, and Benos, DJ. (2004) Cation selectivity and inhibition of malignant glioma Na+ channels by Psalmotoxin 1. American Journal of Physiology: Cell Physiology. Nov; 287(5):C1282-1291.
- Berdiev BK, Xia J, McLean LA, Gillespie GY, Mapstone TB, Naren AP, Jovov B, Bubien JK, Ji HL, Fulle CM, Kirk KL, Benos DJ. (2003) Acid-sensing ion channels in malignant gliomas. Journal of Biological Chemistry. 278(17):15023-15034.
- Ji HL, Fuller CM, Benos DJ. (2002) Intrinsic gating mechanisms of epithelial sodium channels (ENaC). American Journal of Physiology: Cell Physiology. 283: C646-C650.
- Ji HL, Jovov B, Fu J, Bishop LR, Mebane HC, Fuller CM, Stanton BA, Benos DJ. (2002) Up-regulation of Acid-Gated Na+ Channels (ASICs) by CFTR Co-Expression in Xenopus Oocytes. Journal of Biological Chemistry. Mar 8; 277(10):8395-405.
- Jovov B, Berdiev BK, Fuller CM, Ji HL, Benos DJ. (2002) The serine-protease trypsin cleaves C-termini of beta and gamma subunits of ENaC. Journal of Biological Chemistry. Feb 8; 277(6):4134-40.
