title: CD147 required for corneal endothelial lactate transport.
abstract: OBJECTIVE
  CD147/basigin is a chaperone for lactate:H(+) cotransporters (monocarboxylate transporters) MCT1 and MCT4. We tested the hypothesis that MCT1 and -4 in corneal endothelium contribute to lactate efflux from stroma to anterior chamber and that silencing CD147 expression would cause corneal edema.
  
  
  METHODS
  CD147 was silenced via small interfering ribonucleic acid (siRNA) transfection of rabbit corneas ex vivo and anterior chamber lenti-small hairpin RNA (shRNA) pseudovirus in vivo. CD147 and MCT expression was examined by Western blot, RT-PCR, and immunofluorescence. Functional effects were examined by measuring lactate-induced cell acidification, corneal lactate efflux, [lactate], central cornea thickness (CCT), and Azopt (a carbonic anhydrase inhibitor) sensitivity.
  
  
  RESULTS
  In ex vivo corneas, 100 nM CD147 siRNA reduced CD147, MCT1, and MCT4 expression by 85%, 79%, and 73%, respectively, while MCT2 expression was unaffected. CD147 siRNA decreased lactate efflux from 3.9 ± 0.81 to 1.5 ± 0.37 nmol/min, increased corneal [lactate] from 19.28 ± 7.15 to 56.73 ± 8.97 nmol/mg, acidified endothelial cells (pHi = 6.83 ± 0.07 vs. 7.19 ± 0.09 in control), and slowed basolateral lactate-induced acidification from 0.0034 ± 0.0005 to 0.0012 ± 0.0005 pH/s, whereas apical acidification was unchanged. In vivo, CD147 shRNA increased CCT by 28.1 ± 0.9 μm at 28 days; Azopt increased CCT to 24.4 ± 3.12 vs. 12.0 ± 0.48 μm in control, and corneal [lactate] was 47.63 ± 6.29 nmol/mg in shCD147 corneas and 17.82 ± 4.93 nmol/mg in paired controls.
  
  
  CONCLUSIONS
  CD147 is required for the expression of MCT1 and MCT4 in the corneal endothelium. Silencing CD147 slows lactate efflux, resulting in stromal lactate accumulation and corneal edema, consistent with lactate efflux as a significant component of the corneal endothelial pump.
authors: School of Optometry, Indiana University, Bloomington, Indiana, United States.
authors: Shimin
authors: S
authors: Li
authors: School of Optometry, Indiana University, Bloomington, Indiana, United States.
authors: Tracy T
authors: TT
authors: Nguyen
authors: School of Optometry, Indiana University, Bloomington, Indiana, United States.
authors: Joseph A
authors: JA
authors: Bonanno
mesh_terms: D000818:Animals; D000867:Anterior Chamber / Q000378:metabolism; D051926:Basigin / Q000502:physiology*; D015153:Blotting, Western; D002257:Carbonic Anhydrase Inhibitors / Q000494:pharmacology; D003319:Corneal Stroma / Q000378:metabolism; D004728:Endothelium, Corneal / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D020868:Gene Silencing / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D019344:Lactic Acid / Q000378:metabolism*; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology; D013843:Thiazines / Q000494:pharmacology; D014162:Transfection
chemical_list: D002257:Carbonic Anhydrase Inhibitors; D027501:Monocarboxylic Acid Transporters; D034741:RNA, Small Interfering; D013449:Sulfonamides; D013843:Thiazines; D051926:Basigin; D019344:Lactic Acid; C111827:brinzolamide
keywords: CD147; MCT1; MCT4; corneal endothelial pump; lactate transport