TY - JOUR T1 - Homooligomerization of the ABC-transporter 3 and its functional significance JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P790 AU - Sabrina Frixel AU - Eva Kaltenborn AU - Amelie S. Lotz-Havla AU - Søren W. Gersting AU - Ralf Zarbock AU - Matthias Griese Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P790.abstract N2 - Background and aim: ABCA3 is a surfactant lipid transporter in the limiting membrane of lamellar bodies in alveolar type II cells. Mutations in the ABCA3 gene cause respiratory distress syndrome in newborns and chronic interstitial lung disease in children and adults. ABCA3 belongs to the class of full ABC-transporters, which are supposed to be functional in their monomeric forms. Though other family members e.g. ABCA1 and ABCC7 have been shown to function as oligomers, the oligomerization state of ABCA3 remains to be elucidated.Methods: Oligomerization of ABCA3 was investigated in cell lysates and crude membrane preparations from transiently and stably transfected HEK293 cells using blue native PAGE (BN-PAGE), gel filtration and co-immunoprecipitation. Additionally, homooliomerization was examined in vivo in cells using bioluminescence resonance energy transfer (BRET).Results: Using BN-PAGE and gel filtration, methods that separate proteins in their native state according to their molecular size, we could show that non-denatured ABCA3 exists in different oligomeric forms, such as monomers, dimers, tetramers and even higher oligomers. Homooligomerization of ABCA3-wildtype was shown via co-immunoprecipitation of HA- and YFP-tagged ABCA3. Oligomerization could be verified in vivo by detecting positive interactions using BRET.Conclusion: Besides its monomeric state, ABCA3 was detected in additional oligomeric forms. We therefore suggest transporter oligomerization as a central mechanism for ABCA3 function. Insights into the fundamentals of the transport process will provide a better understanding of ABCA3-related diseases and enable the analysis of patient mutations and its interactions. ER -