title: Coupling of ryanodine receptor 2 and voltage-dependent anion channel 2 is essential for Ca²+ transfer from the sarcoplasmic reticulum to the mitochondria in the heart.
abstract: The structural proximity and functional coupling between the SR (sarcoplasmic reticulum) and mitochondria have been suggested to occur in the heart. However, the molecular architecture involved in the SR-mitochondrial coupling remains unclear. In the present study, we performed various genetic and Ca2+-probing studies to resolve the proteins involved in the coupling process. By using the bacterial 2-hybrid, glutathione transferase pull-down, co-immunoprecipitation and immunocytochemistry assays, we found that RyR2 (ryanodine receptor type 2), which is physically associated with VDAC2 (voltage-dependent anion channel 2), was co-localized in SR-mitochondrial junctions. Furthermore, a fractionation study revealed that VDAC2 was co-localized with RyR2 only in the subsarcolemmal region. VDAC2 knockdown by targeted short hairpin RNA led to an increased diastolic [Ca2+] (calcium concentration) and abolishment of mitochondrial Ca2+ uptake. Collectively, the present study suggests that the coupling of VDAC2 with RyR2 is essential for Ca2+ transfer from the SR to mitochondria in the heart.
authors.affiliation: School of Life Sciences and Systems Biology Research Centre, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
authors.forename: Choon Kee
authors.initials: CK
authors.lastname: Min
authors.forename: Dong Rim
authors.initials: DR
authors.lastname: Yeom
authors.forename: Kyung-Eun
authors.initials: KE
authors.lastname: Lee
authors.forename: Hye-Kyeong
authors.initials: HK
authors.lastname: Kwon
authors.forename: Moonkyung
authors.initials: M
authors.lastname: Kang
authors.forename: Yeon-Soo
authors.initials: YS
authors.lastname: Kim
authors.forename: Zee Yong
authors.initials: ZY
authors.lastname: Park
authors.forename: Hyesung
authors.initials: H
authors.lastname: Jeon
authors.forename: Do Han
authors.initials: DH
authors.lastname: Kim
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D055785:Gene Knockdown Techniques; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport; D008297:Male; D051379:Mice; D008929:Mitochondria, Heart / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D050996:Voltage-Dependent Anion Channel 2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D019837:Ryanodine Receptor Calcium Release Channel; D050996:Voltage-Dependent Anion Channel 2; D002118:Calcium