title: MAP4 mechanism that stabilizes mitochondrial permeability transition in hypoxia: microtubule enhancement and DYNLT1 interaction with VDAC1.
abstract: Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption. In this study, we established the hypoxic (1% O(2)) cell models of rat cardiomyocytes, H9c2 and HeLa cells to further test MAP4 function. We demonstrated that increase in the pool of MAP4 could promote the stabilization of MT networks by increasing the synthesis and polymerization of tubulin in hypoxia. Results showed MAP4 overexpression could enhance cell viability and ATP content under hypoxic conditions. Subsequently we employed a yeast two-hybrid system to tag a protein interacting with mitochondria, dynein light chain Tctex-type 1 (DYNLT1), by hVDAC1 bait. We confirmed that DYNLT1 had protein-protein interactions with voltage-dependent anion channel 1 (VDAC1) using co-immunoprecipitation; and immunofluorescence technique showed that DYNLT1 was closely associated with MTs and VDAC1. Furthermore, DYNLT1 interactions with MAP4 were explored using a knockdown technique. We thus propose two possible mechanisms triggered by MAP4: (1) stabilization of MT networks, (2) DYNLT1 modulation, which is connected with VDAC1, and inhibition of hypoxia-induced mitochondrial permeabilization.
authors.affiliation: State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Ya-dong
authors.initials: YD
authors.lastname: Fang
authors.forename: Xue
authors.initials: X
authors.lastname: Xu
authors.forename: Yong-ming
authors.initials: YM
authors.lastname: Dang
authors.forename: Yi-ming
authors.initials: YM
authors.lastname: Zhang
authors.forename: Jia-ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Jiong-yu
authors.initials: JY
authors.lastname: Hu
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xia
authors.initials: X
authors.lastname: Dai
authors.forename: Miao
authors.initials: M
authors.lastname: Teng
authors.forename: Dong-xia
authors.initials: DX
authors.lastname: Zhang
authors.forename: Yue-sheng
authors.initials: YS
authors.lastname: Huang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002470:Cell Survival; D004398:Dyneins / Q000378:metabolism*; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D050995:Voltage-Dependent Anion Channel 1 / Q000378:metabolism*
chemical_list: C533376:DYNLT1 protein, human; D008869:Microtubule-Associated Proteins; D011994:Recombinant Proteins; C494762:VDAC1 protein, human; D049452:Green Fluorescent Proteins; D000255:Adenosine Triphosphate; D050995:Voltage-Dependent Anion Channel 1; D004398:Dyneins