排序方式: 共有2条查询结果,搜索用时 15 毫秒
1
1.
Durieux AC Vassilopoulos S Lainé J Fraysse B Briñas L Prudhon B Castells J Freyssenet D Bonne G Guicheney P Bitoun M 《Traffic (Copenhagen, Denmark)》2012,13(6):869-879
Dynamin 2 (Dnm2) is involved in endocytosis and intracellular membrane trafficking through its function in vesicle formation from distinct membrane compartments. Heterozygous (HTZ) mutations in the DNM2 gene cause dominant centronuclear myopathy or Charcot-Marie-Tooth neuropathy. We generated a knock-in Dnm2R465W mouse model expressing the most frequent human mutation and recently reported that HTZ mice progressively developed a myopathy. We investigated here the cause of neonatal lethality occurring in homozygous (HMZ) mice. We show that HMZ mice present at birth with a reduced body weight, hypoglycemia, increased liver glycogen content and hepatomegaly, in agreement with a defect in neonatal autophagy. In vitro studies performed in HMZ embryonic fibroblasts point out to a decrease in the autophagy flux prior to degradation at the autolysosome. We show that starved HMZ cells have a higher number of immature autophagy-related structures probably due to a defect of acidification. Our results highlight the role of Dnm2 in the cross talk between endosomal and autophagic pathways and evidence a new role of Dnm2-dependent membrane trafficking in autophagy which may be relevant in DNM2-related human diseases. 相似文献
2.
Cooperative interaction between Ca2+ binding sites in the hydrophilic loop of the Na+-Ca2+ exchanger
Levitsky Dmitri O. Fraysse Bodvaël Leoty Claude Nicoll Debora A. Philipson Kenneth D. 《Molecular and cellular biochemistry》1996,160(1):27-32
A high affinity Ca2+-binding domain which is located in a middle portion of the large intracellular loop of the Na+-Ca2+ exchanger contains two highly acidic sequences, each characterized by three consecutive aspartic acid residues (Levitsky DO, Nicoll DA, and Philipson KD (1994) J Biol Chem 269: 22847–22852). This portion of the protein provides secondary Ca2+ regulation of the exchanger activity. To determine number of Ca2+ binding sites participating in formation of the high affinity domain, we isolated polypeptides of different lengths encompassing the domain and measured 45Ca2+ binding. The fusion proteins containing the high affinity domain were obtained in a Ca2+-bound form and as evidenced by shifts in there mobility in SDS-polyacrylamide gels after EGTA treatment. The Ca2+ binding curves obtained after equilibrium dialysis reached saturation at 1 M free Ca2+, Kd value being approx. 0.4 M. The Ca2+ binding occured in a highly cooperative manner. Upon saturation, the amount of Ca2+ ion bound varied from 1.3–2.1 mot per mot protein. Proteins with an aspartate in each acidic sequence mutated lacked the positive cooperativity, had lower Ca2+ affinity and bound two to three times less Ca2+. Na+-Ca2+ exchangers of tissues other than heart though different from the cardiac exchanger by molecular weight most likely possess a similar Ca2+ binding site. It is concluded that, by analogy with Ca2+ binding proteins of EF-type, the high Ca2+-affinity domain of the Na+-Ca2+ exchanger is comprised of at least two binding sites interacting cooperatively. 相似文献
1