Unique characteristics of Ca2+ homeostasis of the trans-Golgi compartment.
Taking advantage of a fluorescent Ca(2+) indicator selectively targeted to the trans-Golgi lumen, we here demonstrate that its Ca(2+) homeostatic mechanisms are distinct from those of the other Golgi subcompartments: (i) Ca(2+) uptake depends exclusively on the activity of the secretory pathway Ca(2+) ATPase1 (SPCA1), whereas the sarco-endoplasmic reticulum Ca(2+) ATPase (SERCA) is excluded; (ii) IP(3) generated by receptor stimulation causes Ca(2+) uptake rather than release; (iii) Ca(2+) release can be triggered by activation of ryanodine receptors in cells endowed with robust expression of the latter channels (e.g., in neonatal cardiac myocyte). Finally, we show that, knocking down the SPCA1, and thus altering the trans-Golgi Ca(2+) content, specific functions associated with this subcompartment, such as sorting of proteins to the plasma membrane through the secretory pathway, and the structure of the entire Golgi apparatus are dramatically altered.
Lissandron
Valentina
V
Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy.
Podini
Paola
P
Pizzo
Paola
P
Pozzan
Tullio
T
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D015703:Antigens, CD; D002118:Calcium; D000252:Calcium-Transporting ATPases; D049452:Green Fluorescent Proteins; D012799:Sialyltransferases; C093493:ST6GAL1 protein, human; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase; C403624:ATP2C1 protein, human