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Role of Intracellular Labile Zinc in LPS-Induced Apoptosis in Sheep Pulmonary Arterial Endothelial Cells (SPAECS)

Thambiayya, Kalidasan (2012) Role of Intracellular Labile Zinc in LPS-Induced Apoptosis in Sheep Pulmonary Arterial Endothelial Cells (SPAECS). Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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We recently noted that exogenous zinc was capable of counteracting LPS-induced decreases in labile [Zn]i (i.e., TPEN chelatable, FluoZin-3 detectable) and simultaneously abrogated LPS-induced apoptosis in SPAECs. In an abbreviated survey of the effect of LPS on potential zinc transporters, we noted that LPS increased mRNA of zinc importer, SLC39A14 or ZIP14 (and this effect was mimicked by zinc chelator, TPEN) suggesting that increased expression of SLC39A14 may be an homeostatic mechanism to maintain [Zn]i and reduce cellular toxicity to LPS. In the current study, we noted that knockdown of SLC39A14 with siRNA rendered SPAECs more sensitive to LPS-induced apoptosis and also impaired the ability of exogenous zinc to rescue this effect. We also previously noted that iNOS or chemically derived (S-nitroso-N-acetylpenicillamine (SNAP)) nitric oxide (NO) is associated with resistant phenotype to LPS-induced apoptosis in a zinc dependent fashion. Since ZIP14 expression has been reported to be indirectly upregulated by NO, we pursued this connection in SPAECs by silencing ZIP14 using siRNA technology. We noted that NO-mediated resistance to LPS-induced apoptosis was independent of ZIP14 but was critically dependent upon the presence of sheep metallothionein (MT). In particular, genetic silencing of these collective forms of sheep MT isoforms abrogated the NO-dependent resistant phenotype to LPS-induced apoptosis as well as abolishing NO-mediated increases in [Zn]i. Collectively, these data confirm that increases in labile [Zn]i are an important component of ZIP14- or NO-mediated resistance to LPS-induced apoptosis. Cytoprotection via ZIP14 appears to be secondary to transcellular movement of extracellular zinc whereas NO mediated protection is secondary to S-nitrosation of MT and redistribution of intracellular zinc.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Thambiayya, Kalidasanthk25@pitt.eduTHK25
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairPitt, Brucebrucep@pitt.eduBRUCEP
Committee MemberShroff, Sanjeev sshroff@pitt.eduSSHROFF
Committee MemberRoy, Parthapar19@pitt.eduPAR19
Committee MemberElias, Aizenmanredox@pitt.eduREDOX
Committee MemberStoyanovsky, Detchodas11@pitt.eduDAS11
Date: 26 September 2012
Date Type: Publication
Defense Date: 15 June 2012
Approval Date: 26 September 2012
Submission Date: 20 July 2012
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 118
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Zinc, LPS, Nitric Oxide, Metallothionein, ZIP14, SLC39A14, apoptosis, pulmonary endothelium, Acute lung injuey, S-nitrosation, caspase-3, zinc homeostasis.
Date Deposited: 26 Sep 2012 14:59
Last Modified: 15 Nov 2016 14:00


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