Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


Dissertation_Fazlur.pdf (5.07 MB)

ETD Abstract Container

Abstract Header

MOLECULAR MECHANISMS AND REGULATION OF NUCLEOSIDES AND NUCLEOSIDE ANALOGS TRANSPORT BY HUMAN EQUILIBRATIVE NUCLEOSIDE TRANSPORTER 3 (hENT3)

Rahman, Md Fazlur
http://rave.ohiolink.edu/etdc/view?acc_num=osu1512058137411356

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Pharmacy.
Nucleoside transporters play essential biological, pathological and pharmacological roles including nucleosides provision for salvage nucleotide synthesis, regulating various cellular signaling pathways and determining the therapeutic effectiveness and toxicities of nucleoside analog drugs. Nucleoside transporters are from two unrelated protein families: SLC29 and SLC28 family. In human SLC29 family has four members (hENT1, hENT2, hENT3, and hENT4) with hENT1, hENT2 and hENT4 transporting nucleosides and nucleoside analogs across the cell membrane. Unlike, hENT1, hENT2 and hENT4, hENT3 is an acidic pH-activated lysosomal transporter and partially localized in mitochondria. Despite hENT3’s prominent role in lysosome pathophysiology and mitochondrial toxicities of nucleoside analogs, the molecular basis of hENT3-mediated nucleosides and nucleoside analogs transport and its regulation in nucleoside homeostasis is unknown. Therefore, we sought to examine the mechanistic basis as well as its regulation in transporting nucleosides and nucleoside analogs. Scanning mutagenesis of putative residues responsible for pH-dependent transport via hENT3 revealed that the ionization states of Asp219 and Glu447, and not His, strongly determined the pH-dependent transport permissible-impermissible states of the transporter. Here we also identified the molecular determinants of hENT3 that dictate membrane translocation of 3'-deoxy-nucleoside analogs. Our findings indicated that whereas hENT1 demonstrated no significant transport activity towards 3'-deoxy-nucleoside analogs, hENT3 is capable of transporting 3'-deoxy-nucleoside analogs similar to hENT2. Molecular analyses of hENT3-hENT1 chimeric constructs demonstrated that the N-terminal half of hENT3 is primarily responsible for the hENT3-3'-deoxy-nucleoside analogs interaction. Furthermore, mutagenic studies identified that 225D and 231V in the N-terminus of hENT3 to partially contribute to hENT3’s ability to transport AZT and DDI. The identification of the transporter motifs and amino acid residues important in pH-dependent hENT3-mediated transport of nucleosides and nucleoside analogs may present implications for overcoming adverse toxicities and rational development of nucleoside analogs. Finally, we demonstrated that hENT3 as well as hENT2 and hENT1 may potentially be regulated by bile acids to maintain optimal and balanced level of cellular adenosine provision. Here, we propose a working model to elucidate the roles of bile acids in regulating adenosine metabolism by modulating the function of hENTs.
Rajgopal Govindarajan, Ph.D (Advisor)
196 p.
Pharmaceuticals; Pharmacology; Pharmacy Sciences

Recommended Citations

Citations

  • Rahman, M. F. (2017). MOLECULAR MECHANISMS AND REGULATION OF NUCLEOSIDES AND NUCLEOSIDE ANALOGS TRANSPORT BY HUMAN EQUILIBRATIVE NUCLEOSIDE TRANSPORTER 3 (hENT3) [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512058137411356

    APA Style (7th edition)

  • Rahman, Md Fazlur. MOLECULAR MECHANISMS AND REGULATION OF NUCLEOSIDES AND NUCLEOSIDE ANALOGS TRANSPORT BY HUMAN EQUILIBRATIVE NUCLEOSIDE TRANSPORTER 3 (hENT3). 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1512058137411356.

    MLA Style (8th edition)

  • Rahman, Md Fazlur. "MOLECULAR MECHANISMS AND REGULATION OF NUCLEOSIDES AND NUCLEOSIDE ANALOGS TRANSPORT BY HUMAN EQUILIBRATIVE NUCLEOSIDE TRANSPORTER 3 (hENT3)." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512058137411356

    Chicago Manual of Style (17th edition)

osu1512058137411356
22
© 2017, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.