Association of PDZ-containing protein PDZD11 with the human sodium-dependent multivitamin transporter

Abstract

Nabokina SM, Subramanian VS, Said HM. Association of PDZcontaining protein PDZD11 with the human sodium-dependent multivitamin transporter. Am J Physiol Gastrointest Liver Physiol 300: G561-G567, 2011. First published December 23, 2010 doi:10.1152/ajpgi.00530.2010Intestinal absorption of biotin is mediated via the sodium-dependent multivitamin transporter (SMVT). Studies from our laboratory and others have characterized different aspects of the human SMVT (hSMVT), but nothing is currently known about protein(s) that may interact with hSMVT and affect its physiology/biology. In this study, a PDZ-containing protein PDZD11 was identified as an interacting partner with hSMVT using yeast two-hybrid screen of a human intestinal cDNA library. The interaction between hSMVT and PDZD11 was confirmed by in vitro GST-pull-down assay and in vivo in a mammalian cell environment by a two-hybrid luciferase and coimmunoprecipitation assays. Furthermore, confocal imaging of live human intestinal epithelial HuTu-80 cells expressing hSMVT-GFP and DsRed-PDZD11 demonstrated colocalization of these two proteins. We also examined the functional consequence of the interaction between hSMVT and PDZD11 in HuTu-80 cells and observed significant induction in [ 3 H]biotin uptake upon coexpression of hSMVT and PDZD11. In contrast, knocking down of PDZD11 with genespecific small interfering RNA led to a significant decrease in biotin uptake; biotinylation assay showed this to be associated with a marked decrease in level of expression of hSMVT at the cell membrane. By truncation approach, we also demonstrated that the PDZ binding domain that is located in the COOH-terminal tail of hSMVT polypeptide is involved in the interaction with PDZD11. These results demonstrate for the first time that PDZD11 is an interacting partner with hSMVT in intestinal epithelial cells and that this interaction affects hSMVT function and cell biology. biotin transport; protein-protein interactions; yeast two-hybrid analysis

PLEKHA7 Recruits PDZD11 to Adherens Junctions to Stabilize Nectins

“…The proposed function of PDZD11, a ubiquitously expressed protein, was to provide a scaffold for these transmembrane proteins, by binding through its PDZ domain, to the PDZ-binding motif at their C terminus. Supporting this idea, depletion of PDZD11 reduced the cell surface expression of the sodium-dependent multivitamin transporter, as assessed by cell surface biotinylation assay (32). Other single PDZ proteins, such as MALS (mammalian homolog of , are implicated in intracellular transport and targeting of their partner proteins (38), and future studies should determine whether PDZD11 also plays this role, for example by promoting the efficient transport of PDZ-binding proteins such as nectins to the cell surface.…”

“…PDZD11 is also known as AIPP1 through its binding to the cytoplasmic tail of the Menkes copper ATPase ATP7A (31) and as an interactor of the sodium-dependent multivitamin transporter (32). The proposed function of PDZD11, a ubiquitously expressed protein, was to provide a scaffold for these transmembrane proteins, by binding through its PDZ domain, to the PDZ-binding motif at their C terminus.…”

Intestinal absorption of water-soluble vitamins in health and disease

“…Another recent study, using yeast two-hybrid screening of a human intestinal cDNA library, has identified PDZD11 (PDZ domain-containing protein 11), a PDZ-containing protein, as an interacting partner with hSMVT [62]. The interaction between hSMVT with PDZD11 was confirmed further in vitro [by a GST (glutathione transferase) pull-down assay] and in vivo (by two-hybrid luciferase and co-immunoprecipitation assays), as well as by confocal imaging of living cells.…”

“…Furthermore, the interaction had a functional consequence in that co-expression of hSMVT with PDZD11 led to an increase in biotin uptake, whereas knocking down PDZD11 (with the use of gene-specific siRNA) led to an inhibition of uptake. Moreover, the PDZ-binding domain of the hSMVT polypeptide that interacts with PDZD11 was localized to the C-terminal tail of the transporter [62]. …”

Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas

“…Other studies have described the existence of an accessory protein, PDZD11, in human colonic epithelial cells that interacts with the SMVT (at the COOH terminus of the transporter) and affects its function and cell biology ( Fig. 1) (57). While another potential biotin transport system has been suggested in other tissues (108), the SMVT system appears to be the only system that operates in the mammalian gut.…”