The human urothelial tight junction: claudin 3 and the ZO-1α(+) switch

TY - JOUR

T1 - The human urothelial tight junction

T2 - claudin 3 and the ZO-1α(+) switch

AU - Smith, Nicholas J

AU - Hinley, Jennifer

AU - Varley, Claire L

AU - Eardley, Ian

AU - Trejdosiewicz, Ludwik K

AU - Southgate, Jennifer

PY - 2015/8/14

Y1 - 2015/8/14

N2 - OBJECTIVE: Tight junctions are multicomponent structures, with claudin proteins defining paracellular permeability. Claudin 3 is a candidate for the exceptional "tightness" of human urothelium, being localised to the terminal tight junction (TJ) of superficial cells. Our aim was to determine whether claudin 3 plays an instigating and/or a functional role in the urothelial TJ.MATERIALS AND METHODS: Normal human urothelial (NHU) cells maintained as non-immortalised cell lines were retrovirally-transduced to over-express or silence claudin 3 expression. Stable sublines induced to stratify or differentiate were assessed for TJ formation by immunocytochemistry and transepithelial electrical resistance (TER). Expression of claudin 3, ZO-1 and ZO-1α(+) was examined in native urothelium by immunohistochemistry.RESULTS: Claudin 3 expression was associated with differentiation and development of a tight barrier and along with ZO-1 and ZO-1α(+) was localised to the apical tight junction in native urothelium. Knockdown of claudin 3 inhibited formation of a tight barrier in three independent cell lines, however, overexpression of claudin 3 was not sufficient to induce tight barrier development in the absence of differentiation. A differentiation-dependent induction of the ZO-1α(+) isoform was found to coincide with barrier formation. Whereas claudin 3 overexpression did not induce the switch to co-expression of ZO-1α(-)/ZO-1α(+), claudin 3 knockdown decreased localisation of ZO-1 to the TJ and resulted in compromised barrier function.CONCLUSIONS: Urothelial cytodifferentiation is accompanied by induction of claudin 3 which is essential for the development of a terminal TJ. A coordinated switch to the ZO-1α(+) isotype was also observed and for the first time may indicate that ZO-1α(+) is involved in the structural assembly and function of the urothelial terminal TJ.

AB - OBJECTIVE: Tight junctions are multicomponent structures, with claudin proteins defining paracellular permeability. Claudin 3 is a candidate for the exceptional "tightness" of human urothelium, being localised to the terminal tight junction (TJ) of superficial cells. Our aim was to determine whether claudin 3 plays an instigating and/or a functional role in the urothelial TJ.MATERIALS AND METHODS: Normal human urothelial (NHU) cells maintained as non-immortalised cell lines were retrovirally-transduced to over-express or silence claudin 3 expression. Stable sublines induced to stratify or differentiate were assessed for TJ formation by immunocytochemistry and transepithelial electrical resistance (TER). Expression of claudin 3, ZO-1 and ZO-1α(+) was examined in native urothelium by immunohistochemistry.RESULTS: Claudin 3 expression was associated with differentiation and development of a tight barrier and along with ZO-1 and ZO-1α(+) was localised to the apical tight junction in native urothelium. Knockdown of claudin 3 inhibited formation of a tight barrier in three independent cell lines, however, overexpression of claudin 3 was not sufficient to induce tight barrier development in the absence of differentiation. A differentiation-dependent induction of the ZO-1α(+) isoform was found to coincide with barrier formation. Whereas claudin 3 overexpression did not induce the switch to co-expression of ZO-1α(-)/ZO-1α(+), claudin 3 knockdown decreased localisation of ZO-1 to the TJ and resulted in compromised barrier function.CONCLUSIONS: Urothelial cytodifferentiation is accompanied by induction of claudin 3 which is essential for the development of a terminal TJ. A coordinated switch to the ZO-1α(+) isotype was also observed and for the first time may indicate that ZO-1α(+) is involved in the structural assembly and function of the urothelial terminal TJ.

UR - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4530542/pdf/nihms667737.pdf

U2 - 10.14440/bladder.2015.33

DO - 10.14440/bladder.2015.33

M3 - Article

C2 - 26269793

SN - 2327-2120

VL - 2

JO - Bladder

JF - Bladder

IS - 1

M1 - e9

ER -