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Roles of uroplakins in plaque formation, umbrella cell enlargement, and urinary tract diseases.

Kong XT, Deng FM, Hu P, Liang FX, Zhou G, Auerbach AB, Genieser N, Nelson PK, Robbins ES, Shapiro E, Kachar B, Sun TT - J. Cell Biol. (2004)

Bottom Line: Both knockouts also had small superficial cells, suggesting that continued fusion of uroplakin-delivering vesicles with the apical surface may contribute to umbrella cell enlargement.Both knockouts experienced vesicoureteral reflux, hydronephrosis, renal dysfunction, and, in the offspring of some breeding pairs, renal failure and neonatal death.These results highlight the functional importance of uroplakins and establish uroplakin defects as a possible cause of major urinary tract anomalies and death.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, New York University School of Medicine, New York, NY 10016, USA.

ABSTRACT
The apical surface of mouse urothelium is covered by two-dimensional crystals (plaques) of uroplakin (UP) particles. To study uroplakin function, we ablated the mouse UPII gene. A comparison of the phenotypes of UPII- and UPIII-deficient mice yielded new insights into the mechanism of plaque formation and some fundamental features of urothelial differentiation. Although UPIII knockout yielded small plaques, UPII knockout abolished plaque formation, indicating that both uroplakin heterodimers (UPIa/II and UPIb/III or IIIb) are required for plaque assembly. Both knockouts had elevated UPIb gene expression, suggesting that this is a general response to defective plaque assembly. Both knockouts also had small superficial cells, suggesting that continued fusion of uroplakin-delivering vesicles with the apical surface may contribute to umbrella cell enlargement. Both knockouts experienced vesicoureteral reflux, hydronephrosis, renal dysfunction, and, in the offspring of some breeding pairs, renal failure and neonatal death. These results highlight the functional importance of uroplakins and establish uroplakin defects as a possible cause of major urinary tract anomalies and death.

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Altered uroplakin expression pattern in the UPII-deficient urothelium. Paraffin sections of wild-type (WT; a, c, e, g, and i) or UPII-deficient (UPII KO; b, d, f, h, and j) mouse urothelium were immunohistochemically stained for keratins (a and b) using a mixture of AE1 and AE3 mouse monoclonal antibodies (Tseng et al., 1982; for review see Cooper et al., 1985), uroplakin Ia (c and d), UPIb (e and f), UPII (g and h), and UPIII (i and j). k shows the silver nitrate–stained (SN) SDS-PAGE patterns of the detergent-insoluble membrane proteins from (lanes 1) bovine urothelium, (2) normal mouse urothelium, (3) UPIII-deficient mouse urothelium, and (4) UPII-deficient mouse urothelium, and the immunoblotting of these proteins using antibodies to UPs Ia, Ib, II, IIIa, and IIIb. Note, in the thickened UPII KO urothelium, the absence of UPII, the diffused cytoplasmic distribution and lack of apical surface association of UPIa, the greatly reduced but still noticeably apical surface association (arrowheads) of UPIb and UPIII, and the reduced amounts of detergent-insoluble uroplakins in the UPIII-deficient urothelium (lanes 3) and their further reduction in the UPII-deficient urothelium (lanes 4). Bar, 50 μm.
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fig3: Altered uroplakin expression pattern in the UPII-deficient urothelium. Paraffin sections of wild-type (WT; a, c, e, g, and i) or UPII-deficient (UPII KO; b, d, f, h, and j) mouse urothelium were immunohistochemically stained for keratins (a and b) using a mixture of AE1 and AE3 mouse monoclonal antibodies (Tseng et al., 1982; for review see Cooper et al., 1985), uroplakin Ia (c and d), UPIb (e and f), UPII (g and h), and UPIII (i and j). k shows the silver nitrate–stained (SN) SDS-PAGE patterns of the detergent-insoluble membrane proteins from (lanes 1) bovine urothelium, (2) normal mouse urothelium, (3) UPIII-deficient mouse urothelium, and (4) UPII-deficient mouse urothelium, and the immunoblotting of these proteins using antibodies to UPs Ia, Ib, II, IIIa, and IIIb. Note, in the thickened UPII KO urothelium, the absence of UPII, the diffused cytoplasmic distribution and lack of apical surface association of UPIa, the greatly reduced but still noticeably apical surface association (arrowheads) of UPIb and UPIII, and the reduced amounts of detergent-insoluble uroplakins in the UPIII-deficient urothelium (lanes 3) and their further reduction in the UPII-deficient urothelium (lanes 4). Bar, 50 μm.

Mentions: Consistent with the UPIII knockout results, the UPII-deficient urothelium lacked a typical superficial umbrella cell layer (Fig. 2 b). This urothelium was hyperplastic, as indicated by an elevated level of BrdU incorporation (the labeling index increased almost 100-fold from 0.12%, which is normal, to 10.7%; Fig. 2, c and d), and was three- to sixfold thicker than normal (Fig. 2, a and b). Immunohistochemical staining with monospecific rabbit and mouse antibodies to individual uroplakins confirmed that all four major uroplakins were preferentially expressed in superficial umbrella cells in normal mouse urothelium (Fig. 3, a, c, e, g, and i; Hu et al., 2000). The staining of the UPII-deficient urothelium showed that UPIa (the partner of UPII) was diffusely distributed in all upper cells, which is consistent with its entrapment in the ER (Fig. 3 d). Uroplakins Ib and III (of the other uroplakin pair), although expressed at a lower level than normal, were clearly associated with the apical, as well as some basal/lateral, cell surface(s) (Fig. 3, f and j).


Roles of uroplakins in plaque formation, umbrella cell enlargement, and urinary tract diseases.

Kong XT, Deng FM, Hu P, Liang FX, Zhou G, Auerbach AB, Genieser N, Nelson PK, Robbins ES, Shapiro E, Kachar B, Sun TT - J. Cell Biol. (2004)

Altered uroplakin expression pattern in the UPII-deficient urothelium. Paraffin sections of wild-type (WT; a, c, e, g, and i) or UPII-deficient (UPII KO; b, d, f, h, and j) mouse urothelium were immunohistochemically stained for keratins (a and b) using a mixture of AE1 and AE3 mouse monoclonal antibodies (Tseng et al., 1982; for review see Cooper et al., 1985), uroplakin Ia (c and d), UPIb (e and f), UPII (g and h), and UPIII (i and j). k shows the silver nitrate–stained (SN) SDS-PAGE patterns of the detergent-insoluble membrane proteins from (lanes 1) bovine urothelium, (2) normal mouse urothelium, (3) UPIII-deficient mouse urothelium, and (4) UPII-deficient mouse urothelium, and the immunoblotting of these proteins using antibodies to UPs Ia, Ib, II, IIIa, and IIIb. Note, in the thickened UPII KO urothelium, the absence of UPII, the diffused cytoplasmic distribution and lack of apical surface association of UPIa, the greatly reduced but still noticeably apical surface association (arrowheads) of UPIb and UPIII, and the reduced amounts of detergent-insoluble uroplakins in the UPIII-deficient urothelium (lanes 3) and their further reduction in the UPII-deficient urothelium (lanes 4). Bar, 50 μm.
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Related In: Results  -  Collection

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fig3: Altered uroplakin expression pattern in the UPII-deficient urothelium. Paraffin sections of wild-type (WT; a, c, e, g, and i) or UPII-deficient (UPII KO; b, d, f, h, and j) mouse urothelium were immunohistochemically stained for keratins (a and b) using a mixture of AE1 and AE3 mouse monoclonal antibodies (Tseng et al., 1982; for review see Cooper et al., 1985), uroplakin Ia (c and d), UPIb (e and f), UPII (g and h), and UPIII (i and j). k shows the silver nitrate–stained (SN) SDS-PAGE patterns of the detergent-insoluble membrane proteins from (lanes 1) bovine urothelium, (2) normal mouse urothelium, (3) UPIII-deficient mouse urothelium, and (4) UPII-deficient mouse urothelium, and the immunoblotting of these proteins using antibodies to UPs Ia, Ib, II, IIIa, and IIIb. Note, in the thickened UPII KO urothelium, the absence of UPII, the diffused cytoplasmic distribution and lack of apical surface association of UPIa, the greatly reduced but still noticeably apical surface association (arrowheads) of UPIb and UPIII, and the reduced amounts of detergent-insoluble uroplakins in the UPIII-deficient urothelium (lanes 3) and their further reduction in the UPII-deficient urothelium (lanes 4). Bar, 50 μm.
Mentions: Consistent with the UPIII knockout results, the UPII-deficient urothelium lacked a typical superficial umbrella cell layer (Fig. 2 b). This urothelium was hyperplastic, as indicated by an elevated level of BrdU incorporation (the labeling index increased almost 100-fold from 0.12%, which is normal, to 10.7%; Fig. 2, c and d), and was three- to sixfold thicker than normal (Fig. 2, a and b). Immunohistochemical staining with monospecific rabbit and mouse antibodies to individual uroplakins confirmed that all four major uroplakins were preferentially expressed in superficial umbrella cells in normal mouse urothelium (Fig. 3, a, c, e, g, and i; Hu et al., 2000). The staining of the UPII-deficient urothelium showed that UPIa (the partner of UPII) was diffusely distributed in all upper cells, which is consistent with its entrapment in the ER (Fig. 3 d). Uroplakins Ib and III (of the other uroplakin pair), although expressed at a lower level than normal, were clearly associated with the apical, as well as some basal/lateral, cell surface(s) (Fig. 3, f and j).

Bottom Line: Both knockouts also had small superficial cells, suggesting that continued fusion of uroplakin-delivering vesicles with the apical surface may contribute to umbrella cell enlargement.Both knockouts experienced vesicoureteral reflux, hydronephrosis, renal dysfunction, and, in the offspring of some breeding pairs, renal failure and neonatal death.These results highlight the functional importance of uroplakins and establish uroplakin defects as a possible cause of major urinary tract anomalies and death.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, New York University School of Medicine, New York, NY 10016, USA.

ABSTRACT
The apical surface of mouse urothelium is covered by two-dimensional crystals (plaques) of uroplakin (UP) particles. To study uroplakin function, we ablated the mouse UPII gene. A comparison of the phenotypes of UPII- and UPIII-deficient mice yielded new insights into the mechanism of plaque formation and some fundamental features of urothelial differentiation. Although UPIII knockout yielded small plaques, UPII knockout abolished plaque formation, indicating that both uroplakin heterodimers (UPIa/II and UPIb/III or IIIb) are required for plaque assembly. Both knockouts had elevated UPIb gene expression, suggesting that this is a general response to defective plaque assembly. Both knockouts also had small superficial cells, suggesting that continued fusion of uroplakin-delivering vesicles with the apical surface may contribute to umbrella cell enlargement. Both knockouts experienced vesicoureteral reflux, hydronephrosis, renal dysfunction, and, in the offspring of some breeding pairs, renal failure and neonatal death. These results highlight the functional importance of uroplakins and establish uroplakin defects as a possible cause of major urinary tract anomalies and death.

Show MeSH
Related in: MedlinePlus