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Cellular basis of urothelial squamous metaplasia: roles of lineage heterogeneity and cell replacement.

Liang FX, Bosland MC, Huang H, Romih R, Baptiste S, Deng FM, Wu XR, Shapiro E, Sun TT - J. Cell Biol. (2005)

Bottom Line: Although the epithelial lining of much of the mammalian urinary tract is known simply as the urothelium, this epithelium can be divided into at least three lineages of renal pelvis/ureter, bladder/trigone, and proximal urethra based on their embryonic origin, uroplakin content, keratin expression pattern, in vitro growth potential, and propensity to keratinize during vitamin A deficiency.During vitamin A deficiency, mouse urothelium form multiple keratinized foci in proximal urethra probably originating from scattered K14-positive basal cells, and the keratinized epithelium expands horizontally to replace the surrounding normal urothelium.These data suggest that the urothelium consists of multiple cell lineages, that trigone urothelium is closely related to the urothelium covering the rest of the bladder, and that lineage heterogeneity coupled with cell migration/replacement form the cellular basis for urothelial squamous metaplasia.

View Article: PubMed Central - PubMed

Affiliation: Epithelial Biology Unit, The Ronald O. Perelman Department of Dermatology.

ABSTRACT
Although the epithelial lining of much of the mammalian urinary tract is known simply as the urothelium, this epithelium can be divided into at least three lineages of renal pelvis/ureter, bladder/trigone, and proximal urethra based on their embryonic origin, uroplakin content, keratin expression pattern, in vitro growth potential, and propensity to keratinize during vitamin A deficiency. Moreover, these cells remain phenotypically distinct even after they have been serially passaged under identical culture conditions, thus ruling out local mesenchymal influence as the sole cause of their in vivo differences. During vitamin A deficiency, mouse urothelium form multiple keratinized foci in proximal urethra probably originating from scattered K14-positive basal cells, and the keratinized epithelium expands horizontally to replace the surrounding normal urothelium. These data suggest that the urothelium consists of multiple cell lineages, that trigone urothelium is closely related to the urothelium covering the rest of the bladder, and that lineage heterogeneity coupled with cell migration/replacement form the cellular basis for urothelial squamous metaplasia.

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Bovine bladder and ureteral urothelial cells remain morphologically and biochemically distinct when cultured under identical in vitro conditions. Bovine bladder urothelial cells (a) and ureteral urothelial cells (b) form morphologically distinct colonies in the presence of 3T3 feeder cells (300 urothelial cells plated per 60-mm dish containing 5 × 105 mitomycin-treated 3T3 feeder cells). (c) Bovine bladder (B) and trigone (TG) urothelial cells have a much higher in vitro growth potential, as measured by cumulative cell number and by a later onset of senescence than the urothelial cells of the renal pelvis (RP), ureter (UR), and proximal urethra (PU). Similar results were obtained from two independent experiments. (d) The in vitro growth advantage of the bladder over ureteral urothelial cells could be seen in both DFM (a 1:1 mixture of DME and F-12 medium containing 1.05 mM calcium) or in KSFM (keratinocyte serum-free medium containing 0.09 mM calcium; Surya et al., 1990). 105 urothelial cells were plated in DFM medium in the presence of 3T3 feeder cells (5 × 105 per 60-mm dish) or in KSFM medium in the absence of the feeder, and the urothelial cells were trypsinized and counted after 6 d. The results shown are averages of quadruplicates ± SD (error bars). (e) Immunoblot analyses of the UPs (using antibodies with indicated specificities) and actin (Act) synthesized by cultured bovine urothelial cells of the renal pelvis, ureter, trigone, bladder, urachus (UC), prostatic urethra (PU), and membranous urethra (MU; ∼150 μg of total cellular proteins each). UPs of AUM (5 μg) were used as controls. (f) Semiquantification of the UPs synthesized by cultured urothelial cells of bovine bladder and ureter showing that cultured bladder urothelial cells contained ∼10 times more UPs than cultured ureteral urothelial cells. The immunoblot experiments were performed twice with similar results.
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fig2: Bovine bladder and ureteral urothelial cells remain morphologically and biochemically distinct when cultured under identical in vitro conditions. Bovine bladder urothelial cells (a) and ureteral urothelial cells (b) form morphologically distinct colonies in the presence of 3T3 feeder cells (300 urothelial cells plated per 60-mm dish containing 5 × 105 mitomycin-treated 3T3 feeder cells). (c) Bovine bladder (B) and trigone (TG) urothelial cells have a much higher in vitro growth potential, as measured by cumulative cell number and by a later onset of senescence than the urothelial cells of the renal pelvis (RP), ureter (UR), and proximal urethra (PU). Similar results were obtained from two independent experiments. (d) The in vitro growth advantage of the bladder over ureteral urothelial cells could be seen in both DFM (a 1:1 mixture of DME and F-12 medium containing 1.05 mM calcium) or in KSFM (keratinocyte serum-free medium containing 0.09 mM calcium; Surya et al., 1990). 105 urothelial cells were plated in DFM medium in the presence of 3T3 feeder cells (5 × 105 per 60-mm dish) or in KSFM medium in the absence of the feeder, and the urothelial cells were trypsinized and counted after 6 d. The results shown are averages of quadruplicates ± SD (error bars). (e) Immunoblot analyses of the UPs (using antibodies with indicated specificities) and actin (Act) synthesized by cultured bovine urothelial cells of the renal pelvis, ureter, trigone, bladder, urachus (UC), prostatic urethra (PU), and membranous urethra (MU; ∼150 μg of total cellular proteins each). UPs of AUM (5 μg) were used as controls. (f) Semiquantification of the UPs synthesized by cultured urothelial cells of bovine bladder and ureter showing that cultured bladder urothelial cells contained ∼10 times more UPs than cultured ureteral urothelial cells. The immunoblot experiments were performed twice with similar results.

Mentions: To determine whether different local stromal environments were responsible for the observed in vivo phenotypic differences among the various urothelia (Cunha et al., 1983; Li et al., 2000), we compared the growth and differentiation properties of bovine bladder and ureteral urothelial cells that were serially cultured under identical in vitro conditions. In the presence of 3T3 feeder cells, bladder cells formed colonies that were stained much more intensely by Rhodanille blue than ureteral cells as a result of increased stratification (Fig. 2, a and b; and not depicted). Moreover, urothelial cells of the bladder wall and the trigone had a higher in vitro proliferative potential than those of the renal pelvis, ureteral, and proximal urethra, as measured by their cumulative cell numbers (Fig. 2 c). Similarly, monkey bladder urothelial cells grew better than ureteral urothelial cells (not depicted). The superior in vitro growth potential of bovine bladder urothelial cells could be demonstrated not only in our standard urothelial growth medium containing 1.05 mM calcium (with feeder cells) but also in a serum-free medium (Surya et al., 1990) containing 0.09 mM calcium (without feeder; Fig. 2 d). Finally, immunoblot analyses showed that the UP contents of cultured bovine bladder wall, trigone, and urethral urothelial cells were ∼10 times higher than those of cultured renal pelvis and ureteral urothelial cells (Fig. 2, e and f; and Table I).


Cellular basis of urothelial squamous metaplasia: roles of lineage heterogeneity and cell replacement.

Liang FX, Bosland MC, Huang H, Romih R, Baptiste S, Deng FM, Wu XR, Shapiro E, Sun TT - J. Cell Biol. (2005)

Bovine bladder and ureteral urothelial cells remain morphologically and biochemically distinct when cultured under identical in vitro conditions. Bovine bladder urothelial cells (a) and ureteral urothelial cells (b) form morphologically distinct colonies in the presence of 3T3 feeder cells (300 urothelial cells plated per 60-mm dish containing 5 × 105 mitomycin-treated 3T3 feeder cells). (c) Bovine bladder (B) and trigone (TG) urothelial cells have a much higher in vitro growth potential, as measured by cumulative cell number and by a later onset of senescence than the urothelial cells of the renal pelvis (RP), ureter (UR), and proximal urethra (PU). Similar results were obtained from two independent experiments. (d) The in vitro growth advantage of the bladder over ureteral urothelial cells could be seen in both DFM (a 1:1 mixture of DME and F-12 medium containing 1.05 mM calcium) or in KSFM (keratinocyte serum-free medium containing 0.09 mM calcium; Surya et al., 1990). 105 urothelial cells were plated in DFM medium in the presence of 3T3 feeder cells (5 × 105 per 60-mm dish) or in KSFM medium in the absence of the feeder, and the urothelial cells were trypsinized and counted after 6 d. The results shown are averages of quadruplicates ± SD (error bars). (e) Immunoblot analyses of the UPs (using antibodies with indicated specificities) and actin (Act) synthesized by cultured bovine urothelial cells of the renal pelvis, ureter, trigone, bladder, urachus (UC), prostatic urethra (PU), and membranous urethra (MU; ∼150 μg of total cellular proteins each). UPs of AUM (5 μg) were used as controls. (f) Semiquantification of the UPs synthesized by cultured urothelial cells of bovine bladder and ureter showing that cultured bladder urothelial cells contained ∼10 times more UPs than cultured ureteral urothelial cells. The immunoblot experiments were performed twice with similar results.
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Related In: Results  -  Collection

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fig2: Bovine bladder and ureteral urothelial cells remain morphologically and biochemically distinct when cultured under identical in vitro conditions. Bovine bladder urothelial cells (a) and ureteral urothelial cells (b) form morphologically distinct colonies in the presence of 3T3 feeder cells (300 urothelial cells plated per 60-mm dish containing 5 × 105 mitomycin-treated 3T3 feeder cells). (c) Bovine bladder (B) and trigone (TG) urothelial cells have a much higher in vitro growth potential, as measured by cumulative cell number and by a later onset of senescence than the urothelial cells of the renal pelvis (RP), ureter (UR), and proximal urethra (PU). Similar results were obtained from two independent experiments. (d) The in vitro growth advantage of the bladder over ureteral urothelial cells could be seen in both DFM (a 1:1 mixture of DME and F-12 medium containing 1.05 mM calcium) or in KSFM (keratinocyte serum-free medium containing 0.09 mM calcium; Surya et al., 1990). 105 urothelial cells were plated in DFM medium in the presence of 3T3 feeder cells (5 × 105 per 60-mm dish) or in KSFM medium in the absence of the feeder, and the urothelial cells were trypsinized and counted after 6 d. The results shown are averages of quadruplicates ± SD (error bars). (e) Immunoblot analyses of the UPs (using antibodies with indicated specificities) and actin (Act) synthesized by cultured bovine urothelial cells of the renal pelvis, ureter, trigone, bladder, urachus (UC), prostatic urethra (PU), and membranous urethra (MU; ∼150 μg of total cellular proteins each). UPs of AUM (5 μg) were used as controls. (f) Semiquantification of the UPs synthesized by cultured urothelial cells of bovine bladder and ureter showing that cultured bladder urothelial cells contained ∼10 times more UPs than cultured ureteral urothelial cells. The immunoblot experiments were performed twice with similar results.
Mentions: To determine whether different local stromal environments were responsible for the observed in vivo phenotypic differences among the various urothelia (Cunha et al., 1983; Li et al., 2000), we compared the growth and differentiation properties of bovine bladder and ureteral urothelial cells that were serially cultured under identical in vitro conditions. In the presence of 3T3 feeder cells, bladder cells formed colonies that were stained much more intensely by Rhodanille blue than ureteral cells as a result of increased stratification (Fig. 2, a and b; and not depicted). Moreover, urothelial cells of the bladder wall and the trigone had a higher in vitro proliferative potential than those of the renal pelvis, ureteral, and proximal urethra, as measured by their cumulative cell numbers (Fig. 2 c). Similarly, monkey bladder urothelial cells grew better than ureteral urothelial cells (not depicted). The superior in vitro growth potential of bovine bladder urothelial cells could be demonstrated not only in our standard urothelial growth medium containing 1.05 mM calcium (with feeder cells) but also in a serum-free medium (Surya et al., 1990) containing 0.09 mM calcium (without feeder; Fig. 2 d). Finally, immunoblot analyses showed that the UP contents of cultured bovine bladder wall, trigone, and urethral urothelial cells were ∼10 times higher than those of cultured renal pelvis and ureteral urothelial cells (Fig. 2, e and f; and Table I).

Bottom Line: Although the epithelial lining of much of the mammalian urinary tract is known simply as the urothelium, this epithelium can be divided into at least three lineages of renal pelvis/ureter, bladder/trigone, and proximal urethra based on their embryonic origin, uroplakin content, keratin expression pattern, in vitro growth potential, and propensity to keratinize during vitamin A deficiency.During vitamin A deficiency, mouse urothelium form multiple keratinized foci in proximal urethra probably originating from scattered K14-positive basal cells, and the keratinized epithelium expands horizontally to replace the surrounding normal urothelium.These data suggest that the urothelium consists of multiple cell lineages, that trigone urothelium is closely related to the urothelium covering the rest of the bladder, and that lineage heterogeneity coupled with cell migration/replacement form the cellular basis for urothelial squamous metaplasia.

View Article: PubMed Central - PubMed

Affiliation: Epithelial Biology Unit, The Ronald O. Perelman Department of Dermatology.

ABSTRACT
Although the epithelial lining of much of the mammalian urinary tract is known simply as the urothelium, this epithelium can be divided into at least three lineages of renal pelvis/ureter, bladder/trigone, and proximal urethra based on their embryonic origin, uroplakin content, keratin expression pattern, in vitro growth potential, and propensity to keratinize during vitamin A deficiency. Moreover, these cells remain phenotypically distinct even after they have been serially passaged under identical culture conditions, thus ruling out local mesenchymal influence as the sole cause of their in vivo differences. During vitamin A deficiency, mouse urothelium form multiple keratinized foci in proximal urethra probably originating from scattered K14-positive basal cells, and the keratinized epithelium expands horizontally to replace the surrounding normal urothelium. These data suggest that the urothelium consists of multiple cell lineages, that trigone urothelium is closely related to the urothelium covering the rest of the bladder, and that lineage heterogeneity coupled with cell migration/replacement form the cellular basis for urothelial squamous metaplasia.

Show MeSH
Related in: MedlinePlus