The atypical RhoU/Wrch1 Rho GTPase controls cell proliferation and apoptosis in the gut epithelium.
Apoptosis
Gut epithelium
Knockout mice
Rho GTPases
RhoU/Wrch1
Journal
Biology of the cell
ISSN: 1768-322X
Titre abrégé: Biol Cell
Pays: England
ID NLM: 8108529
Informations de publication
Date de publication:
May 2019
May 2019
Historique:
received:
31
08
2018
revised:
07
01
2019
accepted:
07
02
2019
pubmed:
6
3
2019
medline:
30
7
2019
entrez:
6
3
2019
Statut:
ppublish
Résumé
The mammalian gut epithelium displays among the highest rates of self-renewal, with a turnover time of less than 5 days. Renewal involves concerted proliferation at the bottom of the crypt, migration and differentiation along the crypt-villus axis and anoïkis/shedding in the luminal epithelium. Renewal is controlled by interplay between signalling pathways, among which canonical and non-canonical Wnt signals play prominent roles. Overall 92% of colon tumours show increased canonical Wnt signalling resulting from mutations, established as major driver steps towards carcinogenesis. Here, we examined the physiological role of RhoU/Wrch1 in gut homeostasis. RhoU is an atypical Rho GTPase related to Cdc42/Rac1 and identified as a transcriptional target of non-canonical Wnt signalling. We found that RHOU expression is reduced in human colorectal tumour samples. We show that RhoU is mainly expressed in the differentiated compartment of the gut epithelium. Rhou specific invalidation in the mouse gut elicits cell hyperplasia and is associated in the colon with a highly disorganized luminal epithelium. Hyperplasia affects all cell types in the small intestine and colon and has a higher impact on goblet cells. Hyperplasia is associated with a reduction of apoptosis and an increased proliferation. RhoU knockdown in human DLD-1 colon cancer cells also elicits a higher growth index and reduces cell apoptosis. Last, loss of RhoU function in the mouse gut epithelium or in DLD-1 cells increases RhoA activity and the level of phosphorylated Myosin Light Chain-2, which may functionally link RhoU activity to apoptosis. RhoU is mostly expressed in the differentiated compartment of the gut. It plays a role in homeostasis as its specific invalidation elicits hyperplasia of all cell types. This mainly results from a reduction of apoptosis, through actomyosin-dependent mechanisms. RhoU negatively controls cell growth in the intestinal epithelium. Since its expression is sensitive to non-canonical Wnt signals and is reduced in colorectal tumours, downregulating RhoU may thus have an instrumental role in tumour progression.
Sections du résumé
BACKGROUND
BACKGROUND
The mammalian gut epithelium displays among the highest rates of self-renewal, with a turnover time of less than 5 days. Renewal involves concerted proliferation at the bottom of the crypt, migration and differentiation along the crypt-villus axis and anoïkis/shedding in the luminal epithelium. Renewal is controlled by interplay between signalling pathways, among which canonical and non-canonical Wnt signals play prominent roles. Overall 92% of colon tumours show increased canonical Wnt signalling resulting from mutations, established as major driver steps towards carcinogenesis.
RESULTS
RESULTS
Here, we examined the physiological role of RhoU/Wrch1 in gut homeostasis. RhoU is an atypical Rho GTPase related to Cdc42/Rac1 and identified as a transcriptional target of non-canonical Wnt signalling. We found that RHOU expression is reduced in human colorectal tumour samples. We show that RhoU is mainly expressed in the differentiated compartment of the gut epithelium. Rhou specific invalidation in the mouse gut elicits cell hyperplasia and is associated in the colon with a highly disorganized luminal epithelium. Hyperplasia affects all cell types in the small intestine and colon and has a higher impact on goblet cells. Hyperplasia is associated with a reduction of apoptosis and an increased proliferation. RhoU knockdown in human DLD-1 colon cancer cells also elicits a higher growth index and reduces cell apoptosis. Last, loss of RhoU function in the mouse gut epithelium or in DLD-1 cells increases RhoA activity and the level of phosphorylated Myosin Light Chain-2, which may functionally link RhoU activity to apoptosis.
CONCLUSION
CONCLUSIONS
RhoU is mostly expressed in the differentiated compartment of the gut. It plays a role in homeostasis as its specific invalidation elicits hyperplasia of all cell types. This mainly results from a reduction of apoptosis, through actomyosin-dependent mechanisms.
SIGNIFICANCE
CONCLUSIONS
RhoU negatively controls cell growth in the intestinal epithelium. Since its expression is sensitive to non-canonical Wnt signals and is reduced in colorectal tumours, downregulating RhoU may thus have an instrumental role in tumour progression.
Identifiants
pubmed: 30834544
doi: 10.1111/boc.201800062
doi:
Substances chimiques
RHOU protein, human
EC 3.6.1.-
RhoU protein, mouse
EC 3.6.5.2
rho GTP-Binding Proteins
EC 3.6.5.2
Types de publication
Journal Article
Langues
eng
Pagination
121-141Subventions
Organisme : Fondation Arthritis
ID : AO2005
Organisme : Ligue Nationale Contre le Cancer
ID : CT LS105434
Organisme : Ligue Nationale Contre le Cancer
ID : CT N°LS 105434
Informations de copyright
© 2019 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.