Impaired tight junction sealing and precocious involution in mammary glands of PKN1 transgenic mice.
The mammary gland undergoes a complex set of changes to establish copious milk secretion at parturition. To test the hypothesis that signaling through the Rho pathway plays a role in secretory activation, transgenic mice expressing a constitutively activated form of the Rho effector protein PKN1 in the mammary epithelium were generated. PKN1 activation had no effect in late pregnancy but inhibited milk secretion after parturition, diminishing the ability of transgenic dams to support a litter. Mammary gland morphology as well as increased apoptosis and expression of IFGBP5 and TGFbeta3 suggest precocious involution in these animals. Furthermore, tight junction sealing at parturition was impaired in transgenic mammary glands as demonstrated by intraductal injection of [14C]sucrose. Consistent with this finding, tight junction sealing in response to glucocorticoid stimulation was highly impaired in EpH4 mammary epithelial cells expressing constitutively activated PKN1, whereas expression of a dominant-negative PKN1 mutant resulted in accelerated tight junction sealing in vitro. Tight junction formation was not impaired as demonstrated by the correct localization of occludin and ZO1 at the apical cell borders. Our results provide evidence that PKN1 participates in the regulation of tight junction sealing in the mammary gland by interfering with glucocorticoid signaling.
Fischer
Andreas
A
Institute of Pharmacology, Center for Cardiovascular Research, Charité University Medicine, 10115 Berlin, Germany.
Stuckas
Heiko
H
Gluth
Markus
M
Russell
Tanya D
TD
Rudolph
Michael C
MC
Beeman
Neal E
NE
Bachmann
Sebastian
S
Umemura
Shinobu
S
Ohashi
Yasuhiro
Y
Neville
Margaret C
MC
Theuring
Franz
F
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002460:Cell Line; D005260:Female; D005799:Genes, Dominant; D005938:Glucocorticoids / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D062793:Occludin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D053782:Transforming Growth Factor beta3 / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
D005938:Glucocorticoids; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; D053782:Transforming Growth Factor beta3; D062826:Zonula Occludens-1 Protein; C061570:protein kinase N; D011493:Protein Kinase C