| First Author | Zhao L | Year | 2002 |
| Journal | Mol Endocrinol | Volume | 16 |
| Issue | 12 | Pages | 2902-12 |
| PubMed ID | 12456808 | Mgi Jnum | J:125449 |
| Mgi Id | MGI:3758538 | Doi | 10.1210/me.2001-0330 |
| Citation | Zhao L, et al. (2002) Loss of interleukin 6 results in delayed mammary gland involution: a possible role for mitogen-activated protein kinase and not signal transducer and activator of transcription 3. Mol Endocrinol 16(12):2902-12 |
| abstractText | We have investigated the role of IL-6 in the initiation and progression of mouse mammary gland involution in IL-6-null mice. This study was based on the hypothesis that IL-6 is the activating cytokine for signal transducer and activator of transcription 3 (Stat), the transcription factor whose presence is required for controlled mammary gland involution. We now show that expression of IL-6 is low during lactation but increases at the onset of involution in parallel with the activation of Stat3 and p44/42 MAPK. Moreover, we demonstrated that injection of IL-6 into virgin and lactating mice activates Stat3 in mammary epithelium. The in vivo role of IL-6 was investigated using mutant mice. Involution of mammary tissue in IL-6-null mice was delayed similar to that seen in mammary conditional Stat3- and Bax-null mice. However, Stat3 activation during involution was independent of the IL-6 status. This suggests that either IL-6 does not induce Stat3 in vivo or its absence is compensated for by other cytokines, such as leukemia-inhibitory factor (LIF). In contrast, the increase of p44/42 MAPK (ERK1/2) phosphorylation at the onset of involution was dependent on the presence of IL-6. Delayed involution corresponded with a decrease of epithelial cell death, and a delayed induction of Bax and sulfated glycoprotein 2 (SGP2, or clusterin) expression. Our experiments demonstrate on a genetic level that IL-6 contributes to the induction of the controlled remodeling of mammary tissue during involution, possibly through the MAPK pathway and by mediating the expression of the cell death protein Bax. |
