SOCS3 negatively regulates the gp130-STAT3 pathway in mouse skin wound healing.

Proliferation and differentiation of keratinocytes during wound healing are regulated by cytokines and chemokines, which are secreted by resident and inflammatory cells and activate the transcription factor signal transducer and activator of transcription (STAT)3. However, it is not clear to what extent STAT3 in keratinocytes is activated by gp130-containing receptors. We addressed this question genetically by deleting the suppressor of cytokine signaling (SOCS)3, a negative regulator of gp130-mediated STAT3 activation. Socs3 alleles flanked by loxP sites were deleted in mice with either an MMTV-Cre or K5-Cre transgene. While both transgenes are active in keratinocytes, the MMTV-Cre deletes floxed genes also in immune cells. Deletion of Socs3 using the MMTV-Cre transgene resulted in aberrant STAT3 activation, impaired wound healing, prolonged secretion of chemokines, a hyperproliferative epidermis, and neutrophil infiltration into wounds. Simultaneous deletion of the Socs3 and gp130 genes restored normal wound healing. Moreover, deletion of Socs3 only in keratinocytes caused impaired wound healing. These results demonstrate that wound healing is controlled in keratinocytes by the gp130-SOCS3-STAT3 pathway and an imbalance of this pathway results in delayed wound healing.

Socs 3 modulates the activity of the transcription factor Stat3 in mammary tissue and controls alveolar homeostasis.

Signal transducer and activator of transcription 5 and 3 (Stat5 and Stat3) control pregnancy-mediated mammary development and involution-dependent remodeling, respectively. Suppressor of cytokine signaling 3 (Socs3) has been implicated in the modulation of both Stat3 and Stat5 activity. To explore the biology of Socs3 in mammary tissue, the gene was deleted using Cre-mediated recombination. Deletion of the Socs3 gene from mammary stem or early progenitor cells did not grossly alter pregnancy-mediated mammary development but resulted in impaired lactation due to attenuated proliferation. Loss of Socs3 from differentiated luminal cells did not interfere with glandular function during lactation, but resulted in accelerated tissue remodeling upon weaning. Loss of Socs3 led to enhanced and precocious Stat3 activation. Thus, Socs3 serves as a modulator of Stat3 activity to ensure controlled proliferation and apoptosis in pregnancy and involution, respectively.

Selective regulatory function of Socs3 in the formation of IL-17-secreting T cells.

Suppressor of cytokine signaling (Socs) 3 is a cytokine-inducible inhibitor with critical but selective cell-specific effects. We show that deficiency of Socs3 in T cells had minimal effects on differentiation of T cells to the T helper (Th) 1 or Th2 subsets; accordingly, Socs3 had no effect on IL-12-dependent signal transducer and activator of transcription (Stat) 4 phosphorylation or IL-4-dependent Stat6 phosphorylation. By contrast, Socs3 was found to be a major regulator of IL-23-mediated Stat3 phosphorylation and Th17 generation, and Stat3 directly binds to the IL-17A and IL-17F promoters. We conclude that Socs3 is an essential negative regulator of IL-23 signaling, inhibition of which constrains the generation of Th17 differentiation.

Use of high-throughput protein array for profiling of differentially expressed proteins in normal and malignant breast tissue.

cDNA arrays provide a powerful tool to identify gene expression pattern that are potentially associated with tumor invasion and metastasis. However, genes work at the protein level and, since the transcriptional activity of a gene does not necessarily reflect cellular protein expression, the identification and quantification of proteins is essential for the understanding of molecular events leading to malignant transformation. We have therefore employed a high-throughput protein microarray system which contains 378 well-characterized monoclonal antibodies in order to compare the gene expression pattern of malignant and adjacent normal breast tissue in a patient with primary breast cancer. Using this technique, we have identified a number of proteins that show increased expression levels in malignant breast tissues such as casein kinase Ie, p53, annexin XI, CDC25C, eIF-4E and MAP kinase 7. The expression of other proteins, such as the multifunctional regulator 14-3-3e was found to be decreased in malignant breast tissue, whereas the majority of proteins remained unchanged when compared to the corresponding non-malignant samples. The protein expression pattern was confirmed by immunohistochemistry, in which antibodies against 8 representative proteins known to be involved in carcinogenesis were employed in paraffin-embedded normal and malignant tissue sections deriving from the same patient. In each case, the results obtained by IHC matched the data obtained by antibody microarray system. Taken together, we have described for the first time a tumor cell specificity protein expression pattern by use of a novel commercially available antibody microarray system. We have thus demonstrated the feasibility of high-throughput protein arrays in the proteomic analysis of human breast tissue. We hypothesize that the use of protein arrays will not only increase our understanding of the molecular events, but could prove useful in evaluating prognosis and in determining optimal antineoplastic therapy.