Hepatocyte growth factor exerts multiple biological functions on bovine mammary epithelial cells.

The met proto-oncogene product Met is a member of the family of tyrosine kinase growth factor receptors, and hepatocyte growth factor/scatter factor (HGF/SF) has been identified as its only ligand. Bovine Met and HGF/SF have been recently cloned and their expression has been characterized in the mammary gland, but no data regarding the biological effects of this ligand/receptor couple in bovine mammary cells are yet available. We examined the role of HGF/SF and its receptor in a bovine mammary epithelial cell line (BME-UV). Expression of Met at the mRNA level in BME-UV mammary epithelial cells evaluated by real-time PCR was similar to the expression in MDCK cells, a widely used model for Met biology. Met expression in BME-UV at the protein level was confirmed by western blot. The analysis of some signal transductional pathways downstream from the Met receptor revealed that HGF/SF addition to BME-UV cells induced activation of the extracellular signal-regulated kinase 1/2 proliferative pathway and the Akt antiapoptotic pathway. The BME-UV cells treated with HGF responded with increased proliferation, cell scatter, and motility. Met activation by HGF induced degradation of the extracellular matrix and migration through matrigel coated transwells. Moreover, BME-UV cells included in a 3-dimensional matrix of collagen and treated with HGF developed tubular structures, reminiscent of the mammary gland ducts. These data indicate that HGF and Met might be important regulators of mammary gland growth, morphogenesis, and development in the bovine

Functional effect of mir-27b on myostatin expression: a relationship in Piedmontese cattle with double-muscled phenotype

BACKGROUND: In Piedmontese cattle the double-muscled phenotype is an inherited condition associated to a point mutation in the myostatin (MSTN) gene. The Piedmontese MSTN missense mutation G938A is translated to C313Y myostatin protein. This mutation alters MSTN function as a negative regulator of muscle growth, thereby inducing muscle hypertrophy. MiRNAs could play a role in skeletal muscle hypertrophy modulation by down-regulating gene expression. RESULTS: After identifying a 3(′)-UTR consensus sequence of several negative and positive modulator genes involved in the skeletal muscle hypertrophy pathway, such as IGF1, IGF1R, PPP3CA, NFATc1, MEF2C, GSK3b, TEAD1 and MSTN, we screened miRNAs matching to it. This analysis led to the identification of miR-27b, miR-132, miR-186 and miR-199b-5p as possible candidates. We collected samples of longissimus thoracis from twenty Piedmontese and twenty Friesian male bovines. In Piedmontese group miR-27b was up-regulated 7.4-fold (p < 0.05). Further, we report that the level of MSTN mRNA was about 5-fold lower in Piedmontese cattle vs Friesian cattle (p < 0.0001) and that less mature MSTN protein was detected in the Piedmontese one (p < 0.0001). Cotransfection of miR-27b and psi-check2 vector with the luciferase reporter gene linked to the bovine wild-type 3(′)-UTR of MSTN strongly inhibited the luciferase activity (79%, p < 0.0001). CONCLUSIONS: These data demonstrate that bovine MSTN is a specific target of miR-27b and that miRNAs contribute to explain additive phenotypic hypertrophy in Piedmontese cattle selected for the MSTN gene mutation, possibly outlining a more precise genetic signature able to elucidate differences in muscle conformation

External and internal EGFR-activating signals drive mammary epithelial cells proliferation and viability

During puberty, the mammary gland undergoes an intense growth, dependent on the interplay between the Epidermal Growth Factor Receptor (EGFR) in the stroma and different mammary epithelial receptors. We hypothesize that EGFR expressed in the mammary epithelium also has a role in puberty and the epithelial cells can self-sustain by EGFR-mediated autocrine signaling. We adopted mammary cell lines from different species, as in vitro model for the epithelium, and we observed that EGFR-signaling positively affects their survival and proliferation. Once deprived of external growth factors, mammary cells still showed strong Erk 1/2 phosphorylation, abolished upon EGFR inhibition, coupled with a further reduction in survival and proliferation. Based on gene expression analysis, three EGFR-ligands (AREG, EREG and HBEGF) are likely to mediate this autocrine signaling. In conclusion, internal EGFR-activating signals sustain mammary epithelial cell proliferation and survival in vitro

Epidermal growth factor and hepatocyte growth factor receptors collaborate to induce multiple biological responses in bovine mammary epithelial cells

The aim of this work was to explore whether epidermal growth factor (EGF) and hepatocyte growth factor (HGF) could increase the biological responses of a mammary epithelial cell line of bovine origin when added simultaneously. We also investigated a possible molecular mechanism underlying this cooperation. The development of mammary gland requires several circulating and locally produced hormones. Hepatocyte growth factor and its tyrosine kinase receptor, mesenchymal-epithelial transition factor (MET), are expressed and temporally regulated during mammary development and differentiation. Epidermal growth factor receptor and its ligands have also been implicated in the growth and morphogenesis of the mammary epithelium. Both EGF and HGF seem to exert a morphogenic program in this tissue; therefore, we hypothesized that these cytokines could act cooperatively in bovine mammary epithelial cells. We have already shown that the bovine BME-UV cell line, a nontumorigenic mammary epithelial line, expresses both MET and EGF receptor. Simultaneous treatment with HGF and EGF elicited an increase in proliferation, dispersion, degradation of extracellular matrix, and motility. Following EGF treatment, BME-UV mammary cells exhibited an increase in MET expression at both the mRNA and protein levels. Long-term treatment of BME-UV cells with HGF and EGF together increased the level of activation of the extracellular signal-regulated kinase 1/2 and protein kinase B signaling pathways when compared with HGF or EGF alone. These data outline a possible cooperative role of the EGF and HGF pathways and indicate that cross-talk between their respective receptors may modulate mammary gland development in the cow

Analysis of mesenchymal cells (MSCs) from bone marrow, synovial fluid and mesenteric, neck and tail adipose tissue sources from equines

Mesenchymal stem cells (MSCs) have been used in equines as an alternative therapy. A comparative study about the phenotype and in vitro performance of different MSCs tissue sources in adult equines was needed. This study might serve to provide the knowledge to select a valuable harvesting source of MSCs. Bone marrow, synovial and adipose (mesenteric, neck and tail fat) tissues were collected from adult equines. Cell surface markers expression (CD11α/CD18, CD45, CD79α, CD90, CD105 and MHC II) and in vitro differentiation assays were made. In vitro cell migration, cell growth and wound healing capacity tests helped to study their behavior and properties. MSCs phenotype was positively confirmed by the cell surfaces markers and a tri-lineage differentiation profile. Bone marrow cells showed the highest migration capacity, while synovial fluid cells displayed the highest cell growth. Bone marrow cells showed a better wound healing when compared with all the different MSCs. We conclude that bone marrow, synovial and adipose tissue derived from adult equines are a good source for cell therapy but they conserve different functional properties: bone marrow showed an interesting migration and wound healing capacity while synovial fluid cells and their highest cell growth suggest that these MSCs would yield higher cell numbers in a shorter time

Biological role of the HGF/MET ligand/receptor couple in bovine mammary epithelial cells

The mammary gland is an organ in which numerous remodelling events follow each other during the development and the reproductive cycle of the animal. After puberty and during pregnancy morphogenesis and proliferation transform the primordial epithelium to an extended network composed of hollow tubules and secreting acini. The development of the mammary gland requires several locally-derived growth factors such Hepatocyte Growth Factor (HGF). Hepatocyte Growth Factor (HGF) is a cytokine originally described as a mitogenic factor for hepatocytes during liver regeneration. HGF is secreted by mesenchymal/stromal cells and acts as a paracrine factor on adjacent epithelial cells that express the c-met tyrosine kinase receptor (Sonnenberg et al., 1993). Binding of HGF to its receptor induces multiple biological responses including proliferation, motility, invasion of the extracellular matrix, resistance to apoptosis and activation of angiogenesis (Bussolino et al., 1992; Brinkmann et al., 1995; Bardelli et al., 1996; Medico et al., 1996). HGF and c-met are expressed and temporally regulated during mammary development and differentiation; some mammary epithelial cell lines grown in a three dimensional collagen matrix with HGF generate tubules (Soriano et al., 1995) with a morphology resembling mammary ducts. Recently, bovine HGF and c-met have been analyzed for their expression in the mammary gland, but no data regarding their biological roles are yet available. We have therefore investigated whether the bovine mammary epithelial cell line BME-UV1 was responsive to HGF and what the biological effects induced by this cytokine were