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Articles by R.C.Gorewit
Total Records ( 2 ) for R.C.Gorewit
  Yongji Chung and R.C.Gorewit
  Little is known about the role of TGF-ß in ruminant mammary growth and development. The literature suggests that TGF-ß could play an active role in influencing early mammary development and involution. SMADs are proteins that function as intracellular signaling effectors for the TGF-ß super family of polypeptides. We cloned bovine SMAD 4 and examined its mRNA expression in the mammary gland at various developmental stages. Sequencing analysis showed that bovine SMAD 4 had 96 and 94% homology to human and rat SMAD 4, respectively. Therefore, SMAD 4 appeared to be a very conserved gene in these species. SMAD 4 mRNA expression was highest in early pregnancy and involution, and then decreased in late pregnancy and maintained a low level through lactation. We speculate that SMAD 4 is involved in induction of regulatory genes involved in mammary gland growth and apoptosis. BRCA1 is a breast and ovarian cancer-specific tumor suppressor protein, with properties of a transcription factor involved in cell cycle regulation, DNA repair and apoptosis. BRCA1 gene expression is induced by steroid hormones and its pattern of mRNA expression mimicks that for TGF-ß and SMAD 4. We thought it of interest to determine if various doses of TGF- ß would induce BRCA1 gene expression. TGF- ß1 treated bovine mammary cells showed a dose dependent increase in BRCA1 mRNA expression compared to control treatments. Our results suggest that TGF- ß1, SMAD 4 and BRCA1 may play important roles in regulating ruminant mammary cell proliferation, differentiation, and involution or apoptosis.
  Yongji Chung and R.C.Gorewit
  Breast ovarian cancer susceptibility (BRCA) proteins appear to be involved in cell cycle regulation, DNA repair or genome integrity and induction of apoptosis in a variety of cells from humans and laboratory animals. The BRCA gene and protein have not been identified in cattle. The pattern of BRCA1 gene expression during normal mammary gland development and involution has not been examined in detail in any mammalian species. Therefore, the purpose of the present study was to clone the BRCA1 gene in Holstein dairy cattle and determine if the BRCA1 gene is differentially expressed through various stages of mammary gland development. We also localized immunoreactive BRCA1 protein in bovine mammary cells and milk fat globule membrane. Bovine BRCA1 cDNA was highly conserved to the human. Five hundred base pairs of exon 11 (+3384/ + 3866, human BRCA1 cDNA position) and the C-terminus 1 kb were identical to the human. Seven hundred base pairs of the N-terminus, which contain two ring domains, showed 90 % homology to human BRCA1. In bovine tissues, the degree of BRCA1 gene expression, from highest to lowest , was as follows: liver, spleen, mammary tissues and kidney. The mammary tissues of early pregnancy heifers (3 months) showed much higher mammary gland BRCA1 mRNA expression than other mammary developmental stages. BRCA1 expression declined during the remainder of pregnancy and remained low for lactating cows. However, its expression increased when involution proceeded. Immunohistochemical studies showed that immunoreactive BRCA1 was localized in the nucleus and cytoplasm of mammary epithelial cells from lactating cows. It was not present in myoepithelial cells. The protein was also localized in the milk fat globule membranes. Our data suggest that BRCA1 is involved in bovine mammary gland development and/or differentiation, is specifically localized in secretary epithelial cells and is likely a secreted protein during normal lactation.
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