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M Alhadeff

Publications and source records attributed to M Alhadeff.

4 recordsLinked to original sources
PubMed1993

TGF beta induction of extracellular matrix associated proteins in normal and transformed human mammary epithelial cells in culture is independent of growth effects.

We have previously characterized a human mammary epithelial cell (HMEC) culture system for the effects of TGF beta 1 on cell growth. In the current report, the effects of TGF beta 1 on synthesis and secretion of proteins associated with the extracellular matrix and proteolysis were examined. In particular, we compared the TGF beta responses of normal finite lifespan HMEC, which are growth inhibited by TGF beta, to two immortally transformed cell lines derived from the normal HMEC. One of these lines maintains active growth in the presence of TGF beta and the other shows partial growth inhibition. In contrast to the differing effects of TGF beta on cell growth, we found that all these cell types showed strong induction of most of the mRNA and protein species examined, including fibronectin, collagen IV, laminin, type IV collagenase, urokinase type plasminogen activator (uPA), and plasminogen activator inhibitor 1 (PAI-1). The profile of TGF beta 1 binding proteins was the same in HMEC that were, and were not growth suppressed by TFG beta. Therefore, the effects of TGF beta on cell growth could be dissociated from its effects on specialized responses, indicating that within this one cell type there must be at least two independent pathways for TGF beta activity, one which leads to cessation of proliferation and one which induces a specific set of cellular responses. This cell system may be useful for examining the pathway of TGF beta induced growth inhibition using closely matched cells which vary in their growth-induced response but retain similar specialized responses to TGF beta.

Breast↗
PubMed1987

Isolation and characterization of a cDNA encoding rat cationic trypsinogen.

A cDNA encoding rat cationic trypsinogen has been isolated by immunoscreening from a rat pancreas cDNA library. The protein encoded by this cDNA is highly basic and contains all of the structural features observed in trypsinogens. The amino acid sequence of rat cationic trypsinogen is 75% and 77% homologous to the two anionic rat trypsinogens. The homology of rat cationic trypsinogen to these anionic trypsinogens is lower than its homology to other mammalian cationic trypsinogens, suggesting that anionic and cationic trypsins probably diverged prior to the divergence of rodents and ungulates. The most unusual feature of this trypsinogen is the presence of an activation peptide containing five aspartic acid residues, in contrast to all other reported trypsinogen activation peptides which contain four acidic amino acid residues. Comparisons of cationic and anionic trypsins reveal that the majority of the charge changes occur in the C-terminal portion of the protein, which forms the substrate binding site. Several regions of conserved charge differences between cationic and anionic trypsins have been identified in this region, which may influence the rate of hydrolysis of protein substrates.

Amino Acid Sequence↗
PubMedDate not supplied

Light-triggered organization of the stigma in dark-grown nondividing cells of Euglena gracilis.

Dark-grown cells of Euglena gracilis Klebs var. bacillaris Cori contain amorphous stigma material. When these cells are placed on resting medium for 3 days in darkness, the cells cease division; the organization of a normal stigma from the amorphous material requires continuous illumination for 72-96 hr. We have now found that if dark-grown cells are placed on resting medium for 8 days, a 40-min light pulse is sufficient to cause normal organization of the stigma in a subsequent 72-hr dark period. Thus stigma development is light-dependent at 3 days of resting but becomes light-triggered at 8 days. Other examples of light-triggered phenomena in Euglena are discussed and a model based on turnover of protein molecules repressing development that are ordinarily removed by exposure to light is presented; it is suggested that as the cells become more starved their ability to replace repressor molecules removed by light becomes limited and the system thereby becomes light-triggered rather than light-dependent.

Cell Division↗