Regulation of flotillin-1 in the establishment of NIH-3T3 cell-cell interactions.
Flotillin-1 is a lipid raft-associated protein involved in neuronal regeneration, insulin signaling in adipocytes, and phagosome maturation in macrophages. We detected abundant flotillin-1 mRNA expression in confluent cultures of mouse NIH-3T3 fibroblasts. These cells were used as a model to assess the regulation of flotillin-1 mRNA and protein expression by cell-cell interactions. The disruption of cell-cell interactions triggered the downregulation of the flotillin-1 gene. However, the establishment of new cell interactions, and finally confluence, increased both the flotillin-1 transcript and its protein. Despite flotillin-1 having been described as an integral protein of the cell membrane, it is also very conspicuous in the hydrophilic fraction (the non-membrane fraction) of confluent cell extracts. The promoter region of the flotillin-1 gene was isolated and analyzed by transfection experiments, and the regulatory domains containing motifs for binding transcription factors involved in cell differentiation were identified.
López-Casas
Pedro P
PP
Department of Cell and Developmental Biology, Centro de Investigaciones Biológicas, Ramiro de Maeztu 9, 28040 Madrid, Spain.
del Mazo
Jesús
J
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002450:Cell Communication / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D018899:CpG Islands / Q000235:genetics; D015536:Down-Regulation; D005786:Gene Expression Regulation / Q000502:physiology*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection
D008565:Membrane Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C106354:flotillins; D008156:Luciferases