An increased expression of nucleolin is associated with a physiological nucleolar segregation.
Nucleolar segregation is the most striking cellular phenotypic feature of cold-acclimatized carp and depicts the cyclical reprogramming that the physiology of the fish undergoes between summer and winter, where a clear differential expression of some nucleolar related genes occurs. We characterized carp nucleolin, a nucleolar protein involved in multiple steps of ribosome biogenesis, and evaluated its expression upon fish acclimatization. We show that the carp cDNA deduced amino acid sequence exhibits the same tripartite structural organization found in other species. Nevertheless, we observed that nucleolin mRNA expression was strongly induced in the cold-adapted carp as was the nuclear protein content, assessed by immunocytochemistry in liver sections. The physiological up-regulation of nucleolin in the cold-acclimatized carp, where rRNA transcription and processing are depressed concomitantly with the nucleolus segregation, is consistent with the notion that nucleolin plays a fundamental role in repressing rRNA synthesis.
Alvarez
M
M
Facultad de Ciencias de la Salud, Millenium Institute for Fundamental and Applied Biology, Universidad Andrés Bello, República 217, 4to Piso, Santiago, Chile.
Quezada
C
C
Navarro
C
C
Molina
A
A
Bouvet
P
P
Krauskopf
M
M
Vera
M I
MI
D000064:Acclimatization / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002347:Carps / Q000502:physiology*; D002466:Cell Nucleolus / Q000378:metabolism*; D003080:Cold Temperature; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation; D008099:Liver / Q000166:cytology / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D020537:RNA, Small Nucleolar / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism; D012621:Seasons; D000097796:Nucleolin
D018076:DNA, Complementary; D010750:Phosphoproteins; D020537:RNA, Small Nucleolar; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D000097796:Nucleolin; C117378:RNA, U3 small nucleolar