Peculiarities of Proteasome Pool Formation in Rat Spleen and Liver during Postnatal Development

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N. P. Sharova^1*, T. M. Astakhova¹, L. A. Bondareva², S. B. Dmitrieva¹, and P. A. Erokhov¹

¹Koltsov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, 119334 Moscow, Russia; fax: (495) 135-8012; E-mail: nsharova@proxima.idb.ac.ru

²Institute of Biology, Karelian Research Center, Russian Academy of Sciences, ul. Pushkinskaya 11, 185610 Petrozavodsk, Russia; fax: (8142) 76-9810; E-mail: bondareva@bio.krc.karelia.ru

^* To whom correspondence should be addressed.

Received April 10, 2006; Revision received May 25, 2006

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Changes in the specific activity and amounts of 26S and 20S proteasome pools in rat spleen and liver during postnatal development and appearance in them of immune subunits were studied. Two decreases in chymotrypsin-like activity of the proteasome pools were recorded during the first three weeks after birth. The activity minimums fell on the 11th and 19th days, and the first decrease was more prolonged and pronounced than the second. The decrease in the specific activity of the 26S proteasome pools was associated with a reduction of their quantity. The 20S proteasome pools displayed no such decreases. Noticeable quantities of immune subunits LMP7 and LMP2 were revealed by Western blotting in the spleen on the 7th day and on the 19th day in the liver, concurrently with the beginning of the decrease in the proteasome activity. It was concluded that during the first three weeks of postnatal development the proteasome pools in rat spleen and liver were replaced twice, and in the spleen (a lymphoid organ) a qualitatively new pool containing immune subunits appeared nearly two weeks earlier than in the liver (a non-lymphoid organ). The appearance of immune proteasomes in different organs and tissues during some weeks after birth seems to explain the immune system inefficiency during embryogenesis and early postnatal development.

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KEY WORDS: immune and constitutive proteasomes, postnatal development

DOI: 10.1134/S0006297906090136

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