VOL. 3, No. 2, April 2006

N. Sjakste, et al. [2006] Med Hypotheses Res 3: 665-677.

Various Chromatin and Nuclear Matrix Proteins as
Autoantigens: A Possible Link to the Protein
Degradation Mechanisms

N. Sjakste*, I. Rumba and T. Sjakste

Faculty of Medicine of the University of Latvia, Sharlotes 1a, Riga LV1001  LATVIA (N.S.,
I.R.), and Institute of Biology of the University of Latvia, Miera 3, Salaspils LV2169,

Abstract. Development of autoantibodies to DNA and nuclear proteins is a
characteristic feature of several autoimmune diseases. These are widely used in clinical
practice for diagnostic purposes and are known as “nuclear antigens” or “extractable nuclear
antigens” as autoantibodies to given nuclear protein or group of proteins appear to be
disease-specific. It was suggested that autoantoibodies to nuclear proteins develop in the case
when the nuclear proteins are degraded in ubiquitin-proteasome system. To our opinion
hereditary individual peculiarities of the proteasomal proteins can also provoke development
of nuclear autoantibodies. Data on associations of autoimmune diseases with proteasome
gene polymorphism confirm our point of view. The present review summarizes data on
development of autoan¬tibodies to groups of nuclear proteins and individual proteins
(histones, HMG-proteins, transcriptions factors, RNP proteins, nuclear envelope and nuclear
matrix proteins) in patients with autoimmune diseases. Data on proteasomal degradation of
nuclear proteins and polymorphism of the ubiquitin-proteasome system in humans are
discussed in context of the above hypothesis.

*Address all correspondence to: Dr. Nikolajs Sjakste, Faculty of Medicine of the
University of Latvia, Sharlotes iela 1a, Riga LV1001, Latvia.  Phone: 371-7034120. Fax: 371-
7553142. E-Mail:

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