TY - JOUR

T1 - The karyosphere capsule in rana temporaria oocytes contains structural and dna-binding proteins

AU - Ilicheva, Nadya

AU - Podgornaya, Olga

AU - Bogolyubov, Dmitry

AU - Pochukalina, Galina

PY - 2018/1/1

Y1 - 2018/1/1

N2 - During the last stages of oogenesis, oocyte chromosomes condense and come close together, forming the so-called karyosphere. Karyosphere formation is accompanied by an essential decrease in transcriptional activity. In the grass frog Rana temporaria, the karyosphere is surrounded by an extrachromosomal capsule that separates the chromosomes from the rest of the nucleoplasm. The karyosphere capsule (KC) of R. temporaria has been investigated in detail at the ultrastructural level, but its protein composition remained largely unknown. We demonstrate here that nuclear actin, especially F-actin, as well as lamins A/C and B are the most abundant proteins of the KC. Key proteins of nuclear pore complexes, such as Nup93 and Nup35, are also detectable in the KC. New antibodies recognizing the telomere-binding protein TRF2 allowed us to localize TRF2 in nuclear speckles. We also found that the R. temporaria KC contains some proteins involved in chromatin remodeling, including topoisomerase II and ATRX. Thus, we believe that KC isolates the chromosomes from the rest of the nucleoplasm during the final period of oocyte growth (late diplotene) and represents a specialized oocyte nuclear compartment to store a variety of factors involved in nuclear metabolism that can be used in future early development.

AB - During the last stages of oogenesis, oocyte chromosomes condense and come close together, forming the so-called karyosphere. Karyosphere formation is accompanied by an essential decrease in transcriptional activity. In the grass frog Rana temporaria, the karyosphere is surrounded by an extrachromosomal capsule that separates the chromosomes from the rest of the nucleoplasm. The karyosphere capsule (KC) of R. temporaria has been investigated in detail at the ultrastructural level, but its protein composition remained largely unknown. We demonstrate here that nuclear actin, especially F-actin, as well as lamins A/C and B are the most abundant proteins of the KC. Key proteins of nuclear pore complexes, such as Nup93 and Nup35, are also detectable in the KC. New antibodies recognizing the telomere-binding protein TRF2 allowed us to localize TRF2 in nuclear speckles. We also found that the R. temporaria KC contains some proteins involved in chromatin remodeling, including topoisomerase II and ATRX. Thus, we believe that KC isolates the chromosomes from the rest of the nucleoplasm during the final period of oocyte growth (late diplotene) and represents a specialized oocyte nuclear compartment to store a variety of factors involved in nuclear metabolism that can be used in future early development.

KW - ATRX

KW - Karyosphere

KW - Karyosphere capsule

KW - Lamins

KW - Nuclear actin

KW - Nucleoporins

KW - Oogenesis

KW - Rana temporaria

KW - Topoisomerase II

KW - Transcription

UR - http://www.scopus.com/inward/record.url?scp=85055071939&partnerID=8YFLogxK

U2 - 10.1080/19491034.2018.1530935

DO - 10.1080/19491034.2018.1530935

M3 - Article

C2 - 30272509

AN - SCOPUS:85055071939

VL - 9

SP - 516

EP - 529

JO - Nucleus

JF - Nucleus

SN - 1949-1034

IS - 1

ER -