Telophase is the final stage in both meiosis and mitosis in a eukaryotic cell. During telophase, the effects of prophase and prometaphase are reversed. As chromosomes reach the cell poles, a nuclear envelope is re-assembled around each set of chromatids, the nucleoli reappear, and chromosomes begin to decondense back into the expanded chromatin that is present during interphase. The mitotic spindle is disassembled and remaining spindle microtubules are depolymerized. Telophase accounts for approximately 2% of the cell cycle's duration.
Lamins, also known as nuclear lamins are fibrous proteins in type V intermediate filaments, providing structural function and transcriptional regulation in the cell nucleus. Nuclear lamins interact with inner nuclear membrane proteins to form the nuclear lamina on the interior of the nuclear envelope. Lamins have elastic and mechanosensitive properties, and can alter gene regulation in a feedback response to mechanical cues. Lamins are present in all animals but are not found in microorganisms, plants or fungi. Lamin proteins are involved in the disassembling and reforming of the nuclear envelope during mitosis, the positioning of nuclear pores, and programmed cell death. Mutations in lamin genes can result in several genetic laminopathies, which may be life-threatening.
Intermediate filaments (IFs) are cytoskeletal structural components found in the cells of vertebrates, and many invertebrates. Homologues of the IF protein have been noted in an invertebrate, the cephalochordate Branchiostoma.
The nuclear lamina is a dense fibrillar network inside the nucleus of eukaryote cells. It is composed of intermediate filaments and membrane associated proteins. Besides providing mechanical support, the nuclear lamina regulates important cellular events such as DNA replication and cell division. Additionally, it participates in chromatin organization and it anchors the nuclear pore complexes embedded in the nuclear envelope.
In biology, the nuclear matrix is the network of fibres found throughout the inside of a cell nucleus after a specific method of chemical extraction. According to some it is somewhat analogous to the cell cytoskeleton. In contrast to the cytoskeleton, however, the nuclear matrix has been proposed to be a dynamic structure. Along with the nuclear lamina, it supposedly aids in organizing the genetic information within the cell.
Emerin is a protein that in humans is encoded by the EMD gene, also known as the STA gene. Emerin, together with LEMD3, is a LEM domain-containing integral protein of the inner nuclear membrane in vertebrates. Emerin is highly expressed in cardiac and skeletal muscle. In cardiac muscle, emerin localizes to adherens junctions within intercalated discs where it appears to function in mechanotransduction of cellular strain and in beta-catenin signaling. Mutations in emerin cause X-linked recessive Emery–Dreifuss muscular dystrophy, cardiac conduction abnormalities and dilated cardiomyopathy.
Laminopathies are a group of rare genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina. They are included in the more generic term nuclear envelopathies that was coined in 2000 for diseases associated with defects of the nuclear envelope. Since the first reports of laminopathies in the late 1990s, increased research efforts have started to uncover the vital role of nuclear envelope proteins in cell and tissue integrity in animals.
Prelamin-A/C, or lamin A/C is a protein that in humans is encoded by the LMNA gene. Lamin A/C belongs to the lamin family of proteins.
Lamin-B receptor is a protein, and in humans, it is encoded by the LBR gene.
LEM domain-containing protein 3 (LEMD3), also known as MAN1, is an integral protein in the inner nuclear membrane (INM) of the nuclear envelope. It is encoded by the LEMD3 gene and was first identified after it was isolated from the serum of a patient with a collagen vascular disease.
Barrier-to-autointegration factor is a protein that in humans is encoded by the BANF1 gene. It is a member of the barrier-to-autointegration factor family of proteins.
Chromatin assembly factor 1 subunit A is a protein that in humans is encoded by the CHAF1A gene.
Chromatin assembly factor 1 subunit B is a protein that in humans is encoded by the CHAF1B gene.
A-kinase anchor protein 8-like is a protein that in humans is encoded by the AKAP8L gene.
Chromobox protein homolog 5 is a protein that in humans is encoded by the CBX5 gene. It is a highly conserved, non-histone protein part of the heterochromatin family. The protein itself is more commonly called HP1α. Heterochromatin protein-1 (HP1) has an N-terminal domain that acts on methylated lysines residues leading to epigenetic repression. The C-terminal of this protein has a chromo shadow-domain (CSD) that is responsible for homodimerizing, as well as interacting with a variety of chromatin-associated, non-histone proteins.
Torsin-1A-interacting protein 1 is a protein that in humans is encoded by the TOR1AIP1 gene. More commonly known as lamina associated polypeptide 1 (LAP1), it is a type II integral membrane protein that resides in the inner nuclear membrane. The luminal domain of LAP1 interacts with Torsin A and is necessary for the ATPase activity of Torsin A. LAP1 plays a critical role in skeletal and heart muscle. Mutations in TOR1AIP1 have been linked to muscular dystrophy and cardiomyopathy. It's deletion from mouse hepatocytes leads to defected very-low density lipoprotein secretion and causes non-alcoholic fatty liver disease and non-alcoholic steatohepatitis
Lamin-B1 is a protein that in humans is encoded by the LMNB1 gene.
Inner nuclear membrane proteins are membrane proteins that are embedded in or associated with the inner membrane of the nuclear envelope. There are about 60 INM proteins, most of which are poorly characterized with respect to structure and function. Among the few well-characterized INM proteins are lamin B receptor (LBR), lamina-associated polypeptide 1 (LAP1), lamina-associated polypeptide-2 (LAP2), emerin and MAN1.
In molecular biology, barrier-to-autointegration factor (BAF) is a family of essential proteins that is highly conserved in metazoan evolution, and which may act as DNA-bridging proteins. BAF binds directly to double-stranded DNA, to transcription activators, and to inner nuclear membrane proteins, including lamin A filaments that anchor nuclear pore complexes in place, and nuclear LEM-domain proteins that bind to lamin filaments and chromatin. New findings suggest that BAF has structural roles in nuclear assembly and chromatin organization, represses gene expression and might interlink chromatin structure, nuclear architecture and gene regulation in metazoans.
Nuclear organization refers to the spatial distribution of chromatin within a cell nucleus. There are many different levels and scales of nuclear organisation. Chromatin is a higher order structure of DNA.
