Sinkkisormiproteiinien fysiologisesta osasta. Lihas. Myogeneesin positiivinen ja negatiivinen säätely.

LÄHDE: M. Cassandri (2017). Muscle; (sivulta 5)
Myogeneesin säätelijöitä:
SMYD1 (ZMYND)
KLF5 (ZNF)
CCX5 (CXXC)
EGR3 (ZNF) 

ZNF-sinkkisormiproteiineilla on osuutensa lihaksen erilaistumisessa.
Esim. SMYD1- sinkkisormiproteiinia  esiintyy erityisesti juovikkaassa ( tahdonalaisessa lihaksessa).
Se sisältää SET ja MYND-domeenit ja toimii myogeneesin essentiellinä säätelijänä.
SMYD1-geenin  ( MYND- tyyppinen ei-transkriptionaalinen faktori)  deleetio  huonontaa myoblastien differentioitumista alentaen myofibrillien muodostumista ja vähentäen lihasspesifisten geenien ilmentymistä.

ZMYND
SMYD1(2p11.2) , SET ja MYND domeenin omaava,   https://www.ncbi.nlm.nih.gov/gene/150572-
 BOP; KMT3D; ZMYND18; ZMYND22. Expression. Restricted expression toward heart (RPKM 63.9) See more
Preferred name: Histone-Lysine N-methyl transferase SMYD1.
Names: ZMYND18, BOP, KMT3D, ZMYND22. CD8 beta opposite.

 ZNF
Lisäksi on havaittu, että KLF5:n ilmentymän estäminen viljellyissä C2 C12-myoblasteissa tukahduttaa myotubulusten muodostumisen, mikä viittaa tämän sinkkisormiproteiinin tarpeeseen myogeenisessä erilaistumisessa.  Erityisesti molekyylitasolla KLF5 edistää myoblastien muuttumista myotuubeiksi rekrytoimalla MyoD:tä lihasspesifisille kohdegeeneille (MYOG, MYBPH, MYL4, MYOM2). Kuva 2c  on myoblastien erilaistumisesta.

 KLF5 (13q22.1) https://www.ncbi.nlm.nih.gov/gene/688.
 CKLF; IKLF; BTEB2 This gene encodes a member of the Krüppel-like factor subfamily of zinc finger proteins. The encoded protein is a transcriptional activator that binds directly to a specific recognition motif in the promoters of target genes. This protein acts downstream of multiple different signaling pathways and is regulated by post-translational modification. It may participate in both promoting and suppressing cell proliferation. Expression of this gene may be changed in a variety of different cancers and in cardiovascular disease. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2013].

Preferred Names: Krüppel-like factor 5.

Names: (intestinal Krüppel-like factor,

BTE-binding protein 2,

GC box binding protein 2,

Klf5C isoform,

Krüppel-like factor 5 (intestinal),

basic transcription element binding protein 2,

colon krüppel-like factor,

colon krueppel-like factor,

epididymis secretory sperm binding protein,

intestinal-enriched krueppel-like factor,

intestinal-enriched kruppel-like factor,

transcription factor BTEB2.

 CXXC

Lisäesimerkkejä sinkkisormiproteiinien osallistumisesta luustolihasten myogeneesin säätelyyn ovat geenit  CXXC5 (CXXC-tyyppinen sinkkisormiproteiini) ja varhaisen kasvuvasteen geeni 3, EGR3, Early Growth Response 3). Todellakin CXXC5 nopeuttaa myosyytin erilaistumista säätelemällä positiivisesti luustolihaksen erilaistumisgeenejä, kun taas EGR3  edistää myoblastien proliferoitumista stimuloimalla NF-kB-signalointia ( nuclear factor kappa B).

CXXC5, (5q31.2), https://www.ncbi.nlm.nih.gov/gene/51523 ,
CF5; WID; RINF; HSPC195.
The protein encoded by this gene is a retinoid-inducible nuclear protein containing a CXXC-type zinc finger motif. The encoded protein is involved in myelopoiesis, is required for DNA damage-induced p53 activation, regulates the differentiation of C2C12 myoblasts into myocytes, and negatively regulates cutaneous wound healing. Several transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Nov 2015].

Preferred Names: CXXC-type zinc finger protein.

Names: CXXC finger 5 protein,

WT1-induced Inhibitor of Dishevelled,

putative MAPK-activating protein PM08,

putative NF-kappa-B-activating protein 102,

retinoid-inducible nuclear facto.

(Kommenttini: Wnt inhibiittorivaikutusta)

ZNF

EGR3, (8p21.3),  https://www.ncbi.nlm.nih.gov/gene/1960, 
 Early Growth response 3,EGR-3; PILOT. This gene encodes a transcriptional regulator that belongs to the EGR family of C2H2-type zinc-finger proteins. It is an immediate-early growth response gene which is induced by mitogenic stimulation. The protein encoded by this gene participates in the transcriptional regulation of genes in controling biological rhythm. It may also play a role in a wide variety of processes including muscle development, lymphocyte development, endothelial cell growth and migration, and neuronal development. Alternative splicing results in multiple transcript variants encoding distinct isoforms.[provided by RefSeq, Dec 2010]

Preferred Names: early growth response protein 3. Names: zinc finger protein pilot.

 (Kommenttini:  proteiinissa qp, pq,  qppq, pqpp jaksoja; säätelee biologisen rytmin geenejä, vaikuttaa  aivofunktioon)

.......
ZNF32 (10q11.21), KOX30.
https://www.ncbi.nlm.nih.gov/gene/7580

Suomennosta: Vastakohtana on negatiivisen säätelyn tie: myogeenista soludifferentiaatiota säätelee negatiivisesti hiirellä  sinkkisormi Zfp637 (C2H2- tyyppinen ei-transkriptiofaktori). Vaikka sen transkriptionaalista aktiivisuuta ei ole täysin selvitelty Zfp637:n yli-ilmentymä estää myoblastien erilaistumista ja edistää niiden proliferoitumista ja mahdollisesti säätelee hiirellä  mTERT- ilmentymää ( mTERT = hiiren  telomeraasi-käänteistranskriptaasi).

(Kommenttini:
 Koetan löytää hiiren Zfp637 geenin ortologia ja päädyn geeniklustereihin ihmisellä.
Yksi hiiren geenin  nimistä oli Znf32 ja lähden sitä kautta hakemaan.
Löydän  ihmiseltä Kox-geenit: KOX30 , ZNF32, (10q11.21) ja siinä geenissä on sinkkisormiproteiinien geeniklusteri kohdassa 10q23-q24. Kox16 niminen on ZFN23 ja sijaitsee klusterissa  16q22.  Tässä yhteydessä en vielä näe yhteyttä myogeneesiin.
Katson myös ihmisen TERT geenin (5p15.33), https://www.ncbi.nlm.nih.gov/gene/7015
 ja sen ilmenemää ei havaita normaalisti somaattisissa soluissa.  Geenin yksi alue TERT on selitetty näin:
TERT: Telomerase reverse transcriptase (TERT). Telomerase is a ribonucleoprotein (RNP) that synthesizes telomeric DNA repeats. The telomerase RNA subunit provides the template for synthesis of these repeats. The catalytic subunit of RNP is known as telomerase reverse transcriptase (TERT). The reverse transcriptase (RT) domain is located in the C-terminal region of the TERT polypeptide. Single amino acid substitutions in this region lead to telomere shortening and senescence. Telomerase is an enzyme that, in certain cells, maintains the physical ends of chromosomes (telomeres) during replication. In somatic cells, replication of the lagging strand requires the continual presence of an RNA primer approximately 200 nucleotides upstream, which is complementary to the template strand. Since there is a region of DNA less than 200 base pairs from the end of the chromosome where this is not possible, the chromosome is continually shortened. However, a surplus of repetitive DNA at the chromosome ends protects against the erosion of gene-encoding DNA. Telomerase is not normally expressed in somatic cells. It has been suggested that exogenous TERT may extend the lifespan of, or even immortalize, the cell. However, recent studies have shown that telomerase activity can be induced by a number of oncogenes. Conversely, the oncogene c-myc can be activated in human TERT immortalized cells. Sequence comparisons place the telomerase proteins in the RT family but reveal hallmarks that distinguish them from retroviral and retrotransposon relatives. )

Lisäys 5.6. 2018 Ihmisen lihaksen erilaistumisen negatiivisesta säätelystä

 ZBP89, ZNF148, BERF1

Transcription factor ZNF148 is a negative regulator of human muscle differentiation. Bakke J, et al. Sci Rep, 2017 Aug 15. PMID 28811660, Free PMC Article

Sci Rep. 2017 Aug 15;7(1):8138. doi: 10.1038/s41598-017-08267-5.Transcription factor ZNF148 is a negative regulator of human muscle differentiation.

Bakke J¹, Wright WC^1,2, Zamora AE³, Ong SS¹, Wang YM¹, Hoyer JD^1,2, Brewer CT^1,2, Thomas PG³, Chen T^4,5.Abstract

Muscle differentiation is a complex process in which muscle progenitor cells undergo determination and eventually cellular fusion. This process is heavily regulated by such master transcription factors as MYOD and members of the MEF2 family. Here, we show that the transcription factor ZNF148 plays a direct role in human muscle cell differentiation. Downregulation of ZNF148 drives the formation of a muscle phenotype with rapid expression of myosin heavy chain, even in proliferative conditions. This phenotype was most likely mediated by the robust and swift upregulation of MYOD and MEF2C.

PMID:

28811660

PMCID:

PMC5557752

DOI:

10.1038/s41598-017-08267-5

[Indexed for MEDLINE]

Free PMC Article

 The Kruppel-like zinc finger protein 148 (ZNF148), also known as β enolase repressor factor 1 (BERF1, ZBP-89, and BFCOL1), was first identified in skeletal muscle tissue. Although it represses transcription of the ENO3 gene by binding to a G-rich box (GTGG(G/C)GGGGGGGTG) in the promoter, it exerts both enhancing and repressing effects on its target genes¹¹. The human and mouse ZNF148 genes have similar promoter sequences and are overall relatively homologous¹². ZNF148 expression is downregulated during mouse myogenesis and in C2C12 cells¹¹. Interestingly, ZNF148 overexpression modestly augments muscle differentiation in C2C12 cells¹³. ZNF148 expression, in concert with reduced Sp1/3, c-Jun, and Stat3 levels, is required for downregulation of vimentin during C2C12 myogenesis¹⁴. Desmin and vimentin are expressed in regenerating muscle fibers and are the main subunits of fibroblast intermediate filaments. Indeed, they are common to most cells of mesenchymal origin¹⁵. Vimentin is downregulated during myogenesis, whereas desmin is upregulated as myogenesis progresses. Additionally, ZNF148 indirectly induces expression of cytochrome c oxidase 5b, which is highly expressed in muscle tissue, by regulating the co-interacting partners yin and yang 1 and heterogeneous nuclear ribonucleoprotein d-like protein¹⁶.
With the goal of identifying positive and negative regulators of muscle differentiation we conducted a screen using a human transcription factor siRNA library, and we identified human ZNF148 as a negative regulator of muscle differentiation in vitro. ZNF148 knockdown enhanced and accelerated muscle differentiation in the LHCN-M2 cell line and in primary skeletal muscle myoblasts (HSMM) isolated from human donors. ZNF148 knockdown was sufficient to drive differentiation, even in proliferative conditions. Moreover, MYOD and MEF2C were rapidly upregulated in these conditions, potentially driving the overall gene program change necessary for myogenesis.