SAFB

Last update 08 May 2025

Basic Info

Synonyms

HAP, HET, HSP27 ERE-TATA-binding protein

+ [7]

Introduction

Binds to scaffold/matrix attachment region (S/MAR) DNA and forms a molecular assembly point to allow the formation of a 'transcriptosomal' complex (consisting of SR proteins and RNA polymerase II) coupling transcription and RNA processing (PubMed:9671816). Functions as an estrogen receptor corepressor and can also bind to the HSP27 promoter and decrease its transcription (PubMed:12660241). Thereby acts as a negative regulator of cell proliferation (PubMed:12660241). When associated with RBMX, binds to and stimulates transcription from the SREBF1 promoter (By similarity).

100 Clinical Results associated with SAFB

100 Translational Medicine associated with SAFB

0 Patents (Medical) associated with SAFB

120

Literatures (Medical) associated with SAFB

01 May 2024·Molecular Cell

SAFB restricts contact domain boundaries associated with L1 chimeric transcription

Article

Author: Liu, Nian ; Li, Pilong ; Chen, Zhuo ; Jin, Guangpu ; Xie, Wei ; Hong, Yantao ; Gong, Liang ; Wang, Yang ; Hong, Yaqiang ; Bie, Luyao ; Zhu, Yanfen ; Zhang, Tao ; Shen, Xiaohua ; Li, Xiufeng ; Zhang, Yongyan ; Yan, Xiaohan ; Pei, Gaofeng

Long interspersed element-1 (LINE-1 or L1) comprises 17% of the human genome, continuously generates genetic variations, and causes disease in certain cases. However, the regulation and function of L1 remain poorly understood. Here, we uncover that L1 can enrich RNA polymerase IIs (RNA Pol IIs), express L1 chimeric transcripts, and create contact domain boundaries in human cells. This impact of L1 is restricted by a nuclear matrix protein scaffold attachment factor B (SAFB) that recognizes transcriptionally active L1s by binding L1 transcripts to inhibit RNA Pol II enrichment. Acute inhibition of RNA Pol II transcription abolishes the domain boundaries associated with L1 chimeric transcripts, indicating a transcription-dependent mechanism. Deleting L1 impairs domain boundary formation, and L1 insertions during evolution have introduced species-specific domain boundaries. Our data show that L1 can create RNA Pol II-enriched regions that alter genome organization and that SAFB regulates L1 and RNA Pol II activity to preserve gene regulation.

01 Apr 2024·European Journal of Human GeneticsQ2 · BIOLOGY

Silencing XIST on the future active X: Searching human and bovine preimplantation embryos for the repressor

Q2 · BIOLOGY

Article

Author: Migeon, Barbara R ; Yu, Bo ; Aksit, Melis A ; Roelen, Bernard A J

X inactivation is the means of equalizing the dosage of X chromosomal genes in male and female eutherian mammals, so that only one X is active in each cell. The XIST locus (in cis) on each additional X chromosome initiates the transcriptional silence of that chromosome, making it an inactive X. How the active X in both males and females is protected from inactivation by its own XIST locus is not well understood in any mammal. Previous studies of autosomal duplications suggest that gene(s) on the short arm of human chromosome 19 repress XIST on the active X. Here, we examine the time of transcription of some candidate genes in preimplantation embryos using single-cell RNA sequencing data from human embryos and qRT-PCR from bovine embryos. The candidate genes assayed are those transcribed from 19p13.3-13.2, which are widely expressed and can remodel chromatin. Our results confirm that XIST is expressed at low levels from the future active X in embryos of both sexes; they also show that the XIST locus is repressed in both sexes when pluripotency factors are being upregulated, during the 4-8 cell and morula stages in human and bovine embryos - well before the early blastocyst (E5) when XIST on the inactive X in females starts to be upregulated. Our data suggest a role for DNMT1, UHRF1, SAFB and SAFB2 in XIST repression; they also exclude XACT and other 19p candidate genes and provide the transcriptional timing for some genes not previously assayed in human or bovine preimplantation embryos.

29 Feb 2024·Nature

Autonomous transposons tune their sequences to ensure somatic suppression

Article

Author: Ilık, İbrahim Avşar ; Smith, Zachary D ; Brändl, Björn ; Glažar, Petar ; Tse, Kevin ; Aktaş, Tuğçe ; Müller, Franz-Josef ; Meierhofer, David

AbstractTransposable elements (TEs) are a major constituent of human genes, occupying approximately half of the intronic space. During pre-messenger RNA synthesis, intronic TEs are transcribed along with their host genes but rarely contribute to the final mRNA product because they are spliced out together with the intron and rapidly degraded. Paradoxically, TEs are an abundant source of RNA-processing signals through which they can create new introns1, and also functional2 or non-functional chimeric transcripts3. The rarity of these events implies the existence of a resilient splicing code that is able to suppress TE exonization without compromising host pre-mRNA processing. Here we show that SAFB proteins protect genome integrity by preventing retrotransposition of L1 elements while maintaining splicing integrity, via prevention of the exonization of previously integrated TEs. This unique dual role is possible because of L1’s conserved adenosine-rich coding sequences that are bound by SAFB proteins. The suppressive activity of SAFB extends to tissue-specific, giant protein-coding cassette exons, nested genes and Tigger DNA transposons. Moreover, SAFB also suppresses LTR/ERV elements in species in which they are still active, such as mice and flies. A significant subset of splicing events suppressed by SAFB in somatic cells are activated in the testis, coinciding with low SAFB expression in postmeiotic spermatids. Reminiscent of the division of labour between innate and adaptive immune systems that fight external pathogens, our results uncover SAFB proteins as an RNA-based, pattern-guided, non-adaptive defence system against TEs in the soma, complementing the RNA-based, adaptive Piwi-interacting RNA pathway of the germline.

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