CREB3L1

CREB3L1 (cAMP responsive element binding protein 3-like 1) is a protein that in humans is encoded by the CREB3L1 gene. CREB3L1 is normally found in the membrane of the endoplasmic reticulum (ER). However, CREB3L1 is cleaved and the released cytoplasmic transcription factor domain translocates to the nucleus upon stress to the ER. There it activates the transcription of target genes by binding to box-B elements.

CREB3L1

Transcription factor involved in unfolded protein response (UPR). Binds the DNA consensus sequence 5'-GTGXGCXGC-3' (PubMed:21767813).

In the absence of endoplasmic reticulum (ER) stress, inserted into ER membranes, with N-terminal DNA-binding and transcription activation domains oriented toward the cytosolic face of the membrane. In response to ER stress, transported to the Golgi, where it is cleaved in a site-specific manner by resident proteases S1P/MBTPS1 and S2P/MBTPS2. The released N-terminal cytosolic domain is translocated to the nucleus to effect transcription of specific target genes. Plays a critical role in bone formation through the transcription of COL1A1, and possibly COL1A2, and the secretion of bone matrix proteins. Directly binds to the UPR element (UPRE)-like sequence in an osteoblast-specific COL1A1 promoter region and induces its transcription. Does not regulate COL1A1 in other tissues, such as skin (By similarity).

Required to protect astrocytes from ER stress-induced cell death. In astrocytes, binds to the cAMP response element (CRE) of the BiP/HSPA5 promoter and participate in its transcriptional activation (By similarity).

Required for TGFB1 to activate genes involved in the assembly of collagen extracellular matrix (PubMed:25310401).

(Microbial infection) May play a role in limiting virus spread by inhibiting proliferation of virus-infected cells. Upon infection with diverse DNA and RNA viruses, inhibits cell-cycle progression by binding to promoters and activating transcription of genes encoding cell-cycle inhibitors, such as p21/CDKN1A (PubMed:21767813).

Endoplasmic reticulum unfolded protein response Source: UniProtKB
Extracellular matrix constituent secretion Source: UniProtKB
Multicellular organism development Source: UniProtKB-KW
Negative regulation of endoplasmic reticulum stress-induced intrinsic apoptotic signaling pathway Source: ParkinsonsUK-UCL
Negative regulation of fibroblast growth factor receptor signaling pathway Source: BHF-UCL
Negative regulation of gene expression Source: BHF-UCL
Negative regulation of sprouting angiogenesis Source: BHF-UCL
Negative regulation of transcription, DNA-templated Source: BHF-UCL
Osteoblast differentiation Source: UniProtKB
Positive regulation of collagen biosynthetic process Source: UniProtKB
Positive regulation of transcription from RNA polymerase II promoter in response to endoplasmic reticulum stress Source: ParkinsonsUK-UCL
Regulation of transcription by RNA polymerase II Source: GO_Central
Viral process Source: UniProtKB-KW

Endoplasmic reticulum membrane. ER membrane resident protein. Upon ER stress, translocated to the Golgi apparatus where it is cleaved. The cytosolic N-terminal fragment (processed cyclic AMP-responsive element-binding protein 3-like protein 1) is transported into the nucleus.
Processed cyclic AMP-responsive element-binding protein 3-like protein 1: Nucleus. Upon ER stress, transported into the nucleus.

Osteogenesis imperfecta 16 (OI16):
The disease may be caused by variants affecting the gene represented in this entry. OI16 affected patients show a genomic deletion encompassing CREB3L1 and the first exon of DGKZ. The absence of this exon does not affect all DGKZ isoforms, some are still produced at normal level. It cannot be ruled out that DGKZ could contribute to the phenotype, but in view of its role in bone formation, CREB3L1 is a strong OI16-causing candidate (PubMed:24079343). This hypothesis is corroborated by the observation of CREB3L1 knockout mice which exhibit features reminiscent of severe human osteogenesis imperfecta. An autosomal recessive form of osteogenesis imperfecta, a connective tissue disorder characterized by low bone mass, bone fragility and susceptibility to fractures after minimal trauma. Disease severity ranges from very mild forms without fractures to intrauterine fractures and perinatal lethality. Extraskeletal manifestations, which affect a variable number of patients, are dentinogenesis imperfecta, hearing loss, and blue sclerae. OI16 is a severe form.

Cytoplasmic: 1-374
Helical: 375-395
Lumenal: 396-519

Upon ER stress, translocated to the Golgi apparatus, where it is processed by regulated intramembrane proteolysis (RIP) to release the cytosol-facing N-terminal transcription factor domain. The cleavage is performed sequentially by site-1 and site-2 proteases (S1P/MBTPS1 and S2P/MBTPS2). RIP is induced by TGFB1 and ceramide (PubMed:25310401, PubMed:27499293).
N-glycosylated.
Ubiquitinated by HRD1/SYVN1; undergoes 'Lys-48'-linked ubiquitination, followed by rapid proteasomal degradation under normal conditions. Upon ER stress, SYVN1 E3 ubiquitin-protein ligase dissociates from its substrate, ubiquitination does not occur and CREB3L1 is stabilized.