| 2016 |
ALAS1 undergoes heme-dependent degradation in mitochondria via the ATP-dependent protease ClpXP (CLPX/CLPP heteromultimer). ALAS1 forms a complex with ClpXP in a heme-dependent manner, and siRNA-mediated suppression of CLPX or CLPP induces ALAS1 accumulation. A specific heme-binding motif at the N-terminal end of the mature ALAS1 protein is required for this heme-dependent complex formation. Additionally, hemin-mediated oxidative modification of ALAS1 recruits LONP1, another mitochondrial matrix protease, into the ALAS1 complex. |
Co-immunoprecipitation, siRNA knockdown of CLPX/CLPP in HepG2 cells, site-directed mutagenesis of heme-binding motif |
The Journal of biological chemistry |
High |
27496948
|
| 2024 |
POLDIP2 serves as a heme-sensing adaptor protein that delivers ALAS1 to the mitochondrial protease CLPXP for degradation, establishing the molecular basis of heme-induced negative feedback. POLDIP2 directly recognizes heme-bound ALAS1 to drive assembly of the degradation complex. The C-terminal element of ALAS1 is dispensable for interaction with POLDIP2 but necessary for degradation by CLPXP. |
Biochemical reconstitution, loss-of-function (POLDIP2 depletion) with ALAS turnover assay, direct binding assays |
bioRxivpreprint |
High |
bio_10.1101_2024.07.05.602318
|
| 2008 |
Heme and cobalt protoporphyrin (CoPP) downregulate ALAS1 mRNA by decreasing mRNA half-life (post-transcriptional mechanism), while simultaneously upregulating cytosolic precursor ALAS1 protein by increasing its half-life. Mature mitochondrial ALAS1 protein is downregulated 60–70% by heme/CoPP treatment. |
Actinomycin D mRNA stability assay, cycloheximide protein stability assay, Western blotting in human hepatocytes |
Molecular and cellular biochemistry |
Medium |
18719978
|
| 2002 |
Drug-induced transcriptional activation of ALAS1 is mediated by the chicken xenobiotic-sensing nuclear receptor (CXR) binding to two drug-responsive enhancer sequences (DR5 and DR4 type nuclear receptor binding sites) in the 5'-flanking region of the gene. Mutagenesis of individual nuclear receptor binding sites reduced enhancer activation by ≥60%, and mutagenesis of both sites virtually eliminated it. EMSA confirmed direct CXR binding to these sites. |
Reporter gene assays in hepatoma cell line LMH, site-directed mutagenesis of nuclear receptor binding sites, electrophoretic mobility shift assay (EMSA), transactivation studies |
The Journal of biological chemistry |
High |
12121995
|
| 2009 |
PPARα directly regulates ALAS1 transcription in human liver via two functional PPAR binding sites at positions -9 kb and -2.3 kb relative to the ALAS1 transcription start site. PPARα agonists induced ALAS1 mRNA in primary human hepatocytes and HepG2 cells; effect was abolished by PPARα silencing. ChIP showed increased association of PPARα, RXR, PGC-1α, and activated RNA Pol II with the ALAS1 transcription start site upon PPARα ligand treatment and during fasting. |
Reporter gene assays, PPARα siRNA knockdown, chromatin immunoprecipitation (ChIP), primary human hepatocyte treatment |
Journal of molecular biology |
High |
19289130
|
| 2001 |
Human ALAS1 gene transcription uses tissue-specific initiation sites directed by closely similar core promoters. In liver, initiation is TATA-driven from a single downstream site used exclusively for drug induction. In brain, initiation occurs from within and upstream of the TATA box including an initiator-like element. Mutation of the TATA box in transfected HeLa cells activates upstream start sites, recapitulating the brain pattern. |
Transcript mapping in human and rat tissues, TATA box mutagenesis in transfected HeLa cells, mRNA transcript analysis |
Biochimica et biophysica acta |
Medium |
11267664
|
| 2000 |
The beta subunit of ATP-specific succinyl-CoA synthetase (SCS-betaA) specifically associates with the erythroid-specific ALAS isoform (ALAS-E) but NOT with the nonspecific ALAS (ALAS-N/ALAS1) in mitochondria. The ALAS-E mutant D190V (found in pyridoxine-refractory X-linked sideroblastic anemia) failed to associate with SCS-betaA, suggesting the interaction promotes efficient succinyl-CoA use or mitochondrial translocation of ALAS-E. |
Yeast two-hybrid screen of human bone marrow cDNA library, transient expression and co-immunoprecipitation |
The Journal of clinical investigation |
Medium |
10727444
|
| 2022 |
Doxorubicin intercalates into mitochondrial DNA and decreases the abundance of ALAS1 (the rate-limiting enzyme in heme synthesis), thereby impairing iron utilization, causing mitochondrial iron overload and ferroptosis in cardiomyocytes. ALAS1 overexpression prevented this iron overload outcome. Supplementation with 5-ALA (the product of ALAS1) suppressed iron overload and lipid peroxidation in both cultured cardiomyocytes and mice. |
ALAS1 overexpression rescue experiment in cardiomyocytes, 5-ALA supplementation in cardiomyocytes and mouse model, measurement of mitochondrial iron and lipid peroxidation |
Science signaling |
High |
36318618
|
| 2024 |
ALAS1 functions as a general repressor of miRNA accumulation and limits Argonaute complex assembly and activity in a heme-independent manner via a cytoplasmic role (previously considered inactive outside mitochondria). Conditional depletion of ALAS1 activity from mouse hepatocytes increases miRNA levels and enhances siRNA-mediated knockdown. This noncanonical function is specific to ALAS1 and not shared by other heme biosynthesis enzymes. |
Conditional ALAS1 depletion in mouse hepatocytes, Argonaute complex assembly assays, miRNA quantification, siRNA knockdown efficiency assays |
Science (New York, N.Y.) |
High |
39700288
|
| 2023 |
Measles virus V protein antagonizes ALAS1 by sequestering it to the cytosol, preventing its normal mitochondrial localization. This relocalization decreases mitochondrial volume and impairs mitochondrial metabolic potential, leading to release of mitochondrial dsDNA into the cytosol. Released mtDNA is transcribed by DNA-dependent RNA Pol III to produce dsRNA intermediates that activate RIG-I and type I interferon production. |
Subcellular fractionation post-infection, MeV mutant lacking V gene as control, IFNAR-/- hCD46 transgenic mouse infection model, deep sequencing of cytosolic mtDNA |
PLoS pathogens |
High |
36802406
|
| 2015 |
REV-ERBα represses ALAS1 transcription in rat granulosa cells. REV-ERBα knockdown via siRNA upregulated ALAS1 transcript levels, and treatment with REV-ERBα agonists (GSK4112, heme) repressed ALAS1 expression, while antagonist SR8278 increased it. |
Rev-erbα siRNA knockdown, agonist/antagonist treatment, real-time monitoring of Per2-dLuc circadian oscillations in primary granulosa cells |
Chronobiology international |
Medium |
26102301
|
| 2009 |
Estrogen receptor alpha (ERα) mediates increased transcriptional activity of ALAS1 through a half-palindromic estrogen response element in the 5' regulatory region (near position -853). Co-transfection with ERα expression vector in HepG2 cells showed the -853C>T variant generates a stronger enhancer response (66% increase) in the presence of estrogen compared to wild-type (47% increase). |
Co-transfection reporter assay in HepG2 cells with ERα expression vector, site-directed mutagenesis of putative estrogen response element |
Cellular and molecular biology |
Low |
19656447
|
| 2021 |
In heterozygous ALAS1 null mice, fasting induces ALAS1 mRNA in both WT and heterozygous mice, but only heterozygous mice show this manifest as increased ALAS1 protein. Hepatic heme oxygenase 1 (HMOX1) mRNA expression was significantly lower in heterozygous mice. No upregulation of the WT allele ALAS1 mRNA was detected as a compensatory mechanism in heterozygous liver. |
Heterozygous ALAS1 null mouse model (βGEO insert), fasting induction experiment, RT-PCR, Western blotting, HMOX1 mRNA measurement |
Molecular genetics and metabolism reports |
Medium |
34900592
|
| 2018 |
In zebrafish, Alas1 deficiency blocks neutrophil maturation at a specific stage (proper initiation preserved but further maturation blocked) due to heme deficiency, resulting in lipid storage and granule formation deficiencies, and loss of heme-dependent granule protein activities. Alas1-deficient zebrafish showed impaired bactericidal ability and augmented inflammatory responses when challenged with E. coli. |
Alas1-deficient zebrafish model, neutrophil maturation staging, granule protein activity assays, bacterial challenge |
Haematologica |
Medium |
29954941
|
| 1995 |
The human housekeeping ALAS1 gene was mapped to chromosome band 3p21.1 by PCR analysis of somatic cell and radiation hybrids. |
PCR analysis of somatic cell hybrids and radiation hybrids |
Cytogenetics and cell genetics |
Medium |
7698013
|