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| 銆€銆€ | 銆€銆€ |
|---|---|
| Gene Symbol | SMC1A |
| Full Name | Structural Maintenance of Chromosomes 1A |
| Chromosomal Location | Xp11.22 |
| NCBI Gene ID | 27151 |
| OMIM | 300040 |
| Ensembl ID | ENSG00000101057 |
| UniProt ID | Q14683 |
| Associated Diseases | Cornelia de Lange syndrome (CdLS), X-linked ID, early-onset neurodegeneration |
| Protein Class | Cohesin complex subunit |
| Molecular Function | Sister chromatid cohesion, DNA repair, gene regulation |
SMC1A is a human gene whose product sMC1A encodes the Structural Maintenance of Chromosomes 1A protein, a key component of the cohesin complex essential for sister chromatid cohesion during mitosis and meiosis [1]. The cohesin complex forms a ring structure that encircles sister chromatids, holding them together from S phase until anaphase [2]. SMC1A partners with SMC3 to form the cohesin heterodimer core, which is loaded onto chromatin by the NIPBL-SCC2 complex and stabilized by SA1/2 (STAG1/2) proteins [3]. Variants in SMC1A have been implicated in Cornelia de Lange Syndrome (CdLS), Neurodegeneration, Cancer. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.
SMC1A encodes the Structural Maintenance of Chromosomes 1A protein, a key component of the cohesin complex essential for sister chromatid cohesion during mitosis and meiosis [1]. The cohesin complex forms a ring structure that encircles sister chromatids, holding them together from S phase until anaphase [2]. SMC1A partners with SMC3 to form the cohesin heterodimer core, which is loaded onto chromatin by the NIPBL-SCC2 complex and stabilized by SA1/2 (STAG1/2) proteins [3].
Beyond its canonical role in chromosome segregation, SMC1A participates in DNA double-strand break repair through the S-phase checkpoint [4]. It recruits repair proteins to damaged DNA and facilitates homologous recombination. Additionally, SMC1A regulates gene expression by mediating chromatin looping and topologically associating domain (TAD) formation, affecting developmental gene expression programs critical for neuronal differentiation [5].
In the brain, SMC1A is expressed in neurons and glial cells, with high expression in the prefrontal cortex and hippocampus—regions affected in neurodegenerative diseases [6]. Its role in DNA repair makes it particularly important in post-mitotic neurons, which are highly susceptible to genotoxic stress accumulation.
Haploinsufficiency of SMC1A causes approximately 5% of CdLS cases, characterized by distinctive facial features, growth retardation, intellectual disability, and limb anomalies [7]. Neurodevelopmental manifestations include autism spectrum disorder, seizures, and behavioral problems. Interestingly, some SMC1A variant carriers show progressive cerebellar atrophy and early-onset neurodegeneration, suggesting a role for cohesin dysfunction in age-related neuronal decline [8].
SMC1A variants have been implicated in X-linked intellectual disability with progressive neurodegeneration [9]. Recent studies link cohesin dysfunction to accelerated aging phenotypes and increased DNA damage accumulation in neurons [10]. Altered SMC1A expression is observed in post-mortem brain tissue from Alzheimer's disease patients, particularly in regions showing amyloid pathology [11].
While not directly cancer-causing, reduced SMC1A expression impairs the G2/M checkpoint, potentially increasing genomic instability [12]. Some studies suggest SMC1A overexpression in certain cancers as a compensatory mechanism for increased proliferation.
SMC1A is ubiquitously expressed across all tissues, with highest levels in proliferating cells [1]. In the brain:
Expression is cell cycle-regulated, peaking in S and G2 phases [2]. In neurons, SMC1A expression remains relatively stable, reflecting its essential role in maintaining genomic integrity in non-dividing cells [6].
| Variant | Type | Effect | Disease Association |
|---|---|---|---|
| p.R258C | Missense | DNA binding defect | CdLS [7] |
| p.E1287K | Missense | Cohesion impairment | X-linked ID [9] |
| p.Q776* | Nonsense | Truncation | CdLS [7] |
Therapeutic strategies targeting SMC1A-related neurodegeneration focus on: