Table 1.
Examples of H1 subtypes and their specific functions
| H1 subtypea | Functions | References |
|---|---|---|
| Saccharomyces cerevisiae (1 subtype) | ||
| Hho1p | DNA repair, inversely linked with gene expression | 91 |
| Tetrahymena thermophila (1 subtype) | ||
| H1 | Depletion results in up- and downregulation of specific genes, not essential | 9 |
| Caenorhabditis elegans (8 subtypes) | ||
| HIS24me | Regulation of innate immune genes and stress response genes | 86 |
| Drosophila melanogaster (2 subtypes) | ||
| Somatic H1 | Heterochromatin formation, silencing of TEs (involved in Su(var)39/HP1 pathway, JAK/STAT29E pathway) essential | 69,70 |
| dBigH1 | Prevents premature zygotic genome activation | 95 |
| Xenopus laevis (5 subtypes) | ||
| B4 (germ cell-specific) | Open chromatin conformation, ATP-dependent chromatin remodelling required for successful reprogramming of somatic mammalian cell nuclei in transplantation experiments | 97,98 |
| Chicken (7 subtypes) | ||
| H1R | DNA damage response | 92 |
| Mouse (11 subtypes) | ||
| H1a-H1e | Somatic, replication-dependent subtypes, both general and specific functions | 41 |
| H1c, H1d, H1e (H1.2, H1.3, H1.4) | Triple knockout is embryonic lethal | 14 |
| H1b (H1.5) | Interacts with Msx1, repression of muscle cell differentiation | 85 |
| H1c (H1.c) | Heterochromatin condensation in photoreceptors | 76 |
| H1(0) (H1.0) | Replacement subtype in differentiated cells | 45 |
| H1x (H1.10) | Function not clarified, replacement subtype | |
| H1oo (H1.8) | Expression of pluripotency genes in early embryos | 49,100 |
| H1t2 (H1.7) | Sperm cell differentiation | 48 |
| Human (11 subtypes) | ||
| H1.1-H1.5 | Somatic, replication-dependent subtypes, both general and specific functions | 41 |
| H1.2 | Maintenance of active gene transcription, recruitment of Cul4A ubiquitin ligase/PAF1 | 83 |
| H1.2S173p: active transcription | 116 | |
| Repressor of p53-mediated transcription | 87 | |
| H1.3 | Inhibition of h19 noncoding RNA transcription | [90,90] |
| H1.4 | H1.4K26me: heterochromatin formation via binding to HP1 and L3MBTL1 | 72,75 |
| H1.4K34ac: recruitment of TAF, active transcription | 122 | |
| H1.4S172p, H1.4S187p: active transcription | 116 | |
| H1.0 | Replacement subtype in differentiated cells | 45 |
| H1x (H1.10) | Mitotic progression | 128 |
| H1oo, H1t, H1T2, HILS1 (H1.8, H1.6, H1.7, H1.9) | Germ cell-specific subtypes, function not clarified | 47,48,129 |
For further description, see also 20.
a
For mouse and human subtypes/variants, the systematic names are in parentheses.