Biomedical subjects

L Holmer

Publications and source records attributed to L Holmer.

6 recordsLinked to original sources

PubMed2001

Inner nuclear membrane proteins: functions and targeting.

We summarize the properties of integral membrane proteins that reside in the inner nuclear membrane, including lamin B receptor (LBR), lamina-associated polypeptide (LAP) 1, LAP2, emerin, MAN1 and nurim. Most of these proteins interact with lamins and chromatin. Some data also suggest more speculative functions such as gene regulation and possibly sterol metabolism. Mutations in emerin and nuclear lamins have been associated with muscular dystrophies and lipodystrophy, raising new questions about the functions of inner nuclear membrane proteins. Integral proteins of the inner nuclear membrane are synthesized on the rough endoplasmic reticulum (ER) and reach the inner nuclear membrane by lateral diffusion in the connected ER and nuclear envelope membranes. Associations with nuclear ligands retain them in the inner nuclear membrane. Further investigation of the functions and targeting of inner nuclear membrane proteins are needed to determine how they are involved in human disease.

Animals↗

PubMed2000

MAN1, an inner nuclear membrane protein that shares the LEM domain with lamina-associated polypeptide 2 and emerin.

The "MAN antigens" are polypeptides recognized by autoantibodies from a patient with a collagen vascular disease and localized to the nuclear envelope. We now show that one of the human MAN antigens termed MAN1 is a 82.3-kDa protein with an amino-terminal domain followed by two hydrophobic segments and a carboxyl-terminal tail. The MAN1 gene contains seven protein-coding exons and is assigned to human chromosome 12q14. Its mRNA is approximately 5.5 kilobases and is detected in several different cell types that were examined. Cell extraction experiments show that MAN1 is an integral membrane protein. When expressed in transfected cells, MAN1 is exclusively targeted to the nuclear envelope, consistent with an inner nuclear membrane localization. Protein sequence analysis reveals that MAN1 shares a conserved globular domain of approximately 40 amino acids, which we term the LEM module, with inner nuclear membrane proteins lamina-associated polypeptide 2 and emerin. The LEM module is also present in two proteins of Caenorhabditis elegans. These results show that MAN1 is an integral protein of the inner nuclear membrane that shares the LEM module with other proteins of this subcellular localization.

Amino Acid Sequence↗

PubMed1998

The human lamin B receptor/sterol reductase multigene family.

LBR (lamin B receptor) is an integral protein of the inner nuclear membrane encoded by a gene on human chromosome 1q42.1. LBR has a nucleoplasmic, amino-terminal domain of approximately 200 amino acids followed by a carboxyl-terminal domain similar in sequence to yeast and plant sterol reductases. We have determined the primary structures of two human proteins with strong sequence similarity to the carboxyl-terminal domain of LBR and sterol reductases. Their genes have recently been assigned the symbols TM7SF2 and DHCR7. TM7SF2 mRNA is most predominantly expressed in heart and DHCR7 mRNA mostly in liver and brain. Whereas LBR is localized to the inner nuclear membrane, these two related proteins are in the endoplasmic reticulum. The TM7SF2 gene contains 10 coding exons, and its intron positions are exactly conserved in the part of the LBR gene encoding its carboxyl-terminal domain. Intron positions in the DHCR7 gene are also similar. Both of these new LBR-like genes are on chromosome 11q13. These results describe a human gene family encoding proteins of the inner nuclear membrane and endoplasmic reticulum that function in nuclear organization and/or sterol metabolism.

Amino Acid Sequence↗

PubMed1998

A human HP1 pseudogene maps to chromosome 11p14.

The chromo multigene superfamily encodes numerous proteins involved in chromatin structure or organization. The prototypical member of this superfamily is HP1 of Drosophila melanogaster. We now present the sequence of a human HP1Hs gamma pseudogene and assign it to chromosome 11p14 by radiation hybrid mapping. The coding regions of at least three other human genes for HP1 orthologues and another pseudogene are very similar in sequence. These results demonstrate that HP1-type sequences have been duplicated multiple times in the mammalian genome.

Base Sequence↗

PubMed1998

BEACOPP: a new regimen for advanced Hodgkin's disease. German Hodgkin's Lymphoma Study Group.

The BEACOPP chemotherapy regimen for advanced Hodgkin's disease employs a rearranged schedule permitting a shortened three-week cycle. With haematological growth factor support, the dosages of cyclophosphamide, etoposide and adriamycin could be moderately escalated. The 3-armed multicentre HD9 trial (recruitment 1993-1998; 1300 patients randomised) aimed to compare BEACOPP with the standard COPP/ABVD chemotherapy and to detect and measure the gain in efficacy, if any, due to moderate dose escalation of BEACOPP. Eight cycles were given, followed by local irradiation. The most recent interim analysis, with 689 evaluable patients, circa 40% of all expected events and a median observation time of 27 months, showed significant differences in progression rate (P) and in two-year freedom from treatment failure (F) between the treatment arms, with escalated BEACOPP (P = 2%, F = 89%) better than baseline BEACOPP (P = 9%, F = 81%) better than COPP/ABVD (P = 13%, F = 72%). Survival was not significantly different. Acute toxicity was more severe due to dose escalation, but remained manageable. These preliminary results suggest that BEACOPP improves efficacy. Moderate dose escalation is feasible with G-CSF support and appears likely to make a worthwhile improvement in the cure rate. The results must await confirmation (or otherwise) by the final analysis including all randomised patients and sufficiently mature data.

Adolescent↗

PubMed1998

BEACOPP, a new dose-escalated and accelerated regimen, is at least as effective as COPP/ABVD in patients with advanced-stage Hodgkin's lymphoma: interim report from a trial of the German Hodgkin's Lymphoma Study Group.

PURPOSE: The HD9 trial aims to evaluate whether moderate dose escalation and/or acceleration of standard polychemotherapy is beneficial for advanced-stage Hodgkin's disease (HD). Two variants of a novel bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP) scheme (standard and escalated dose) are compared with cyclophosphamide, vincristine, procarbazine, and prednisone (COPP)/doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). PATIENTS AND METHODS: The randomized, three-arm trial recruited patients in stages IIB and IIIA with risk factors and stages IIIB and IV. BEACOPP in baseline dose contains all drug dosages of COPP/ABVD (except vincristine and procarbazine) rearranged in a shorter, 3-week cycle. Escalated BEACOPP uses higher doses of cyclophosphamide, doxorubicin, and etoposide with granulocyte colony-stimulating factor (G-CSF) support. After eight chemotherapy cycles, initial bulky and residual disease is irradiated. The trial is monitored and analyzed by means of a sequential strategy. RESULTS: An interim analysis with 505 assessable patients and a median follow-up of 23 months showed a significant inferiority (according to sequential monitoring strategy) of the COPP/ABVD regimen in progression rate and freedom from treatment failure (FFTF) compared with the pooled results of both BEACOPP variants. The 24-month FFTF rate was 75% for COPP/ABVD and 84% for BEACOPP pooled (P = .034). There was 12% progressive disease with COPP/ABVD and 6% with BEACOPP pooled. Differences in survival were not significant in sequential analysis. The acute toxicity of baseline BEACOPP resembled that of COPP/ABVD; escalated BEACOPP showed increased but manageable hematologic toxicity. CONCLUSION: Combined with local irradiation, BEACOPP in one or both variants shows superior disease control compared with COPP/ABVD, with acceptable acute toxicity. Further follow-up is required to assess the effect of dosage and the effect on survival and late toxicities.

Adolescent↗