Effects of plyometric- and cycle-based high-intensity interval training on body composition, aerobic capacity, and muscle function in young females: a field-based group fitness assessment.

High-intensity interval training (HIIT) is an effective alternative to moderate intensity continuous training for improvements in body composition and aerobic capacity; however, there is little work comparing different modalities of HIIT. The purpose of this study was to compare the effects of plyometric- (PLYO) and cycle-oriented (CYC) HIIT on body composition, aerobic capacity, and skeletal muscle size, quality, and function in recreationally trained females. Young (21.7 ± 3.1 yrs), recreationally active females were quasi-randomized (1:1 ratio) to 8 weeks of twice weekly PLYO (n = 15) or CYC (n = 15) HIIT. Body composition (four-compartment model), VO2peak, countermovement jump performance, muscle size, and echo intensity (muscle quality), as well as strength and power of the knee extensors and plantar flexors were measured before and after training. Both groups showed a similar decrease in body fat percentage (p < 0.001; η p 2   = 0.409) and echo intensity (p < 0.001; η p 2 = 0.558), and an increase in fat-free mass (p < 0.001; η p 2   = 0.367) and VO2peak (p = 0.001; η p 2 = 0.318). Muscle size was unaffected (p > 0.05), whereas peak torque was reduced similarly in both groups (p = 0.017; η p 2 = 0.188) and rapid torque capacity was diminished only for the knee extensors after CYC (p = 0.022; d = -0.67). These results suggest that PLYO and CYC HIIT are similarly effective for improving body composition, aerobic capacity, and muscle quality, whereas muscle function may express moderate decrements in recreationally active females. ClinicalTrials.gov (NCT05821504).

Weight cycling promotes fat gain and altered clock gene expression in adipose tissue in C57BL/6J mice.

Repeated attempts to lose weight by temporary dieting may result in weight cycling, eventually further gain of body fat, and possible metabolic adaptation. We tested this with a controlled experiment in C57BL/6J mice subjected to four weight cycles (WC), continuous hypercaloric feeding (HF), or low-fat feeding (LF). To search for genes involved in an adaptive mechanism to former weight cycling and avoid acute effects of the last cycle, the last hypercaloric feeding period was prolonged by an additional 2 wk before euthanization. Total energy intake was identical in WC and HF. However, compared with HF, the WC mice gained significantly more total body mass and fat mass and showed increased levels of circulating leptin and lipids in liver. Both the HF and WC groups showed increased adipocyte size and insulin resistance. Despite these effects, we also observed an interesting maintenance of circulating adiponectin and free fatty acid levels after WC, whereas changes in these parameters were observed in HF mice. Global gene expression was analyzed by microarrays. Weight-cycled mice were characterized by a downregulation of several clock genes (Dbp, Tef, Per1, Per2, Per3, and Nr1d2) in adipose tissues, which was confirmed by quantitative PCR. In 3T3-L1 cells, we found reduced expression of Dbp and Tef early in adipogenic differentiation, which was mediated via cAMP-dependent signaling. Our data suggest that clock genes in adipose tissue may play a role in metabolic adaptation to weight cycling.

H2A.Z-dependent crosstalk between enhancer and promoter regulates cyclin D1 expression.

H2A.Z association with specific genomic loci is thought to contribute to a chromatin structure that promotes transcription activation. Acetylation of H2A.Z at promoters of oncogenes has been linked to tumorigenesis. The mechanism is unknown. Here, we show that in triple negative breast cancer cells, H2A.Z bound to the promoter of the constitutively, weakly expressed cyclin D1 oncogene (CCND1), a key regulator of cellular proliferation. Depleting the pool of H2A.Z stimulated transcription of CCND1 in the absence of its cognate transcription factor, the estrogen receptor (ER). During activation of CCND1, H2A.Z was released from the transcription start site (TSS) and downstream enhancer (enh2) sequences. Concurrently, acetylation of H2A.Z, H3 and H4 at the TSS was increased but only H2A.Z was acetylated at enh2. Acetylation of H2A.Z required the Tip60 acetyltransferase to be associated with the activated CCND1 on both TSS and enh2 sites. Depletion of Tip60 prevented CCND1 activation. Chromosome conformation capture experiments (3C) revealed specific contacts between the TSS and enh2 chromatin regions. These results suggest that release of a histone H2A.Z-mediated repression loop activates CCND1 for transcription. Our findings open new avenues for controlling and understanding aberrant gene expression associated with tumorigenesis.

Assessment of the influence of foot orthoses in the hip loading conditions during walking: a single case study.

Despite their large clinical application, the understanding of the effects of foot orthoses on the lower limb kinematics and kinetics is limited. In this context, we propose an advanced musculoskeletal model to assess the influence of foot orthoses in the loading conditions within an osteoarthritic hip joint during gait. Experimental data are collected for a single pathological subject presenting a coxarthrosis (with and without orthoses), and a healthy subject during walking. An inverse dynamic approach coupled with an optimisation method evaluates the forces developed by 14 muscles and the hip contact reaction force. Contact reaction and muscular force magnitudes are closed whether the patient is walking with or without foot orthoses. Nevertheless, contact reaction amplitudes and orientations show differences in relation to those calculated for the healthy subject. The results obtained allow us to formulate some assumptions concerning the causes of coxarthrosis evolution and treatment.

Eliminating epigenetic barriers induces transient hormone-regulated gene expression in estrogen receptor negative breast cancer cells.

In breast cancer, approximately one-third of tumors express neither the estrogen receptor (ERalpha) nor estrogen-regulated genes such as the progesterone receptor gene (PR). Our study provides new insights into the mechanism allowing hormone-activated expression of ERalpha target genes silenced in ERalpha-negative mammary tumor cells. In cell lines derived from ERalpha-negative MDA-MB231 cells, stable expression of different levels of ERalpha from a transgene did not result in transcription of PR. A quantitative comparative analysis demonstrates that inhibiting DNA methyltransferases using 5-aza-2'-deoxycytidine or specific disruption of DNMT1 by small interfering RNAs and treatment with the histone-deacetylase inhibitor trichostatin A enabled ERalpha-mediated hormone-dependent expression of endogenous PR. We show that demethylation of a CpG island located in the first exon of PR was a prerequisite for ERalpha binding to these regulatory sequences. Although not a general requirement, DNA demethylation is also necessary for derepression of a subset of ERalpha target genes involved in tumorigenesis. PR transcription did not subsist 4 days after removal of the DNA methyltransferase blocking agents, suggesting that hormone-induced expression of ERalpha target genes in ERalpha-negative tumor cells is transient. Our observations support a model where an epigenetic mark confers stable silencing by precluding ERalpha access to promoters.

The human transcription factor IID subunit human TATA-binding protein-associated factor 28 interacts in a ligand-reversible manner with the vitamin D(3) and thyroid hormone receptors.

Using coexpression in COS cells, we have identified novel interactions between the human TATA-binding protein-associated factor 28 (hTAF(II)28) component of transcription factor IID and the ligand binding domains (LBDs) of the nuclear receptors for vitamin D3 (VDR) and thyroid hormone (TRalpha). Interaction between hTAF(II)28 and the VDR and TR LBDs was ligand-reversible, whereas no interactions between hTAF(II)28 and the retinoid X receptors (RXRs) or other receptors were observed. TAF(II)28 interacted with two regions of the VDR, a 40-amino acid region spanning alpha-helices H3-H5 and alpha-helix H8. Interactions were also observed with the H3-H5 region of the TRalpha but not with the equivalent highly related region of the RXRgamma. Fine mapping using RXR derivatives in which single amino acids of the RXRgamma LBD have been replaced with their VDR counterparts shows that the determinants for interaction with hTAF(II)28 are located in alpha-helix H3 and are not identical to those previously identified for interactions with hTAF(II)55. We also describe a mutation in the H3-H5 region of the VDR LBD, which abolishes transactivation, and we show that interaction of hTAF(II)28 with this mutant is no longer ligand-reversible.

Human TAF(II)55 interacts with the vitamin D(3) and thyroid hormone receptors and with derivatives of the retinoid X receptor that have altered transactivation properties.

We have identified novel interactions between the human (h)TATA-binding protein-associated factor TAF(II)55 and the ligand-binding domains (LBDs) of the nuclear receptors for vitamin D(3) (VDR) and thyroid hormone (TRalpha). Following expression in Cos cells, hTAF(II)55 interacts with the VDR and TRalpha LBDs in a ligand-independent manner whereas no interactions with the retinoid X receptors (RXRs) or with other receptors were observed. Deletion mapping indicates that hTAF(II)55 interacts with a 40-amino-acid region spanning alpha-helices H3 to H5 of the VDR and TRalpha LBDs but not with the equivalent highly related region of RXRgamma. TAF(II)55 also interacts with chimeric receptors in which the H3-to-H5 region of RXRgamma has been replaced with that of the VDR or TRalpha. Furthermore, replacement of two single amino acids of the RXRgamma LBD with their VDR counterparts allows the RXRgamma LBD to interact with hTAF(II)55 while the corresponding double substitution allows a much stronger interaction. In transfection experiments, the single mutated RXRgamma LBDs activate transcription to fivefold higher levels than wild-type RXRgamma while the double mutation activates transcription to a level comparable to that observed with the VDR. There is therefore a correlation between the ability of the modified RXRs to interact with hTAF(II)55 and transactivation. These results strongly suggest that the TAF(II)55 interactions with the modified RXR LBDs modulate transcriptional activation.

Synergistic transcriptional activation by TATA-binding protein and hTAFII28 requires specific amino acids of the hTAFII28 histone fold.

Coexpression of the human TATA-binding protein (TBP)-associated factor 28 (hTAFII28) with the altered-specificity mutant TBP spm3 synergistically enhances transcriptional activation by the activation function 2 of the nuclear receptors (NRs) for estrogen and vitamin D3 from a reporter plasmid containing a TGTA element in mammalian cells. This synergy is abolished by mutation of specific amino acids in the alpha2-helix of the histone fold in the conserved C-terminal region of hTAFII28. Critical amino acids are found on both the exposed hydrophilic face of this helix and the hydrophobic interface with TAFII18. This alpha-helix of hTAFII28 therefore mediates multiple interactions required for coactivator activity. We further show that mutation of specific residues in the H1' alpha-helix of TBP either reduces or increases interactions with hTAFII28. The mutations which reduce interactions with hTAFII28 do not affect functional synergy, whereas the TBP mutation which increases interaction with hTAFII28 is defective in its ability to synergistically enhance activation by NRs. However, this TBP mutant supports activation by other activators and is thus specifically defective for its ability to synergize with hTAFII28.

Interaction of human papillomavirus 8 regulatory proteins E2, E6 and E7 with components of the TFIID complex.

Human papillomavirus 8 (HPV8) is one of the oncogenic HPV types specifically associated with skin cancers of epidermodysplasia verruciformis patients. The early gene products of this virus exert functions in transformation (E2, E6, E7), replication (E1, E2) and in the control of viral transcription (E2, E7). Many viral and cellular transactivators of transcription have been shown to interact selectively and directly with a number of TATA-box-binding protein (TBP)-associated factors (TAFIIs), which then play a role as coactivators. Using glutathione-S-transferase (GST) pull-down experiments, we tested in vitro interactions between GST-HPV8-E1, -E2, -E6 and -E7 and 7 in-vitro-translated TAFIIs in the human (h) system (hTAFII18, hTAFII20, hTAFII28, hTAFII30, hTAFII55, hTAFII100, hTAFIIDeltaN135) or TBP. We could show that GST-HPV8-E2 interacts directly at least with hTAFII55 and TBP. Deletion analysis indicated that a domain overlapping with the C-terminal moiety of HPV8-E2 is required for binding to TBP, whereas determinants for interactions with hTAFII55 are in the central and C-terminal part of the E2 protein. In similar binding studies, GST-HPV8-E6 interacted with hTAFII28, hTAFIIDeltaN135 and TBP, and more weakly with hTAFII20, whereas GST- HPV8-E7 bound to hTAFII20, hTAFII28, hTAFII55, hTAFIIDeltaN135 and TBP. Deletion analysis revealed that the C-terminal part of HPV8-E7 is required for the interaction with these hTAFIIs. In contrast, no interactions were observed between GST-HPV8-E1 and in-vitro-translated hTAFIIs.

Human TAF(II)28 and TAF(II)18 interact through a histone fold encoded by atypical evolutionary conserved motifs also found in the SPT3 family.

Determination of the crystal structure of the human TBP-associated factor (hTAF(II))28/hTAF(II)18 heterodimer shows that these TAF(II)s form a novel histone-like pair in the TFIID complex. The histone folds in hTAF(II)28 and hTAF(II)18 were not predicted from their primary sequence, indicating that these TAF(II)s define a novel family of atypical histone fold sequences. The TAF(II)18 and TAF(II)28 histone fold motifs are also present in the N- and C-terminal regions of the SPT3 proteins, suggesting that the histone fold in SPT3 may be reconstituted by intramolecular rather than classical intermolecular interactions. The existence of additional histone-like pairs in both the TFIID and SAGA complexes shows that the histone fold is a more commonly used motif for mediating TAF-TAF interactions than previously believed.

The putative cofactor TIF1alpha is a protein kinase that is hyperphosphorylated upon interaction with liganded nuclear receptors.

Ligand-induced gene activation by nuclear receptors (NRs) is a complex process requiring dissociation of corepressors and recruitment of coactivators. The putative transcriptional intermediary factor TIF1alpha has been previously characterized as a nuclear protein that interacts directly with the AF-2 ligand-dependent activating domain present in the ligand-binding domain of numerous steroid and nonsteroid receptors, including the estrogen (ERalpha) and retinoid X (RXRalpha) receptors. We report here that TIF1alpha is both a phosphoprotein and a protein kinase. TIF1alpha coexpressed in COS-1 cells with RXRalpha or ERalpha is phosphorylated and becomes hyperphosphorylated upon ligand treatment. This hyperphosphorylation requires the binding of TIF1alpha to transcriptionally active NRs since it is prevented by mutations either in the core (alpha-helix 12 of the ligand-binding domain) of the AF-2 activating domains of RXRalpha and ERalpha or in the NR box of TIF1alpha that are known to prevent TIF1alpha-NR interactions. Thus, TIF1alpha is a phosphoprotein that undergoes ligand-dependent hyperphosphorylation as a consequence of nuclear receptor binding. We further show that purified recombinant TIF1alpha possesses intrinsic kinase activity and that, in addition to autophosphorylation, TIF1alpha selectively phosphorylates the transcription factors TFIIEalpha, TAFII28, and TAFII55 in vitro. These latter results raise the possibility that TIF1alpha may act, at least in part, by phosphorylating and modifying the activity of components of the transcriptional machinery.

Functional and structural analysis of the subunits of human transcription factor TFIID.

The past few years have brought many new insights concerning the structure and function of TAFII proteins. In the future, further biochemical and structural studies will no doubt lead to a greater understanding of the molecular organization of TFIID complexes. A better understanding of the function of metazoan, in particular, mammalian, TAFIIs in cell cycle progression and gene activation will, however, require the use of novel genetic techniques in addition to the biochemical analyses.

Multiple interactions between hTAFII55 and other TFIID subunits. Requirements for the formation of stable ternary complexes between hTAFII55 and the TATA-binding protein.

We have cloned and characterized the human TATA-binding protein (TBP)-associated factor hTAFII55. hTAFII55, which has no known Drosophila counterpart, is present in both of the previously described TFIIDalpha and TFIIDbeta subpopulations. We describe the interactions of hTAFII55 with other subunits of the transcription factor TFIID. By cotransfection in COS cells, we show that hTAFII55 interacts with hTAFII250, hTAFII100, hTAFII28, hTAFII20, and hTAFII18, but not with hTAFII30 or TBP. Analysis of the binding of hTAFII55 and TBP to hTAFII28 deletion mutants indicates that distinct regions of hTAFII28 are required for these interactions. Although hTAFII55 does not interact by itself with TBP, stable ternary complexes containing hTAFII55 and TBP can be formed in the presence of hTAFII250, hTAFII100, or hTAFII28. These results not only show that hTAFII100 and hTAFII28 interact with TBP, but also that they can nucleate the formation of partial TFIID complexes.

Distinct domains of hTAFII100 are required for functional interaction with transcription factor TFIIF beta (RAP30) and incorporation into the TFIID complex.

TFIID is the DNA binding component of the RNA polymerase II transcriptional machinery and is composed of the TATA binding protein (TBP) and TBP-associated factors (TAFIIs). Here we report the characterization of a new human TAF, hTAFII100, which is the human homologue of Drosophila TAFII80 and yeast TAFII90. hTAFII100 interacts strongly with hTAFII250, hTAFII55 and hTAFII28, less with hTAFII20 and hTAFII18, weakly with TBP and not at all with delta NTAFII135 and hTAFII30. Deletion analysis revealed that the C-terminal half of hTAFII100, which contains six WD-40 repeats, is not required for incorporation into the TFIID complex. Our results suggest that hTAFII100 can be divided into two domains, the N-terminal region responsible for interactions within the TFIID complex and the C-terminal WD repeat-containing half responsible for interactions between hTAFII100 and other factors. An anti-hTAFII100 antibody, raised against a C-terminal epitope, selectively inhibited basal TFIID-dependent in vitro transcription and the specific interaction between hTAFII100 and the 30 kDa subunit of TFIIF (RAP30). We demonstrate that the hTAFII100-TFIIF interaction supports pre-initiation complex formation in the presence of TFIID. Thus, this is the first demonstration that a TAFII functionally interacts with a basal transcription factor in vitro.

Human TAF(II28) promotes transcriptional stimulation by activation function 2 of the retinoid X receptors.

Transcriptional activation in vitro involves direct interactions of transactivators with the TATA binding protein (TBP) and the TBP-associated factors (TAF(II)s) which constitute the TFIID complex. However, the role of TAF(II)s in transcriptional regulation in mammalian cells has not been addressed. We show that activation function 2 of the retinoid X receptors (RXR AF-2) does not activate transcription from a minimal promoter in Cos cells. However, coexpression of human (h) TAF(II)28 promotes a strong ligand-dependent activity of the RXR AF-2 on a minimal promoter and potentiates the ability of the RXRalpha AF-2 to activate transcription from a complex promoter. The expression of hTAF(II)28 also potentiated transactivation by several nuclear receptors, notably the oestrogen and vitamin D3 receptors (ER and VDR), whereas other classes of activator were not affected. The effect of hTAFII(28) on RXR AF-2 activities did not appear to require direct RXR-TAFII(28) interactions, but correlated with the ability of hTAFII(28) to interact with TBP. In contrast to Cos cells, the RXR AF-2s had differential abilities to activate transcription from a minimal promoter in HeLa cells, and a lesser increase in their activity was observed upon hTAFII28 coexpression. Moreover, coexpression of hTAFII(28) did not increase but rather repressed activation by the ER and VDR AF-2s in HeLa cells. In agreement with these data, showing that TAF(II)28 is limiting in the AF-2 activation pathway in Cos cells, TAF(II)28 is selectively depleted in Cos cell TFIID.

Growth of hand-reared American kestrels I. The effect of two different diets and feeding frequency.

Seventy captive-bred American kestrels (Falco sparverius) were hand-reared on diets of either day-old cockerels (Gallus domesticus) (n = 38) or laboratory mice (Mus musculus) (n = 32) at meal frequencies of 4 or 6 times per day. Ad libitum food was provided in all meals. A proximate analysis of the two diets was performed and showed that cockerels when compared to mice contained more crude protein (60.0% versus 42.7% dry matter) and less fat (28.1% versus 46.5% dry matter). Body mass of nestlings was recorded daily until fledging, while lengths of the antebrachium and 9th primary remex were measured at intervals of 2 to 5 days. Data were fitted to the Richards growth model. Cockerel-fed nestlings exhibited growth patterns similar to those found in free-ranging kestrels. Mouse-fed birds however, grew more slowly which could be related to inadequate protein intake. No effect of hand-feeding frequency (4 versus 6 times daily) on growth rates was noted under any of the two diets. Irrespective of the dietary group, female kestrels were significantly heavier at the end of the experiment, as expected from the reversed sexual size dimorphism present in adult American kestrels.

Growth of hand-reared American kestrels. II. Body composition and wingloading of fledglings hand-fed two different diets.

The body composition of young American kestrels (Falco sparverius) hand-fed either a protein-rich diet (day-old cockerels Gallus domesticus) or a fat-rich diet (laboratory mice Mus musculus) was determined one day after fledging. Mouse-fed fledglings (n = 16) had significantly greater fat deposits than cockerel-fed birds (n = 15), while the crude protein content of the carcass was unaffected by the diets. At fledging, mouse-fed birds showed a significantly greater wingloading than cockerel-fed birds. Larger fat reserves (as in mouse-fed birds) might be mobilised in the event of a food shortage and thus these birds would be at an advantage in relation to fledglings with smaller reserves. On the other hand, large fat deposition, which alters wingloading, might impair the flight performance of the fledglings.

[Determination, by the immunogold method, of T lymphocyte sub-populations during HIV infections (LAV/HTLV III)]. / Détermination par la méthode immunogold des sous-populations lymphocytaires T au cours des infections par le virus HIV (LAV/HTLV III).

This study analyzes a method of indirect marking of T lymphocytes subpopulations using a 2nd antibody coupled to colloidal gold particles (Immunogold). There is an excellent correlation between this technique and the classical technique of indirect immunofluorescence. Immunogold enables an easy and rapid count of lymphocytes CD4+ and CD8+ during infections secondary to HIV virus (LAV/HTLV III). The permanent nature of the preparations and the cytological control make this method an interesting tool for the diagnosis and follow-up of patients suffering from AIDS, ARC or only asymptomatic seropositive individuals.