Regulation of Gonad Morphogenesis in Drosophila melanogaster by BTB Family Transcription Factors

During embryogenesis, primordial germ cells (PGCs) and somatic gonadal precursor cells (SGPs) migrate and coalesce to form the early gonad. A failure of the PGCs and SGPs to form a gonad with the proper architecture not only affects germ cell development, but can also lead to infertility. Therefore, it is critical to identify the molecular mechanisms that function within both the PGCs and SGPs to promote gonad morphogenesis. We have characterized the phenotypes of two genes, longitudinals lacking (lola) and ribbon (rib), that are required for the coalescence and compaction of the embryonic gonad in Drosophila melanogaster. rib and lola are expressed in the SGPs of the developing gonad, and genetic interaction analysis suggests these proteins cooperate to regulate gonad development. Both genes encode proteins with DNA binding motifs and a conserved protein-protein interaction domain, known as the Broad complex, Tramtrack, Bric-à-brac (BTB) domain. Through molecular modeling and yeast-two hybrid studies, we demonstrate that Rib and Lola homo- and heterodimerize via their BTB domains. In addition, analysis of the colocalization of Rib and Lola with marks of transcriptional activation and repression on polytene chromosomes reveals that Rib and Lola colocalize with both repressive and activating marks and with each other. While previous studies have identified Rib and Lola targets in other tissues, we find that Rib and Lola are likely to function via different downstream targets in the gonad. These results suggest that Rib and Lola act as dual-function transcription factors to cooperatively regulate embryonic gonad morphogenesis

No Difference in Patient-Reported Outcomes for Periacetabular Osteotomy and Hip Arthroscopy With Capsular Plication in the Setting of Borderline Hip Dysplasia: A Propensity-Matched Multicenter Study With Minimum 5-Year Follow-up

PURPOSE To compare minimum 5-year patient-reported outcome measures after hip arthroscopy (HA) and periacetabular osteotomy (PAO) for borderline hip dysplasia. METHODS Hips with a lateral center-edge angle (LCEA) between 18° and less than 25° that underwent either PAO or HA were selected from 2 institutions. The exclusion criteria were as follows: LCEA less than 18°, Tönnis osteoarthritis grade greater than 1, prior hip surgical procedures, active inflammatory disease, Workers' Compensation, and concomitant surgery. Patients underwent propensity matching based on age, sex, body mass index, and Tönnis osteoarthritis grade. Patient-reported outcome measures included the modified Harris Hip Score, as well as calculation of the minimal clinically important difference, patient acceptable symptom state, and maximum outcome improvement satisfaction threshold. Preoperative radiographic predictors included comparison of the Femoro-epiphyseal Acetabular Roof index and ligamentum teres lesions. RESULTS A total of 28 PAO patients underwent propensity matching to 49 HA patients. The 2 groups were similar in terms of mean age, sex, preoperative body mass index, and LCEA. The PAO group had a longer mean follow-up period (95.8 months vs 81.3 months, P = .001). The mean Femoro-epiphyseal Acetabular Roof index was significantly lower preoperatively in the HA group (P < .001). The 2 groups showed similar and significant improvements in the mean modified Harris Hip Score from preoperatively to latest follow-up (P < .001). The relative risk of subsequent surgery in the PAO group was 3.49 (P = .024), mostly attributed to hardware removal (25%). The revision rate was 3.6% in the PAO group and 8.2% in the HA group (P = .65). One patient in the PAO group required revision HA for intra-articular adhesions. Three of the patients requiring revision in the HA group underwent PAO because of persistent pain, and one underwent revision HA alone. Conversion to total hip arthroplasty was required in 1 patient in the HA group and no patients in the PAO group. CONCLUSIONS Both PAO and HA with capsular plication provide borderline hip dysplasia patients with clinically significant improvements and low revision rates at a minimum of 5 years postoperatively. LEVEL OF EVIDENCE Level III, retrospective, comparative therapeutic trial

Arthroscopic Capsular Reconstruction of the Hip With Acellular Dermal Extracellular Matrix: Surgical Technique

Atraumatic instability of the hip has become an increasingly studied occurrence in recent years. There are several established surgical techniques that help restore stability of the native hip joint. In some cases, these procedures are not an option. As the phenomenon has become recognized more frequently, a greater number of revision surgeries are warranted in patients with ligamentous laxity. A durable solution for irreparable microinstability needs to be formulated to address this vulnerable patient demographic. We describe the surgical technique for capsular reconstruction with acellular dermal extracellular matrix

Circumferential Labral Reconstruction Using the Knotless Pull-Through Technique—Surgical Technique

Arthroscopic labral reconstruction is an alternative procedure for an irreparable hip labrum in the nonarthritic hip population. Although labral reconstruction is a relatively new procedure, data in the literature show favorable outcomes. Patients have shown beneficial outcomes from labral reconstructive surgery as well as when compared with labral repair and debridement patients. However, one of the challenges in performing labral reconstruction has been correctly measuring the graft to perfectly fit the area of labral deficiency. We propose a labral reconstruction technique that will eliminate inaccuracies in graft measurement while incorporating beneficial characteristics of the knotless suture. The advantages of this technique will increase procedural accuracy and brevity

Arthroscopic Technique for Iliopsoas Fractional Lengthening for Symptomatic Internal Snapping of the Hip, Iliopsoas Impingement Lesion, or Both

Pathology of the iliopsoas may cause painful internal snapping of the hip or labral damage from soft impingement. Favorable outcomes have been reported after arthroscopic release or fractional lengthening of the iliopsoas. In patients with risk factors for instability, restoration of other soft-tissue constraints such as the labrum and capsule should be performed if iliopsoas fractional lengthening is undertaken. The purpose of this article is to detail the step-by-step surgical technique of arthroscopic iliopsoas fractional lengthening, in addition to the indications, pearls, and pitfalls of the technique

<i>rib and lola</i> genetically interact.

<p>Graph of phenotypic frequency for stage 15 embryonic gonads. The following gonad phenotypes were scored: fusion (red), compaction (blue) and wild-type (green). Gonads were scored by staining somatic gonadal precursor cells for the <i>68-77-lacZ</i> enhancer trap. A chi-square test was performed to test the null hypothesis that the phenotype ratios would be the same across all genotypes. Results allow us to reject the null hypothesis: <i>Χ</i>² _{<i>22</i>, <i>0</i>.<i>05</i>} = 313.31, p<0.001.</p

<i>lola</i> and <i>rib</i> mutants exhibit defects in gonad morphogenesis.

<p>(A) Schematic of the stages of embryonic gonad formation. At stage 12 SGP (red) clusters and PGCs (green) begin to intermingle. At stage 13 SGP clusters fuse and coalesce with the PGCs, sending out extensions around PGCs to ensheath them. By the end of stage 15 SGPs and PGCs compact to form a spherical gonad. (B) Molecular structure of Lola and Rib with BTB domains (light blue), Lola common region (dark blue), zinc finger DNA binding motifs (ZF; yellow), pipsqueak DNA binding motif (PSQ; pink), and the corresponding mutations found in alleles used in this study. (C-G) Stage 15 mutant embryos immunostained for the <i>68-77</i>-<i>lacZ</i> enhancer trap, which labels the cytoplasm of SGPs for analysis of gonad morphology. Posterior to the right. (C) Control embryos expressing the <i>68-77-lacZ</i> enhancer trap. Scale bar: 10μm. (D-E) <i>lola</i>^{<i>46</i>.<i>38/22</i>.<i>05</i>} embryonic gonads exhibiting fusion (D) and compaction (E) defects. (E-F) <i>rib</i>^{<i>35</i>.<i>14/55</i>.<i>25</i>} embryonic gonads exhibiting (F) fusion and (G) compaction defects. (H) Quantification of the frequency of gonad phenotypes observed in control, <i>lola</i> mutant and <i>rib</i> mutant embryos. Gonad morphology was assessed using the <i>68-77-</i>lacZ enhancer trap. The following phenotypes were scored: fusion (red), compaction (blue) and wild-type (green). A chi-square test was performed to test the null hypothesis that the phenotypic ratios will be the same across all genotypes. Results allow us to reject the null hypothesis: <i>Χ</i>² _{<i>28</i>, <i>0</i>.<i>05</i>} = 118.95, p<0.001.</p

Calculated Interactions Energies for BTB Dimers.

<p>Calculated Interactions Energies for BTB Dimers.</p

Expression of Rib and Lola in the embryonic gonad.

<p>(A-A”‘) Expression of Lola in an Oregon-R stage 13 gonad. (A) Anti-Lola (green). (A’) Anti-Traffic jam (TJ) marks somatic gonadal precursors (SGPs; red). (A”) Anti-Vasa marks primordial germ cells (PGCs; blue). (A”‘) Merged image with anti-Lola (green), anti-TJ (SGPs; red), and anti-Vasa (PGCs; blue). (B-B”‘) Expression of Lola in an Oregon-R stage 15 gonad. (B) Anti-Lola (green). (B’) Anti-TJ (SGPs; red). (B”) Anti-Vasa (PGCs; blue). (B”‘) Merged image with anti-Lola (green), anti-TJ (SGPs; red), and anti-Vasa (PGCs; blue). (C-C”‘) Expression of Rib in an Oregon-R stage 13 gonad. (C) Anti-Rib (green). (C’) Anti-TJ (SGPs; red). (C”) Anti-Vasa (PGCs; blue). (C”‘) Merged image with anti-Rib (green), anti-TJ (SGPs; red), anti-Vasa (PGCs; blue). Same scale as (A). (D-D”‘) Expression of Rib in an Oregon-R stage 15 gonad. Same scale as (B). (D) Anti-Rib (green). (D’) Anti-TJ (SGPs; red). (D”) Anti-Vasa (PGCs; blue). (D”‘) Merged image with anti-Rib (green), anti-TJ (SGPs; red), anti-Vasa (PGCs; blue). (E-E”‘) Colocalization of Rib and Lola in an Oregon-R stage 13 gonad. Same scale as (A). (E) Anti-Rib (green). (E’) Anti-Lola (red). (E”) Anti-TJ (SGPs; blue). (E”‘) Merge of anti-Rib (green) and anti-Lola (red). (F-F”‘) Colocalization of Rib and Lola in an Oregon-R stage 15 gonad. Same scale as (B). (F) Anti-Rib (green). (F’) Anti-Lola (red). (F”) Anti-TJ (SGPs; blue). (F”‘) Merge of anti-Rib (green) and anti-Lola (red). Gonads are outlined by dotted lines. Areas of high Rib-Lola colocalization are indicated by arrows. For all images posterior is to the right. Scale bars: 10μm.</p