Peer review of: Diaphanous-related formin mDia2 regulates beta2 integrins to control hematopoietic stem (2020)


 

Reviewers' comments: 

Reviewer #1 (Remarks to the Author): 

Mei et al are submitting their revised manuscript, now entitled “Diaphanous-related formin mDia2 
regulates beta2 integrins to control hematopoietic stem and progenitor cell engraftment”. The authors 
have chosen to remove the incomplete dataset describing the mDia1 knockout and mDia1/mDia2 
knockouts, and focus the manuscript on mDia2 function in hematopoietic stem and progenitor 
engraftment (therefore excluding the response to Major Point 5 from the original review). In support 
of the mDia2 knockout phenotype, the authors have provided additional experimental data to address 
the Major concerns cited, including: (1) Analysis of (New Figure 1) non-competitive Vav1-cre; 
mDia2fl/fl BMT 16 weeks post-transplantation; HSPCs now demonstrate an expansion of phenotypic 
HSPCs and an increase in cell cycling. This is more reflective of the previously described SRF knockout 
mice. Previously mislabeled 10 month post-transplantation data has been moved to Supplemental 
Figure 2B. (2) Addition of representative images of in vivo transmigration with improved delineation of 
the vasculature and (3) intrafemoral HSPC injections that partially circumvent the lodgment 
phenotype. In summary, the authors have adequately addressed most concerns and have significantly 
strengthened the manuscript. However, there are Minor points that the authors can address via 
changes to the figures/text to improve the manuscript. 

Minor Points: 
1. Page 5, line 108-111; please immunophenotypically define all populations (i.e. MPPs, LT-HSCs, ST-
HSCs). 
2. Page 6, line 122; “were transplanted non-competitively into lethally irradiated CD45.1+ mice. 
3. While not necessary for all cell cycle analysis, can the authors include a representative flow plot in 
the main figures (e.g. for Figure 1D)? 
4. Figure 2C; please fully define “Gran” and “MO” cell types. 
5. Page 7, line 155-157; “Importantly, the absence of mDia2 deficient cells in LSK, LK, LT-HSC, and 
ST-HSC, and multipotent progenitor (MPP) populations (Figure 2B-C…). I do not see this data in Figure 
2. 
6. Vav1-cre; mDia2fl/+ heterozygous knockout data was removed from new Figure 2, but is still in 
Sup. Figure 1D and F. Please remove. 
7. Supplemental Figure 2C-E; please include long-term competitive engraftment data, if available. In 
addition, it is not clear why the non-competitive Mx1-cre; mDia2 knockout data was removed. I 
believe the Mx1-cre; mDia2 knockout data is included to confirm a postnatal (and not developmental) 
HSPC phenotype. Moreover, please detail in the discussion what information the Mx1-cre data tells the 
reader in this system (i.e. confirming a postnatal and not a developmental phenotype). 
8. Is the hCD4+ labeling (Y-axis) of Figure 5A correct? Please address. 

Reviewer #2 (Remarks to the Author): 

See attached annotated rebuttal letter 

Reviewer #3 (Remarks to the Author): 

The authors have adequately addressed the comments from the reviewers and this very interesting 
study seems now acceptable for publication