FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * KANIA EDWIN M JR   2. Issuer Name and Ticker or Trading Symbol ACCELERON PHARMA INC [XLRN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O FLAGSHIP VENTURES, 1 MEMORIAL DRIVE 3. Date of Earliest Transaction (Month/Day/Year) 12/12/2014 (Street) CAMBRIDGE, MA 02142 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 12/12/2014   J(1)   500,421 D $ 0 500,420 I See Footnote (2) Common Stock 12/12/2014   J(3)   60,496 D $ 0 30,248 I See Footnote (4) Common Stock 12/12/2014   J   51,163 A $ 0 51,163 I See Footnote (5) Common Stock 12/12/2014   J   3,187 A $ 0 3,187 I See Footnote (6) Common Stock 12/12/2014   J   36,542 A $ 0 36,542 I See Footnote (7) Common Stock 12/12/2014   J   712 A $ 0 37,254 I See Footnote (8) Common Stock 12/12/2014   J(9)   13,136 D $ 0 24,118 I See Footnote (10) Common Stock 12/12/2014   J(9)   13,136 A $ 0 13,136 I See Footnote (11) Common Stock 12/12/2014   J(9)   23,867 D $ 0 251 I See Footnote (12) Common Stock 12/12/2014   J(9)   23,867 A $ 0 28,734 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
KANIA EDWIN M JR C/O FLAGSHIP VENTURES, 1 MEMORIAL DRIVE CAMBRIDGE, MA 02142	X

Signatures

/s/Edwin M. Kania, Jr.		12/16/2014
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	This Form 4 is being filed to report, among other things, a pro rata distribution by Applied Genomic Technology Capital Fund, L.P. ("AGTC Fund") to its partners for no consideration.
(2)	These shares are held directly by AGTC Fund. NewcoGen Group, Inc. ("NewcoGen Inc.") is the sole general partner of AGTC Partners, L.P. ("AGTC Partners"), which is the sole general partner of AGTC Fund. NewcoGen Inc. is a wholly-owned subsidiary of Flagship Ventures Management, Inc. Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. are the directors of Flagship Ventures Management, Inc. and, accordingly, may be deemed to have beneficial ownership with respect to all shares held by AGTC Fund. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(3)	This Form 4 is being filed to report, among other things, a pro rata distribution by AGTC Advisors Fund, L.P. ("AGTC Advisors") to its partners for no consideration.
(4)	These shares are held directly by AGTC Advisors. NewcoGen Inc., is the sole general partner of AGTC Partners, which is the sole general partner of AGTC Advisors. NewcoGen Inc. is a wholly-owned subsidiary of Flagship Ventures Management, Inc. As the directors of Flagship Ventures Management, Inc., Noubar B. Afeyan Ph.D. and Edwin M. Kania, Jr. may be deemed to have beneficial ownership with respect to all shares held by AGTC Advisors. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(5)	These shares are held directly by OneLiberty Ventures 2000, L.P. ("OLV"), which is a limited partner of AGTC Fund and, as such, received these shares as part of the distribution described in footnote 1. OneLiberty Partners 2000, LLC ("OLP") is the general partner of OLV. Edwin M. Kania, Jr. is the managing member of OLP and, accordingly, may be deemed to have beneficial ownership with respect to all shares held by OLV. Mr. Kania disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(6)	These shares are held directly by OneLiberty Advisors Fund 2000, L.P. ("OLA"), which is a limited partner of AGTC Advisors and, as such, received these shares as part of the distribution described in footnote 3. OLP is the general partner of OLA. As managing member of OLP, Edwin M. Kania, Jr. may be deemed to have beneficial ownership with respect to all shares held by OLA. Mr. Kania disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(7)	These shares are held directly by AGTC Partners, which is the general partner of AGTC Fund and as such, received the shares as part of the distribution described in footnote 1. NewcoGen Inc. is the general partner of AGTC Partners. NewcoGen Inc. is a wholly-owned subsidiary of Flagship Ventures Management, Inc. As the directors of Flagship Ventures Management, Inc., Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. may be deemed to have beneficial ownership with respect to all shares held by AGTC Partners. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(8)	These shares are held directly by AGTC Partners, which is the general partner of AGTC Advisors and, as such, received the shares as part of the distribution described in footnote 3. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(9)	Following its receipt of shares in connection with the distributions described in footnotes 1 and 3, AGTC Partners distributed 37,003 shares to its limited partners, NewcoGen Group LLC and Edwin M. Kania, Jr., for no consideration.
(10)	These shares are held directly by AGTC Partners. AGTC Partners distributed 13,136 shares to NewcoGen Group LLC in connection with the distribution described in footnote 9. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(11)	These shares are held by NewcoGen Group LLC, which is a limited partner of AGTC Partners. The shares were received in connection with the distribution described in footnote 9. NewcoGen Inc. is the manager of NewcoGen Group LLC and is a wholly-owned subsidiary of Flagship Ventures Management, Inc. As the directors of Flagship Ventures Management, Inc., Noubar B. Afeyan, Ph.D. and Edwin M. Kania, Jr. may be deemed to have beneficial ownership with respect to all shares held by NewcoGen Group LLC. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.
(12)	These shares are held directly by AGTC Partners. AGTC Partners distributed 23,867 shares to Edwin M. Kania, Jr. in connection with the distribution described in footnote 9. Each of Mr. Kania and Dr. Afeyan disclaims beneficial ownership of such shares, except to the extent of his pecuniary interest therein.

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